Volume II - Annexes 1-10 | INTERNATIONAL COURT OF JUSTICE

Document Number

18530

Parent Document Number

18520

Document File

INTERNATIONAL COURT OF JUSTICE
INTERNATIONAL COURT OF JUSTICE

DISPUTE CONCERNING THE CONSTRUCTION OF A ROAD IN
DISPUTE CONCERNING THE CONSTRUCTION OF A ROAD IN
COSTA RICA ALONG THE SAN JUAN RIVER

COSTA RICA ALONG THE SAN JUAN RIVER

NICARAGUA v. COSTA RICA
INTERNATIONAL COURT OF JUSTICE
NICARCOUR INTERNATIONALE DE JUSTICE

CERTAIN ACTIVITIES CARRIED OUT BY NICARAGUA IN THE BORDER
AREA (COSTA RICA v. NICARAGUA)
CERTAINES ACTIVITÉS MENÉES PAR LE NICARAGUA DANS LA RÉGION
FRONTALIÈRE (COSTA RICA c. NICARAGUA
REQUEST FOR THE INDICATION OF PROVISIONAL MEASURES
COUNTER-MEMORIAL OF COSTA RICA
COUNTER-MEMORIAL OF COSTA RICAMESURES CONSERVATOIRES

VOLUME II
VOLUME I

JUDGES’ANNE14 OCTOBER 2013ICA’S PRESENTATION

DOSSIER DE PLAIDOIRIES DU COSTA RICA
14 OCTOBRE 2013
19 DECEMBER 2013

19 DECEMBER 2013 LIST OF ANNEXES

VOLUME II

TECHNICAL AND ENVIROMENTAL REPORTS

No. DOCUMENT Pag
1 University of Costa Rica Centre for Research in Sustainable 1

Development, Department of Civil Engineering, Report on
Systematic Field monitoring of Erosion and Sediment Yield
along Route 1856, September 2013

2 Comisión de Desarrollo Forestal de San Carlos (CODEFORSA), 29
Consulting Services for the Development and Implementation
of an Environmental Plan for the Juan Rafael Mora Porras
Border Road, Report of Activities to the Ministry of Foreign
Affairs of the Republic of Costa Rica, January 2013

English Translation
3 Allan Astorga G. and Andreas Mende, Route 1856: Analysis of 103

the Change in Land use Based on Satellite Images Before and
After the Construction of the Border Road, August 2013
4 Costa Rican Institute of Electricity (ICE), SBU Projects and 133

Associated Services, Centre for Basic Engineering Studies,
Department of Hydrology, Report on Hydrology and Sediments
for the Costa Rican River Basins draining to the San Juan River,
August 2013

5 Andreas Mende, with Allan Astorga G. and Olivier Chassot, 291
Border Road No 1856 – Evaluation of the 54 Sites of Purported
Direct Sediment Delivery mentioned by Ph.D. Mathias Kondolf,
September 2013

iii 6 Dr. Andreas Mende and Dr. Allan Astorga, Inventory of Slopes 369
and Water Courses related to the Border Road Nº 1856 between

Mojón II and Delta Costa Rica, September 2013
7 Report from Ana Lorena Guevara Fernández, Vice-Minister 409
of the Environment, Costa Rica, to Enrique Castillo Barrantes,

Minister of Foreign Affairs, Costa Rica, Reference DVM-293-
2013, 8 October 2013
English Translation

8 Consejo Nacional de Vialidad (CONAVI), Program for the 421
Consolidation and Continued Improvement of Route No 1856,
Reference DIE-02-13-3107, 25 October 2013
English Translation

9 Professor Colin Thorne, Report on the Risk of Irreversible 453
Harm to the Río San Juan relating to the Construction of the
Border Road in Costa Rica, 4 November 2013

10 Costa Rica, Centro Científico Tropical, Environmental 499
Diagnostic Assessment (EDA), Route 1856 Project – Ecological
Component, November 2013

iv ANNEX 1

University of Costa Rica Centre for Research in Sustainable Development

Department of Civil Engineering

Report on Systematic Field monitoring of Erosion and Sediment Yield along
Route 1856

September 2013

12 Annex 1

UNIVERSIDAD
DE
COSTA
RICA

FACULTAD
DE
INGENIERÍA

ESCUELA
DE
INGENIERÍA
CIVIL

CENTRO
DE
INVESTIGACIONES
EN
DESARROLLO
SOSTENIBLE

CIEDES

Report
on
Systematic
Field
monitoring
of

Erosion
and
Sediment
Yield
along
Route
1856

By:

Eng.
Rafael
Oreamuno
Vega,
M.
Eng.

Roberto
Villalobos
Herrera

September,
2013

3Annex 1

This document has been prepared by personnel of the Universidad de Costa
Rica’s Centre for Research in Sustainable Development (known as CIEDES

in Spanish) under the direction of Eng. Rafael Oreamuno , according to the
allocation of responsibilities shown below .

Field work:
Carlos Aguilar, Rafael Oreamuno , and Roberto Villalobos .

Sediment sample processing:

Mauricio Mendoza , and Luis Diego Ramírez.

Analyses and elaboration of the Report:

Rafael Oreamuno , and Roberto Villalobos.

Administrative officer of CIEDES:

Marco Arias, MP A.

Eng. Rafael Oreamuno , M. Eng. is a professional c ivil engineer registered in
Costa Rica’s Colegio Federado de Ingenieros y Arquitectos (license number
IC- 2423) and Profes sor of the Department of Civil Engineering at the

Universi dad de Costa Rica since 19 87, private consultant, he currently
holds the office of Director of CIEDES . His degrees are:

¥ Licenciado en Ingeniería Civil from the Universidad de Costa Rica,
1980.

¥ Master of Engineering in River Engineering and Hydrology from the
University of New Brunswick , Canada, 1983.

Marco Arias, MPA is the administrative officer at CIEDES; as such he has
coordinated the logistics and transport for all visits .

Carlos Aguilar, Mauricio Mendoza, Luis Diego Ramírez and Roberto
Villalobos a re senior year Civil Engineering students at the Universidad de

Costa Rica which work as Assistants for CIEDES. All have soil laboratory
experience as part of the standard Civil Engineering Programme . The Civil

Engineering programme at the Universidad de Costa Rica is deemed as
Substantially Equivalent by the Canadian Engineering Accreditation Board .
The Substantially Equivalent Accreditation means that the Civil

4 Annex 1

Engineering Program of the Universidad de Costa Rica complies with all
the international standards, defined in the Washington Agreement, for the

education of c ivil engineers.

5Annex 1

Contents
Table

Introduction ................................ ................................ .......................... 1

Sediment yield estimation ................................ ................................ ...... 3

Sheet erosion ................................ ................................ ..................... 3

Cut slope erosion ................................ ................................ ................ 4

Road fill slope erosion ................................ ................................ ........ 5

Rills ................................ ................................ ................................ .. 6

Sediment size distribution and classification ................................ ............ 9

Cut slope ................................ ................................ ........................... 9

Sediment trap #2 ................................ ................................ .............. 10

Sediment trap #3 ................................ ................................ .............. 11

Sediment trap #4 ................................ ................................ .............. 12

Summary of Sediment Size and Limit Results ................................ ..... 13

Contrasts between Landslide and Gully erosion Forms, Triggers and
Processes ................................ ................................ ............................ 14

Landslides ................................ ................................ ....................... 14

Gullies ................................ ................................ ............................ 14

Contrasts between Landslide and Gully erosion ................................ ... 15

Conclusions ................................ ................................ ........................ 16

Bibliography ................................ ................................ ....................... 19

Annex I – Sediment trap #2 configuration ................................ .............. 20

6 Annex 1

Introduction

The Universidad de Costa Rica’s Centre for Research in Sustainable

Development (known as CIEDES in Spanish) has been asked to assess the
average annual erosion rate and the average erosion depths from the road

bed, cut slopes, and fill slopes on Costa Rica ’s Route 1856. In order to
provide this assessment, a series of sites have been monitored by CIEDES’
personnel between 8 June and 17 August 2013. These sites include the two

largest rotational landslides and three erosion gullies found in the stretch of
road extending from Boundary Marker II to the Infiernito River (referred to

as the study area), as well as a sediment trap which collects material from
cut slopes which only show evidence of sheet erosion, and a slope which

displayed most intense rill formation. The location of each site is indicated
in Figure 1.

In preparing this Report, we have reviewed the Report prepared by G.
Mathias Kondolf entitled “Environmental Impacts of Juan Rafael Mora

Porras Route 1856, Costa Rica, on the Rio San Juan, Nicaragua”, December
2012, Annex 1 to Nicaragua’s Memorial in Construction of a Road case (the

Kondolf Report).

Weather conditions (listed on Table 1) varied between all five visits as the

rainy season in the region became more established. The first two visits
took place during fair cond itions with partly cloudy skies . During the first

visit, there was a brief, albeit intense rain shower. The third and fourth
visits, in July and August , took place during much heavier cloud cover and
rainfall, with a constant drizzle interrupted by heavy showers on both days.

Weather conditions during the final visit were sunny and dry, and the soil
was visibly dry.

Table 1. Site visit dates and w eather conditions .

Visit number Date Weather conditions
1 June 8 t, 2013 Partly cloudy, s ingle shower
2 June 23 rd, 2013 Partly cloudy
nd
3 July 22 , 2013 Overcast, rainy
4 August 17 th, 2013 Cloudy, rainy
st
5 September 21 , 2013 Sunny, dry

The selected sites include some of the most heavily eroded slopes in the
study area, however most slopes and fills in the study area have been

protected with geotextile and been subject to re -vegetation or (where

7Annex 1

possible) re- forestation, and are experiencing much less erosion than the
sites selected for study.

The selected sites therefore represent ‘worst case ’ examples of erosion by
land sliding, sheet erosion, rilling and gullying that exist along Route
185 6.

In this regard, the dimensions of erosion f eatures measured at each site, and
annual rates of lowering of the land surface estimated on the basis of those

direct observations are much higher than average for Route 1856 as a
whole. Consequently, the rates of erosion presented here are highly
conserv ative when applied to the rest of Route 1856.

Figure 1. Location of monitored sites.

8 Annex 1

Sediment yield estimation

The analysis of each of the monitored sites is detailed below; results are

given as average annual rate of land surface lowering or average erosion
depth, depending on the type of site.

Sheet erosion

Sediment trap #2, shown in Figure 2, was used to provide the estimate for
sheet erosion occurring on the road bed and cut slopes. The depth of

sediment trapped within the area confined by geo- membrane (Figure 2) was
measured at up to sixteen points . These measurements were then combined
with the area of the trap to estimate the volume of soil eroded from the

trap’s tributary area. Finally the eroded volume was divided by the tributary
area to determine the average depth of soil lost each day. This was

multiplied by the number of days in a year to determine the average annual
erosion rate shown in Table 2. The trap is located at the following
coordinates: 10°56'26.2"N, 84°20'6.9"W.

Two type of surfaces drain into the sediment trap: a 505.0 square metre bare

earth slope and a 332.0 square metre portion of road surface. The area of
the trap itself is 58.5 square metres.

Table 2. Field Observations of sediment in Sediment Trap #2.
Average Annual rate
Date Average depth Estimated Change in of land surface
(m) volume (m 3) volume (m 3) lowering (m/yr)

08/06/2013 0.18 10.70 N/A N/A
23/06/2013 0.22 12.81 2.11 0.061

22/07/2013 0.33 19.11 6.30 0.095
17/08/2013 0.32 18.47 -0.64 -0.011

The estimated annual rate between 22 July and 17 August 2013 is negative
because of a one centimetre reduction in average sediment depth. It is

unlikely that the volume deposited within the trap decreased during this
period, rather the trap was filled to capacity between the dates above. As

shown in Figure 2, the trap was nearly full on 22 July. The difference in
depth can then be explained as an error margin in the sediment depth
measurements in the magnitude of +/ - 0.01 m.

As to the difference between the average annual rates on 8 June and 23

July , these can be explained due to an increase in precip itation as the rainy
3

9Annex 1

season bega n. The 9.5 cm/year estimate represents condition s during the
wet months of the year, while the lower erosion rate measured between June

and July is representative of conditions during the dry season , because there
is less precipitation eroding the road’s cuts and fills. It is therefore

concluded that using 9.5 cm/year to represent the average annual rate of
land surface lowering is conservative because it applies rainy season rate
estimates to the whole year .

Figure 2. Sediment trap #2 on June 8th (left) and July 22nd (right) .

Cut slope erosion

As stated above, the area which drains to the sediment trap only showed
evidence of sheet erosion. Three cut slopes, two with a landslide and one

with a gully, were surveyed in order to establish their average erosion
depth. Site 1 has a landslide with an average depth of 2.96 m which affect s
2
an area of 150 m ; the landslide in Site 2 is smaller, its average depth is
1.01 m and its eroded area is 80 m ; and finally the gully in Site 3 has an
average depth of 0.43 m and a surface area of 14 m 2. Using this

information, we obtained an eroded volume for each site , which is then
distributed over the entire area of the slope to calculate the average erosion

depth for each slope. The results of the measurements made on each feature
are shown in Table 3.

The results below are first given as an average depth for the slope and not
an annual rate because , unlike the sediment trap, the recorded erosion sites

have not shown any appreciable change in size during the five visits to the
road between 8 June and 21 September 2013. As the measurements have

remained constant over this period of time, an erosion rate cannot be
calculated in the same way as was calculated for the sediment trap . Taken
together, the average depth of landslide an d gully features observed on the

10 Annex 1

three slopes is 0.17 metres and they occupied 8.6% of total area of the

slopes.

In order to estimate an annual rate for these slopes, it is reasonable to
assume that these slopes were created when Route 1856 was under

construction in 2011, which makes them two years old. This would imply an

average annual rate of lowering of the land surface for the slope area as a
whole of around 0.0 85 m/yr (which is 8.5 c m/yr) ; nevertheless, as discussed

below, it is not appropriate to combine landslides and gullies as a uniform
geomorphological feature. The average erosion depth for each feature can

be found separately in this document’s conclusions.

Table 3. Average erosion depth in slopes featuring landslides or gullies.

Eroded Eroded Average Average Annual
Site GPS Type of Area Erosion erosion rate of land
# coordinates Feature (m ) type ar2a area/Area of depth (m) surface lowering
(m ) feature (%)
(m/yr)
10° 59’ 3N.9’’ Rotational
1 Road 756 80 10.58 0.11 0.06
84°21’ 44.’’ Cut landslide

2 10° 56’ 5N’’ Road 1 168 Rotational 150 12.84 0.38 0.19
84° 20’ 46’’ Cut landslide

10° 56’ 5N.1’’Road
3 612 Gully 14 2.29 0.01 0.005
84° 20’ 25’’ Cut

Road fill slope erosion

In addition to the surveyed cut slopes, two road fills with gully erosion
were sampled. These two sites had not been included in the original sites

because they did not show any erosion featur es during a preliminary visit
during the 2013 dry season . Measurements on these sites were taken during

the June and July visit s; however final measurements were taken during the

September visit . These sites were included to avoid using the same erosion
rates for road cuts and fills due to the differing origin of these features. In

essence the soil which comprises road cuts has been deposited and
compacted over time through natural processes. Road fills are man -made

deposits. This difference in origin results in different proper ties, including

their susceptibility to erosion.

Site 8 corresponds to a gully that has been formed due to the flow of water
over the road surface and road fill. The softer material of the fill slope had

been eroded up to the edge of the road surface by t he June visit, however
the coarser material of the road seems to be preventing any further

11Annex 1

headcutting by the gully and no increase in size was registered up to the
July visit . The surface area of this gully is 121 m 2, and its average depth is

1.5 m. In this case it is known that the erosion on this site began after the
dry season visit; that is approximately six months prior to the September

visit. Therefore the average annual rate of surface lowering may be
estimated by doubling the average erosion depth measured over six months ,

both of these figures are given in Table 4.

Site 9 is a road fill which has been left without a coarse road surface and it

feature s 16 individual gullies of differing sizes . Of these, the largest gully
was selected for measurement; it has an area of 7.36 m and a 1 m erosion
3
depth, resulting in an eroded volume of 7.36 m . This volume was
conservatively multiplied by the number of gullies in the fill to produce an
3
estimated total gully erosion of 118 m for the entire fill feature . The area
eroded by the gullies is approximately 118 m 2. When divided by the total

area of the fill slope, an Average E rosion Depth of 0.10 m was calculated.
Finally, as these measurements were made over the same 6 -month time

frame used above , the Average Annual Rate of Land Surface Lowering for
the fill slope was approximated as double the amount measured over six

months, which yields and estimate of 0.20 m/yr.

Table 4. Average erosion depth in fill slopes featuring landslides or gullies.
Average Average Annual
Eroded Eroded
Site GPS Type of Ar2a Erosion area area/Area of erosion rate of land
# coordinates Feature (m ) type (m ) feature (%) depth (m) surface lowering
(m/yr)

10° 59’ 27.0’’
8 84° 21’ 19’’ Road Fill 3 080 Gully 121 3.93 0.06 0.12

10° 54’ 52N9’’
9 Road Fill 1183 Gully 118 9.97 0.10 0.20
84° 18’ 2W’’

Rills

A spatial analysis method was used in order to estimate the amount of soil
lost due to rill erosion during the monitoring period and therefore to

estimate the average erosion depth for slopes which feature rills. Height,
depth and width measurements were taken of a metre tall section of a large

rill located on the fill slope showing the most intense rill erosion in the
studied stretch of road. The measured section had a width of 0.3 m and a

depth of 0.6 m which combine with the height and triangular configuration
of the rill to indicate a volume of 0.090 m 3 of soil loss for that section. The

12 Annex 1

location of the studied slope is given by the following coordinates:
10°55'15.9"N, 84°19'33.4"W.

A photograph taken on 17 August 2013 (Figure 3) was then used with the

volume calculated above to estimate the volume of soil loss per unit of area
of slope. To do this the photograph was scaled using AutoCAD software
using a visible measuring tape as reference . The complete photograph and

the metre scale are shown in Figure 3 .

Figure 3. Cut slope with rill erosion and 1 metre of measuring tape for scale.

Once the photograph above had been scaled , a grid was superimposed over

the image (Figure 4). I ncomplete grid squares were then clipped before
finally counti ng the number of one metre long rill segments present in the
3
photograph. The 0.090 m of soil loss per metre of rill measured for the
largest rill was then applied to all the other metre long segments of rill
identified in Figure 4. As Figure 4 shows, most rill segments are shallower

and narrower than the measured segment (that labe lled 1, in Figure 4);
therefore applying the measured volume of soil loss to all the other

segment s is conservative in that it over- estimates the actual amount of soil
eroded by the smaller, narrower rills.

13Annex 1

Overall , 26 segments of one metre in length were considered; these yielded
3 2
a total loss of 2.34 m of soil. When this volume is divided by the 20 m
area of the fill slope shown in Figure 4, the average land surface lowering

for rills on slopes is 0.12 m. As before, if we accept that this slope was
created during the construction of the road in 2011, the annual rate of land
surface lowering due to rill erosion since then has been 0.06 m/yr.

Figure 4. 1 metre rill segments and g rid used for Spatial Analysis .

14 Annex 1

Sediment size distribution and classification

Sediment samples were gathered at four sites: three sediment traps and one
cut slope. The cut slope sample was taken from the loose material at the

foot of the rotational landslide found Site #2 (see Table 3) and is
considered to be representative of the soil of the entire slope. Visual

inspection identified a shallow (15 -30 cm deep) ‘A’ horizon and a very
deep and uniform ‘ B’ horizon within the soil ma ss. The sample was taken

from this ‘B’ horizon. The sediment traps are located at the ends of gutters
which drain both road surfaces (coarse material) and slopes cut into the

terrain

All four samples were processed using the ASTM International (formerly
known as the American Society for Testing and Materials) Standard Test

Method for Particle -Size Analysis of Soils: D422 – 63 (2007) as well as the
Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index

of Soils: D4318 – 10 (2010). The first Standard Test Method i nvolves the
use of sieves and hydrometers to determine the particle size distribution of
a soil sample, while the second uses two separate tests for the Plastic Limit

and the Liquid Limit. The results of the sediment size distribution and its
limits are then used to classify the soil samples according to the Unified

Soil Classification System.

Cut slope

100

80

70

60

50

% 40
sing

30

10

0

10.000
1.000
0.100
0.010
0.001

Par5cle
diameter
(mm)

Figure 5. Particle size distrib ution for the sampled cut slope .

(Note: Red line indicates less than 97 % of the sediment is finer than 0.075mm)

15Annex 1

As the results in Figure 5 (above) clearly show, the material composing the

cut slope is markedly fine (fine sediment being defined as those particl es
retained by the #200 sieve due to having diameters larger than 0.075 mm) ,

with very little (less than 3%) soil composed of particles with diameters
larger than 0.075 mm. This indicates that the behaviour of the soil is likely

to be dominated by cohesion between the mainly fine partic les that
comprise it. The soil’s cohesive nature helps explain why most cut slopes

have remained stable despite their steep (1:1) gradients.

Sediment trap #2

As shown in Figure 6, this sample contains the greatest amount of coarse
material (defined as those particles retained by the #200 sieve or with

diameters larger than 0.075 mm) of all the samples . Approximately 23% of
the sample passed through the #200 sieve and is therefore classified as fine.

During visual inspection of the trap ( Figure 7) coarse, grey material eroded
from the road bed (which makes up 40% of the area draining to trap #2) was

plainly visible among the reddish , fine material derived from the erosion of
the cut slopes (which make up 60% of the drainage area) . It is believed that

the larger amount of coarse mat erial in this sample is due to this trap
receiving a greater proportion of runoff and material eroded from the road

bed via road gutters compared to the other samples , and is not the result of
any difference in the area’s soil type compared to the other samples.

(Note: Red line indicates less than 97 % of the sediment is finer than 0.075mm)

100

90

80

70

60

%
40
ing

30

20

10

0

10
1
0.1
0.01
0.001

Par5cle
diameter
(mm)

Figure 6. Particle size di stribution for sediment trap #2 .

(Note: Red line indicates less than 23% of the sediment is finer than 0.075mm)

16 Annex 1

Figure 7. In -situ photograph of sediment retai ned by the second sediment trap .

Sediment trap # 3

100

90

80

%
40
ing

30

0

10
1
0.1
0.01
0.001

Par5cle
diameter
(mm)

Figure 8. Particle size distribution for sediment trap #3.
(Note: Red line indicates that about 43% of the sedi ment is finer than 0.075mm)

17Annex 1

The sediment sampled in trap #3 has the second highest content of coarse

material for all four samples, in that approximately 43% of the soil
particles passed through the #200 sieve and are classed as fine . It was not

possible to visually examine the sediment found in the trap when it was
sampled because the sediment was submerged. The grain size distribution

suggests this trap receives coarse material eroded from the road bed as well
as fine material eroded from cut slopes that contribute to it; however the

percentage of coarse material is smaller than that found in trap #2.

Sediment trap #4

The proportion of coarse sediment in trap #4 is lower than in traps #2 and
#3, with fine sediment making up about 75% of the sample . Mo re than half

of the soil found in this trap is in fact very fine and Figure 10 shows that
the trapped sediment has the reddish -brown colour common to most s oils in

the studied area. The difference in sediment composition between this and
the other two traps may be explained by the prese nce of an 8.7m wide

buffer of bare ground between the concrete gutter and the coarse surface of
the road bed, whi ch contrasts with traps #2 and #3, which receive some

runoff from gutters connected to the road bed itself.

100

80

70

50

%
40
ing

20

10

0

10
1
0.1
0.01
0.001

Par5cle
diameter
(mm)

Figure 9. Particle size distribution for sediment trap #4.

(Note: Red line indicates that about 75% of the sediment is finer than 0.075mm)

18 Annex 1

Figure 10. Sediment collected in trap #4.
(Note reddish- brown colour common to most soils in the studied area)

Summary of Sediment Size and Limit Results

Table 5 lists the overall results for each of the four sampled sites.

Table 5. Result summary and soil classification for each sample .

Sample Attribute Cut slope Trap #2 Trap #3 Trap #4 Average
Coarse (%) 1.9 76.7 57.6 24.9 40

Fine (%) 98.1 23.3 42.4 75.1 60
Liquid limit 72 35 30 51

Plastic limit 40 29 22 39
Plasticity index 32 6 8 12
MH - SM - SC - ML -
USCS Elastic silt Silty sand Clayey Elasticsilt
classification
sand with sand

As mentioned above, the sieve and particle size selected to distinguish

between fine and coarse sediment is the #200 sieve which correspond to a
particle diameter of 0.075 mm. Plastic and Liquid limits are shown for each

soil. The difference between these two limits is then presented as the
Plasticity Index. As a final step in the analysis, the size distribution and the

19Annex 1

plasticity results were used to classify each sample according to the criteria
of the Unified Soil Classification System (USCS).

Contrast s between Landslide and Gully erosion

Forms, Triggers and P rocesses

This section describes and contrasts landslides and gullies as erosive
features .

Landslides

The monitored landslides did not show any appreciable change during the
monitoring period , because the conditions necessary to trigger landslide

activity did not occur during the study period .

Landslides are triggered by one or more of the following :

¥ deep weathering;
¥ in the absence of deep weathering, sedimentary or planar structures

of variable lithology ;
¥ swelling clays ;
¥ large quantities of soil moisture and positive pore water pressures ;

¥ perennial, seasonal or diurnal ice formations ;
¥ earthquakes ; or

¥ basal undercutting by wave action or rivers.

The landslides observed between Marker II and the Infiernito River
occurred only on slopes cut into deeply weather ed soil. The moisture

conditions present during the occurrence of these landslides are unknown;
however, because of the climate in the area it seems likely that high
moisture levels and posit ive pore water pressures triggered these events . No

undercutting of slopes has occurred, and there are no indications of
swelling clays. Hence, it is unlikely that further landslides will occur unless

they are triggered by exceptionally high rainfall (very high moisture
contents and positive pore water pressures) or an earthquake. Either co
uld
occur, but the frequency of such un usual triggering events is low.

Gullies

The monitored gullies, as well as the landslides, did not show any
significant growth during the study period . This can be explained by the

fact that the face of the headwall of the gully will be stationary if the
14

20 Annex 1

material making up the bed of the knick point has a resistance to shear
stress greater than the boundary shear stress provided by the flow , and the

flow is insufficient to transport the eroded material from the base of the
headwall. This seems to be the case in the m onitored gullies. Gullies were
observed at some points along the cut and fill slope s of the road, but they

were not found to be growing through headcutting at a noticeable rate.

It is important to mention that gully erosion is defined as the “erosion
process whereby runoff water accumulates and often recurs in narrow
channels and, over short periods, removes soil from these narrow areas to

considerable depths ” (Poesen et al., 2002). Gullies are often defined for
agricultural land in terms of channels t hat occur in the low areas of the
macro topography and that are too deep to ameliorate with ordinary farm

tillage equipment, typically ranging in size from 0.5 metres to as much as
25 to 30 metres (Soil Science Society of America , 2001). In the 1980s, the

term “ephemeral gully” was introduce d to describe concentrated flow
erosion larger than a rill but smaller than a classical gully . According to the
Soil Science Society of America (2001), ephemeral gullies are “small

channels eroded by concentrated overland flow that can easily be filled by
normal tillage, only to be reformed in the same location by additional

runoff events” (Sedimentation Engineering, American Society of Civil
Engineers, 2008).

Contrasts between Landslide and Gully erosion

As discus sed in detail above, landslides present in the slopes of Route 1856
are triggered by a specific set of conditions, with soil saturation as one of
the most probable causes. Once triggered, landslides occur in a sudden

fashion after which there may or not be further landslides in the same site ,
and the landslides observed in Route 1856 show no evidence of further

growth after the initial event

Unlike landslides , gullies are triggered by concentrated overland flow

which removes soil in a superficial fashion; the removal of material during
the rain events eventually leads to a deepening and widening of the gully.

The above implies that gully formation is a gradual process and not a
sudden event like a landslide .

Due to the differen ces inherent to the origination and development between
landslides and gullies, it is not meaningful to combine both erosion features
when estimating land surface lowering. In addition, no slope in the study

area shows b oth gully and landslide erosion; therefore the locations where
15

21Annex 1

these two separate processes occur are different and have not to date
overlapped.

Conclusions

Based on field measurements , rates of soil loss due to sheet erosion of the

road bed and cut slopes vary between 0.061 metres and 0.095 metres per
year. The diff erence in the estimates is due to the differ ences in the amount

of soil lost between re- surveys of features made during relatively dry (June
- July) and relatively wet (July - August) periods in 2013 . Based on these
direct measurements it is concluded that the average annual rate of lowering

of the land surface due to sheet erosion along Route 1856 lies in the range
of ~0.06 to ~ 0.1 metres per year.

On the monitored cut slopes where landslides were obs erved , landslides
occupied 10 to 13% of the overall area of the slope and had lowered the

land surface in those areas by between 0. 11 and 0.38 metres. It is
reasonable to assume that the slopes were created when Route 1856 was

under construction in 2011. Therefore, they have now existed for at least
two years. This implies average rates of lowering of the land surface for the
entire areas of the slopes due to landsliding of between 0.0 6 and 0.19

metres per year.

Gullies on cut slopes are the rarest erosio n feature in the studied section of
Route 1856, while rills are the most common. The gully monitored in the
section of road under study had a maximum depth of three metres but

covers only just over 2% of the slope it was located in and has a surface
area of 13.1 m 2. The total volume of soil eroded to create the gully is
3
approximately 6 m . When this volume is divided by the total area of the
slope, the average lowering of the surface due to erosion by the gully is
0.01 metres. If it is again assumed that th e slope was created when Route

1856 was under construction in 2011, this implies an average rate of
lowering of the land surface for the entire area of the slope due to gullying

of around 0.005 metres per year.

The majority of slopes along Route 1856 in the study area experience rill
erosion . At the rill study site, the largest rill had a maximum width of 0.3
metr es and a maximum depth of 0.6 metres , and this represents a ‘worst

case’ example of rill er osion in the study area. Based on spatial analysis of
all the rills in the sample area, and with the conservative assumption that

they all had widths and depths equal to that of the largest rill, it may be

22 Annex 1

concluded that rill erosion has on average lowered the land surface of the
slope by 0.12 metres. Again assuming that the slope was created when

Route 1856 was under construction in 2011, this implies an average rate
of
lowering of the land surface for the entire area of the slope due to rilling of
around 0.06 metres per year. This estimate of land surface lowering rate is

considered to be conservative for the reasons mentioned above.

Fill slopes in the studied area do not feature landslide erosion. Rill erosion
is observed, though it affects smaller areas, with less intensity than in the
cut slopes. Theref ore use of the depths and annual rates calculated for rill

erosion of cut slopes is recommended for fill slopes as well.

Gully erosion on fill slopes is sig nificant, covering approximately 4% to

10% of the measured fills, and resulting in ave rage erosion depths between
0.10 m and 0.06 m. In contrast to erosion of road cuts , this has taken place

in a shorter time frame of 6 months . Therefore the estimated average annual
rate of land surfa ce lowering for gully erosion of fill slopes is higher, being
between 0.12 and 0.20 m/yr.

The results listed in Table 5 show that on average 40% of the sediment

reaching the sediment traps is coarse ( mainly sand) and that the remaining
60% is fine (silt and clay). It is reasonable to expect that the delivery r atio
for coarse sediment (sand) to the San Juan River is much lower than that for

silt and clay. Due to its size and mass, co arse material is deposited closer to
its point of origin than fine sediment and it is, therefore, much more likely
for sand and gra vel particles eroded from Route 1856 to remain within

Costa Rican territory than it is for them to reach the San Juan River. In
addition, a s silt and clay move as suspended load through the Rio San Juan ,

which is a sand -bed river, any silt and clay that we re to reach that river is
likely to be transferred downstream through the fluvial system to the Delta,
where at least 90% of it would return to Costa Rican territory through the

Rio Colorado.

In view of the fact that landslide and gully erosion are two di fferent type s
of geomorphic phenomena, controlled by different geophysical principles, it
is not correct to combine or treat landslide and gully erosion as a single

geomorphic entity.

Table 6 contains a summary of all the observed average erosion depth s and

the average annual rates of land surface lowering mentioned in the
preceding text. As t his summary lists the highest values of eroded area/area

23Annex 1

of feature, average eroded depth , and average annual rate of land surface
lowering for each erosion type , all estimates conservative .

Table 6. Summary of Results.

Type of Erosion Eroded Average Average rate of land
feature type Area/Area of erosion depth surface lowering (m/yr)
Feature (%) (m)
Cut Slope Landslide 13 0.38 0.19

Cut Slope Gully 2 0.01 0.005
Cut Slope * Rill 50 0.12 0.06

Road bed and Sheet N/A 0.02 0.095
Cut Slopes
Fill Slope Gully 9 0.1 0 0.2 0

*may also be conservatively applied to Fill Slopes .

While the assumption that erosion in the studied features has occurred
during the last two years is valid, and therefore the average rates of surface

lowering calculated for Landslides, Gullies and Rills on cut slopes are also
valid, the use of average erosion depth for these features is recommended as

these values are the most conservative for use in further calculations of the
impact of Route 1856’s sediment production on Nicaragua’s San Juan River.

Due to the different procedure used to monitor sheet erosion, the use of an
average rate of surface lowering of 0.095 m/yr for sheet erosion is

recommended. Finally the average rate of surface lowering of 0.20 m/yr is
the most conservative value which can be used to estimate gully erosion on

road fills and its use is recommended for any further studies.

24 Annex 1

Bibliography

ASCE Manuals and Reports on Engineering Practice N° 110 2007.

Sedimentation Engineering, Processes, Measurements, Modeling and
Practice. Edited by Marcelo H. García, ASCE, New York, USA.
ASTM International 2007. ASTM D422 - 63(2007) Standard Test Method for

Particle- Size Analysis of Soils . ASTM International , West
Conshohocken, PA , USA.
ASTM International 2010. D4318 - 10 Standard Test Methods for Liquid

Limit, Plastic Limit, and Plasticity Index of Soils . ASTM
International, West Conshohocken, PA , USA.

Dunne T. and Leopold , L.B. 1978. Water in Environmental Planning. W.H .
Freeman and Company, New York , USA.
Knighton , D. 1998. Fluvial Form s and Processes: A New Perspective.

Hodder Arnold, UK.
Leopold L.B., Wolman M.G. and Miller J.P. 1995. Fluvial Processes in
Geomorpholo gy. Reprinted by Dover Public ations, Inc. New York,

USA.
Ministerio de Medio Ambiente 1998. Restauración Hidrológico Fore stal de

Cuencas Hidrográficas . Editado por Filiberto López Cadenas de
Llano.
Poesen, J. et al. 2002. Gully Erosion in Dry Land Environments. Dry land

Rivers, in, Hydrology and Geomorphology of Semi -arid Channels .
Edited by Bull, L. J. and Kirk by, M. J. , Wiley, New York,
Soil Science Society of America 2001. Glossary of Science Terms . Soil

Science Society of America. Madison, Wisconsin, USA.

25Annex 1

Annex
I
–
Sediment
trap
#2
configuration

Sediment reaches trap #2 through a concrete trench nearly 90 m in length.
Three distinct types of terrain tribute runoff and sediment to this trench; the
2
first consists of a 332 m section of road surface formed by half the width
of the road along 83 m of gutter. The second surface consists of two bare

slopes; these are separated for 44.3 m by a terrace which forms the third
surface. This terrace is seen edge -on in Figure 11 as the line which divides
the slope approxima tely 1.5 m above the edge of the concrete gutter. Figure

12 shows each area and its dimensions (in metres ) separately.

Figure 11. Portion of the area draining to sediment trap #2.

26 Annex 1

oad areas.

slope and r

drained
its

12. Diagram of sediment trap #2 and

Figure

(Note: the diagram corresponding to the slope is a profile view, all other diagrams are plan view)

2728 ANNEX 2

Comisión de Desarrollo Forestal de San Carlos (CODEFORSA)

Consulting Services for the Development and Implementation of an

Environmental Plan for the Juan Rafael Mora Porras Border Road

Report of Activities to the Ministry of Foreign Affairs of the Republic of Costa
Rica

January 2013

English Translation

2930 Annex 2

COMISIÓN DE DESARROLLO FORESTAL

DE SAN CARLOS
Corporate ID number: 3-002-066610-06

Telephone: 2460-1055 Fax: 2460-1650
Email: [email protected]

Webpage: www.codeforsa.org
P.O. Box 205-4400 Ciudad Quesada, San Carlos

Consulting Services for the Development and
Implementation of an Environmental Plan for the
Juan Rafael Mora Porras Border Road
SINAC-CDE-004-2012

Report of Activitiesto the
Ministry of Foreign Affairs of the
Republic of Costa Rica

January 2013

31Annex 2

Progress Report
Consulting Services for the Development and Implementation of an
Environmental Plan for the Juan Rafael Mora Porras Border Road

Direct contracting by emergency exception SINAC-CDE-004-2012

I. Table of Contents

Page

I. TABLE OF CONTENTS………………………………………………….……….. 1

II. INDEX OF APPENDIXES……………………………….…………………..…...... 2

1. INTRODUCTION……………………………………………………………….. 3
2. PROJECT PHASES…………..……………………….….…….…..…..…….. 4

2.1 PHASE 1: PLANNING AND COORDINATION…………………..... 4

a. Coordination with the Conservation Areas involved….…….4…..

b. Coordination with landowners…………..……………….….………… 6
c. Coordination with volunteer groups………………..…………………. 10

d. Transportation and support of volunteer groups……..…………….

2.2 PHASE 2: IMPLEMENTATION OF THE WORK PLAN…………… 18

a. Scheduling of planting events……………….……………. 18
b. Availability of trees for planting……………………………. 19
c. Preparing the ground and protecting the trees……..……..
19
d. Planting of the trees……………………………………………………... 22

2.3 PHASE 3: MAINTENANCE OF PLANTED AREAS……………….. 28

a. Monitoring ofplanted areas……………………….…………………….. 28
b. Mowing……………….………………………………………………....... 28
c. Clearing of spots around trees……….…………….…..…………...
29
d. Replanting……….………………………………………..………………… . 31
e. Fertilizing………….………………………………………………….…… … 31
f. De-suckering………………………………………………………………….
31
g. Maintenance of fe…………………………………..…..………… … 31
h. Follow-up visits to planted areas……………………………………… 32
i. Quarterly follow-up reports…………………………………………..…
32
2.4 SLOPES………………………………………………..……………… 33
1.Recoveryof slopes………………………………………..……..……….. 33

2.Maintenance of slopes…..……………………………….………........ 35
3. APPENDIXES………………….…..……………………….….…….……..………. 37

COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS Page 1
Tel: (506) 2460Fax: (506) 2460-1Webpage: www.codeforsa.org

32 Annex 2

Progress Report
Consulting Services for the Development and Implementation of an
Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

II. INDEX OF APPENDIXES

APPENDIX 1: Material prepared for participants of the activities and members of
public institutions involved

APPENDIX 2: Maps of the areas planted

APPENDIX 3: Visit to the slopes before and after planting

COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS Page 2
Tel: (506) 2460-Fax: (506) 2460-1650Webpage: www.codeforsa.org

33Annex 2

Consulting Services for the Development and Implementation of
an Environmental Plan for the Juan Rafael Mora Porras

Border Road

Direct Contract by Emergency Exception SINAC-CDE-004-2012

Start date: APRIL 2012
End date: APRIL 2014

Proposed project term: 2 years

1. INTRODUCTION

By means of Tender Award Order SINAC-CDE-004-2012 of April 12, 2012, which
was declared final on April 19, 2012 , the Consulting Services for the
Development and Implementation of an Environmental Plan for

the Juan Rafael Mora Porras Border Road tender was officially awarded
to COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS (CODEFORSA,
Commission for Forestry Development in San Carlos).

In conformity with the consul ting services agreement signed, a Work Plan wa s

submitted on May 1, 2012 to the office of the Vice -Minister of the Environment for
her review and approval. Through official communication DVM-156-2012 the Work
Plan for the consulting services was approved; thus, the first phase of the pro ject
was completed.

This is a progress report on the activities conducted to implement the

Environmental Management Plan for Ruta 1856, the border road.

This document details the progress made in coordinating with the SINAC offices;
the signing of participation agreements with the landowners of the areas
surrounding San Juan R iver; and the preparation of the land and planting othe

trees by means of 20 events that involved the participation of volunteers from
several areas in the country.

One of the commitments included the re -vegetation of 12 slopes located on the
built portion of Ruta 1856.

COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS Page 3
Tel: (506) 2460-1Fax: (506) 2460-1650Webpage: www.codeforsa.org

34 Annex 2

2. PHASES OF THE PROJECT:

2.1 PHASE 1: PLANNING AND COORDIN ATION OF THE ACTIONS
INCLUDED IN THE ENVIRONMENTAL PLAN FOR REVEGETATION

The work plan was developed based on CODEFORSA’s field experience in thearea
where the work was to be performed, and taking into account the terms of reference

of the consulting services.

The activities carried out with the different parties involved in the border road sector
are presented below.

a. Coordination with Conservation Areas involved:

Map of the built portion of Ruta 1856.

The meetings scheduled with the Conservation Areas of the Sistema Nacional de
Áreas de Conservación (SINAC) were determined based on the area of influence of
each conservation area. As observable in the image above, approximately 80% of
the total border road area is inACAHN territory, followed by ACTO and lastly by

ACCVC, which has a 7 km area of influence of the border road in the area currently
covered by Ruta 1856, which goes from the Costa Rica n Delta to Los Chiles de
Alajuela, with an approximate length of 167 km.

To date, eight coordination meetings have been held with the Conservation Areas,

as follows: four meetings with the Arenal Hueta r Norte Conservation Area
(ACAHN); two meetings with the Tortuguero Conservation Area (ACTO); and two
meetings with the northern sub-region of the Conservation Area of the Central

COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS Page 4
Tel: (506) 2460-1Fax: (506) 2460-1650Webpage: www.codeforsa.org

35Annex 2

Volcanic Range (ACCVC). The project was presented d uring said meetings, as
well as the activities to be carried out as part of the consulting work, with the goal
of listening to the opinions of the members of the Conservation Areas.

The problems in the Costa Rican Delta zone were analyzed and discussed with the
Tortuguero Conservation Area . Residents are hesitant to participate in the
reforestation of the lands they occupy. Their disagreement is mainly related to
MINAE’s initiative to create a protected wildlife area in Isla Calero . The residents

were informed of the details of the project, and the strategy to persuade them was
changed to visiting them individually, bring ing along a respected person from the
area. This allowed earning their trust , and the neighbors signed the agreements
necessary to achieve the goal of planting trees for the project in the land held by

them and obtaining their collaboration.

The first four tree planting events were conducted i n the area of influence of the
ACCVC Sarapiquí sub-region, with volunteers accompanied by the officers of this
sub-region.

Four meetings were held with the Arenal Huetar Norte Conservation Area (ACAHN).
The project was also presented to the Regional Cou ncil of the Conservation Area
(CORAC HN) and to ACAHN’s Forestry Council.

At a meeting with ACAHN’s Technical Committee we were provided with a list of
possible species to be used for the reforestation of Ruta 1856. They
recommended, among other , species for areas susceptible or not susceptible to
flooding. All of the species recommended by the Committee agreed with the

species currently used at the planting sites.

A total of 5 meetings and 18 monitoring field visits are still pending for the period
until April 2014. The goal of the pending meetings is to show the progress of the

activities at each sector, namely : Costa Rican Delta, Trinidad (Mouth of Sarapiquí
River), Mouth of San Carlos River and Tiricias, as well as monitoring visits to verify
the maintenance of the trees planted and slopes treated.

COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS Page 5
Tel: (506) 2460-10Fax: (506) 2460-1650 Webpage: www.codeforsa.org

36 Annex 2

Progress Report
Consulting Services for the Development and Implementation of an

Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

Table Nº1: Schedule of meetings and visits with the different SINAC Areas of

Conservation involved

Conservation
Coordination meetings
Area

Month
Sep Oct Nov- Dec Jan- Feb Mar- Abr- May- Jun Jul Aug- Sep Oct Nov- Dec Jan Feb Mar Abr
TOTAL
t-12 -12 12 -12 13 -13 13 13 13 -13 -13 13 t-13 -13 13 -13 -14 -14 -14 -14
Tortuguero 1 1 2
(ACTO)
Central

Volcanic 1 1
Range
(ACCVC)
Arenal Huetar
Norte 1 1 2

(ACAHN)
TOTAL 0 0 0 0 0 2 0 0 0 0 0 0 0 0 3 0 0 0 0 0 5

Conservation
Area Field visits with Conservation Areas

Month

Sep Oct Nov- Dec Jan- Feb Mar- Abr- May- Jun Jul Aug- Sep Oct Nov- Dec Jan Feb Mar Abr TOTAL
t-12 -12 12 -12 13 -13 13 13 13 -13 -13 13 t-13 -13 13 -13 -14 -14 -14 -14
Tortuguero
(ACTO) 1 1 1 1 1 1 6

Central
Volcanic
Range 1 1 1 1 1 1 6
(ACCVC)

Arenal Huetar
Norte 1 1 1 1 1 1 6
(ACAHN)
TOTAL 0 0 0 0 0 3 0 0 3 0 0 3 0 0 3 0 0 3 0 3 18

b. Coordination with landowners or occupants to obtain approval for the

establishment of plant cover

Meetings were held with the communities i n order to obtain the occupants’

approval and establish agreements whereby they facilitate a portion of their land to

plant trees and also commit to taking care of the m once the project is completed .
This included meeting with the inhabitants of : Costa Rica n Delta, Trinidad and

Fátima; Cureña and the mouth of San Carlos River; and Jocote, Tiricias and Llano
Verde in the district of Cutris de San Carlos.

COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS Page 6

Tel: (506) 2460-1055 Fax: (506) 2460-1650 Webpage: www.codeforsa.org

37Annex 2

The meetings with the communities were carried out to inform them of the project
being executed and its benefits, and of the construction of Ruta 1856, in order to

counteract the media’s negative attacks on the construction of the border road.

Meeting held at Fátima de Sarapiquí on 5-15-2012

Meeting held at Boca San Carlos on 07-04-2012

COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS Page 7
Tel: (506) 2460-10Fax: (506) 2460-1650Webpage: www.codeforsa.org

38 Annex 2

Meeting held at Tiricias on 08-16-2012

Two additional meetings are pending for 2013, one in Tambor, Sarapiquí canton,
and the other in Las Tablillas, Los Chiles de Alajuela canton.

In addition to the meetings held at the communities, the approach ing strategy also
consisted of an individual visit to each landholder interested in participatin g in the
project, accompanied by a respected person from the area, which allowed us to
gain the residents’ trust and thus achieve the signing of the agreements necessary

to plant the project’s trees in their land and obtain their collaboration.

A total of 23 agreements were signed with
occupants along Ruta 1856. It is worth

noting that t he reforestation agreements
located in the area from the Costa Rica n
Delta to the Mouth of Sarapiquí River are
small blocks, with areas ranging from 0.2
ha to 1 ha available to plant the trees. The

agreements signed for the reforestation of
the areas near the mouth of San Carlos
River and Tiricias include areas ranging
from 1 to 8 hectares, which allowed us to

increase the amount of trees to be
planted.

COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS Page 8
Tel: (506) 2460-10Fax: (506) 2460-1650 Webpage: www.codeforsa.org

39Annex 2

Table Nº 2: List of agreements signed with the landowners for the planting of trees.

No. Name Location Number of trees
agreed

1 Félix Hernández Jarquín Boca Caño La Ceiba 200
2 Adilia Com Hernández (La Boca Caño La Ceiba
Ceiba Church) 150

3 Segundo Gaitán Mora Boca Río Sarapiquí 450
4 Fabio Vargas Vargas Boca Caño La Ceiba
300
5 Boca La Ceiba School Boca Caño La Ceiba 100

6 Melis Góngora Moraga Boca Caño La Ceiba 300
7 Tito Hernández Ferreto Delta Costa Rica 250

8 Delta Costa Rica School Delta Costa Rica 400
9 María Hilaria Miranda Rivas Boca Caño Las
Marías 300

10 Olman Quesada Campos Tiricias 1.000
11 Daniel Jiménez Berrocal Tiricias 5.000

12 Gerardo Quirós Picado Delta Costa Rica 200
13 Olga Retana Miranda Delta Costa Rica 400

14 Fabio Cedeño G. (Ochoa Boca Río San Carlos
Farm) (Ochoa Farm) 7.000

15 Víctor Ballestero Álvarez Tiricias 3.000
16 Víctor Ballestero Álvarez Tiricias
Morehead University 3.000

17 Edgar Salazar Ramírez Tiricias 1.000
18 William Cortés Madrigal Tiricias
1.000
19 Marcelo Méndez Morales Tiricias 1.000

20 German Díaz Ruiz Tiricias 3.000
21 Henry Perera Cunnigham Cureña 1.000

22 Fritz Perera Jiménez Cureña 2.000
23 Freddy Ulate Castro Cureña 5.000

TOTAL TREES ESTIMATED 36.050

COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS Page 9
Tel: (506) 2460-10Fax: (506) 2460-1650Webpage: www.codeforsa.org

40 Annex 2

c. Coordination with volunteer groups for their participation in the

planting events

Twenty planting events have already been completed, with the participation of 766
volunteers from the Central Valley, the Northern area, the Scouts of Cartago,

Elementary and High Schools in the Northern area, as well as members of public
institutions such as FONAFIFO and SINAC, among others.

To coordinate each planting event with the volunteers it was necessary to carry out

significant administrative work, for instance , creating a database of the calls
transferred by MINAET to CODEFORSA, of the radio and television campaign
encouraging the reforestation of Ruta 1856.

The information of the volunteers who called expressing their interest in planting
was taken down , incl uding their names, phone numbers, email addresses and
place of residence, as well as on which day they were interested in participating,
according to the schedule.

Each volunteer who participated in the planting events was given a shirt, as shown
in the photos, along with a cap which had the MINAET and SINAC logos, a pen, a
waterproof poncho for the rain, a magazine with project information , highlighting

the highway and its characteristics, the reason behind the road’s n ame, and the
environmental commitment that is being mitigated by the planting of trees
throughout Ruta 1856.

Front of shirt Back of shirt Magazine cover

COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS Page 10

Tel: (506) 2460-10Fax: (506) 2460-1650 Webpage: www.codeforsa.org

41Annex 2

Progress Report

Consulting Services for the Development and Implementation of an
Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

Shirts and hats handed out at Pens handed out to the

each activity participants

Each participant was given breakfast, consisting of gallo pinto, eggs, sour cream,
tortillas or bread, coffee or juice. For lunch they were given a casado (typical dish)

including meat with sauce, chicken or fish, a natural beverage and desse rts, and
finally a coffee with a sandwich for their return trip.

Breakfast at Toños Restaurant, October 23, 2012 event, C.T.P high school. Aguas Zarcas

Lunch at San Juan Restaurant, June 23, 2012 event. Volunteers Northern Area

COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS Page 11
Tel: (506) 2460-1055Fax: (506) 2460-1650 Webpage: www.codeforsa.org

42 Annex 2

Progress Report
Consulting Services for the Development and Implementation of an

Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

The planting of trees, as mentioned before, was conducted with the assistance of
volunteers and CODEFORSA staff. Table No. 3 includes the planting date, the

names and places of origin of the assistants, and the number of participants in the
planting event.

Table Nº 3 Participation of volunteers in the 20 different planting events

TREE PLANTING EVENTS

Number of
Number Date Planting Location Assistants
participants

Central valley volunteers,
1 05/06/2012 La Ceiba MINAET employees 24

Sarapiquí

2 12/06/2012 Boca del Río Central valley volunteers 21
Sarapiquí

FONAFIFO employees,
3 16/06/2012 La Ceiba 40
Guías y Scouts Cartago.

Central valley volunteers,
4 19/06/2012 La Ceiba, Escuela students from Liceo rural 41
La Ceiba Las Marías and Boca La
Ceiba school

Boca del Río San
5 23/06/2012 Northern area volunteers 44
Carlos
Northern area
Boca del Río San volunteers, Colegio
6 28/06/2012 30
Carlos Saíno, ACAHN
employees
Central SINAC
7 30/06/2012 Delta Costa Rica 45
employees

8 22/08/2012 Tiricias Colegio El Concho 41

Boca del Río San Colegio Saíno, Northern
9 23/08/2012 41
Carlos area volunteers

10 29/08/2012 Tiricias Colegio La Guaria 39

11 04/09/2012 Tiricias Escuela San Isidro 38

12 06/09/2012 Boca del Río San Colegios Boca Tapada, 38
Carlos Boca San Carlos

COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS Page 12

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43Annex 2

Progress Report

Consulting Services for the Development and Implementation of an
Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

13 11/09/2012 Tiricias Escuela Llano Verde and 46
Las Tiricias
Fuerza Juvenil Youth
Boca del Río San
14 29/09/2012 Carlos Group from Ciudad 41
Quesada

15 02/10/2012 Tiricias Escuela El Concho, 41
Escuela Banderas

16 04/10/2012 Tiricias Colegio Banderas de 41
Pocosol
Boca del Río San Colegio Gastón Peralta
17 11/10/2012 39
Carlos de Altamira
Boca del Río San
18 16/10/2012 Carlos Colegio Técnico de Pital 42

Boca del Río San Colegio Técnico de
19 23/10/2012 Carlos Aguas Zarcas 45

CODEFORSA
20 01/12/2012 Delta Costa Rica employees and special 29
guests

TOTAL 766

According to the table above, 766 volunteers participated in the 20 planting events,
for an average of 38 persons per event. This number is higher the average

estimated in the work plan, which was 35 volunteers per activity.

It is also worth noting that the events were carried out along Ruta 1856, as the
work was performed at: Costa Rican Delta, La Ceiba, Mouth of Sarapiquí River,
Mouth of San Carlos River and Tiricias.

Appendix 1 includes the material prepared to communicate the goals of the

consulting services and of the construction of Ruta 1856, as well as the progress in
the tree planting activities and a map with the location of the planted sites.

d. Transportation and support of volunteer groups

In all cases, the units used to transport volunteers comply with the MOPT’s
(Ministry of Transport) technical vehicle inspection requirements, and all vehicle

permits were current . During the planting activity , water is provided to the
participants, in addition to sun block, mosquito repellent and a waterproof poncho
for protection against the rain.

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44 Annex 2

June 5 event June 16 event October 16 event

After each planting event a report is prepared describing the day’s activity, a list of
participants, the place where they came from or institution they represented, and
phone number and signature of each person as evidence of the activity performed.

In order to assess the results of the activity, once it is completed the volunteers fill
out an evaluation form and provide recommendations.

The form consists of six brief response questions, a space for comments and lastly

a space for general recommendations to improve the events. All of these
assessments are presented in an appendix to the progress report.

2.2 PHASE 2: IMPLEMENTATION OF THE WORK PLAN

a. Scheduling of the planting events

Once the participation agreements were signed by the inhabitants of the different

areas, the activities were scheduled based on the list of agreements.
st
As indicated in table 4, the last planting event was held on December 1 . Thus, the
programming and execution of these events has been completed.

Some sites and dates were changed due to force majeure events. For example,
the bridge over Río Sucio fell due to the Sámara earthquake . Consequently, the
events programmed for Costa Rica n Delta and Trinidad had to be changed; they
were performed at the mouth of San Carlos River.

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45Annex 2

Progress Report

Consulting Services for the Development and Implementation of an
Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

Table Nº 4 Schedule of planting events with volunteers

Name of Planting events with volunteer and student groups
the area

Week
01- 02- 03- 04- 01- 02- 03- 04- 01- 02- 03- 04- 01- 02- 03- 04- 01- 02- 03- 01- TOTAL
jun jun jun jun jul jul jul julago ago ago ago sep sep sep sep oct oct oct dic
Delta
Costa 1 1 1 3

Rica
Trinidad 1 1 2 1 5

Boca San 2 1 1 1 1 1 7
Carlos
Tiricias 1 1 1 1 1 5

TOTAL 1 1 2 3 0 0 0 0 0 0 2 1 2 2 1 1 1 1 1 1 20
Performed Not performed

A total of 20 planting events were performed in the three areas where the work with

the volunteers had been contemplated.

Planting event 23-06-2012 Planting event 22-08-2012 Planting event11-10-2012

b. Availability of trees for planting

CODEFORSA has a certified nursery, from which most of the material planted in
the project was sourced. According to the planting schedule, the trees were

transferred to the planting site on dates close to or on the same day of the event, in
order to prevent damage s or theft of trees at the site, and to guarantee optimal

strength and development conditions of the trees at the time of planting.

c. Preparing the ground and protecting the trees

Once the agreements of participation in the planting of trees were signed with the

inhabitants of the different areas, the planning for preparation of the ground at the
different sites began.

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46 Annex 2

Progress Report
Consulting Services for the Development and Implementation of an

Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

BEFORE PLANTING CURRENT STATE
PLOT IGLESIA BOCA CAÑO LA CEIBA

PLOT FREDDY ULATE CASTRO

PLOT TITO HERNANDEZ FERRETO

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47Annex 2

Progress Report
Consulting Services for the Development and Implementation of an

Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

BEFORE PLANTING CURRENT STATE

PLOT DANIEL JIMENEZ (ALONSO)

PLOT DANIEL JIMENEZ (BISMARK)

PLOT FELIX HERNANDEZ JARQUIN

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48 Annex 2

BEFORE PLANTING CURRENT STATE

PLOT FABIO CEDEÑO (SAN ANTONIO)

Initial mowing and herbicide spots

For all cases, the preparation of the ground began
with a general mowing, tracing and staking.

Subsequently, herbicide was applied in the spots
around each stake, covering a radius of 1 meter, to
guarantee that weeds would not compete with the
trees to be planted. Lastly, holes were dug at the

sites so that when the planting events took place
the volunteers could focus on planting the trees.

Fences

In some cases it was not necess ary to place wire fences for protection since there
were previous ones in place, while in others a fence was placed to separate the
planting area from the rest of the site. In all cases maintenance will be given to the

fences as protection of the areas planted.

d. Planting of trees

As visible in table 6, to date the tree planting goal of the project has been reached,

with 26.675 trees. The activities began on June 5, 2012 in the Trinidad area,
specifically the mouth of L a Ceiba River, in the plots of Mr. Félix Hernández and
Mrs. Adilia Com. This was followed by activities in the Costa Rica n Delta, mouth of
San Carlos River and Tiricias. The last tree planting activity was held on December

4, 2012 in the Tiricias area.

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49Annex 2

The trees were planted at 31 sites, most with the collaboration of volunteers, and
another portion planted by the employees of CODEFORSA. It is worth noting that,as

indicated in the Work Plan, the blocks that were not completed by the volunteers would
be finished by employees of our institution. Consequently, there are more reforested

sites than events performed with volunteers.

The species used wereas follows:

For protection of the banks of rivers and creek:sZygia longifolia(Sotacaballo).

For humid areas: Vochysia guatemalensis (Cebo), Calophyllum brasiliense (Cedro
María),Tabebuia rosea(Roble sabana),Hyeronima alchorneoides(Pilón),Anacardium
excelsum(Espavel).

For high areas: Vochysia ferruginea (Botarrama),Dipteryx panamensis (Almendro),
Tabebuia ochracea (Corteza amarilla), Terminalia amazonia (Roble coral), Cordia

alliodora (Laurel), Delonix regia (Malinche), Samanea saman (Cenizaro) y
Schizolobium parahyba(Gallinazo).

Table Nº 5: Real number of trees planted at the sites with a plantation agreement
and species planted per site

Name of the party Number of Date of
No. to the agreement Place trees planted planting (year Species planted
2012)

Boca La sotacaballo, roble coral, pilón,
1 Félix Hernández Ceiba 260 June 05 cebo, almendro, maría, roble
Jarquín (Trinidad) sabana, bota, malinche, gallinazo,
laurel

Boca La sotacaballo, roble coral, pilón,
2 Iglesia Boca La Ceiba 225 June 05 cebo, almendro, maría, roble
Ceiba sabana, bota, malinche, gallinazo,
(Trinidad) laurel

Segundo Gaitán Boca Río
3 Mora Sarapiquí 100 June 12 sotacaballo

Fabio Vargas Boca La June 16 and cebo, pilón, sotacaballo, almendro,
4 Ceiba 407
Vargas (Trinidad) 19 roble sabana, maría

Escuela Boca La Boca La cebo, pilón, sotacaballo, almendro,
5 Ceiba 117 June 19 roble sabana, maría
Ceiba (Trinidad)

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50 Annex 2

Progress Report
Consulting Services for the Development and Implementation of an

Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

Date of
No. Name of the party Place Number of planting (year Species planted
to the agreement trees planted
2012)
Boca La
6 Melis Góngora Ceiba 252 June 19 cebo, pilón, sotacaballo, almendro,
Moraga roble sabana, maría
(Trinidad)
María Hilaria Boca Las
7 500 July 15 cebo, sotacaballo, botarrama
Miranda Rivas Marías
sotacaballo, roble coral, pilón,
Tito Hernández Delta Costa
8 Ferreto Rica 366 June 30 cebo, roble sabana, maría,
cenízaro
sotacaballo, roble coral, pilón,
Escuela Delta Delta Costa
9 Costa Rica Rica 325 June 30 cebo, roble sabana, maría,
cenízaro
cebo, pilón, sotacaballo, almendro,
Freddy Ulate
10 Castro Remolinito 3180 September 22 roble sabana, corteza amarilla,
frutales

sotacaballo, roble coral, pilón,
11 Fabio Cedeño G. Boca Río 420 June 23 cebo, maría, laurel, guapinol,
(F. San Antonio 1 ) San Carlos
botarrama, roble sabana

Fabio Cedeño G. Boca Río sotacaballo, roble coral, pilón,
12 1180 June 28 cebo, almendro, maría, laurel,
(F. San Antonio 2 ) San Carlos guapinol

Fabio Cedeño G. Boca Río sotacaballo, roble coral, cebo,
13 875 July 04
(Saíno) San Carlos almendro, espavel, maría

Fabio Cedeño G. Boca Río sotacaballo, cebo, botarrama,
14 (Boca Tapada ) San Carlos 770 September 06 cedro maría

15 Fabio Cedeño G. Boca Río 1000 September 29 sotacaballo, botarrama, cebo,
(Jóvenes ) San Carlos guapinol, cenízaro

Olman Quesada roble coral, pilón, maría, laurel,
16 Campos Tiricias 650 July 25 cebo

Daniel Jiménez B. sotacaballo, cebo, cedro maría,
17 (El Guabo) Tiricias 1907 August 22 almendro

Daniel Jiménez B. sotacaballo
18 (Slopees) Tiricias 1000 August 14

Daniel Jiménez B. sotacaballo, cedro maría, roble
19 Tiricias 200 August 16 sabana, malinche, corteza amarilla,
(Alonso) espavel

20 Daniel Jiménez B. sotacaballo, cebo, cedro maría,
(Pilo) Tiricias 950 August 20 pilón

21 Daniel Jiménez B. Tiricias 1280 August 29 sotacaballo, botarrama, almendro,
(Bismark) malinche

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51Annex 2

Progress Report
Consulting Services for the Development and Implementation of an
Environmental Plan for the Juan Rafael Mora Porras Border Road

Direct contracting by emergency exception SINAC-CDE-004-2012

Date of
No. Name of the party Place Number of planting (year Species planted
to the agreement trees planted 2012)

Marcelo Méndez pilón, sotacaballo, cebo, corteza
22 Morales Tiricias 1870 August 27 amarilla, almendro, roble coral,
botarrama, maría

William Cortés sotacaballo, roble sabana, cebo,
23 Tiricias 1460 August 25 espavel, cedro maría, corteza
Madrigal amarilla

24 German Díaz Ruiz Mojón 2 2570 September 26 sotacaballo, cebo, botarrama,
cedro maría
German Díaz Ruiz sotacaballo, cebo, botarrama,
25 Mojón 2 668 October 02
(El Concho) cedro maría
German Díaz Ruiz sotacaballo, cebo, botarrama,
26 Mojón 2 857 October 04 cedro maría
(Banderas)

27 Fabio Cedeño G. Boca Río 900 October 11 Sotacaballo, Roble coral, cebo,
(Gastón Peralta ) San Carlos botarrama, cedro maría

Fabio Cedeño G. Boca Río sotacaballo, roble coral,
28 1000 October 16 guanacaste
(Pital ) San Carlos

29 Fabio Cedeño G. Boca Río 800 October 23 sotacaballo, roble coral,
(Aguas Zarcas ) San Carlos guanacaste, cenízaro, botarrama

Escuela Delta Delta Costa
30 500 December 01 roble coral, botarrama, sotacaballo
Costa Rica Rica
roble coral, pilón, laurel, nogal,
Edgar Salazar
31 Ramírez Tiricias 86 December 04 aguacate, guanábana, guaba,
mango

TOTAL TREES PLANTED 26.675

The following figure shows a map of the location of all sites already planted along
Ruta 1.856. As visible in the map, projects have been established all along this

road. The map indicates each point with numbers 1 through 26, given that some
lots were joined. The number in the map can be related to the name of each party

to the agreement indicated in table 5.

Appendix 2 includes the maps of the lots planted, in which we can see the location

of the trees planted in relation to Ruta 1856 and San Juan River.

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52 Annex 2

CODEFORSA’s Facebook page includes pictures of the planting events. It is
attached to this report in digital format, showing the volunteers who participated in

each event, material prepared and external signs provided, as well as the sites
where the trees were planted.

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53Annex 2

2012

-04-

CDE 23
-
:ww.codeforsa.org
Page
SINAC

1650 Webpage
Juan Rafael Mora Porras Border Road -

Progress Report

-055 Fax: (506) 2460

Environmental Plan for themergency exception
Consulting Services for the Development and Implementation of an

Tel: (506) 2460

COMISIÓN DE DESARROLLO FORESTAL DE SAN CARLOS

54 Annex 2

2.3 PHASE NO. 3. MAINTENANCE OF THE PLANTCOVER

a. Monitoring of plantedareas

As of July 2012 follow -up visits are performed to the planted areas, both by the
volunteers and by the employees of CODEFORSA.

As part ofthe initial maintenance stage of allplots planted, once a month hadpasseda

general maintenance program was applied, given that maintenance needs are very
similar. The following activities were implemented:

1. Total mowing of the planted area with a hedge trimmer.

2. Manual mainten ance, with a shovel, of a circular spot with a 30 cm diameter

around the tree, followed by earthing-up of each tree.

3. Replanting in the event of dead trees.
4. With the earthing -up of each tree, planting defects such as crooked trees, trees

planted below the soil level, etc. are corrected.

5. For leaning trees, anchor with a stake and tie with a string.

6. Apply 60 grams of fertilizer to each tree.
7. Check the fence to see if any repairs are required, by sector.

8. If leaf-cutter ants are found, apply insecticide.

In the accompanying photos you can see the progress of the activities performed on
the plots planted.

Three teams are working on this task, one in the mouth of San Carlos River, another in
La Ceiba- Trinidad de Sarapiquí area, and the third one in theCosta Rican Delta area.

b. Mowing:

The first activity for each plot is a complete mowing with a hedge trimmer. There is a

variety of weeds in each lot. T he one that causes the main problems is called
gamalote, or bullgrass,which grows very aggressively and its roots spread through the
ground which makes its cleaning difficult.

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55Annex 2

Progress Report

Consulting Services for the Development and Implementation of an

Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

Mowing ofrotanagrass(ischaemum indicum) Mowing ofbullgrass (gamalotein Spanish)

As the plots were established, the initial maintenance plan was applied. At this time all

plots have undergone the initial maintenance plan.Generalmowing is being applied to

all planted plotsas of January.

Table 6showsthe scheduled mowingto be performed during the effective period of the

consulting work.

Table Nº 6 Scheduled maintenance mowing for each planted plot

Name

of the Maintenance mowing
area

Month
jA
may- jun- jul-ago- sep- oct- nov- dic-ene- feb mar- abr- may- jun- ul- ago- sep- oct- nov- dic- ene- feb mar- abr- TO
12 12 12 12 12 12 12 12 13 -13 13 13 13 13 13 13 13 13 13 13 14 -14 14 14 TAL

Delta
Costa 2 2 2 6

Rica

Fátima 1 1 1 3
7 7 7 21
Trinidad
Boca
9 9 9 27
San
Carlos
12 12 12 36
Tiricias
TOTAL 0 0 31 0 0 0 0 0 0 31 0 0 0 0 0 0 0 31 0 0 0 0 0 0 93

Performed In process Not performed

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56 Annex 2

Progress Report
Consulting Services for the Development and Implementation of an

Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

c. Clearing of circular spots around trees:

Herbicide spots Manual clearing of spots and earthin-gup

Part of the maintenance program consists of manually clearing circular spots with a

shovel, 40 cm wide, around each tree. As visible in the picture, this works guarantees

that there is no competition between the planted trees and weeds. Due to the
aggressiveness of bullgrass ( gamalote in Spanish, scientific name: paspalum

fasciculatum wild), in theplots were this type of grassy weed existed a n herbicide spot

was applied, specifically glyphosate, which is a green -label herbicide permitted by

international certifiers such asFSC or ISO 14001.

Along with the manual and chemical spot, earthing -up was performed around each

tree. As shown in the picture, this consists of putting an amount ofsoil around the tree

so it has fertile and non -compacted soil available for the development of roots.
Earthing-up also helps correct planting defects such as trees planted below the soil’s

level, exposed roots, inclined trees or lack of compacting at the time of planting, which

may cause fungus in the roots and death of the tree.

Table Nº 7 Scheduled maintenance of circular spots for each planted unit

Name of
the area Maintenance of circular spots around trees

Month
jul-ago- sep- oct- nov- dic-ene- feb-mar- abr-may- jun- jul-ago- sep- oct-nov- dic-ene- feb- mar- TOTAL
12 12 12 12 12 12 13 13 13 13 13 13 13 13 13 13 13 13 14 14 14

Delta
Costa 2 2 2 2 2 8
Rica

Fátima 1 1 1 1 1 4
Trinidad 7 7 7 7 7 28

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57Annex 2

Progress Report
Consulting Services for the Development and Implementation of an

Environmental Plan for the Juan Rafael Mora Porras Border Road

Direct contracting by emergency exception SINAC-CDE-004-2012

Name of Maintenance of circular spots around trees
the area

Month
jul-ago- sep- oct- nov- dic-ene- feb-mar- abr-may- jun- jul-ago- sep- oct-nov- dic-ene- feb- mar- TOTAL
12 12 12 12 12 12 13 13 13 13 13 13 13 13 13 13 13 13 14 14 14
Boca San
8 1 9 9 9 9 36
Carlos
10 2 12 12 12 12 48
Tiricias
TOTAL 20 11 0 0 0 31 0 0 31 0 0 31 0 0 0 31 0 0 0 0 124

Performed In process Not performed

d. Replanting:

When the maintenance program was applied to each plot, the trees that had been
lost at that time were replanted.

In the monthly visit reports we verify and indicate the number of trees to be

replaced, if necessary, to maintain the initial number of trees planted at that plot.

This activity is constantly performed at the plots until the end of the project.

e. Fertilizer application:

This work was performed after the earthing -up of the trees, as part of the initial

maintenance plan. A dose of60 grams of 10-30-10 fertilizer was applied to each tree.

Table Nº 8 Application of soil amendments for each planted unit

Name of
the area Amendments applied to the sites

Month

jul- ago- sep- oct- nov- dic- ene- feb- mar- abr- may- jun- jul- ago- sep- oct-
12 12 12 12 12 12 13 13 13 13 13 13 13 13 13 13
Delta

Costa A B C
Rica

Fátima A B C

Trinidad A B C
Boca San
A B C
Carlos

Tiricias A B C
A: Compound fertilizer, B: Foliar fertilizer, C: Liming. For the 31 planting units.

Performed Not performed

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58 Annex 2

Progress Report
Consulting Services for the Development and Implementation of an

Environmental Plan for the Juan Rafael Mora Porras Border Road

Direct contracting by emergency exception SINAC-CDE-004-2012

f. De-suckering:

This work will not be performed at this time. It has been programmed as of June of next

year.

g. Maintenance of the fences:

According to the approved Work Plan, this activity will be performed until June of this

year. However, as part of the maintenance visits program carried out at the planted

plots, the fences are checked, to prevent the entrance of cattle to the sites. In some

cases they have been reinforced with more fence posts when the land is uneven and

this allows small animals to pass through.

h. Follow-up visits to the planted areas

As of July 2012 follow-up visits are performed to the planted areas. As per the work

plan, during the firstyear of the project visits must be performed monthly. The quarterly

reportsof the visits performed arepresentedby the unit executing the project, including

the reports of the visits performed.

Table Nº 9 Schedule of follow-up visits to each planting unit

Name of Follow-up visits
the area

Mes

may- jun- jul-ago- sep- oct- nov- dic- ene- feb- mar- abr- may- jun-jul- ago- sep- oct- nov- dic- ene- feb- mar- abr- TOTAL
12 12 12 12 12 12 12 12 13 13 13 13 13 13 13 13 13 13 13 13 14 14 14 14
Delta

Costa 0 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 28
Rica
Fátima 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 17

Trinidad 0 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 119

Boca San
Carlos 0 2 3 4 6 9 9 9 9 9 9 9 9 9 9 9 9 9 132

Tiricias 0 0 1 9 11 11 11 12 12 12 12 12 12 12 12 12 12 12 175

TOTAL 0 11 13 22 26 29 29 31 31 31 31 31 31 31 31 31 31 31 471

Performed Not performed

The approved work plan had proposed and budgeted 422 follow -up visits in total.

However, during its execution 31 planting sites were established, and the number of

visits were increased. Currently, 471 visits remain to be performed until the end of the

project.

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59Annex 2

i. Quarterly follow-up reports

Table 10 shows the schedule for presentation of the quarterly progress reports to the
unit executing the project, which is the office oÁrea de Conservación Tortuguero.
After the presentation of each report a visit is performed with the technical supervisors
of the consulting work, which are employees of the three SINAC conservation areas

involved. With the supervision reports of SINAC officers the payments are authorized
by the project’s financial supervisor.

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60 Annex 2

Progress Report

Consulting Services for the Development and Implementation of an
Environmental Plan for the Juan Rafael Mora Porras Border Road

Direct contracting by emergency exception SINAC-CDE-004-2012

Table Nº 10. Schedule for presentation of progress reports of the project

Name of Progress reports
the area

Month

may- jun- jul-ago- sep- oct-nov- dic- ene- feb- mar- abr- may- jun- jul-ago- sep- oct-nov- dic-ene- feb-mar- abr- TOTAL
12 12 12 12 12 12 12 12 13 13 13 13 13 13 13 13 13 13 13 13 14 14 14 14

Presentation
of reports 1 1 1 1 1 1 1 1 8

TOTAL 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 8

Performed Not performed

2.4 SLOPES

a. Recovery of slopes

To carry out the recovery of slopes, as part of the project’s commitments, the

decision was made, after walkthroughs of the areas of influence of the project, that

the Tiricias area has the most pronounced terrain cuts. Thus, the approved

recovery of 12 slopes shall be performed there.

Design ofgrass planting on each slope

To date, a total of 8 slopes have been planted and signs were put in place. The

work performed is for maintenance.

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61Annex 2

Progress Report
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Environmental Plan for the Juan Rafael Mora Porras Border Road

Direct contracting by emergency exception SINAC-CDE-004-2012

View of SlopeNo. 2 Signs placed at each of tslopes

Regarding the progress of the slope recovery schedule, this activity was delayed a

little, taking advantage of the winter, to complete the tree planting events. Thus, the
four slopes pending work has not begun.

The work on these slopes will be performed as of March of this year, when the teams
that are working on the construction of Ruta 1856 allow access to the east of the mouth

of Infiernillo River, given that in this area between the mouth of Infiernillo and Chorreras
there are areas with sig nificant slopes.

Table Nº 11 Work schedule for recovery of slopes

Work area Recovery of slopes

Week

03-sep 04-sep 01-oct 02-oct 03-oct 04-oct TOTAL
Slope 1 1 1

Slope 2 1 1

Slope 3 1 1
Slope 4 1 1

Slope 5 1 1

Slope 6 1 1
Slope 7 1 1

Slope 8 1 1

Slope 9 1 1
Slope 10 1 1

Slope 11 1 1
Slope 12 1 1

TOTAL 2 2 2 2 2 2 12

Performed Not performed

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62 Annex 2

b. Maintenance of plant cover on slopes:

To date the maintenance work of the plant cover on slopes has consisted of
applying foliar fertilizer to promote its establishment and to guarantee that the

slopes are covered with vegetation.

Foliar fertilizer is used, with the formula10-50-10, to favor vertical growth. It is
applied with a back pump, using a rod and long hose to completely cover each
step of the slopes that were treated. Two applications have been made, one in

December, which was not programmed, but it was performed to strengthen the
plant cover before the dry season began. A new application is programmed for
May, when the rainy season begins.

Foliar fertilization low part of the slopFoliar fertilization top part of the slope

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Progress Report

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Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

Table Nº 12 Schedule for maintenance of plant cover on slopes

Name of
Maintenance of slopes
the area

Month
jun- jul-ago- sep- oct-nov- dic- ene- feb- mar- abr- may- jun- jul-ago- sep- oct- nov- dic- ene- feb- mar- abr-
12 12 12 12 12 12 12 13 13 13 13 13 13 13 13 13 13 13 13 14 14 14 14 TOTAL

Slope 1 1 1 1 1 3

Slope 2 1 1 1 1 3
1 1 1 1 3
Slope 3
Slope 4 1 1 1 1 3

Slope 5 1 1 1 1 3

Slope 6 1 1 1 1 3

Slope 7 1 1 1 1 3
1 1 1 1 3
Slope 8
Slope 9 1 1 1 3

Slope 10 1 1 1 3

Slope 11 1 1 1 3
1 1 1 3
Slope 12
TOTAL 0 0 0 12 0 0 8 0 0 0 0 12 0 0 0 0 0 0 0 12 0 0 0 36

(A)Foliar fertilization Not executed

applied

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64 Annex 2

III. APPENDIXES

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Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

APPENDIX 1: MATERIAL PREPARED FOR PARTICIPANTS OF THE
ACTIVITIES AND MEMBERS OF PUBLIC INSTITUTIONS INVOLVED

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Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

8-PAGE MAGAZINE GIVEN TO EACH VOLUNTEER AT THE
PLANTING EVENTS

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CDE 37
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:ww.codeforsa.org
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-055 Fax: (506) 2460

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Consulting Services for the Development and Implementation of an

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69Annex 2

APPENDIX 2: MAPS OF THE AREAS PLANTED

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70 Annex 2

Progress Report

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Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

TOTAL TREES PLANTED, AVERAGE PLANTING DATE, PLANTED AREA

KEY: Access roads; Ruta 1856; Plot loScale 1:4.500

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88 Annex 2

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91Annex 2

Progress Report

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Environmental Plan for the Juan Rafael Mora Porras Border Road
Direct contracting by emergency exception SINAC-CDE-004-2012

APPENDIX 3: VISIT TO THE SLOPES BEFORE AND AFTER
PLANTING OF THE VEGETATION COVER

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SLOPENo. 1

BEFORE AFTER

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SLOPENo. 2

BEFORE AFTER

This slope had ageomembrane cover that was stolen by unknown persons.

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SLOPENo. 6

BEFORE AFTER

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102 ANNEX 3

Allan Astorga G. and Andreas Mende

Route 1856: Analysis of the Change in Land use Based on Satellite Images
Before and After the Construction of the Border Road

August 2013

103104 Annex 3

Route 1856: analysis of the change in land use

Astorga & Mende (2013)

Route 1856: analysis of

the change in land use
Based on satellite images before and after the

construction of the border road

Allan Astorga G. & Andreas Mende

August 2013

1 Index | Astorga & Mende (2013)

105Annex 3

Route 1856: analysis of the change in land use

Index

Index..................................................................................................................................................2

Foreword...........................................................................................................................................3

1. Introduction ..................................................................................................................................4

1.1 P RESENTATION .......................................................................................................................4

1.2 OBJECTIVE ...............................................................................................................................5

1.3 M ETHODOLOGY .......................................................................................................................5

1.4 O RGANIZATION OF THE DOCUMENT ........................................................................................7

2. Results: net effect of changes in land use ...............................................................................8

2.1 T YPES OF LAND USE ................................................................................................................8

2.2 C OMPARATIVE MAPS .............................................................................................................10

2.3 S UMMARY OF RESULTS ........................................................................................................24

3. Conclusions ...............................................................................................................................27

4. References.................................................................................................................................28

2 Index | Astorga & Mende (2013)

106 Annex 3

Route 1856: analysis of the change in land use

Foreword

This study has been prepared by Dr. Allan Astorga and Dr. Andreas Mende
following a request of the Ministry of Foreign Affairs of the Republic of Costa Rica.

Dr. Allan Astorga -Gättgens is a Professor of Sedimentology and
Environmental Geology at the University of Costa Rica since 1991, and Consultant

in Environmental Impact Assessment, Environmental Management and
Environmental Land. He holds the degrees of Licentiate in Geology by the School

of Geology at the University of Costa Rica (1987), and Doctor of Natural Sciences
by the University of Stuttgart, Germany(1996).

Dr. Andreas Mende is a Consultant and expert in Geogra phic Information
Systems, Remote Sensing, Environmental Geology, Sedimentology and

Hydrogeology. He has been Investigator at the University of Costa Rica with a
three-year Postdoc-Scholarship from the German Research Foundation (DFG) and

works since 2005 a s an Independent Consultant based in San José, Costa Rica.
He holds a Diploma in Geology by the University of Bonn (Germany) (1995), and a

Doctorate in Natural Sciences by the University of Stuttgart, Germany (1999).

3 Foreword | Astorga & Mende (2013)

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Route 1856: analysis of the change in land use

1. Introduction

1.1 P RESENTATION

Based on the circumstances that surrounded the initial construction of Route
1856 and the need for an accurate assessment of the “effect of the change in land

use” that it brought about, a need arose to perform an analysis of this change. Said
analysis is documented herein.

Figure 1 presents the approximate geographic location of Route 1856, built
as a border road that commun icates the area of Los Chiles to the Delta of the

Colorado River (Delta CR) sector in the northern sector of Costa Rica.

It is important to clarify that this analysis focuses on the change of land use

in the portion of Route 1856 that runs parallel to the San Juan River, that is,
between Marker 2 and Delta CR. It seeks to perform a quantitative assessment of

the net effects produced in th e different ecosystems present in the area (see
Figure 2). The full length of Route 1856 from Los Chiles to Delta CR is 159.7 km,

while from Marker 2 to Delta CR it is 108.2 km. The latter is the length of road

covered by this study.

Fig. 1. Map of the approximate geographic location of Route1856

4 1. Introduction | Astorga & Mende (2013)

108 Annex 3

Route 1856: analysis of the change in land use

Fig. 2. Portion of Route 1856 subject to this analysis of change in land use. Map
based on the topographic sheets with scale 1:50.000 according to the Costa Rican

National Institute of Geography.

1.2 OBJECTIVE

The objective of this study is to perform a comparative analysis of land use,
following a standardized method, based on information obtained from satellite

images taken before and after the construction of Route 1856 in 2011, using a
Geographic Information System to determine the net effect of the change in land

use that resulted from the construction of said border road.

1.3 M ETHODOLOGY

The methodological steps applied for this analysis were the following:

1) Use of a standardized methodology, previously established in Costa Rica

through Executive Decree No. 32967 – MINAE, to determine land use in

a previously selected area of study, defined as a one-kilometre wide strip
measured from the right bank of San Juan River into Costa Rican

territory.

5 1. Introduction | Astorga & Mende (2013)

109Annex 3

Route 1856: analysis of the change in land use

2) Development of the topographic bas is according to the topographic

sheets with scale 1:50.000 of the Costa Rican National Geographic

Institute (Instituto Geográfico Nacional de Costa Rica).
3) Interpretation of aerial photos and satellite images, with a resolution

ranging from 0.5 - 5 m/pixel, before and after Route 1856, provided by a
specialized company and obtained from the Government of Costa Rica.

4) Systematic field verification, including fly -overs and work performed

jointly with Forestry Engineer Rafael Bolaños from the Tropical Science
Centre (Centro Científico Tropical).

5) Entering of all of the information interpreted in to a Geographic

Information System.
6) Comparative analysis and generation of statistics for mapping before and

after Route 1856.

The satellite images with a resolution of 0.5 to 5.m/pixel, as well as the

aerial photographs used as basis for the land use interpretation presented in this
study are of a sufficiently high quality to differentiate various details, in particular

types of vegetation present in the study area. Moreover, the interpretation obtained

from these images was complemented by a systematic field review, which allowed
for the information obtained from the images to be verified . The information

obtained was processed using a Geographic Information System ( GIS), through

which it was possible to refine the accuracy of the data and in particular the
calculations of the areas shown in Table 2 (p.23). This methodology makes it

possible to specify with accuracies in the order of meters for different types of land

use analyzed in Table 2, with an error margin of less than 1 %.

It is worth noting that prior to the construction of Route 1856 there were pre-
existing roads in significant parts of its length. Of the total length of the route

between Los Chiles and Delta CR, consisting of 159.7 km, there were previously

existing rustic roads in 101.5 km (63.6%, see Figure 2). Similarly, the area between
Marker 2 and Delta CR, 50.0 km (46.2%) of Route 1856 was built on pre -existing

rustic roads. These roads had different characteristics in terms of width and

easements, and they joined several villages. Route 1856 was built over this route
design. This factor is taken into account in this analysis.

6 1. Introduction | Astorga & Mende (2013)

110 Annex 3

Route 1856: analysis of the change in land use

1.4 O RGANIZATION OF THE DOCUMENT

Apart from the introductory chapter, this technical report includes two

additional chapters, namely:

- Main results

- Conclusions

7 1. Introduction | Astorga & Mende (2013)

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Route 1856: analysis of the change in land use

2. Results: net effect of changes in land

use

2.1 TYPES OF LAND USE

The 15 types of land use identified in the interpretation of photos and

satellite images documented in this report are described inTable 1.

Furthermore, Figure 3 presents, for illustrative purposes, an example of the
interpretation of land use on a portion of Route 1856 that runs parallel to the right

bank of San Juan River. Specific examples of the interpretation of satellite images
are provided in Appendix 1.

Pasture
Route 1856

Forest

Fig. 3. Picture of the right bank of San Juan River, with an example of the interpretation of
land use discussed in this report.

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112 Annex 3

Route 1856: analysis of the change in land use

Table 1

Types of land use identified in the interpretation of images before and after the

construction of Route 1856

N O. CATEGORY DESCRIPTION

1. Urbanized areas Areas with very few or no trees. Comprises surfaces
covered by constructions such as houses or related
(Zonas urbanizadas) buildings.

2. Crops Areas dedicated to agricultural production , which are
mainly distinguished by patterns and shapes that can
(Cultivos) be easily identified in the images and through field

verification.

3. Pastures Highly disturbed areas, dominated by perennial
grasses, non-prickly, with a height of less than 1
(Pastos)
meter. This land is mainly for silvopastural use, and
there maybe variations in its composition.

4. Pastures mixed with trees Corresponds to the previous category, except that

(Pastos mezclados con there are trees spread out across a pasture.
árboles)

5. Mountainous primary Primary forests are located in areas with moderate to
forest high slopes, without significant or reduced human
disturbance, and their structure and composition of
(Bosque primario de
montaña) flora show a state of climax.

6. Mountainous secondary Are those forests located in areas with moderate to
forest high slopes, which were once primary but have bee n
disrupted by human activity. Their structure is similar
(Bosque secundario de to that of a primary forest in terms of strata, but they
montaña)
may differ in the diameter of their canopies,
composition or homogeneity.

7. Plains primary forest Similarto that indicated for primary forests, but on a

(Bosque primario de plain or slightly undulating surface.
planicie)

8. Plains secondary forest Similar to that indicated for secondary forests, but on
a plain or slightly undulating surface.
(Bosque secundario de
planicie)

9. Tree plantations
Crop areas with presence of scattered trees.
(Plantaciones de árboles)

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Route 1856: analysis of the change in land use

NO. C ATEGORY DESCRIPTION

10. Scrubland, degenerated Remnants of primary or secondary forests that were
forest disturbed and logged, in which there is
heterogeneous vegetation cover (less than 3 meters).
(Charrales, bosque
degenerado)

11. Temporarily flooded areas Low areas close to river beds or water mirrors which
(Zonas temporalmente in conditions of high precipitation may become
flooded temporarily.
inundadas)

12. Raffia palms Low areas, with humid soil, covered by raffia palms.
They qualify as wetlands.
(Yolillales)

13. Lake wetlands Low areas with saturated soil and presence of water,
with hydrophytic vegetation.
(Humedales lacustrinos)

14. Bodies of water Permanent or intermittent channels of water, and

(Cuerpos de agua) bodies of accumulated water.

15. Areas affected by the Line of relief subject to earthworks for the
construction of Route construction of Route 1856. It includes cut slopes and
1856 fill slopes, road surface, shoulders and ditches, as
well as temporarily loaned areas for aggregates for
(Áreas afectadas por la
Ruta 1956) construction of the road.

2.2 C OMPARATIVE MAPS

Figures 4-9 present the comparative maps of interpretation of land use for

the one-kilometre wide strip analysed in this study. Component (a) of the figures

shows the interpretation of land use before the construction of Route 1856, while
component (b) shows after the construction of Route 1856.

In total, the portion from Marker 2 to Delta Costa Rica covered by this
analysis includes six segments, namely:

Segment 1 (figures 4a & 4b): Marker 2 to Crucitas

Segment 2 (figures 5a & 5b): Crucitas to Mouth of San Carlos

Segment 3 (figures 6a & 6b): Mouth of San Carlos to Remolino Grande

Segment 4 (figures 7a & 7b): Remolino Grande to northwest of Trinidad

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114 Annex 3

Route 1856: analysis of the change in land use

Segment 5 (figures 8a & 8b): Northwest of Trinidad to west of Tigra

Segment 6 (figures 9a & 9b): West of Tigra to Delta Costa Rica

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Route 1856: analysis of the change in land use

Fig. 4.a. Segment 1, Marker 2 to Crucitas Sector before Route 1856

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116 Annex 3

Route 1856: analysis of the change in land use

Fig. 4.b. Segment 1, Marker 2 to Crucitas Sector after Route 1856

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117Annex 3

Route 1856: analysis of the change in land use

Fig. 5.a. Segment 2, from Crucitas to Mouth of San Carlos before Route 1856

14 2. Results: net effect of changes in land use | Astorga & Mende (2013)

118 Annex 3

Route 1856: analysis of the change in land use

Fig. 5.b. Segment 2, from Crucitas to Mouth of San Carlos after Route 1856

15 2. Results: net effect of changes in land use | Astorga & Mende (2013)

119Annex 3

before Route 1856

Remolino Grande,

River to Astorga & Mende (2013)
|
Route 1856: analysis of the change in land use

San Carlos

from the Mouth of

2. Results: net effect of changes in land use
Segment 3,

Fig. 6.a.

120 Annex 3

1856

oute
R

after

Remolino Grande,

torga & Mende (2013)
River tAs
|
Route 1856: analysis of the change in land use

San Carlos

from the mouth of

2. Results: net effect of changes in land use
Segment 3,

Fig. 6.b.

121Annex 3

Rute 1856

before

Trinidad,

Astorga & Mende (2013)
|
Route 1856: analysis of the change in land use
to northwest of

of changes in land use
Remolino Grande

from
4,

2. Results: net effect
Segment

Fig. 7.a.

122 Annex 3

after Route 1856

Trinidad,

torga & Mende (2013)
As
|
Route 1856: analysis of the change in land use
to northwest of

Remolino Grande

from
4,

ment
2. Results: net effect of changes in land use
Seg

Fig. 7.b.

123Annex 3

before Route 1856

Tigra,

torga & Mende (2013)
As
|
Route 1856: analysis of the change in land use

Trinidad to west of

from northwest of
5,

2. Results: net effect of changes in land use
Segment

Fig. 8.a.

124 Annex 3

1856.

torga & Mende (2013)
As
|
Route 1856: analysis of the change in land use

2. Results: net effect of changes in land use
Segment 5, from northwest of Trinidad to west of Tigra, after Route

Fig. 8.b.

125Annex 3

1856

before Route

torga & Mende (2013)
As
|
Route 1856: analysis of the change in land use

Delta Costa Rica,

from west of Tigra to
6,
t

2. Results: net effect of changes in land use
Segmen
a.
22

Fig. 9.

126 Annex 3

1856

after Route

torga & Mende (2013)
As
|
Route 1856: analysis of the change in land use e

Delta Costa Rica,

Tigra to

from west of

2. Results: net effect of changes in land us
Segment 6,

Fig. 9.b.

127Annex 3

Route 1856: analysis of the change in land use

2.3 SUMMARY OF RESULTS

Table 2 presents the statistics, obtained using the Geographic Information

System, of the different land uses before the construction of Route 1856 on the

one-kilometre wide strip subject to this analysis, which represents a total of
2
10.475,2 hectares, i.e. 104.75 Km .

As we can see in Table 2, the most predominant land use in the a rea of

study corresponds to the various types of forest, amounting to 5.469,6 hectares
which represents 54.70% of the total. Pastures are in second place, with

4.497,9 hectares, or 44.98% of the total. Constructions (urbanized areas) represent

coverage of 26.6 hectares, representing 0.3% of the total.

Table 2

Statistics of land use before the construction of Route 1856

Types of land use before Route 1856 Area (ha) Area (km ) Area (%)

Urbanized areas 26.6 0.27 0.3

Annual / permanent crops 67.5 0.68 0.6

Pastures 4497.9 44.98 42.9

Pastures mixed with trees 103.1 1.03 1.0
Mountainous primary forest 3598.3 35.98 34.4

Mountainous secondary forest 211.4 2.11 2.0

Plains primary forest 1519.8 15.20 14.5

Plains secondary forest 140.1 1.40 1.3

Scrubland / Degenerated forest 89.5 0.89 0.9

Tree plantations 15.9 0.16 0.2

Raffia palms 150.4 1.50 1.4

Lake wetlands 18.0 0.18 0.2
Temporarily flooded areas 36.8 0.37 0.4

Sum 10475.2 104.75 100.00

Table 3 , on the other hand, presents the statistics obtained using the

Geographic Information System for the interpreted maps of land use after the

construction of Route 1856. As we can see, the area directly affected by Route

1856 is 350 hectares, which represents 3.3% of the total area under analysis.

24 2. Results: net effect of changes in land use | Astorga & Mende (2013)

128 Annex 3

Route 1856: analysis of the change in land use

Table 4 presents the statistics of the effects of the construction of Route

1856 on the different land used identified in the area of study (see Table 2). As can

be observed, the land use mainly affected by the construction of Route 1856 is

pastures (253.5 hectares, representing 72.4% of the total). The forests (primary
and secondary, mountainous and plains) affected by the construction of the Route

represent 83.2 hectares, corresponding to23.8% of the total area affected.

Table 3

Statistics of land use after the construction of Route 1856
2
Types of land use after Route 1856 Area (ha) Area (km ) Area (%)

Urbanized areas 24.6 0.25 0.2
Annual / permanent crops 64.5 0.64 0.6

Pastures 4244.4 42.44 40.5

Pastures mixed with trees 103.0 1.03 1.0

Mountainous primary forest 3538.7 35.39 33.8

Mountainous secondary forest 202.0 2.02 1.9

Plains primary forest 1511.0 15.11 14.4

Plains secondary forest 134.7 1.35 1.3

Scrubland / Degenerated forest 84.5 0.84 0.8

Tree plantations 14.8 0.15 0.1

Raffia palms 149.7 1.50 1.4
Lake wetlands 17.9 0.18 0.2

Temporarily flooded areas 35.4 0.35 0.3

Areas affected by Route 1856 350 3.50 3.3

Sum 10475.2 104.75 100.00

25 2. Results: net effect of changes in land use | Astorga & Mende (2013)

129Annex 3

Route 1856: analysis of the change in land use

Table 4

Net change in land use with the construction of Route 1 856

Areas lost due to the construction Area (ha) Area (km ) Area (%)
of Route 1856

Urbanized areas 2.0 0.020 0.6

Annual / permanent crops 3.0 0.030 0.9

Pastures 253.5 2.535 72.4

Pastures mixed with trees 0.1 0.001 0.0

Mountainous primary forest 59.6 0.596 17.0

Mountainous secondary forest 9.4 0.094 2.7
Plains primary forest 8.8 0.088 2.5

Plains secondary forest 5.5 0.055 1.6

Scrubland / Degenerated forest 5.0 0.050 1.4

Tree plantations 1.1 0.011 0.3

Raffia palms 0.7 0.007 0.2

Lake wetlands 0.1 0.001 0.0

Temporarily flooded areas 1.5 0.015 0.4

Sum 350.2 3.50 100.00

26 2. Results: net effect of changes in land use | Astorga & Mende (2013)

130 Annex 3

Route 1856: analysis of the change in land use

3. Conclusions

1. The area occupied by Route 1856 between Marker 2 and Delta Costa
Rica is 350.2 hectares.

2. This represents 3.3% of the 10 447.2 hectare study area (which is a

one kilometre wide corridor extending between Marker 2 and Delta Costa Rica).

3. The area of pasture which is now used for Route 1856 is 253.5

hectares, which constitutes 72.4% of the areawhich is now used for the Road.

4. As the pasture land had already been cleared of natural vegetation
and developed for agriculture prior to construction of Route 1856, the impacts of

the Road on the environment, ecology, soil erosion and sediment production along

nearly three quarters of its length are likely to range between low and
imperceptible.

5. The overall area of forest lost to Route 1856 is 83.2 hectares,

representing 23.8 % of the area now used for the Road. However, only 68.4

hectares of area now used for the Road was mapped as primary forest prior to
construction and most of this ( 59.56 hectares, i.e . 87%) is located upstream of

Boca San Carlos.

6. In total, the area of forest now used for Route 1856 constitutes only

0.014 % of the 5 869.6 hectares of forest found within the study corridor.

7. The relatively small area of forest now used for Route 1856 reflects
the fact that its route was planned to avoid primary forest as much as possible and

examination of the land use maps in Figures 4 to 9 illustrates the degree to which
the Road skirts around rather than passing through forested areas, particularly

downstream of Boca San Carlos.

5. Based on the foregoing, we conclude that the land use impacts of

Route 1856 are mainly confined to pastures and that, although a total of 83.2
hectares of forest are now used for the Road, the route selected minimised t he

amount of primary forest that had to be cut.

27 3. Conclusions | Astorga & Mende (2013)

131Annex 3

Route 1856: analysis of the change in land use

4. References

Executive Decree No. 32967 - (Ministry of the Environment and Energy) MINAE:

Manual of Technical Instruments for Environmental Impact
Assessments (EIA Manual), Part III -. TECHNICAL PROCEDURE TO

INTRODUCE THE ENVIRONMENTAL VARIABLE IN REGULATORY
PLANS OR OTHER PLANS FOR LAND USE. Official Gazette, May 6,

2006).

28 4. References| Astorga & Mende (2013)

132 ANNEX 4

Costa Rican Institute of Electricity (ICE), SBU Projects and Associated

Services, Centre for Basic Engineering Studies, Department of Hydrology

Report on Hydrology and Sediments for the Costa Rican River Basins draining
to the San Juan River

August 2013

133134 Annex 4

COSTA RICAN INSTITUTE OF ELECTRICITY (ICE)

SBU PROJECTS AND ASSOCIATED SERVICES

CENTRE FOR BASIC ENGINEERING STUDIES
DEPARTMENT OF HYDROLOGY

REPORT ON HYDROLOGY AND SEDIMENTS

FOR THE COSTA RICAN RIVER BASINS
DRAINING TO THE SAN JUAN RIVER

August 2013
San José, Costa Rica

135Annex 4

Prepared by:

Federico Gómez Delgado
Juan José Leitón Montero
Carlos Aguilar Cabrera

With the collaboration of:

Sadí Laporte Molina
José Alberto Zúñiga Mora

Marcelo Avendaño Castro and the URM Unit
José Francisco Fernández Araya and the ULQ Unit
Berny Fallas López and the UPA Unit

136 Annex 4

Contents

1.
Introduction ............................................................................................................1

2.
Hydrology and sediment measurements in the San Juan - Colorado river
system..........................................................................................................................3

2.1.
Study area and gauging stations ......................................................................3

2.2.
Mean monthly discharge for ICE’s hydrological stations ..................................4

2.3.
Suspended sediment load from Costa Rican basins draining to the San
Juan River................................................................................................................6

2.3.1
Suspended sediment rating curves for the stations 01 -03 La Trinidad
and 11-04 Delta Colorado ...................................................................................7

2.3.2
Seasonal behavior of the suspended sediment concentrations at
Delta Colorado station (11-04) ............................................................................8

2.3.3
Mean annual suspended sediment load at La Trinidad (01 -03) and
Delta Colorado (11-04) gauging stations.............................................................9

2.4.
Bed-load sediment from Costa Rican basins draining to the San Juan
River 10

3.
Discharge balance in the San Juan - Colorado river system...............................14

4.
Hydrological regime in the tributary basins draining from Costa Rica t o the
San Juan River, before and after the construction of Route 1856.............................16

4.1.
Impermeable areas in the basins draining to the RSJ ....................................17

4.2.
Hydrological regime of all the rivers and streams flowing to the San Jua
n

River from Costa Rican basins: Evaluation of Route 1856....................................18

5.
Distributed erosion and sediment yield in the San Juan - Colorado river system 21

6.
Sediment balance in the San Juan - Colorado river system, before and after
construction of Route 1856........................................................................................26

6.1.
Total annual sediment load after construction of Route 1856.........................26

6.2.
Estimation of the sediment load produced by Route 1856 .............................28

6.3.
Sediment balance diagrams before and after construction of Route 1856.....32

6.4.
Silting process in the lower San Juan River....................................................34

7.
Conclusions..........................................................................................................36

REFERENCES ..........................................................................................................38

APPENDIX A Suspended sediment rating curves Mean monthly suspended
sediment load Mean annual suspended sediment load............................................40

APPENDIX B Monthly discharge measurements by Doppler device at Delta

Colorado (11-04) gauging station ..............................................................................65

APPENDIX C Daily discharge at Delta Colorado (11 -04) gauging station for the

period December 2010 - July 2013............................................................................66

iii

137Annex 4

APPENDIX D Suspended sediment (SS) samples taken at La Trinidad (0
1 -03,
Jan 1974 - Mar 1976) and Delta Colorado (11 -04, Dec 2010 - Jun 2013) gauging

stations.......................................................................................................................67

APPENDIX E Grain size distribution for bed -load samples, taken in a monthly
basis within the period December 2010 - June 2013 at the mouths of the San

Carlos and Sarapiquí Rivers, and at Delta Colorado station (11-04).........................69

APPENDIX F Distributions of both bed-load median grain size and percentage
of sand, sampled within the period December 2010 - June 2013 at Delta Colorado

station (11-04)............................................................................................................70

APPENDIX G Estimation of the annual bed-load sediment according to the
Einstein method, for the period 2010-2013 in the Lower San Juan and Colorado

Rivers.........................................................................................................................71

APPENDIX H H.1 Flow diagram and description of the CALSITE model H.2

Input and output maps produced for the determination of the potent ial erosion and
sediment yield in both Costa Rican and Nicaraguan drainage basins.......................72

APPENDIX I Disaggregated diagrams, by sediment load component, of the

sediment balance in the San Juan - Colorado River system, before and after
Route 1856 construction............................................................................................80

138 Annex 4

List of Tables

Table 1. Properties of the hydrological gauging stations located in the
San Juan /
Colorado Rivers and in the hydrological-sediment stations located within the Costa
Rican basins draining to the San Juan River..........................................................4

Table 2. Properties of the sediment gauging stations in the Costa Rican basins
draining to San Juan River.....................................................................................7

Table 3. Discharge from Costa Rican river basins draining to the San Juan -
Colorado River (ICE, 2010)...................................................................................14

Table 4. Discharge values from Costa Rican and Nicaraguan sides, drainin
g to
San Juan - Colorado River....................................................................................14

Table 5. Maximum increase in the impermeable area of the basins draining to SJR

from C. Rica..........................................................................................................17

Table 6. Discharge regime for the microbasins draining to the San Juan R
iver,
modelled using HEC-HMS from 1976 to 2013, or conditions with and without the
presence of Route 1856........................................................................................18

Table 7. Discharge regime for all the basins (micro and macro) draining to the San

Juan River. Times series generated from 1971 to 2006 for pre - and post-Route
1856 conditions.....................................................................................................20

Table 8. Estimate sediment yields for Costa Rican basins...................................22

Table 9. Estimate sediment yields for Nicaraguan basins ....................................24

Table 10. Total annual sediment load (including suspended and bed loads
)

produced by the Lake Nicaragua and the basin system draining to the San
Juan
River......................................................................................................................27

Table 11. Corrected annual loads for Lake Nicaragua and the basin system
draining to San Juan River...................................................................................28

Table 12. Potential sediment increments to the San Juan River sediment load due

to construction of Route 1856 (basin discretized).................................................30

Table 13. Sediment yield increments to the San Juan River sediment load due to
construction of Route 1856 (basin discretized).....................................................31

139Annex 4

List of Figures

Figure 1. Hydrological/sediment stations located in Costa Rican basins d
rainin g to
the San Juan River and in the main stream of the San Juan River. ......................3

Figure 2. Mean monthly discharge recorded in fourteen gauging stations p
roperty
of ICE, located in three main river basins and at San Juan and Colorado rivers....6

Figure 3. Suspended sediment (SS) rating curves for La Trinidad (01 -03) and

Delta Colorado (11-04) gauging stations ................................................................8

Figure 4. Suspended sediment (SS) rating curves for Delta Colorado (11 -04)
gauging stations, grouped by climatic season ........................................................9

Figure 5. Mean annual suspended sediment load at La Trinidad station (0
1 -03),
which is located directly in the San Juan River; compared to the weighte
d

estimation of the respective load in the San Juan River, obtained from the
measurements at Delta Colorado station (11-04), which is located in the Colorado
River just after the bifurcation of these two rivers.................................................10

Figure 6. Frequency distribution of the sand percentage for all bed -load samples.
..............................................................................................................................11

Figure 7. Bed-load sediment rating curve for part icles larger than 0.063 mm at the
Delta Colorado (11-04) station..............................................................................12

Figure 8. Streamflow and bed-load sediment load regimes: Station 11 -04 Delta
Colorado (Dec 2010 - Jul 2013)...........................................................................12

Figure 9. Bed-load sediment rating curve for particles larger than 0.063 mm.

Lower San Juan River...........................................................................................13

Figure 10. Streamflow and bed -load sediment load regimes: Lower San Juan
River (Dec 2010 - Jul 2013).................................................................................13

Figure 11. Discharge balance in the San Juan - Colorado River system. ............15

Figure 12. Tributary basins draining to the San Juan River..................................16

Figure 13. Discharge regime for the microbasins draining to the San Juan River,
modelled using HEC-HMS from 1976 to 2013, for conditions with and without the
presence of Route 1856........................................................................................19

Figure 14. Discharge regime for all the basins (micro and macro) drain
ing to the
San Juan River. Times series generated from 1971 to 2006 for pre - and post-

Route 1856 conditions. .........................................................................................20

Figure 15. Specific sediment yields for Costa Rican basins draining to the San
Juan River.............................................................................................................22

Figure 16. Total sediment yields for Costa Rican basins draining to the S
an Juan
River......................................................................................................................23

Figure 17. Delivery ratios for Costa Rican basins draining to the San Ju
an River.
..............................................................................................................................23

Figure 18. Specific sediment yields for Nicaraguan basins draining to th
e San
Juan River.............................................................................................................24

Figure 19. Total sediment yields for Nicaraguan basins draining to the S
an Juan

River......................................................................................................................25

Figure 20. Delivery ratios for Nicaraguan basins draining to the San Juan River. .
..............................................................................................................................25

140 Annex 4

Figure 21. Potential erosion from the r oad bed and cut and fill slopes due to
construction of Route 1856 (displayed by tributary basin, with the length of the

road located in each basin indicated for context)..................................................30

Figure 22. Sediment yields to the San Juan River due to construction of
Route
1856 (displayed by tributary basin, with the length of road located in each basin
indicated for context).............................................................................................31

Figure 23. Average annual sediment balance prior to construction of Rout
e 1856. .

..............................................................................................................................32

Figure 24. Average annual sediment balance post construction of Route 1856. ica.
..............................................................................................................................33

Figure 25. Increases in average annual sediment loads input to the San J
uan –
Colorado River system due to construction of Route 1856 ..................................34

vii

141Annex 4

1. INTRODUCTION

This report has been prepared at the request of the Honourable Laura Chinchilla
Miranda, President of the Republic of Costa Rica, and the Honourable José Enrique
Castillo Barrantes, Minister of Foreign Affairs of the Republic of Costa Rica . It aims
to provide the necessary technical information required by the Government of Costa

Rica to address the claim brought against it by the Government of Nicaragua before
the International Court of Justice (ICJ) in The Hague, Netherlands.

The three primary authors of this report are as follows:

Federico Gómez Delgado is a hydrologist graduated as Civil Engineer from the
University of Costa Rica, where he also received the deg ree of Magister Scientiae in
Statistics. Later he obtained his Ph.D. degree in Hydrology at the SIBAG
HE Doctoral

School of the University of Montpellier, France. In 2002 he began workin
g in the
Department of Hydrology of the Costa Rican Institute of Electricity (ICE, by its
Spanish acronym), and later in the Planning Unit for Integrated Expansion of the
Electrical System. He was subsequently appointed as Coordinator of the Department
of Hydrology, and later on as Director of ICE’s Centre for Basic Engineeri ng Studies.

Among other posts, Mr. Gómez chaired the National Committee for Hydrology and
Meteorology, was a member of the National Meteorological Council, served as
Hydrological Advisor to the Permanent Representative of Costa Rica with WMO, and
also as served as President of the Costa Rican National Committee for UNESCO -
IHP.

Juan José Leitón Montero is a Civil Engineer currently working at the Costa Rican
Institute of Electricity (ICE). He has worked as a hydrology -hydraulic engineering
assistant for civil and hydroelectric projects since 2010, and since 2012 works as
investigator at the Hydrology Department of the Centre for Basic Enginee
ring Studies
of ICE. He graduated with honors by the University of Costa Rica (2012)
and

currently is part of the G raduate Program of Mathematics with emphasis on Applied
Math at the very same university.

Carlos Andrés Aguilar Cabrera is a senior year Civil Engineering and Theoretical
Physics student at the University of Costa Rica. He worked as assistant
for the
Department of Hydrology at ICE, and also supported the field studies as assi
stant for
CIEDES at the University of Costa Rica. He has hydraulic engineering, hy
drology

and soil laboratory experience, as part of the standard Civil Engineerin
g Programme;
the programme is deemed as substantially equivalent by the Canadian Engineering
Accreditation Board.

The Costa Rican Institute of Electricity (ICE) is a national institute
dedicated to the
identification, design, development and operation of electricity and

telecommunications projects, required to provide these kinds of services to the Costa
1

142 Annex 4

Rican society. Since the founding of the Institute in 1949, the Electrical Division has
specialized in conducting hydrological and sedimentological measurements and

studies based on world-class scientific and engineering standards, which have been
applied over time in a large number of basins and microbasins of the country.
In two of the major Costa Rican basins draining to the San Juan River, the San
Carlos and Sarapiquí river basins, ICE has built several hydroelectric facilities of

strategic importance for the country. The most relevant hydro-sedimentological
information collected by ICE over recent decades is provided in this report, along with
the data recorded for nearly three years in a gauging station deployed at Delta Costa
Rica, and the corresponding descriptive and inferential analysis of all these data. In

addition, in accordance with ICE’s knowledge and understanding of the hydro -
sedimentological processes that c haracterize the river basins of this region , the
report includes a chapter establishing the annual discharge (streamflow) balance in
the San Juan - Colorado River system, based on direct measurements performed by
both ICE and the Nicaraguan Institute of Territorial Studies (INETER). An analysis of

the hydrological regime of Costa Rican basins draining to the San Juan River is also
presented, along with a particular hydrological assessment of Route 1856 within this
framework. The distributed erosion and sediment transport processes are modelled
using a high-level scientific methodology, which benefits from the sedimentological
observations carried out over decades in the Costa Rican basins to calibrate the

model, and then estimations of sediment yield for the river basins draining to the San
Juan River are produced. Finally, a sediment balance is presented for the entire
basin system, including a specific analysis of Route 1856.
Throughout all the chapters of this report it becomes clear that the San Juan River

basin is a large system in the local context , which is being governed by large-scale
natural processes at both time and space scales. The natural variability of these
processes implies that, according to scientifically sound methodologies, they can only
be quantified within certain bounds of uncertainty. Different sections of this report

demonstrate that the hydrological and sedimentological effects of the construction of
Route 1856 are not only minuscule in comparison with the order of magnitude of the
natural processes that characterize the San Juan River system, but that they even
fall well within the margin of error of the quantification of such natural processes,
meaning that they are undetectable and th at the Road’s impacts on water flows,

sediment loads, sediment concentrations, sedimentation, and the morpholo
gy of the
San Juan River are not just insignificant, they are, in practice, indiscernible.

143Annex 4

2. HYDROLOGY AND SEDIMEN T MEASUREMENTS IN

THE SAN JUAN - COLORADO RIVER SYSTEM

This chapter describes the different hydrological and sediment measurements that

have been carried out by ICE in the different river basins draining to the
San Juan - Colorado River Basin System.

2.1. Study area and gauging stations

Over time, ICE has installed twelve discharge and sediment flow gauging stations in

three out of seven of the Costa Rican basins draining to the
San Juan River: Frío River basin, San Carlos River basin and Sarapiquí River basin.
In addition, three discharge stations have been deployed directly in the San Juan
River, while by the end of 2010 ICE installed a discharge/sediment gauging station in
the Colorado River, just downstream of the bifurcation of the San Juan River at Delta

Costa Rica. The location of all these sixteen stations, as well as the delineation o
f
the seven major Costa Rican basins draining to the San Juan River, are i
ndicated on
Figure 1.

Figure 1. Hydrological/sediment statiolocated in Costa Ricanbasins draining tothe
San Juan River and in the main stream of the San Juan River.
3

144 Annex 4

In addition, for each of these stations, relevant information such as the tributary
drainage area, the time period during which the measurements were carrie
d out and

the mean discharge recorded in the river over the correspond ing period, among
others, are presented in Table 1.

Table 1. Properties of the hydrological gauging stations located in the San Juan / Colorado
Rivers and in the hydrological -sediment stations located within the Costa Rican basins

draining to the San Juan River
Station DA Record Q Active to
Station Name River Basin 2 3 -1
codea (km )c period c (m sc) date
01-01 San Carlos San Juan San Juan 30 306 1965-1986 297 No
01-02 a El Castillo San Juan San Juan 32 819 d 1971-1981 422b No
b
e 1997-1998 e
01-03 La Trinidad San Juan San Juan 38 730 1973-1976 1123 No

11-04 Delta Colorado Colorado San Juan - 2010-2013 1026 Yes
12-03 Puerto Viejo Sarapiquí Sarapiquí 845 1968-1999 113 No

12-04 Veracruz Toro Sarapiquí 191 1971-2013 26 Yes
12-05 Bajos del Toro Toro Sarapiquí 73 1985-1996 6,7 No

12-06 Toro Toro Sarapiquí 41 1993-2013 4,4 Yes

12-11 San Miguel Volcán Sarapiquí 59 1998-2002 11 Yes
2010-2013
12-13 Río Segundo Segundo Sarapiquí 17 1999-2013 2,7 Yes

14-02 Jabillos San San Carlos 552 1963-2013 51 Yes
Carlos
14-04 Terrón Colorado San San Carlos 1556 1968-2008 166 No
Carlos
f
14-05 Peñas Blancas Peñas San Carlos 293 1968-2013 35 Yes
Blancas
14-20 Pocosol Peñas San Carlos 124 1980-2013 19 Yes

Blancas
16-02 Guatuso Frío Frío 253 1969-2013 28 Yes
16-05 Santa Lucía Venado Frío 34 1982-2013 3,9 Yes

Note: DA = drainage area; Q = mean annual discharge.
aStations installed, coded and operated by the INETER of Nicaragua. bINETER (2001) .
c d e f
INETER (2002) . INETER (2006) . ICE (1973) . Since 2002 the discharges are regulated by the
Peñas Blancas hydropower plant.

2.2. Mean monthly discharge for ICE’s hydrological stations

For the periods indicated in Table 1, the mean monthly discharge in the river at each

station was calculated and represented in Fig. 2. In particular, a special survey was
carried out at the Delta Colorado station, where thirty discharge samples have been

taken between December 2010 and June 2013.

145Annex 4

Mean
discharge:
Sta7on
01-‐03
Mean
discharge:
Sta7on
11-‐04

)
00
)
00

-
s -
s
3 1500
3 1500

1000
1000

500
500

Discharge
(m Discharge
(m
0
0

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dic
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dic

Mean
discharge:
Sta7on
12-‐03
Mean
discharge:
Sta7on
12-‐04

200
40

-‐1 -‐1
3
150
3
30

100
20

50
10

Dischar0
(m Disch0

(m

Jan
Feb
Mar
Apr
Jun
Jul
Aug
Sep
Oct
Nov
Dic
Jan
Feb
Mar
Apr
Jun
Jul
Aug
Sep
Oct
Nov
Dic

May
May

Mean
discharge:
Sta7on
12-‐05
Mean
discharge:
Sta7on
12-‐06

-‐1
-‐1

3
s8
3
s
6

6

4
4

2
2

Discharge
(m Discharge
(m
0
0

Jan
Jun
Jul
Dic
Jan
Jun
Jul
Dic

Feb
Mar
Apr
May
Aug
Sep
Oct
Nov
Feb
Mar
Apr
May
Aug
Sep
Oct
Nov

Mean
discharge:
Sta7on
12-‐11
Mean
discharge:
Sta7on
12-‐13

)

)

-
20
-
4

3 3
15
3

10
2

5
1

Discharge
(m Discharge
(m
0
0

Jul
Jul

Jan
Feb
Mar
Apr
May
Jun
Aug
Sep
Oct
Nov
Dic
Jan
Feb
Mar
Apr
May
Jun
Aug
Sep
Oct
Nov
Dic

Mean
discharge:
Sta7on
14-‐02
Mean
discharge:
Sta7on
14-‐04

)
0
)
0

-‐1 -‐1
3
s80
3
200

60
150

40
100

Discharge
(m Discharge
(m
0
0

Jan
Feb
Mar
Apr
Jun
Jul
Aug
Sep
Oct
Nov
Dic
Jan
Feb
Mar
Apr
Jun
Jul
Aug
Sep
Oct
Nov
Dic

May
May

146 Annex 4

Mean
discharge:
Sta7on
14-‐05
Mean
discharge:
Sta7on
14-‐20

60
30

-‐1 -‐1
3
s
3
s

40
20

30
15

20
10

Discharge
(m Discharge
(m
0
0

Jan
Feb
Apr
Jun
l
Sep
ct
Dic
Jan
Feb
Apr
Jun
l
Sep
ct
Dic

Mar
May
Aug
Nov
Mar
May
Aug
Nov

Mean
discharge:
Sta7on
16-‐02
Mean
discharge:
Sta7on
16-‐05

)

)

-
s -
s
3 40
3 6

30

4

20

10
2

Discharge
(m Discharge
(m
0
0

Jan
Feb
Mar
r
Jun
l
Aug
p
ct
Nov
ic
Jan
Feb
Mar
pr
Jun
ul
Aug
ep
t
Nov
ic

May
May

Figure 2. Mean monthly discharge recorded in fourteen gauging stations property of ICE,
located in three main river basins and at San Juan and Colorado rivers.

2.3. Suspended sediment load from Costa Rican basins draining to
the San Juan River

Both mean monthly suspende d sediment (SS) loads and annual SS loads were

calculated for the fourteen stations which are property of ICE and which are located

within the basins draining to the San Juan River. These loads are based on the SS
rating curves created from the S S sample data collected over time by ICE. The

samples were collected applying standard sampling procedures at each of
the sites
where there is an ICE gauging station.

With the exception of stations 01-03 and 11 -04, the information described above can

be found in Table 2 and in APPENDIX A for all ICE gauging stations reported in

Table 1. For the specific purposes of comparing the historical SS concentrations
and
loads measured at La Trinidad (01-03) station (with recording period 1973-1976) with

those measured in Delta Colorado (11-04) station (recording period: 2010-2013), this
information is presented separately in the sections 2.3.1 and 2.3.3. The purpose of

this comparison is to assess whether there is a statistically significan
t difference

between the SS concentrations recorded at these gauging sites that are v
ery close to
each other, in the subsequent channels of San Juan and Colorado Rivers. The

comparison is performed over the same river system, in two very different periods: in
the San Juan River long before Route 1856 construction (during the seventies), and

in the Colorado River just after the road construction (from December 2010

onwards).

147Annex 4

Table 2. Properties of the sediment gauging stations in the Costa Rican basins draining to
San Juan River

Station Station name Basin River No. of Sampling SSL-1 S-1 -1
code samples period (t yr) (t ha yr )
01-03 La Trinidad San Juan San Juan 12 1974-1976 7 995 000 1.92
11-04 Delta Colorado San Juan Colorado 31 2010-2013 5 981 000a -

12-03 Puerto Viejo Sarapiquí Sarapiquí 264 1970-1998 165 500 1.96
12-04 Veracruz Sarapiquí Toro 285 1972-2012 101 000 5.29

12-05 Bajos del Toro Sarapiquí Toro 137 1985-2001 50 000 6.85
12-06 Toro Sarapiquí Toro 117 1995-2010 20 500 5.00

12-11 San Miguel Sarapiquí Volcán 47 1998-2010 23 000 3.90
12-13 Río Segundo Sarapiquí Segundo 25 1999-2009 1 800 1.06

14-02 Jabillos San Carlos San Carlos 338 1967-2011 600 000 10.9
14-04 Terrón Colorado San Carlos San Carlos 53 1998-2009 1 300 000 8.35

14-05 Peñas Blancas San Carlos Peñas Blancas 308 1970-2011 157 000 5.36
14-20 Pocosol San Carlos Peñas Blancas 278 1980-2012 358 000 28.9

16-02 Guatuso Frío Frío 361 1970-2012 60 800 2.40
16-05 Santa Lucía Frío Venado 153 1984-2011 8 100 2.38

aote: SSL = suspended sediment load; SY = specific yield.
This value is measured at the Colorado River. Hence, not directly comparable to the SS load at
La Trinidad station (01-03).

2.3.1 Suspended sediment rating curves for the stations 01 -03 La

Trinidad and 11-04 Delta Colorado

Suspended sediment (SS) samples were taken by ICE in two stations (La Trinidad

01-03 and Delta Colorado 11-04, APPENDIX D and Fig. 1), which are conveniently
located for the purpose of estimating possible changes in the Discharge - SS

Concentration pattern in the San Juan - Colorado River system. Figure 3 presents
the SS rating curves obtained for both gauging stations, along with their respective
95% confidence prediction intervals.

Given that the relationship between Discharge and SS Concentration is not a direct

function of the total discharge, and also that suspen ded sediment concentrations do
not suffer any alteration because of the bifurcation of the San Juan Riv
er into Lower

San Juan and Colorado Rivers (because the average SS Concentration could be
considered homogeneous in the San Juan and Colorado Rivers) , it is expected that
any significant changes in the Discharge - SS Concentration relationship could be

evidenced by comparing the respective rating curves in these two gauging stations .
However, according to Fig. 3, the rating curves for the two stations are remarkably

similar, demonstrating that the Discharge - Sediment dynamics do not vary either in
space (from La Trinidad site to Delta Colorado site) or in time (comparing

measurements made during the 1970s to those made since December 2010 ). In
addition, due to t he high variability of the relationship between Discharge and SS

Concentration, the uncertainty of the rating curves is very high, which
is translated
into very wide confidence bounds around the mean predicted value s represented by
best-fit regression curves in Fig. 3.

148 Annex 4

8‡‡

ST‰T‹ŒŽ ‡‚-‡3 ‘a Trinidad (J‰Ž ‚9„… -m Š‰R ‚9„ƒ)
„‡‡
-1 ST‰T‹ŒŽ ‚‚-‡… Delta Coloradom (D’C †‡‚‡ - J“Ž †‡m‚3)

ƒ‡‡
‚ „ 0.150…†
‡² „ 0.…0493
5‡‡

…‡‡ ‚ „ 0.149ˆ†
‡² „ 0.4505ƒ

3‡‡

†‡‡

Sediment concentratifon (mg l
‚‡‡

‡

‡ …‡‡ 8‡‡ ‚†‡‡ ‚ƒ‡‡ †‡‡‡ †…‡‡ †8‡‡ 3†‡‡
Discharge (m s )1

Figure 3. Suspended sediment (SS) rating curves for La Trinidad (01-03) and Delta Colorado

(11-04) gauging stations. The two continuous lines represent the regression models fitted to
the Discharge – SS Concentration data sets, for bot h gauging stations. Dotted lines represent
the 95€ confidence prediction interval of the mean predicted response given b‚ each of the
regression models.

The fact that the confidence regions of both rating curves overlap completely (i.e. the
areas between the corresponding dotted lines in Fig. 3) indicates that with 95%
confidence there is no statistical evidence that these two rating curves are different,

which means that there is no scientific evidence to support any hypothesis
suggesting a change in the natural relationship between Discharge and Suspended

Sediment Concentration along the San Juan - Colorado River system between the
two sampling periods€ one long before the construction of Route ‚85ƒ (‚9„…-‚9„ƒ)
and the other aftemr the constructionm of the road (†‡‚‡-m†‡‚3).

ƒ.3.ƒ Seasonal behavior of the suspended sediment concentrations at

Delta Colorado station (11-04)

The suspended sediment (SS) samples from Delta Colorado (‚‚-‡…) station were
also grouped by climatic seasonˆ this is, the dry Season (from January to ‰pril) and
the rainy season (from Šay to December). Figure … presents the corresponding SS

rating curves. ‰ccording to the respective 95% confidence intervals, there is no
statistical evidence to support the proposition that dry and rainy seasons present

different Dischargme - SS Concentrationm relationships.

149Annex 4

Figure 4. Suspended sediment (SS) rating curves for Delta Colorado (1-04) gauging stations ,
grouped by climatic season . The two continuous lines represent the regression models fitted
to the Discharge – SS Concentration relationships for dry (JAN -APR) and rainy (MAY -DEC)
seasons. Dotted lines represent the 95% confidence prediction interval of the mean predicted
response given by each of the regression models.

2.3.3 Mean annual suspended sediment load at La Trinidad (01 -03)
and Delta Colorado (11-04) gauging stations

The SS loads in San Juan River were accumulated for two very different ti
me
periods: the first between 1974 and 1976 (La Trinidad station, 01-03) and the second
between 2010 and 2012 (Delta Colorado station, 11 -04, with data weighte d to

estimate SS load just in the San Juan River).
The annual suspended sediment loads were similar in both record periods,
with a
-1
mean value of 7 -15 000 t yr , and a 95% confidence interval from 5 405 000 to
10 585 000 t yr , as the estimated annual SS load in the San Juan River according
to La Trinidad station (01-03) for the period 1974 -1976; and a mean value of
6 573 000 t yr , with 95% confidence interval from 5 181 000 to 7 966 000 t yr , as -1

the estimated SS load in the San Juan River according to Delta Colorado station
(11-04) between 2010 and 2012.

The overlapping 95% confidence intervals (represented by the whiskers in Fig. 5)
around both mean annual loads, indicate that there is no statistical evi
dence that the
mean annual SS loads are significantly different before and after construction of

Route 1856.

150 Annex 4

12000000

St. 01-03 La Trinidad
10000000
-1 St. 11-04 Delta Colorado

8000000

6000000

4000000
San Juan River (t yr

2000000
Annual Suspenden Sediemnt Load

0 Station

Figure 5. Mean annual suspended sediment load at La Trinidad station (01 -03), which is located

directly in the San Juan Rivercompared to the weighted estimation of the respectiveoad in
the San Juan River , obtained from the measuremen ts at Delta Colorado station (11 -04), which
is located in the Colorado Riverjust after the bifurcation of thetwo rivers. The whiskers
represent the bounds of a 95% confidence interval for both annual means.

2.4. Bed-load sediment from Costa Rican basins draining to the
San Juan River

One hundred and twenty two bed-load samples were taken between December 2010
and June 2013 at three different sites: the mouths of San Carlos and Sarapiquí
Rivers, and the Delta Colorado station (11 -04). All these samples were analysed in

the Chemical Laboratory of the Department of Hydrology and the corresponding
particle size distributions are reported in the APPENDIX E. The analysis of the
samples demonstrates that in this river system the bed -load sediment is almost

entirely composed of sand (Fig. 6). For that reason, the Einstein bed-load func tion
for sediment transport (Einstein, 1950) was used to estimate the annual bed -load at
two sites: the Lower San Juan River and the Colorado Riv er, just after the bifurcation

of the main channel of San Juan River. The detail of the calculations can be found in
APPENDIX F.

151Annex 4

100
90

60
50

Rel20ive frequency (%)
10

0
10 30 50 70 90

Class (% of sand)

Figure 6. Frequency distribution of the sand percentage for all bed-load samples.

Applying the Einstein function to the 115 bed-load samples taken at Delta Colorado

(11-04) station, a d 65mean value of 0.584 mm, and hydraulic properties representing
the cross section of the 11-04 station, a bed-load sediment rating curve was created

for all particles with a size larger than 0 .063 mm (Fig. 7). Then the bed -load
sediment regime was calculated (Fig. 8) based on both the bed-load rating curve and

the hydrograph for the 11-04 station reported in the APPENDIX C.
The resulting bed-loads are: 2 488 000 t yr flowing through the Colorado River, with
-1 -1
estimated lower and upper variability bounds of 2 340 000 t yr and 2 595 000 t yr .
In addition, a bed-load of 71 000 t yr -1 was estimated to flow through the Lower San
-1 -1
Juan River, with lower and upper bounds of 66 600 t yr and 73 800 t yr ,
respectively. Therefore, the total bed-load in the main channel of the San Juan River

should be equal to the sum of the loads estimated for the Colorado and Lower San
Juan Rivers, which amounts to 2 559 000 t yr . -1

152 Annex 4

ˆ0000

60000

‰instein for D Š 0‚0n63 mm
) †0000 Discharge - Σ(‹t ƒt€ range
-1 Œest fit eŽuation
40000

30000
Σ‚t ƒt (t d
20000

10000

0
0 †00 1000 1†00 2000 2†00 3000

Streamflow (m s ) -1

Figure 7. Bed-load sediment rating curve for partic les larger than 0.063 mm at the
Delta Colorado (11-04) station.

#!!! "!!!!!!

"&!! (&!!!!

"!!! &!!!!!

&!! #&!!!!

! !

Figure 8. Streamflow and bed-load sediment load regimes: Station 11-04 Delta Colorado
(Dec 2010 - €ul 2013).

The same methodology was employed to estimate the bed-load transport capacity for
particles larger than 0.063 mm in the Lower San Juan River. A hydrograph for the

Lower San Juan was estimated from the hydrograph recorded at the Delta Colorado
station (11-04€‚ applying a discharge capacity ratio based on the discharge balance
to be presented in Chapter 3. ƒn addition‚ it was assumed that „ust downstream of

the bifurcation the particle si…e distribution remains similar in the cross sections of
Colorado and Lower San Juan Rivers‚ which allows use in the latter of the same

value of d 6†recorded at the Delta Colorado (11-04€ station. ‡inally‚ a value of 100 m

153Annex 4

was directly extracted from recent, georeferenced satellite images, as the
representative width of the San Juan River aht the site of interest.

The bed-load sediment rating curve for particle sizes larger than 0.063 mm was then

produced for the Lower San Juan River (Fig. 9€, and this was then used to estimate
the bed-load regime, which is presented in Fig. 10 along with the corresponding

discharge regime. ‚ccording to this, the annual bed-load sediment in the Lower San
Juan River amounts tho ƒ1 000 t yr -1.

„000

1†00
1600

1…00 ˆinstein for ‰ Š 0,0h63 mm
-1 ‰ischarge - Σ(‹t Œt€ range
1„00
Žest fit e‘uation
1000
†00
Σ€t ‚t (t d
600

…00

„00
0

0 ‡0 100 1‡0 „00 „‡0 300
Streamflow (m s ) -1

Figure 9. Bed-load sediment rating curve for partic les larger than 0.063 mm. Lower San Juan
River.

#!! #&!!!

"'! #!!!!

"#! "&!!!

)! "!!!!

%! &!!!

! !

Figure 10. Streamflow and bed-load sediment load re gimes: Lower San Juan River
(Dec 2010 - Jul 2013).

154 Annex 4

3. DISCHARGE BALANCE IN THE SAN JUAN -

COLORADO RIVER SYSTEM

A discharge balance was produced for the San Juan - Colorado River system, taking

into account the discharge inputs from the Lake Nicaragua and all the ma
in flow
tributaries from Costa Rica and Nicaragua. For this purpose, the mean annual
discharge presented in Table 1 was used, either directly: for the first three gauging

stations (located in the San Juan River) ; or reprocessed using the Area-Precipitation
method in order to estimate the input discharge (from the Costa Rican drainage

basins to the San Juan River). The results of this latter process are reported in
Table 3 below.

Table 3. Discharge from Costa Rican river basins draining to the San Juan - Colorado River
(ICE, 2010)

Area Mean annual discharge
Basin (km²) (m³ s ) %

Frío River 1556 112 14
Pocosol River and others (Medio Queso, etc.) 1256 58 7

Infiernito River 561 36 5
San Carlos River 2735 209 27

Cureña River 328 25 3
Sarapiquí River 2762 343 44

Total 9198 783 100
aThe area anddischarge of San CarloRiver basin exclude the sub-basin of Lake ArThe area and
discharge of Sarapiquí River basin were corrected in order to takthe change in the course of the
Sucio River, which currently drains to Sarapiquí basin.

Combining the discharge information provided in Tables 1 and 3, the discharge
balance of the San Juan - Colorado River system is presented in Fig. 11. In addition,

a summary of the inputs from Lake Nicaragua, Costa Rican and Nicaraguan ba
sins is
given in Table 4.

Table 4. D ischarge values from Costa Rican and Nicaraguan sides , draining to
San Juan - Colorado River

Mean annual discharge
Source -1 Percentage (%)
(m³ s ) ELN
ILN
Lake Nicaragua 185a 16 -

Costa Rican basins 783 70 83
Nicaraguan basins 155b 14 17

Total 1123 100 100
Note: ILN = including Lake Nicaragua; ELN = excluding Lake Nicaragua.
aThis value was estimated as the difference betwdischarge of San Juan River at San Carlos station
(INETER, 2002) and the input fr om the Frío River basin (ICE, 2010 ). This value was estimated as the difference
between the discharge of San Juan River at La Trinidad station (ICE, 2011) and the sum of inputs from Lake
Nicaragua and from all Costa Rican river basins

155Annex 4

system

River

-olorado

Discharge balance in the San Juan

11.

Figure

156 Annex 4

4. HYDROLOGICAL REGIME IN THE TRIBUTARY
BASINS DRAINING FROM COSTA RICA TO THE
SAN JUAN R IVER, BEFORE AND AFTER THE

CONSTRUCTION OF ROUTE 1856

In order to establthe hydrological (discharge) regime of the system of basins
draining to the San Juan River from Costa Rica, it was necessary to identify not only
the main river basins, but also the minor ones flowing directly tthe
San Juan River. Figure 12 presents this hydrological system, which is constituted by
seven major basins and eighty minor basins, the latter being highlighted in grey. The
delineation of the main basins was based on a digital elevation model, while for the

minor basins the Hydrodem package (Leblois and Sauquet, 2000) was applied with
the purpose of manually correct ing the flow paths in flat regions, a frequent problem
for the delineation of small basins near to natural river banks or floodplains. Once all
these basins were identified, an analysis of the increase in the impermeable area of
each basin due to the construction of Route 1856 was carried out (to be presented in
Section 4.1), to determine pre- and post-Route 1856 hydrological regimes for all the
rivers and streams flowing to tSan Juan River from Costa Rican basins
(Section 4.2).

Figure 12. Tributary basins draining to the San Juan River.

157Annex 4

4.1. Impermeable areas in the basins draining to the RSJ

Table 5 presents the increase in the impermeable area s due to construction of Route
1856 (conservatively assuming that the road surface is 100% impermeable) for all basins

and microbasins d raining to the San Juan River from Costa Rica (Fig. 12). To do this, a

digital polygon was used to represent the Route (including not just the road surface but
the whole right -of-way). The overall increase in the impermeable area for all (major and

micro) basins added together amount to only 0.08%.

Table 5. Maximum increase in the impermeable area of the basins draining to SJR from C. Rica

Basin Area Imperm. Area Change Basin Area Imperm. Area Change
(km2) (km 2) (%) (km 2) (km2) (%)
Microbasins between Mojón II and Delta C.R. Microbasins between Mojón II and Delta C.R.

Basin 01 2.00 0.109 5.40 Basin 46 0.88 0.012 1.33
Basin 02 1.05 0.067 6.40 Basin 47 0.42 0.005 1.25
Basin 03 0.41 0.014 3.30 Basin 48 0.70 0.006 0.80

Basin 04 1.05 0.047 4.50 Basin 49 0.39 0.001 0.36
Basin 05 1.45 0.019 1.30 Basin 50 1.68 0.030 1.76
Basin 06 2.20 0.030 1.40 Basin 51 0.61 0.020 3.33
Basin 07 0.93 0.006 0.60 Basin 52 1.57 0.011 0.69

Basin 08 3.30 0.124 3.70 Basin 53 0.50 0.007 1.47
Basin 09 2.68 0.033 1.20 Basin 54 0.92 0.011 1.20
Basin 10 0.40 0.021 5.30 Basin 55 0.56 0.005 0.96

Basin 11 1.69 0.078 4.60 Basin 56 4.93 0.080 1.63
Basin 12 1.12 0.122 10.90 Basin 57 1.66 0.034 2.08
Basin 13 0.69 0.097 14.00 Basin 58 1.60 0.033 2.07
Basin 14 0.61 0.073 12.10 Basin 59 1.16 0.037 3.16

Basin 15 8.12 0.117 1.40 Basin 60 1.47 0.028 1.88
Basin 16 1.01 0.025 2.40 Basin 61 1.70 0.092 5.42
Basin 17 0.83 0.025 3.00 Basin 62 0.76 0.029 3.78

Basin 18 1.08 0.067 6.20 Basin 63 0.40 0.013 3.26
Basin 19 9.77 0.081 0.80 Basin 64 3.53 0.035 0.98
Basin 20 0.68 0.076 11.30 Basin 65 2.83 0.093 3.29
Basin 21 5.24 0.055 1.00 Basin 66 2.43 0.051 2.10

Basin 22 0.68 0.050 7.40 Basin 67 0.38 0.016 4.34
Basin 23 2.09 0.052 2.50 Basin 68 1.26 0.067 5.31
Basin 24 0.86 0.009 1.00 Basin 69 0.68 0.029 4.24

Basin 25 0.63 0.010 1.60 Basin 70 1.49 0.004 0.30
Basin 26 5.50 0.018 0.30 Basin 71 1.58 0.055 3.47
Basin 27 10.27 0.006 0.10 Basin 72 1.48 0.064 4.32
Basin 28 0.91 0.040 4.40 Basin 73 2.08 0.016 0.77

Basin 29 9.12 0.035 0.40 Basin 74 1.62 0.006 0.35
Basin 30 1.65 0.109 6.60 Basin 75 2.63 0.100 3.80
Basin 31 4.37 0.040 0.90 Basin 76 0.40 0.006 1.56

Basin 32 1.49 0.017 1.20 Basin 77 2.21 0.005 0.23
Basin 33 0.56 0.005 0.87 Basin 78 0.58 0.003 0.47
Basin 34 0.87 0.033 3.84 Basin 79 0.69 0.040 5.74
Basin 35 0.76 0.036 4.70 Basin 80 1.32 0.025 1.91

Basin 36 0.44 0.028 6.35 Major Costa Rican basins along San Juan River
Basin 37 1.71 0.063 3.70 Frío River 1 746 0.00 0.00
Basin 38 1.14 0.039 3.45 Pocosol River 1 224 0.93 0.08

Basin 39 1.07 0.031 2.92 Infiernito River 609 1.99 0.33
Basin 40 0.71 0.041 5.72 S. Carlos River 2 644 0.34 0.01
Basin 41 1.88 0.051 2.73 Cureña River 343 0.76 0.22
Basin 42 0.97 0.020 2.03 Sarapiquí River 2 743 0.06 0.00

Basin 43 0.51 0.034 6.63 Chirripó River 255 0.41 0.16
Basin 44 1.15 0.009 0.77 Summary
Basin 45 0.40 0.003 0.74 Total 9564 4.50 0.05

158 Annex 4

4.2. Hydrological regime of all the rivers and streams flowing to the

San Juan River from Costa Rican basins : Evaluation of Route
1856

Synthetic hydrographs were generated for the period 1976-2013 based on El Bum
(69-578) station’s daily precipitation series using the HEC-HMS model (U.S. Army

Corps of Engineers), the Curve Number (CN) runoff-precipitation relationship model
of the S oil Conservation Service (SCS) and the unit hydrograph proposed by that

same agency. Curve Numbers were estimated for the conditions before and after
Route 1856 construction according to land use maps provided by ICE and

Dr. Andreas Mende, and reference tables proposed by Hawkins et al. (2009) as an
area-weighted average for each basin; antecedent moisture condition (ACM) II,

corresponding to average conditions, was selected . For each microbasin, initial
abstractions (Ia) and time of concentration (tc) were calculated based on CN and

morphometric parameters (area, average slope, length of the longest flow path, etc.);
lag time (tg) was assumed as 0.6 tc, according to SCS Lag Time equation.

In order to quantify hydrological impacts due to Route 1856 construction, discharge

regimes were calculated for the microbasin system in Costa Rica between Mojón II
and the Delta based on El Bum (69-578) station’s 38-year daily precipitation series .

Two hydrological models were constructed to perform hydrologic simulation of
system’s response to rainfall with and without Route 1856 . Table 6 and Fig. 13

present the results of these simulations and illustrate any hydrological impact to be
expected due to construction of Route 1856 , in terms of the monthly discharge

regime.

Table 6. Discharge regime for the microbasins draining to the San Juan River, modelled using
HEC-HMS from 1976 to 2013, or conditions with and without the presence of Route 1856

Discharge without Road (m 3s ) Discharge with Road (m s )-1 Difference
Month 3 -1
Mean value Error bound Mean value Error bound (m s )
January 16.46 1.13 16.47 1.42 3.81 x 10-3
-4
February 11.63 0.81 11.63 1.20 6.39 x 10
March 8.06 0.64 8.06 1.01 1.45 x 10-4
-4
April 8.87 0.76 8.87 1.16 1.03 x 10
-4
May 13.70 0.86 13.70 1.01 1.38 x 10
June 20.46 1.23 20.46 1.43 1.37 x 10-4
-4
July 25.84 1.31 25.84 1.59 1.69 x 10
August 20.05 1.10 20.05 1.33 5.51 x 10-5
-5
September 15.04 0.90 15.04 1.35 3.76 x 10
October 17.05 1.02 17.05 1.20 2.72 x 10-5
-5
November 24.45 1.32 24.45 1.46 2.76 x 10
December 23.09 1.35 23.09 1.54 1.50 x 10-5

159Annex 4

30
) Simulation without the road
-s
325 Simulation with the road

Monthly average streamflow (m
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

Figure 13. Discharge regime for the microbasins draining to theSan Juan River , modelled

using HEC-HMS from 1976 to 2013 , for conditions with and without the presence of Route
1856.

In order to estimate the discharge regimes of the major Costa Rican basin s along

San Juan River prior to construction of the Road, monthly discharge time series from
four stations, over the time period 1971-2006, were studied: Guatuso (16-02) station,
located in the Frio River basin; Terrón Colorado (14-04) station, located in the San

Carlos River basin; and, finally, Puerto Viejo (12 -03) and Veracruz (12-04) stations,
both located in the Sarapiquí River basin. The regime for the whole system was
calculated based on the individual regimes of these four catchments and then

corrected by using the Area-Precipitation method and a factor derived from the
discharge balance presented in Chapter 3. The discharge regime of the major Costa

Rican basins along San Juan River, corresponding to post Route 1856 conditions,
was calculated by adding the absolute differences in discharge, estimated for the
microbasin system, to Pre-Route regime estimated previously. The results are

shown in Table 7 and Fig. 14.

160 Annex 4

Table 7. Discharge regime for all the basins (micro and macro) draining to the San Juan River.
Times series generated from 1971 to 2006 for pre- and post-Route 1856 conditions

Discharge (m s )-1
Month Absolute 3 Relative
PreRoute PostRoute Error bounds difference (m /s) difference (%)
-3 -4
January 765.30 765.44 103.7 3.81 x 10 4.97 x 10
February 535.56 535.59 54.8 6.39 x 10-4 1.19 x 10-4

March 400.64 400.64 34.9 1.45 x 10-4 3.62 x 10-5
-4 -5
April 360.78 360.79 40.2 1.03 x 10 2.86 x 10
May 561.09 561.09 76.8 1.38 x 10-4 2.45 x 10-5

June 781.79 781.80 59.2 1.37 x 10-4 1.75 x 10-5
-4 -5
July 1000.46 1000.47 60.5 1.69 x 10 1.69 x 10
August 1001.94 1001.94 53.0 5.51 x 10-5 5.50 x 10-6

September 894.23 894.23 35.9 3.76 x 10-5 4.21 x 10-6
-5 -6
October 974.93 974.93 54.3 2.72 x 10 2.79 x 10
November 1069.41 1069.41 100.4 2.76 x 10-5 2.58 x 10-6

December 1043.77 1043.78 118.6 1.50 x 10-5 1.44 x 10-6

1400
) PreRuta surface runoff
-1
3s1200 PostRuta surface runoff

1000

800

600

400

200

Monthly avergae streamflow (m
0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

Figure 14. Discharge regime for all the basins (micro and macro) draining to the
San Juan River. Times series generated from 1971 to 2006 for pre- and post-Route 1856

conditions.

161Annex 4

5. DISTRIBUTED EROSION AND SEDIMENT YIELD I N

THE SAN JUAN - COLORADO RIVER SYSTEM

Potential soil erosion, sediment yield and delivery ratfrom major basins draining
directly to the San Juan river from bothCosta Rica (Frío, Pocosol, Infiernito, San

Carlos, Cureña, Sarapiquí y Chirripó ) and Nicaragua (Melchora, Sábalos, Santa
Cruz, Bartola, Caño Machado y Caño Las Banderas ) were estimated using the
CALSITE model ( Bradbury et al., 1993) . CALSITE (Calibrated Simulation of
Transported Erosion) is a software package that applies the USLE (Universal Soil
Loss Equation; Wischmeier and Smith, 1960):

A=R K LS CP (1)

where R = rainfall erosivity factor, K = soil erodability factor, LS = topographic factor

and CP = land use and land management factor,
to predict soil erosion within a basin together with estimation of the a
mount of
transported material which contributes to sediment yield from the basin.CALSITE

makes use of Geographic Information System (GIS) techniques to map and display
soil erosion and sources of sheet/rill sediment yield within abasin (see H.1. in
APPENDIX H). It is intended as a basin management and planning tool to identify
current sources of erosion and sediment yield and to predict the effects of changes in
land management on erosion and sedimentation. CALSITE works in three stages:
(a) the calculation of total (potential) soil erosion; (b) the calibration of sediment

delivery function using either observed sediment measurements or a predefined
delivery function;and (c) the calculation and mapping of transport of eroded
sediment or sediment yield.

Because CALSITE uses a GIS approach, map information on rainfall, land use, soils,
topography and agricultural practices was required. Digital maps of rainfall erosivity,
mean annual rainfall, land use and land management, soil erodability and digital
elevation and slope models were generated for both Costa Rican major basins and
Nicaraguan major basins draining directly to the San Juan River. Both input and
output digital maps generated for this purpose are presented inthe Section H.2 of

the APPENDIX H. Two different sediment delivery functions were calibrated using
sediment data from hydrological gauging stations located in the San Carlos and
Sarapiquí River basins. An average delivery function was then calculated and used
to estimate sediment yields across major Costa Rican and Nicaraguan basins
draining to the San Juan River.

Results for Costa Rican basins are present in Table 8, Figs. 15, 16 and 17. The
whiskers in the following graphs in each case indicate 95% confidence ba
nds.

162 Annex 4

Table 8. Estimate sediment yields for Costa Rican basins

SPE PEL SSY SY
Basin DR (t ha-1yr ) (t yr1) (t ha-1yr ) (t yr1)

Major Costa Rican river basins draining directly to the San Juan River
Frío River 0.39 3.96 691 000 1.54 269 000

Pocosol River 0.20 2.01 246 000 0.40 49 000

Infiernito River 0.38 3.35 204 000 1.28 78 000
San Carlos River 0.56 12.38 3 273 000 6.90 1 824 000

Cureña River 0.41 1.65 57 000 0.67 23 000
Sarapiquí River 0.11 15.68 4 301 000 1.67 458 000

Chirripó River 0.24 4.43 113 000 1.07 27 000

Summary for the entire Costa Rican area that drains directly to the San Juan River
Total 0.31 9.29 8 885 000 2.85 2 728 000

Note: DR = delivery ratio; SPE = specific potential erosion ; PEL = potential erosion load ;
SSY = specific sediment yield; SY = sediment yield.

8

)

-7

yr
-6

Speciﬁc
sediment
yield
(t
ha

0

Río
Frío Río
Pocosol
Río
InﬁernRío
San
Río
Cureña
Río
Sarapiquí
Río
Chirripó

Carlos

River
basin

Figure 15. Specific sediment yields for Costa Rican basins draining to the San Juan River.

163Annex 4

)$,

)$'
!

($,

($'

'$,

'$'

Figure 16. Total sediment yields for Costa Rican basins draining to the San Juan River.

($'

'$0

'$/
'$.

'$-

'$,

'$*

'$)

'$(

'$'

Figure 17. Delivery ratios for Costa Rican basins draining to the San Juan River. The dotted
line represents the mean value for the whole drainage system (which is equal to 0.31)

As mentioned above, sediment yields produced for Nicaraguan basin systems were
estimated using the average delivery function calibrated using data from the

San Carlos and Sarapiquí River basins. Results are presented in Table 9 and in
Figs. 18, 19 and 20. c

164 Annex 4

Table 9. Estimate sediment yields for Nicaraguan basins

Basin DR S-1 -1 PEL -1 S-1 -1 SY-1
(t ha yr ) (t yr ) (t ha yr ) (t yr )
Major Nicaraguan river basins draining directly to the San Juan River

Melchora River 0.24 39.05 1 177 000 9.22 278 000
Sábalos River 0.28 22.47 1 312 000 6.27 366 000

Santa Cruz River 0.35 16.66 691 000 5.88 244 000
Bartola River 0.58 1.84 40 000 1.07 23 000

Machado Creek 0.35 3.44 124 000 1.21 44 000
LasBanderas Creek 0.35 4.87 88 000 1.72 31 000

Summary for the entire Nicaraguan area that drains directly to the San Juan River
Total 0.29 16.65 3 432 000 4.78 986 000

Note: DR = delivery ratio; SPE = specific potential erosion; PEL = potential erosion load;
SSY = specific sediment yield; SY = sediment yield.

It is important to note that even though potential erosion and sediment yield s from
Costa Rican basins are larger than those of Nicaragua (because of the m
uch larger

drainage area on the Costa Rican side), the specific potential erosion and specific
sediment yield (that is, the erosion and sediment yield per unit of are
a) is much

larger on Nicaragua’s side (Fig. 15 versus Fig. 18). This indicates that Nicaraguan
basins draining to the San Juan River produce much more sediment per unit area

than those in Costa Rica.

-‐1

yr
-‐1

8

6

Spe2

sediment
yield
(t
ha

Río
Melchora
Río
Sábalos
Río
Santa
Cruz
Río
Bartola
Caño
Las
o

Banderas

River
basin

Figure 18. Specific sediment yields for Nicaraguan basins draining to the San Juan River.

165Annex 4

'$/

'$.

!'$-

'$,

'$+

'$*

'$(

'$'

Figure 19. Total sediment yields for Nicaraguan basins draining to the San Juan River.

' '$, ( ($, ) )$, * *$, + +$, ,
($'
'$0

'$/

'$.
'$-

'$,

'$+
'$*

'$)

'$(
'$'

Figure 20. Delivery ratios for Nicaraguan basins dr aining to the San Juan River. The dotted line
represents the mean value for the whole drainage sy stem (which is equal to 0.29).

166 Annex 4

6. SEDIMENT BALANCE IN THE SAN JUAN -
COLORADO RIVER S YSTEM, BEFORE AND AFTER

CONSTRUCTION OF ROUTE 1856

Once all the suspended sediment (SS) input loads flowing to the San Juan River
from Costa Rican and Nicaraguan basins were estimated by modelling (as reported

in the previous section), the sediment balance can be established – provided the
sediment loads in the San Juan River just upstream of the bifurcation at the Delta are
known. It must be noted the Delta Colorado (11 -04) station provides the main and
most reliable estimation of sediment load for establishing this balance (because it
integrates all the sediment flows entering the San Juan River system and because it

has been directly measured by ICE, respectively). Also it must be noted that the
sediment load measurements at station 11-04 used to estimate the load were
performed after construction of Route 1856. If follows that the sediment balance
produced here on the basis of those measurements necessarily represents

hydrological and sedimentological conditi ons after construction of Route 1856.
Therefore, after an estimate of the additional sediment yield contribution due to the
construction of Route 1856 is made in Section 6.2, a second sediment balance is
generated by subtracting this contribution to represent the original balance
pre-Route 1856.

6.1. Total annual sediment load after construction of Route 1856

Based on measured records for the Delta Colorado station (11-04) and assuming
that sediment concentrations are homogeneous, it was calculated in S ection 2.3.3
-1
that the SS load i-1the San Juan River just upstream of the D elta -1 6 573 000 t yr
and 5 981 000 t yr in the Colorado River, implying that 592 000 t yr (the difference
between these two loads) passes through the Lower San Juan River. In Section 2.4
the bed-loads of sediment in the Colorado and Lower San Juan Rivers were
-1
estimated as 2 488 000 and 71 000 t yr , respectively. Adding these together, t he
bed-load in th-1San Juan River jus t upstream of the Delta is then estimated to be
2 559 000 t yr . According to the previous figures, the total sediment load (that is
suspended load plus bed-load) in the San Juan River amounts to 9 133 000 t yr ,1
which is divided at the Delta into 8 470 000 t yr passing through the Colorado River
-1
and 663 000 t yr passing through the Lower San Juan River.
The suspended load of the San Juan River is 2.5 times larger than the bed -load. In
order to estimate the bed-load contribution of each of the ma jor basins drainging to

the San Juan River (seven from Costa Rica and six from Nicaragua), and
considering that for all those basins the SS loads have already been determined
(Chapter 5), the bed-load for each basin was estimated as 40% of the suspended
load. In addition, i t was assumed that the Lake Nicaragua acts as a large-scale
sediment trap for coarse sediment and, therefore, that it does not provide any bed-

load sediment to the San Juan River.

167Annex 4

A summary of the suspended, bed and total sediment loads, calculated for
all the
major basins draining from Costa Rica and Nicaragua to the San Juan River, is

presented in Table 10.

Table 10. Total annual sediment load (including suspended and bed loads) produced by the
Lake Nicaragua and the basin system draining to the San Juan River

Suspended sediment Bed-load sediment Total sediment
Basin load (t yr) load (t yr) load (t yr

Major Costa Rican river basins draining directly to the San Juan River
Frío River 269 000 108 000 377 000

Pocosol River 49 000 20 000 69 000
Infiernito River 78 000 31 000 109 000

San Carlos River 1 824 000 730 000 2 554 000
Cureña River 23 000 9 000 32 000

Sarapiquí River 458 000 183 000 641 000
Chirripó River 27 000 11 000 38 000
Major Nicaraguan river basins (including Lake Nicaragua) draining directly to the San Juan River

Melchora River 278 000 111 000 389 000
Sábalos River 366 000 146 000 512 000

Santa Cruz River 244 000 98 000 342 000
Bartola River 23 000 9 000 32 000

Machado Creek 44 000 17 000 61 000
Las Banderas Creek 31 000 12 000 43 000

Lake Nicaragua 365 000 - 365 000
Summary for the whole San Juan - Colorado river system

Total 4 079 000 1 485 000 5 556 000

The reason why the total sediment yield reported in Table 10 (5 566 000 t yr ) is1
-1
lower than the total load measured in San Juan River (9 133 000 t yr ) is that the
CALSITE model (Bradbury et al., 1993) used to determine the SS load produced by
basins draining to the San Juan River, accounts only for sheet and rill erosion,

leaving aside the sediment yield due to larger scale erosion processes (gullies and
landslide). Application of the CALSITE model in the management of multiple

hydropower operative plans and watershed management plans (Gómez -Delgado,
2002 and 2004; Gómez -Delgado et al., 2011; Marchamalo et al., 2007 and 2012),

demonstrates the coherence and reliability of this model for determining
the sheet/rill
component from the total transported sediment yield. However, these multiple

applications have also proved that a non -sheet/rill component is always present in
tropical basins and must be accounted for in order to close a realistic
sediment
balance. In this context, according to Poesen et al. (2003), gullies and landslides

may account for anything between 10% and 94% of total erosion in river basins.

In this particular case, the difference between the total amount of sediment
measured in the San Juan River and the modelled sheet/rill sediment yield from all
-1
the basins (amounting to 3 567 000 t yr ) can be attributed to gullies and landslide
erosion processes and this sediment yield was redistributed in proportion to the total

168 Annex 4

load reported for all the basins draining to the San Juan River and for Lake
Nicaragua. The total (corrected) annual sediment loads by basin are reported in

Table 11.

Table 11. Corrected annual loads for Lake Nicaragua and the basin system draining to
San Juan River

Suspended sediment Bed-load sediment Total sediment
Basin load (t yr load (t yr load (t yr

Major Costa Rican river basins draining directly to the San Juan River
Frío River 433 000 185 000 618 000
Pocosol River
79 000 34 000 113 000
Infiernito River 126 000 54 000 180 000
San Carlos River
2 939 000 1 257 000 4 196 000
Cureña River 37 000 16 000 53 000
Sarapiquí River
738 000 316 000 1 054 000
Chirripó River 44 000 19 000 63 000
Major Nicaraguan river basins draining directly to the San Juan River

Melchora River 448 000 192 000 640 000
Sábalos River 590 000 252 000 842 000

Santa Cruz River 393 000 168 000 561 000
Bartola River 37 000 16 000 53 000

Machado Creek 71 000 30 000 101 000
Las Banderas Creek 50 000 21 000 71 000

Lake Nicaragua 588 000 - 588 000
Summary for the whole San Juan - Colorado river system

Colorado River 5 981 000 2 489 000 8 470 000
San Juan Bajo River 592 000 71 000 663 000

6.2. Estimation of the sediment load produced by Route 1856

Oreamuno and Villalobos (2013) established average erosion depths and annual
erosion rates for the road bed, cut slopes, and fill slopes along Route 1856 by
monitoring nine sites in the stretch of Route 1856 extending from Mojón II to the

Infiernito River. These include the two largest rotational landslides, three gullies, the
most intensively rilled cut slope (with 16 rills) and a sediment trap
collecting sediment

eroded by sheet erosion of the road bed and an adjacent cut slope. The selected
sites include some of the most heavily eroded slopes in the study area a
nd thus

represent worst-case examples of erosion by land sliding, sheet erosion, rilling and
gullying along the steepest part of Route 1856.

Mende & Astorga (2013) characterized, by means of intensive fieldwork , all the cut
and fill slopes around Route 1856 along the entire stretch extending from Mojón II to

Delta Costa Rica in terms of their geographic position, area, slope angle, type (land
sliding, sheet erosion, rilling or gullying) and severity of erosion. Mende & Astorga

also applied the erosion rates derived by Oreamuno and Villalobos to estimate sheet

169 Annex 4

To convert the volume into a mass, a volumetric bulk densitiy of 1.67 t m -3was

assumed. This value is widely used to represent the bulk density of silt-sand soils.

The total volumes and masses of sediment eroded annually from Route 1856 are
summarized in Table 12 and plotted in Fig. 21. Road bed erosion estimates are

based on the land surface lowering rates reported by Oreamuno and Villalobos ,
while cut and fill slope erosion is based on the findings of Mende and A
storga.

Based on this exercise, the total volume of sedim3nt eroded along Route
1856
during one year is estimated to be 60 780 m , which converts to 101 550 t.

Table 12. Potential s ediment increments to the San Juan River sediment load due to
construction of Route 1856 (basin discretized)

Erosion volume (m3) Erosion load (t yr )
Basin Road length
(km) Road a Slopesb Total Road Slopes Total

Major Costa Rican river basins draining directly to the San Juan River

Infiernito River 38 12 260 28 000 40 260 20 450 46 750 67 250
S. Carlos River 11 2 060 600 2 660 3 450 1 000 4 450

Cureña River 28 5 220 7 560 12 780 8 700 12 650 21 350

Sarapiquí River 3 560 160 720 950 250 1 200
Chirripó River 22 4 100 260 4 360 6 850 450 7 300

Costa Rican area that drains directly to the San Juan River
Total 102 24 200 36 580 60 780 40 400 61 100 101 550
a b
Oreamuno and Villalobos (2013) Mende & Astorga (2013).

40 32000 Suspended sediment load (m

35 28000

30 24000

25 20000

20 16000

15 12000

R10d length (km) 8000

5 4000
3
0 0 )

Río Infiernito Río San Carlos Río Cureña Río Sarapiquí Río Chirripó

Road's length Potential erosion: road surface potential erosion: slopes

Figure 21. Potential erosion from the road bed and cut and fill slopes due to construction of
Route 1856 (displayed by tributary basin, with the length of the road located in each basin
indicated for context)

An average delivery ratio of 0.31 was calculated based on potential soil erosion an
d

sediment yields estimated using the CALSITE model for major Costa Rican river
basins draining directly to the San Juan River . However, this delivery ratio is related

171Annex 4

to hydrological and sedimentological processes typical of large river systems with
2
drainage basins of the order of 10 000 km . This delivery ratio is2 therefore,
inapplicable to the small drainage areas around Route 1856 (~ 3.5 km ) due to scale

differences. Recognising this, a much higher delivery ratio of 0.60 was selected, for
use with respect to deliver of road-derived sediment to the San Juan River, based on
the small size of the drainage areas and the particle size distributions
of sediment

eroded from Route 1856 reported by Oreamuno and Villalobos (2013). Inputs of
road-derived sediment to the San Juan River based on a delivery ratio of 0.60 are

shown in Table 13 and Fig. 2 2. According to these figures, the total volume of
sediment delivered by Route 1856 to the San Juan River during one year is
3
estimated to be 36 500 m , which converts to 60 800 t assuming a bulk density of
1.67 t m .3

Table 13. Sediment yield increments to the San Juan River sediment load due to construction
of Route 1856 (basin discretized)

Road length Erosion volume (m3) Erosion load (t yr )
Basin
(km) Road Slopes Total Road Slopes Total

Major Costa Rican river basins draining directly to the San Juan River
Infiernito River 38 7 360 16 800 24 160 12 250 28 050 40 300

S. Carlos River 11 1 240 360 1 600 2 050 600 2 650
Cureña River 28 3 140 4 540 7 680 5 200 7 600 12 800

Sarapiquí River 3 340 100 440 550 150 700

Chirripó River 22 2 460 160 2 620 4 100 250 4 350
Costa Rican area that drains directly to the San Juan River

Total 102 14 540 21 960 36 500 24 150 36 650 60 800

40 20000 Suspended sediment load (m

35 17500

30 15000

25 12500

20 10000

15 7500

R10d length (km) 5000

5 2500
)3
0 0
Río Infiernito Río San Carlos Río Cureña Río Sarapiquí Río Chirripó

Road's length Erosion: road surface Erosion: slopes

Figure 22. Sediment yields to the San Juan River due to construction of Route 1856 (displayed
by tributary basin, with the length of road located in each basin indicated for context).

172 Annex 4

6.3. Sediment balance diagrams before and after cons truction of

Route 1856

The total average annual sediment loads of all the basins draining to the San Juan
River and for Lake Nicaragua reported in Table 11 corresponds to the period after

construction of Route 1856. These results were used to create diagrams illustrating
the pre- and post-Route 1856 sediment transport balances in the San Juan -
Colorado River system (Figs. 23 and 24). The diagrams graphically display
sediment inputs, fluxes and outputs, with the width of the mainstream and each of its

tributary/distributary rivers scaled according to their average annua l sediment loads.
In these diagrams, sediment loads prior to construction of Route 1856 (
illustrated in
Fig. 23) were derived by subtracting from the post-construction sediment balance
(illustrated in Fig. 24) the spatially-distributed, worst case scenario estimates of the
inputs of sediment from Route 1856 that were derived and reported in Section 6.2.

Figure 23. Average annual sediment balance prior to construction of Route 1856. This includes
suspended and bed -loads from both Costa Rican and Nicaraguan basins.The widths of the
inward arrows are proportional to the sediment load contributed by of each of the tributary
river basins that confluence with the San Juan Rive r between Mojón II and the lower
San Juan – Colorado bifurcation at Delta Costa Rica.

173Annex 4

Figure 24. Average annual sediment balance post construction of Route 1856. This includes
suspended and bed -loads input from both Costa Rican and Nicaraguan basins. The widths of
the inward arrows are proportional to the sediment load contributed by of each of the tributary
river basins that confluence with the San Juan River between Mojón II and the
lower San Juan – Colorado bifurcation at Del ta Costa Rica.

As at every step the disaggregated values of the suspended and bed sediment loads
were calculated separately, additional sediment balances were plotted representing

the individual balances for suspended, bed and total sediment loads, before and
after construction of Route 1856. These diagrams are provided in APPENDIX I.

Finally, the two diagrams representing the sediment balance before and after the

construction of Route 1856 (Figs. 23 and 24) were overlapped in order to illustrate
the relative contribution of the additional sediment load attributable to construction of
Route 1856. The resulting difference diagram is shown in Fig. 25.

174 Annex 4

Figure 25. Increases in average annual sediment loads input to the San Juan – Colorado River
system due to construction of Route 1856 are illustrated by the red lines in this version of the

sediment balance diagram . Inputs of road -derived sediment are specified numerically: for
example, the -1rgest change in average annual sediment load input to the San Juan River is
+40 300 t yr from CR5 (the Infiernito Basin). The narrow width of the red band is correctly
scaled and accurately portrays that cumulative sediment inp uts from Route 1856 are so small
relative to pre-construction loads that they are not only difficult to see but inconsequential and

practically undetectable.

6.4. Silting process in the lower San Juan River

The pre- and post-Route 1856 sediment load diagram presented in Fig. 25 illustrates

that the increase in t-1 average annual sediment load input to the low-3 San Juan
River is 5 500 t yr . Assuming a bulk density of 1.67 t m , this is equivalent to
approximately 3 300 m yr . Consultation of recent satellite images indicates that the

length of the Lower San Juan River is approximately 30 km, while examina
tion of 40
available cross-sections of the river reveals that the average width of its channel is

92.2 m. Multiplying these two figur2s suggests that the area of the Lower San Juan
River is approximately 2.77 km .

175Annex 4

On the highly conservative assumption that all of the road -derived sediment input to

the lower San Juan River by Route 1856 was to be deposited within the-1hannel, this
would raise the elevation of the bed by an average of 1. 2 mm yr – or the diameter
of a single grain of medium-size sand. In considering the potential for even this rate
of siltation, it should be remembered that this is an upper bound because

conservative assumptions were made at each stage in estimating erosion, sediment
delivery ratio and sediment yield from Route 1856. It follows that the p
otential
change in the elevation of the bed of the lower San Juan River due to construction of
Route 1856 is not only negligible but lies within the uncertainty band for any
computation and is in any case inside the error range for measuring bed elevation ,

making any impact practically imperceptible.

176 Annex 4

7. CONCLUSIONS

A comprehensive hydrologi cal and sedimentological study was made, integrating
many different hydro-sedimentological measurements that have been performed
from the beginning of the 1960s to the present day, both in Costa Rican basins

draining to the San Juan River, and in the river itself.
From the existing data it must be concluded that there is no scientific evidence to
prove any variation in the natural relationship between Discharge and Su
spended

Sediment (SS) Concentrations along the San J uan - Colorado River system due to
construction of Route 1856, nor is there evidence of a change in the SS load regime
in the San Juan River due to Route 1856. Neither is there scientific evidence to state
that dry and rainy seasons present different Discharge - SS Concentration
relationships.

Under the extreme assumption that after the construction of Route 1856, all the road
and slope areas immediately become completely impermeable, t he overall increase
in the impermeable area for all the river basin systems (including major and minor

basins) is 0.08%. Studying the effect of this change on the hydrological regime of
eighty Costa Rican microbasins draining directly to the San Juan River,
it was
concluded, using two different methods and with a confide nce level of 95%, that
there is no scientific evidence of a change in the hydrological (discha
rge) regime of

these microbasins, due to the construction of Route 1856. Additionally, after adding
into the analysis of eighty microbasins, the seven major basins of Costa Rica that
also drain to the San Juan River, it was demonstrated using scientifically sound
methods that it is impossible to prove the existence of any changes in the
hydrological regime of the basin system due to the construction of Route 1856.

Beyond this, graphic comparison of pre- and post-Route 1856 discharge regimes
showed that any possible hydrological effects attributed to the road tha
t could be
affecting the discharge regime of the Costa Rican basins are not even vi
sible.

An advanced distributed model (CALSITE) was calibrated using available data and
information on the actual sediment loads carried by several different Costa Rican
rivers, allowing estimation of the SS loads produced by each of the Cost
a Rican and
Nicaraguan basins draining to the San Juan River. Bed -load sediment inputs were

also estimated based on the Einstein method, which is measurement -supported.
Using modelled sediment yields, available records of measured SS loads a
nd the
estimated bed-loads, the current (post 2010) sediment balance for the entire river
system was closed by correcting it to account for gully and landslide co
ntributions.

The results of erosion monitoring and an inventory of all cut and fill s
lopes along
Route 1856 between Mojón II and the lower San Juan – Colorado bifurcation at Delta
Costa Rica were used together with application of the USLE and a conserv
ative
assumption concerning the sediment delivery ratio for small basins to es
timate the

increase in average annual sediment yield to the San Juan River that could be
attributed to construction of Route 1856. The resulting average annual sediment
yield of 3 6 500 m yr -1 or 60 800 t yr-1 represents a ‘worst case scenario’ because
conservative assumptions were made at each stage in its estimation. The yield of

road-derived sediment was combined with the sediment balance to generate

177Annex 4

illustrative diagrams for the total sediment balance in the San Juan – Colorado River

system for pre- and post-Route 1856 conditions. These diagrams provide a simple,
visual representation of how the contribution of road -derived sediment compares to
the natural sediment load that San Juan and Lower San Juan Rivers transp
ort in an
average year. What Fig. 25 shows is that the contribution of Route 1856 is so small

relative to pre-construction loads that it is practically undetectable.
In interpreting this analysis, it must also be remembered that all the figures quoted
are averages, that they are subject to scientific uncertainty, and that the annual load

is in any case itself naturally v-1iable. It follows that the estimated
input of road -
derived sediment (60 800 t yr ) must be compared to uncertainty in the average
annual load carried by the San Juan River. For example, the 95% confiden
ce interval
on the average annual load for suspended sediment is 5 181 000 to 7 966 000 t yr , -1

which is more than 50 times the estimated input of road-derived sediment.
Finally, it was demonstrated that even using conservative assumptions to
make a
‘worst case scenario’ estimate of the annual yield of road -derived sediment and then

assuming that all of the additional sediment supplied to the lower San J
uan River
would be deposited, the change in the elevation of the bed due to the construction of
Route 1856 is not only negligible, but it also cannot be measured.

178 Annex 4

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Kingdom: HR Wallingford.

Einstein, H.A. (1950). The bed -load function for sediment transportation in open cannel flows
(Technical bulletin). Washington, United States: U.S. Department o f Agriculture.

Gómez-Delgado, F. (2002) . Evaluation of the potential erosion and sediment yield in three
basins of Costa Rica (Grade thesis). University of Costa Rica, San José, Costa Rica.

(in Spanish)

Gómez-Delgado, F. (2004) . Report on the spatial dis tribution of the potential erosion and
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Gómez-Delgado, F., Marchamalo- Sacristán, M. & Laporte-Molina, S. (2011). Calibrating a

distributed model to estimate the sediment input rate to the Peñas Blancas reservoir
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Isidro de la República de Nicaragua, sobre el territorio de Costa Rica . San José,
Costa Rica: Author.

Instituto Costarricense de Electricida(2011) Estimación de caudal en la estación 690103
La Trinidad. San José, Costa Rica : Author.

INETER (2001) Bolet ín Hidrológico No. 2. Managua, Nicaragua.

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INETER (2002) Boletín Hidrológico No. 4. Managua, Nicaragua.
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Lyon, France.

Marchamalo, M., Gómez -Delgado, F., Gonzalez, B. (2007) . Quantification of soil and water
conservation potencial based on territorial analisys of the catchment. Birris basin
case study (in Spanish). Technical report. Turrialba, Costa Rica: CATIE -UICN

Marchamalo, M., Vignola, R., Gómez -Delgado, F. and González -Rodrigo, B. (2012)
Quantifying Services and Identifying Watershed Priority Areas for Soil and Water
Conservation Programs. In B. Rapidel, F. De Clerk, J.F. Le Coq J. Beer, Ecosystem
Services from Agriculture and Agroforestry, Measurement and Payment . London,
United Kindgdom: Earthscan.

McCool, D.K., George, G.O., Freckleton, M., Douglas, C. L. & Papemdick, R. I. (1993).
Topographic effect on erosion from cro pland in the Northwestern wheat region.
Trans. ASAE 36 (s).

Mende, A. & Astorga, A. (2013). Inventory of slopes and water courses related to the Border

Road Nº 1856 between Mojón II and Delta Costa Rica. San José, Costa Rica:
Authors.

Oreamuno-Vega, R.A & Villalobos- Herrera, R. (2013). Systematic Field monitoring of
Erosion and Sediment Yield along Route 1856 . San José, Costa Rica: Centro de
investigaciones en desarrollo sostenible CIEDES – Universidad de Costa Rica.

Poesen, J., Nachte rgaele, J., Verstraeten, G. & Valentin, C. (2003) . Gully erosion and
environmental change: importance and research needs. CATENA 50, 91-133.

Wischmeier, W. H. & Smith, D.D. (1960). A universal soil-loss equation to guide conservation
farm planning. Transactions of the 7th International Congress Soil Science . Brussels,

Belgium.

180 Annex 4

APPENDIX A

SUSPENDED SEDIMENT RATING CURVES

MEAN MONTHLY SUSPENDED SEDIMENT LOAD

MEAN ANNUAL SUSPENDED SEDIMENT LOAD

Sediment stations:

12-03, 12-04, 12-05, 12-06, 12-11, 12-13, 14-02, 14-04, 14-05, 14-20, 16-02 & 16-05

181Annex 4

Station 12-03 Puerto Viejo

Suspended sediment rating curve

Mean monthly suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD
CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA

TONELAJE
MENSUAL
DE
SEDIMENTOS

Cuenca 12 Sarapiquí
Estación 3 Puerto
viejo

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
264
Periodo
comprendido:
3/9/1970
hasta
2/7/1998

3 -‐1 Distribución
mensual
del
sedimento
Mes Carga
(tQ
(m
s )
Ene 11694 97 30000
Feb 7476 80

Mar 5887 68 25000
Abr 5349 66

May 10030 95 20000
Jun 11571 115
Jul 18861 145
15000
Ago 18573 145
Sep 12133 119
Oct 15051 127 10000

Nov 21122 145
Dic 27754 156 Carga
de
sedimento
en
suspensión
(t)

Total 165507 113 0
Ene Feb Mar Abr May Jun Jul Ago Sep Oct Nov Dic
Mes

182 Annex 4

Mean annual suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD

CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
ANUAL
DE
SEDIMENTOS

Cuenca 12 Sarapiquí

Estación 3 Puerto
viejo

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
264
Periodo
comprendido:
3/9/1970
hasta
2/7/1998

3 -‐1 Distribución
anual
del
sedimento
Año
hidro. Carga
(t)Q
(m
s )
70-‐71 234408 158 300000

71-‐72 120631 105
72-‐73 92570 86 250000

73-‐74 175977 117
74-‐75 145769 106 200000

75-‐76 223037 126
76-‐77 243577 137 150000

77-‐78 202756 125
78-‐79 159076 114
100000
79-‐80 189341 129
80-‐81 201006 130
50000
81-‐82 176042 115 Carga
de
sedimento
en
suspensión
(t)

82-‐83 238041 134 0
83-‐84 123430 98

84-‐85 119953 99 70-‐7711-‐7722-‐7733-‐7744-‐7755-‐7766-‐7777-‐7788-‐7799-‐8800-‐8811-‐8822-‐8833-‐8844-‐8855-‐8866-‐8877-‐8888-‐8899-‐9900-‐9911-‐9922-‐9933-‐9944-‐9955-‐9966-‐9977-‐9988-‐99
85-‐86 114667 91 Año

86-‐87 108464 95
87-‐88 160890 111

88-‐89 120804 100
89-‐90 158884 113

90-‐91 166336 116
91-‐92 224847 130

92-‐93 147813 109
93-‐94 103078 87

94-‐95 154481 104
95-‐96 97271 84

96-‐97 205561 133
97-‐98 220696 129

98-‐99 170323 119

Promedio 165508 114

183Annex 4

Station 12-04 Veracruz

Suspended sediment rating curve

Mean monthly suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD

CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
MENSUAL
DE
SEDIMENTOS

Cuenca 12 Sarapiquií
Estación 4 Veracruz

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
285
Periodo
comprendido:
20/5/1972
hasta
21/11/2012

Distribución
mensual
del
sedimento
Mes Carga
(tQ
(m
s )
Ene 10712 28 25000

Feb 3930 19
Mar 1559 15
20000
Abr 1601 14
May 3129 19
Jun 4253 25 15000

Jul 19481 32
Ago 7957 30
Sep 4703 28 10000

Oct 6900 29
Nov 18515 39 5000
Dic 18218 37
Carga
de
sedimento
en
suspensión
(t)

Total 100963 26 0
Ene Feb Mar Abr May Jun Jul Ago Sep Oct Nov Dic

Mes

184 Annex 4

Mean annual suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD

CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
ANUAL
DE
SEDIMENTOS

Cuenca 12 Sarapiquií

Estación 4 Veracruz

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
285
Periodo
comprendido:
20/5/1972
hasta
21/11/2012

3 -‐1 Distribución
anual
del
sedimento
Año
hidro. Carga
(t)Q
(m
s )
72-‐73 40870 23 900000

73-‐74 77962 27 800000
74-‐75 149836 29
700000
75-‐76 192446 36
76-‐77 49434 23 600000

77-‐78 45056 22 500000
78-‐79 39687 21
400000
79-‐80 38343 22
80-‐81 118947 32 300000

81-‐82 180135 33
82-‐83 117903 27 200000

83-‐84 49813 21 Carga
de
sedimento
en
suspensión
(t)

84-‐85 50687 24 0
85-‐86 40702 20

86-‐87 51858 23
87-‐88 78379 23 Año

88-‐89 36374 22
89-‐90 47104 24

90-‐91 37947 22
91-‐92 52341 23

92-‐93 45820 23
93-‐94 31575 19

94-‐95 26732 18
95-‐96 97421 25

96-‐97 43442 24
97-‐98 66243 25

98-‐99 61921 25
99-‐00 144185 34

00-‐01 81910 28
01-‐02 161940 34

02-‐03 138578 31
03-‐04 94847 32

04-‐05 180686 36
05-‐06 77222 25

06-‐07 37360 20

07-‐08 107278 26
08-‐09 223069 39

09-‐10 765172 52
10-‐11 94483 29

11-‐12 95607 25
12-‐13 68147 26

Promedio 100963 27

185Annex 4

Station 12-05 Bajos del Toro

Suspended sediment rating curve

Mean monthly suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD

CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
MENSUAL
DE
SEDIMENTOS

Cuenca 12 Sarapiquií
Estación 5 Bajos
del
Toro

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
137
Periodo
comprendido:
30/3/1985
hasta
12/12/2001

Distribución
mensual
del
sedimento
Mes Carga
(tQ
(m
s )
18000
Ene 5181 5
Feb 16891 4 16000
Mar 855 3
14000
Abr 110 2
May 541 3 12000
Jun 6329 5
10000
Jul 1307 5
Ago 1526 6 8000
Sep 1440 6
6000
Oct 2220 6
Nov 7311 7 4000

Dic 5970 6 Ca2000
de
sedimento
en
suspensión
(t)

Total 49686 5 0
Ene Feb Mar Abr May Jun Jul Ago Sep Oct Nov Dic

Mes

186 Annex 4

Mean annual suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD
CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA

TONELAJE
ANUAL
DE
SEDIMENTOS

Cuenca 12 Sarapiquií
Estación 5 Bajos
del
Toro

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
137

Periodo
comprendido:
30/3/1985
hasta
12/12/2001

Distribución
anual
del
sedimento
Año
hidro. Carga
(t)Q
(m
s )
400000
84-‐85 0 3
85-‐86 43305 7 350000

86-‐87 14209 6
87-‐88 90750 7 300000

88-‐89 43274 8 250000
89-‐90 39381 7

90-‐91 35238 7 200000
91-‐92 24795 6
150000
92-‐93 50576 8
93-‐94 16758 6 100000

94-‐95 26557 6
95-‐96 344493 7 Carga
de
sedimento
en
suspensión
(t)

06-‐07 0 1 0
07-‐08 12739 1

08-‐09 99342 4
09-‐10 8928 1 Año

10-‐11 10945 1
11-‐12 29518 1

12-‐13 102834 1

Promedio 49686 4

187Annex 4

Station 12-06 Toro

Suspended sediment rating curve

Mean monthly suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD

CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
MENSUAL
DE
SEDIMENTOS

Cuenca 12 Sarapiquií
Estación 6 Toro

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
117
Periodo
comprendido:
18/1/1995
hasta
26/10/2010

3 -‐1 Distribución
mensual
del
sedimento
Mes Carga
(tQ
(m
s )
Ene 2176 5 7000

Feb 1328 4 6000
Mar 143 2
Abr 194 2
5000
May 833 3
Jun 452 4 4000
Jul 623 4

Ago 878 4 3000
Sep 1009 5
Oct 1710 6
2000
Nov 6657 7
Dic 4513 7 Carga
de
sedimento
en
suspensión
(t)

Total 20522 5 0
Ene Feb Mar Abr May Jun Jul Ago Sep Oct Nov Dic
Mes

188 Annex 4

Mean annual suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD
CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA

TONELAJE
ANUAL
DE
SEDIMENTOS

Cuenca 12 Sarapiquií
Estación 6 Toro

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
117

Periodo
comprendido:
18/1/1995
hasta
26/10/2010

Distribución
anual
del
sedimento
Año
hidro. Carga
(t)Q
(m
s )
90000
95-‐96 27859 4
96-‐97 15742 5 80000

97-‐98 10212 4 70000
98-‐99 21619 5
60000
99-‐00 28846 5
00-‐01 10469 4 50000

01-‐02 16666 4 40000
02-‐03 35840 4

03-‐04 25585 6 30000
04-‐05 43453 6
20000
05-‐06 13864 4
06-‐07 3679 3 Carga
de
sedimento
en
suspensión
(t)

07-‐08 16648 4 0
08-‐09 83605 6

09-‐10 8683 4
10-‐11 24324 5 Año

11-‐12 12587 4
12-‐13 10284 4

Promedio 20522 4

189Annex 4

Station 12-11 San Miguel

Suspended sediment rating curve

Mean monthly suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD

CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
MENSUAL
DE
SEDIMENTOS

Cuenca 12 Sarapiquií
Estación 11 San
Miguel

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
47
Periodo
comprendido:
1/7/1998
hasta
12/1/2010

Distribución
mensual
del
sedimento
Mes Carga
(tQ
(m
s )
Ene 4745 15 6000

Feb 714 8
Mar 886 7 5000

Abr 210 5
May 799 9 4000
Jun 1209 10

Jul 1440 12 3000
Ago 1200 11
Sep 456 9
2000
Oct 931 11
Nov 5402 19
Dic 4775 18 1000
Carga
de
sedimento
en
suspensión
(t)

Total 22773 11 0
Ene Feb Mar Abr May Jun Jul Ago Sep Oct Nov Dic

Mes

190 Annex 4

Mean annual suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD
CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA

TONELAJE
ANUAL
DE
SEDIMENTOS

Cuenca 12 Sarapiquií
Estación 11 San
Miguel

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
47

Periodo
comprendido:
1/7/1998
hasta
12/1/2010

3 -‐1 Distribución
anual
del
sedimento
Año
hidro. Carga
(t) Q
(m
s )
98-‐99 15456 10 50000

99-‐00 45897 12 45000
00-‐01 29632 12
40000
01-‐02 40993 12
02-‐03 18920 13 35000

07-‐08 304 6 30000
08-‐09 5041 10
25000
09-‐10 14898 11
10-‐11 13985 10 20000

11-‐12 22926 9 15000
12-‐13 42455 15
10000
Carga
de
sedimento
en
suspensión
(t)
Promedio 22773 11 5000

0
98-‐99 99-‐00 00-‐0101-‐02 02-‐03 07-‐08 08-‐09 09-‐10 10-‐11 11-‐12 12-‐13

Año

191Annex 4

Station 12-13 Río Segundo

Suspended sediment rating curve

Mean monthly suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD
CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
MENSUAL
DE
SEDIMENTOS

Cuenca 12 Sarapiquií

Estación 13 Río
Segundo

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
25

Periodo
comprendido:
3/6/1999
hasta
13/8/2009

Mes Carga
(t) 3 -‐1 Distribución
mensual
del
sedimento
Q
(m
s ) 500
Ene 298 4
Feb 104 2 450

Mar 64 2 400
Abr 41 2
May 70 2 350

Jun 67 2 300
Jul 96 3
Ago 66 2 250
200
Sep 61 2
Oct 72 2 150

Nov 470 5 100
Dic 413 4 Carga
de
sedimento
en
suspensión
(t)
50

Total 1829 3 0
Ene Feb Mar Abr May Jun Jul Ago Sep Oct Nov Dic
Mes

192 Annex 4

Mean annual suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD
CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA

TONELAJE
ANUAL
DE
SEDIMENTOS

Cuenca 12 Sarapiquií
Estación 13 Río
Segundo

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
25

Periodo
comprendido:
3/6/1999
hasta
13/8/2009

3 -‐1 Distribución
anual
del
sedimento
Año
hidro. Carga
(t)Q
(m
s )
99-‐00 2332 3 4500

00-‐01 1707 3 4000
01-‐02 2846 3
3500
02-‐03 2401 3
03-‐04 1725 3 3000

04-‐05 2529 3
05-‐06 1230 2 2500

06-‐07 626 2 2000
07-‐08 1200 2
1500
08-‐09 4065 3
09-‐10 1517 2 1000

10-‐11 1364 2 Carga
de
sedimento
en
suspensión
(t)
11-‐12 2072 2 500

12-‐13 1813 2 0
99-‐00 00-‐01 01-‐02 02-‐03 03-‐04 04-‐05 05-‐06 06-‐07 07-‐08 08-‐09 09-‐10 10-‐11 11-‐12 12-‐13

Promedio 1829 3 Año

193Annex 4

Station 14-02 Jabillos

Suspended sediment rating curve

Mean monthly suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD

CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
MENSUAL
DE
SEDIMENTOS

Cuenca 14 San
Carlos
Estación 2 Jabillos

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
338
Periodo
comprendido:
3/6/1967
hasta
13/1/2011

Distribución
mensual
del
sedimento
Mes Carga
(tQ
(m
s )
200000
Ene 89058 47
Feb 25773 32 180000
Mar 2439 23
160000
Abr 5144 19
May 8530 28 140000
Jun 12712 47 120000

Jul 22199 60 100000
Ago 25718 64
Sep 24752 67 80000

Oct 46766 70 60000
Nov 151673 79
40000
Dic 184054 67 Ca20000 de
sedimento
en
suspensión
(t)

Total 598823 50 0
Ene Feb Mar Abr May Jun Jul Ago Sep Oct Nov Dic

Mes

194 Annex 4

Mean annual suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD

CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
ANUAL
DE
SEDIMENTOS

Cuenca 14 San
Carlos
Estación 2 Jabillos

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
338

Periodo
comprendido:
3/6/1967
hasta
13/1/2011

3 -‐1 Distribución
anual
del
sedimento
Año
hidro. Carga
(t)Q
(m
s )
6000000
67-‐68 616130 67
68-‐69 1015699 62
5000000
69-‐70 5283115 82
70-‐71 2308064 84
4000000
71-‐72 208463 50
72-‐73 119209 42

73-‐74 468902 57 3000000
74-‐75 1871807 54

75-‐76 385737 49 2000000
76-‐77 217122 47

77-‐78 112533 39 1000000
78-‐79 133496 45 Carga
de
sedimento
en
suspensión
(t)

79-‐80 477245 47 0
80-‐81 1590355 60

81-‐82 750198 60 67-‐6689-‐7701-‐7723-‐7745-‐7767-‐7789-‐8801-‐8823-‐8845-‐8867-‐8889-‐9901-‐9923-‐9945-‐9967-‐9989-‐0001-‐0023-‐0045-‐0067-‐0089-‐1101-‐12
Año
82-‐83 428370 50
83-‐84 153825 42

84-‐85 123983 42
85-‐86 74392 37

86-‐87 75879 38
87-‐88 835364 47

88-‐89 310685 47
89-‐90 156424 45

90-‐91 70127 38
91-‐92 117729 41

92-‐93 204789 40
93-‐94 91077 38

94-‐95 51059 32
95-‐96 186980 45

96-‐97 202424 52
97-‐98 107535 44

98-‐99 231787 46

99-‐00 151865 44
00-‐01 196634 51

01-‐02 557392 55
02-‐03 526224 53

03-‐04 228556 57
04-‐05 699629 63

05-‐06 360034 48
06-‐07 126925 44

07-‐08 1204812 59
08-‐09 2312645 79

09-‐10 531934 53
10-‐11 1235213 65

11-‐12 230574 39
12-‐13 202933 42

Promedio 598823 50

195Annex 4

Station 14-04 Terrón Colorado

Suspended sediment rating curve

Mean monthly suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD
CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
MENSUAL
DE
SEDIMENTOS

Cuenca 14 San
Carlos

Estación 4 Terrón
Colorado

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
53

Periodo
comprendido:
7/10/1998
hasta
17/6/2009

Mes Carga
(tQ
(m
s ) Distribución
mensual
del
sedimento
250000
Ene 135187 206
Feb 51437 129

Mar 27158 87 200000
Abr 25720 83
May 85779 144
150000
Jun 114141 188
Jul 134367 214
Ago 116668 196
100000
Sep 108588 197
Oct 115710 200
Nov 189289 253
50000
Dic 195570 237 Carga
de
sedimento
en
suspensión
(t)

Total 1299620 178 0

Ene Feb Mar Abr May Jun Jul Ago Sep Oct Nov Dic
Mes

196 Annex 4

Mean annual suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD
CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA

TONELAJE
ANUAL
DE
SEDIMENTOS

Cuenca 14 San
Carlos
Estación 4 Terrón
Colorado

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
53

Periodo
comprendido:
7/10/1998
hasta
17/6/2009

3 -‐1 Distribución
anual
del
sedimento
Año
hidro. Carga
(t) Q
(m
s )
98-‐99 813368 167 2500000

99-‐00 1211918 161
00-‐01 1218509 166
2000000
01-‐02 1714428 187
02-‐03 1486594 173

03-‐04 1544806 193 1500000
04-‐05 2028312 213

05-‐06 1119198 153
06-‐07 961905 145 1000000

07-‐08 1462592 199
08-‐09 734184 213
500000
Promedio 1299619 179 Carga
de
sedimento
en
suspensión
(t)

0
98-‐99 99-‐00 00-‐0101-‐02 02-‐03 03-‐04 04-‐05 05-‐0606-‐07 07-‐08 08-‐09

Año

197Annex 4

Station 14-05 Peñas Blancas

Suspended sediment rating curve

Mean monthly suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD

CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
MENSUAL
DE
SEDIMENTOS

Cuenca 14 San
Carlos
Estación 5 Peñas
Blancas

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
311
Periodo
comprendido:
16/5/1970
hasta
7/10/2011

3 -‐1 Distribución
mensual
del
sedimento
Mes Carga
(tQ
(m
s )
Ene 16654 35 40000

Feb 5222 25 35000
Mar 3204 19
Abr 1447 14 30000

May 6829 24 25000
Jun 8875 33
Jul 15414 44
20000
Ago 17644 44
Sep 10662 40 15000
Oct 15927 44
10000
Nov 20175 47
Dic 34855 48 Carga
de
sedimento
en
suspensión
(t)
5000

Total 156913 35 0
Ene Feb Mar Abr May Jun Jul Ago Sep Oct Nov Dic
Mes

198 Annex 4

Mean annual suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD

CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
ANUAL
DE
SEDIMENTOS

Cuenca 14 San
Carlos
Estación 5 Peñas
Blancas

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
311

Periodo
comprendido:
16/5/1970
hasta
7/10/2011

3 -‐1 Distribución
anual
del
sedimento
Año
hidro. Carga
(t)Q
(m
s )
500000
70-‐71 290658 51
71-‐72 104112 32 450000

72-‐73 145208 37 400000
73-‐74 127335 35
350000
74-‐75 256882 36
75-‐76 167037 34 300000

76-‐77 296474 41 250000
77-‐78 142675 36 200000

78-‐79 117350 32 150000
79-‐80 109417 33
100000
80-‐81 234097 40
81-‐82 179599 36 Ca50000 de
sedimento
en
suspensión
(t)

82-‐83 250163 39 0
83-‐84 124303 31

84-‐85 155343 35
85-‐86 60047 25 Año

86-‐87 83526 29

87-‐88 132790 33
88-‐89 100262 31

89-‐90 106514 34
90-‐91 108187 33

91-‐92 118663 34
92-‐93 118048 31

93-‐94 59954 25
94-‐95 191928 30

95-‐96 70393 28
96-‐97 130684 35

97-‐98 158647 34
98-‐99 113892 32

99-‐00 141428 35
00-‐01 119728 36

01-‐02 441574 44

02-‐03 186499 38
03-‐04 141442 39

04-‐05 320183 47
05-‐06 87094 27

06-‐07 102228 29
07-‐08 278406 35

08-‐09 245858 42
09-‐10 130313 35

10-‐11 266360 36
11-‐12 123229 32

12-‐13 65387 25

Promedio 156913 34

199Annex 4

Station 14-20 Pocosol

Suspended sediment rating curve

Mean monthly suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD
CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
MENSUAL
DE
SEDIMENTOS

Cuenca 14 San
Carlos
Estación 20 Pocosol

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
278

Periodo
comprendido:
26/6/1980
hasta
12/6/2012
Distribución
mensual
del
sedimento
Mes Carga
(tQ
(m
s )
100000
Ene 62611 20
Feb 31267 15 90000

Mar 8111 11 80000
Abr 3169 9
May 12116 14 70000

Jun 20523 17 60000
Jul 26095 22 50000
Ago 33166 22
40000
Sep 10332 19
Oct 17631 20 30000
Nov 40222 24
20000
Dic 92918 26 Carga
de
sedimento
en
suspensión
(t)
10000
Total 358167 18 0

Ene Feb Mar Abr May Jun Jul Ago Sep Oct Nov Dic
Mes

200 Annex 4

Mean annual suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD

CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
ANUAL
DE
SEDIMENTOS

Cuenca 14 San
Carlos

Estación 20 Pocosol

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
278
Periodo
comprendido:
26/6/1980
hasta
12/6/2012

3 -‐1 Distribución
anual
del
sedimento
Año
hidro. Carga
(t)Q
(m
s )
80-‐81 313027 22 1800000

81-‐82 159535 16 1600000
82-‐83 511584 19
1400000
83-‐84 77552 15
84-‐85 195022 18 1200000

85-‐86 76084 14 1000000
86-‐87 274232 22
800000
87-‐88 653666 24
88-‐89 122636 15 600000

89-‐90 185292 20
90-‐91 145057 16 400000

91-‐92 202426 19 Carga
de
sedimento
en
suspensión
(t)

92-‐93 354275 17 0
93-‐94 81885 14

94-‐95 286548 16
95-‐96 56400 15 Año

96-‐97 293749 21
97-‐98 260690 19

98-‐99 325477 19
99-‐00 374098 19

00-‐01 182818 20
01-‐02 848782 22

02-‐03 339358 21
03-‐04 422327 22

04-‐05 1209970 26
05-‐06 418707 16

06-‐07 310625 18
07-‐08 1076581 20

08-‐09 1617471 29
09-‐10 184318 18

10-‐11 442155 8
11-‐12 88132 5

12-‐13 87117 6

Promedio 358167 17

201Annex 4

Station 16-02 Guatuso

Suspended sediment rating curve

Mean monthly suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD

CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
MENSUAL
DE
SEDIMENTOS

Cuenca 16 Frío
Estación 2 Guatuso

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
367
Periodo
comprendido:
12/1/1970
hasta
4/7/2012

Distribución
mensual
del
sedimento
Mes Carga
(tQ
(m
s )
10000
Ene 4435 27
Feb 1765 18 9000
Mar 1202 13
8000
Abr 562 10
May 2146 16 7000
Jun 4822 29 6000

Jul 9472 43 5000
Ago 8438 41
Sep 5393 33 4000

Oct 6685 36 3000
Nov 7055 37
2000
Dic 8830 38 Ca1000
de
sedimento
en
suspensión
(t)

Total 60806 28 0
Ene Feb Mar Abr May Jun Jul Ago Sep Oct Nov Dic

Mes

202 Annex 4

Mean annual suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD

CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA
TONELAJE
ANUAL
DE
SEDIMENTOS

Cuenca 16 Frío

Estación 2 Guatuso

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
367
Periodo
comprendido:
12/1/1970
hasta
4/7/2012

Año
hidro. Carga
(t) 3 -‐1 Distribución
anual
del
sedimento
Q
(m
s ) 120000
69-‐70 16236 31

70-‐71 71851 34
71-‐72 44505 25 100000

72-‐73 64070 30
73-‐74 43699 26 80000

74-‐75 67458 28
75-‐76 59628 27 60000

76-‐77 45541 26
77-‐78 48025 25 40000

78-‐79 62214 29
79-‐80 71481 30
20000
80-‐81 61661 31 Carga
de
sedimento
en
suspensión
(t)

81-‐82 40723 25 0
82-‐83 58405 27

83-‐84 28748 20
84-‐85 51927 27 Año

85-‐86 27825 20
86-‐87 62535 28

87-‐88 43039 24
88-‐89 55462 27

89-‐90 39488 23
90-‐91 51045 24

91-‐92 54758 27
92-‐93 66142 28

93-‐94 48830 25
94-‐95 51894 25

95-‐96 43141 24

96-‐97 62661 31
97-‐98 66784 27

98-‐99 70259 30
99-‐00 65739 31

00-‐01 77523 35
01-‐02 88779 32

02-‐03 83577 32
03-‐04 95682 36

04-‐05 111367 40
05-‐06 49533 26

06-‐07 51998 24
07-‐08 100959 34

08-‐09 103435 38
09-‐10 64819 28

10-‐11 69750 30

11-‐12 81131 32
12-‐13 51139 32

Promedio 60806 29

203Annex 4

Station 16-05 Santa Lucía

Suspended sediment rating curve

Mean monthly suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD
CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA

TONELAJE
MENSUAL
DE
SEDIMENTOS

Cuenca 16 Frío

Estación 5 Santa
Lucía

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
153

Periodo
comprendido:
23/6/1984
hasta
6/1/2011

Mes Carga
(t) 3 -‐1 Distribución
mensual
del
sedimento
Q
(m
s ) 1600
Ene 462 4
Feb 166 2
1400
Mar 99 2
Abr 38 1 1200
May 308 2
1000
Jun 581 4
Jul 1490 6 800
Ago 1365 6

Sep 656 5 600
Oct 670 5
Nov 769 5 400

Dic 1476 5 Ca200
de
sedimento
en
suspensión
(t)

Total 8079 4 0

Ene Feb Mar Abr May Jun Jul Ago Sep Oct Nov Dic
Mes

204 Annex 4

Mean annual suspended sediment load

INSTITUTO
COSTARRICENSE
DE
ELECTRICIDAD
CENTRO
DE
SERVICIOS
ESTUDIOS
BÁSICOS
DE
INGENIERÍA
-‐
ÁREA
DE
HIDROLOGÍA

TONELAJE
ANUAL
DE
SEDIMENTOS

Cuenca 16 Frío

Estación 5 Santa
Lucía

Número
de
muestras
utilizadas
en
la
confección
de
la
curva
de
descarga
de
sedimentos:
153
Periodo
comprendido:
23/6/1984
hasta
6/1/2011

Distribución
anual
del
sedimento
Año
hidro. Carga
(t)Q
(m
s )
25000
84-‐85 6530 4
85-‐86 2618 3

86-‐87 7596 4 20000
87-‐88 4963 4

88-‐89 7526 4
89-‐90 7881 4 15000

90-‐91 8502 4

91-‐92 8352 4 10000
92-‐93 9212 4

93-‐94 6335 3
94-‐95 8667 4 5000
Carga
de
sedimento
en
suspensión
(t)
95-‐96 3504 3
96-‐97 6567 4
0
97-‐98 8976 4
98-‐99 7964 4 84-‐8855-‐8866-‐8877-‐8888-‐8899-‐9900-‐9911-‐9922-‐9933-‐9944-‐9955-‐9966-‐9977-‐9988-‐9999-‐0000-‐0011-‐0022-‐0033-‐0044-‐0055-‐0066-‐0077-‐0088-‐0099-‐1100-‐1111-‐1122-‐13

99-‐00 5505 4 Año
00-‐01 8696 4

01-‐02 16480 5
02-‐03 8473 4

03-‐04 18505 5
04-‐05 10628 5

05-‐06 3387 3
06-‐07 4801 3

07-‐08 8673 4
08-‐09 8285 5

09-‐10 4764 4
10-‐11 3938 3

11-‐12 23425 6
12-‐13 3546 4

Promedio 8079 4

205Annex 4

APPENDIX B

MONTHLY DISCHARGE MEASUREMENTS BY DOPPLER

DEVICE AT DELTA COLORADO (11-04) GAUGING

STATION

Table B.1 Monthly discharge measurements (using Doppler device) at Delta Colorado (11-04) station
Water Discharge
Date Time 3 -1
stage (m) (m s )
13/12/2010 14:35 1.59 1430

14/12/2010 09:13 1.96 1650
15/12/2010 10:45 1.74 1490
15/12/2010 15:29 1.63 1440

16/12/2010 10:37 1.49 1350
18/01/2011 16:35 2.04 1720

19/01/2011 09:42 1.75 1540
20/01/2011 09:21 1.32 1360
01/03/2011 15:40 2.09 1660

02/03/2011 09:31 2.36 1980
03/03/2011 12:16 1.47 1360

05/04/2011 09:50 0.25 627
27/04/2011 13:23 0.99 533
01/06/2011 12:29 1.58 817

21/06/2011 09:29 2.07 1120
06/07/2011 15:59 1.72 861

30/07/2011 10:00 2.57 1370
30/08/2011 10:31 1.90 991
22/02/2012 10:46 1.38 685

29/03/2012 10:41 1.23 702
27/06/2012 12:39 1.35 636

01/08/2012 10:45 2.53 1,360
29/08/2012 10:37 1.83 923
14/11/2012 10:13 2.91 1,650

19/12/2012 9:57 1.68 786
30/01/2013 10:46 1.11 587

06/03/2013 10:51 1.26 668
23/04/2013 10:08 0.70 424
29/05/2013 09:53 2.35 576

26/06/2013 09:18 3.26 1600

206 Annex 4

FOR THE

JULY 2013
-4) GAUGING STATION
C

APPENDIX

PERIOD DECEMBER 2010

DAILY DISCHARGE AT DELTA COLORADO (11

207Annex 4

APPENDIX D

SUSPENDED SEDIMENT (SS) SAMPLES TAKEN AT LA

TRINIDAD (01-03, JAN 1974 - MAR 1976) AND DELTA

COLORADO (11-04, DEC 2010 - JUN 2013) GAUGING

STATIONS

Table D.1 Suspended sediment and discharge sampling at La Trinidad (01-03) station
Date Time Water stage (m) Discharge (m s )1 Sediment concentration (mg l )1

09/01/1974 - 1,8 955 177
04/06/1974 - 1,61 861 146

06/11/1974 - 2,34 1230 99
07/12/1974 - 5,52 3100 621
14/01/1975 - 1,42 745 70

05/03/1975 - 1 571 38
25/03/1975 - 0,86 514 38

20/08/1975 - 3,17 1690 203
23/09/1975 - 2,78 1549 213
20/11/1975 - 2,95 1570 176

30/01/1976 - 1,93 979 73
17/03/1976 - 1,28 708 40

Table D.2 Sediment and discharge samplig at Delta Colorado3(1-104) station -1
Date Time Water stage (m) Discharge (m s ) Sediment concentration (mg l )
13/12/2010 15:43 1,59 1430 360

16/12/2010 10:05 1,51 1350 227
01/03/2011 16:10 2,07 1660 213

02/03/2011 09:50 2,38 1949 321
02/03/2011 09:59 2,35 1980 262
03/03/2011 13:26 1,46 1356 126

03/03/2011 13:32 1,43 1338 121
05/04/2011 12:26 0,25 627 148

01/06/2011 13:01 1,58 817 138
21/06/2011 09:55 2,12 1120 191
06/07/2011 15:25 1,71 861 129

30/07/2011 11:35 2,56 1370 308
30/08/2011 11:10 1,9 1038 186
05/10/2011 12:25 2,04 1127 177

02/11/2011 10:45 2,97 1691 306
23/11/2011 11:20 3,01 1714 181

04/01/2012 12:10 2,24 1245 117
22/02/2012 11:20 1,39 742 75
29/03/2012 13:10 1,23 647 89

25/04/2012 13:10 1,31 696 89
30/05/2012 13:20 2,47 1407 408

27/06/2012 13:15 1,35 716 80
01/08/2012 11:40 2,53 1420 106
14/11/2012 01:12 2,91 1654 165

19/12/2012 10:35 1,68 909 61
30/01/2013 11:05 1,11 579 87

30/01/2013 11:00 1,11 579 134
06/03/2013 11:45 1,26 664 102
23/04/2013 11:10 0,7 350 91

29/05/2013 10:20 1,05 545 122
26/06/2013 09:45 2,83 1605 229

208 Annex 4

APPENDIX E

GRAIN SIZE DISTRIBUTION FOR BED-LOAD SAMPLES,
TAKEN IN A MONTHLY BASIS WITHIN THE PERIOD
DECEMBER 2010 - JUNE 2013 AT THE MOUTHS OF THE

SAN CARLOS AND SARAPIQUÍ RIVERS, AND AT DELTA
COLORADO STATION (11-04)

209Annex 4

"ICE - 08 - Particle size distribution - DELTA.pptx"

Bed-load sediment:
Station 11-04 Delta Colorado
Particle size distribution

210 Annex 4

Station 11-04 Delta Colorado

14 December 2010

211Annex 4

Station 11-04 Delta Colorado

01 Mar 2011

212 Annex 4

Station 11-04 Delta Colorado

03 Mar 2011

213Annex 4

Station 11-04 Delta Colorado

05 Apr 2011

214 Annex 4

Station 11-04 Delta Colorado

06 Jul 2011

215Annex 4

Station 11-04 Delta Colorado

30 Jul 2011

216 Annex 4

Station 11-04 Delta Colorado

30 Aug 2011

217Annex 4

Station 11-04 Delta Colorado

05 Oct 2011

218 Annex 4

Station 11-04 Delta Colorado

02 Nov 2011

219Annex 4

Station 11-04 Delta Colorado

01 Jan 2012

220 Annex 4

Station 11-04 Delta Colorado

22 Feb 2012

221Annex 4

Station 11-04 Delta Colorado

29 Mar 2012

222 Annex 4

Station 11-04 Delta Colorado

25 Apr 2012

223Annex 4

Station 11-04 Delta Colorado

30 May 2012

224 Annex 4

Station 11-04 Delta Colorado

27 Jun 2012

225Annex 4

Station 11-04 Delta Colorado

01 Aug 2012

226 Annex 4

Station 11-04 Delta Colorado

29 Aug 2012

227Annex 4

Station 11-04 Delta Colorado

14 Nov 2012

228 Annex 4

Station 11-04 Delta Colorado

19 Dec 2012

229Annex 4

Station 11-04 Delta Colorado

30 Jan 2013

230 Annex 4

Station 11-04 Delta Colorado

06 Mar 2013

231Annex 4

Station 11-04 Delta Colorado

22 Apr 2013

232 Annex 4

Station 11-04 Delta Colorado

29 May 2013

233Annex 4

Station 11-04 Delta Colorado

26 Jun 2013

234 Annex 4

Mouth of San Carlos River
Bed-load sediment:
Particle size distribution

235Annex 4

02 August 2011

Mouth of San Carlos River

236 Annex 4

03 November 2011

Mouth of San Carlos River

237Annex 4

24 November 2011

Mouth of San Carlos River

238 Annex 4

05 January 2012

Mouth of San Carlos River

239Annex 4

23 February 2012

Mouth of San Carlos River

240 Annex 4

26 April 2012

Mouth of San Carlos River

241Annex 4

31 May 2012

Mouth of San Carlos River

242 Annex 4

28 June 2012

Mouth of San Carlos River

243Annex 4

02 August 2012

Mouth of San Carlos River

244 Annex 4

30 August 2012

Mouth of San Carlos River

245Annex 4

15 November 2012

Mouth of San Carlos River

246 Annex 4

20 December 2012

Mouth of San Carlos River

247Annex 4

31 January 2013

Mouth of San Carlos River

248 Annex 4

07 March 2013

Mouth of San Carlos River

249Annex 4

25 April 2013

Mouth of San Carlos River

250 Annex 4

30 May 2013

Mouth of San Carlos River

251Annex 4

27 Jun 2013

Mouth of San Carlos River

252 Annex 4

Mouth of Sarapiquí River
Bed-load sediment:
Particle size distribution

253Annex 4

03 August 2011

Mouth of Sarapiquí River

254 Annex 4

02 November 2011

Mouth of Sarapiquí River

255Annex 4

22 November 2011

Mouth of Sarapiquí River

256 Annex 4

03 January 2012

Mouth of Sarapiquí River

257Annex 4

21 February 2012

Mouth of Sarapiquí River

258 Annex 4

27 March 2012

Mouth of Sarapiquí River

259Annex 4

26 April 2012

Mouth of Sarapiquí River

260 Annex 4

29 May 2012

Mouth of Sarapiquí River

261Annex 4

28 June 2012

Mouth of Sarapiquí River

262 Annex 4

31 July 2012

Mouth of Sarapiquí River

263Annex 4

28 August 2012

Mouth of Sarapiquí River

264 Annex 4

13 November 2012

Mouth of Sarapiquí River

265Annex 4

18 December 2012

Mouth of Sarapiquí River

266 Annex 4

29 January 2013

Mouth of Sarapiquí River

267Annex 4

05 March 2013

Mouth of Sarapiquí River

268 Annex 4

22 April 2013

Mouth of Sarapiquí River

269Annex 4

28 May 2013

Mouth of Sarapiquí River

270 Annex 4

25 Jun 2013

Mouth of Sarapiquí River

271Annex 4

APPENDIX F

DISTRIBUTIONS OF BOTH BED-LOAD MEDIAN GRAIN
SIZE AND PERCENTAGE OF SAND, SAMPLED WITHIN
THE PERIOD DECEMBER 2010 - JUNE 2013 AT DELTA

COLORADO STATION (11-04)

272 Annex 4

“ICE - 09 - Distribution of median grain size - DELTA.docx”

Distribution of bed-load median grain size and percentage of sand at Delta Costa Rica

Hydrological station 11-04 (Delta Colorado). Samples from December 2010.

Sample Date d50 (mm) % Sand

1 14/12/2010 0.10 60
2 14/12/2010 0.15 80

3 01/03/2011 0.25 100

4 01/03/2011 0.40 100
5 01/03/2011 0.65 100

6 01/03/2011 0.75 90
7 01/03/2011 0.70 90

8 03/03/2011 0.35 90

9 03/03/2011 0.50 90
10 03/03/2011 0.70 90

11 03/03/2011 0.70 90

12 03/03/2011 0.40 97
13 05/04/2011 0.30 100

14 05/04/2011 0.60 92

15 05/04/2011 0.65 95
16 05/04/2011 0.30 90

17 05/04/2011 0.75 80

18 06/07/2011 0.30 100
19 06/07/2011 0.50 85

20 06/07/2011 0.40 95
21 06/07/2011 0.35 100

22 06/07/2011 0.35 97

23 30/07/2011 0.40 90
24 30/07/2011 0.30 97

25 30/07/2011 0.40 95

26 30/07/2011 0.35 97
27 30/07/2011 0.35 92

28 30/07/2011 0.40 90

29 30/08/2011 0.35 87
30 30/08/2011 0.35 87

31 30/08/2011 0.55 92

32 05/10/2011 0.30 100
33 05/10/2011 0.30 100

34 05/10/2011 0.30 100
35 05/10/2011 0.40 100

36 03/11/2011 0.15 93

37 03/11/2011 0.30 100

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“ICE - 09 - Distribution of median grain size - DELTA.docx”

Sample Date d50 (mm) % Sand
38 03/11/2011 0.55 87

39 03/11/2011 0.30 100
40 03/11/2011 0.60 92

41 04/01/2012 2.00 22

42 04/01/2012 0.30 100
43 04/01/2012 0.65 87

44 04/01/2012 0.70 87

45 04/01/2012 0.65 97
46 30/01/2012 0.25 100

47 30/01/2012 0.35 92

48 30/01/2012 0.30 95
49 30/01/2012 0.30 100

50 30/01/2012 0.30 100

51 22/02/2012 0.35 90
52 22/02/2012 0.60 85

53 22/02/2012 0.55 67
54 22/02/2012 0.80 100

55 22/02/2012 0.70 80

56 06/03/2012 0.28 100
57 06/03/2012 0.55 87

58 06/03/2012 0.40 97

59 06/03/2012 0.40 90
60 06/03/2012 0.50 90

61 29/03/2012 0.55 95

62 29/03/2012 0.30 97
63 29/03/2012 0.30 100

64 29/03/2012 0.28 97
65 29/03/2012 0.09 68

66 25/04/2012 0.55 100

67 25/04/2012 0.45 92
68 25/04/2012 0.40 95

69 25/04/2012 0.28 97

70 25/04/2012 0.09 85
71 30/05/2012 0.09 80

72 30/05/2012 0.30 100

73 30/05/2012 0.25 92
74 30/05/2012 0.25 100

75 30/05/2012 0.10 100

76 27/06/2012 0.50 95
77 27/06/2012 0.30 100

78 27/06/2012 0.30 100

274 Annex 4

“ICE - 09 - Distribution of median grain size - DELTA.docx”

Sample Date d50 (mm) % Sand
79 27/06/2012 0.08 75

80 27/06/2012 0.75 95

81 01/08/2012 0.25 100
82 01/08/2012 0.25 100

83 01/08/2012 0.30 100
84 01/08/2012 0.50 82

85 01/08/2012 0.18 95

86 29/08/2012 0.20 100
87 29/08/2012 0.25 100

88 29/08/2012 0.55 92

89 29/08/2012 0.50 92
90 29/08/2012 0.15 95

91 14/11/2012 0.30 95

92 14/11/2012 0.40 95
93 14/11/2012 0.28 100

94 14/11/2012 0.35 90
95 14/11/2012 0.50 90

96 19/12/2012 0.30 97

97 19/12/2012 0.30 100
98 19/12/2012 0.30 100

99 19/12/2012 0.30 100

100 19/12/2012 0.50 97
101 22/04/2013 0.50 82

102 22/04/2013 0.50 95

103 22/04/2013 0.40 95
104 22/04/2013 0.50 90

105 22/04/2013 0.28 100

106 28/05/2013 0.30 100
107 28/05/2013 0.45 100

108 28/05/2013 0.60 65
109 28/05/2013 0.60 82

110 28/05/2013 0.60 80

111 25/06/2013 0.45 97
112 25/06/2013 0.30 100

113 25/06/2013 0.40 97

114 25/06/2013 0.50 97
115 25/06/2013 0.90 90

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“ICE - 09 - Distribution of median grain size - DELTA.docx”

Frequency distribution of the median grain size (d ):
50

Class Frequency Relative frequenc
(%)
0.08 9 8

0.25 40 35

0.42 38 33

0.58 17 15

0.75 9 8

greater 2 2

Total 115 100

276 Annex 4

“ICE - 09 - Distribution of median grain size - DELTA.docx”

Frequency distribution of the percentage of sand (% Sand):

Class Frequency Relative frequency
(%)
10 0 0

30 1 0

50 1 1

70 9 8

90r 104 90

Total 115 100

277Annex 4

APPENDIX G

ESTIMATION OF THE ANNUAL BED-LOAD SEDIMENT
ACCORDING TO THE EINSTEIN METHOD, FOR THE
PERIOD 2010-2013 IN THE LOWER SAN JUAN AND
COLORADO RIVERS

Refer to the two excel files submitted with this Report,

entitled:
“ICE - 11 – Bedload – Einstein – Lower San Juan”; and

“ICE – 11 – Bedload – Einstein – Delta Colorado”.

278 Annex 4

APPENDIX H

H.1 FLOW DIAGRAM AND DESCRIPTION OF THE
CALSITE MODEL

H.2 INPUT AND OUTPUT MAPS PRODUCED FOR THE
DETERMINATION OF THE POTENTIAL EROSION AND
SEDIMENT YIELD IN BOTH COSTA RICAN AND

NICARAGUAN DRAINAGE BASINS

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H.2 Input and output maps

Figure H.2. Digital elevation model of Costa Rican and Nicaraguan main river basins
draining to the San Juan River.

Figura H.3. Slope map for Costa Rican and Nicaraguan main river basins draining to
the San Juan River.

282 Annex 4

Figura H.4. Mean annual rainfall map for Costa Rican and Nicaraguan main river
basins draining to the San Juan River.

Figura H.5 . R factor map for Costa Rican main basins draining to the
San Juan River.

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Figura H.6. R factor map for Nicaraguan main basins training to the San Juan River.

Figura H.7. C factor map for Costa Rican and Nicaraguan main river basins draining
to the San Juan River.

284 Annex 4

Figura H.8. K factor map for Costa Rican and Nicaraguan main river basins draining
to the San Juan River.

Figura H. 9. LS factor map for Costa Rican and Nicaraguan main river basins

draining to the San Juan River.

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Figura H.10. Potential erosion map for Costa Rican and Nicaraguan main river
basins draining to the San Juan River.

Figura H.11. Specific sediment yield map for Costa Rican and Nicaraguan main river
basins draining to the San Juan River.

286 Annex 4

APPENDIX I

DISAGGREGATED DIAGRAMS, BY SEDIMENT LOAD
COMPONENT, OF THE SEDIMENT BALANCE IN THE
SAN JUAN - COLORADO RIVER SYSTEM, BEFORE AND

AFTER ROUTE 1856 CONSTRUCTION

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I.1. Sediment balance by load component, in the San Juan - Colorado River
system, before the construction of Route 1856

288 Annex 4

I.2. Sediment balance by load component, in the San Juan - Colorado River
system, after the construction of Route 1856

289290 ANNEX 5

Dr. Andreas Mende with Dr. Allan Astorga and Dr. Olivier Chassot

Border Road No. 1856 – Evaluation of the 54 sites of Purported Direct
Sediment Delivery mentioned by Ph.D. Mathias Kondolf

September 2013

291292 Annex 5

Border Road Nº 1856 – Evaluation of the 54

Sites of Purported Direct Sediment Delivery

mentioned by Ph.D. Mathias Kondolf

Elaborated by: Presented to:

Dr. Andreas Mende Ministry of Foreign Affairs
International Expert in Geographic Information
Systems and Remote Sensing Government of Costa Rica

In Collaboration with:
Dr. Allan Astorga

International Expert in Environmental Geology and Land
Management
Dr. Olivier Chassot

General Manager of the Tropical Science Centre

San José - Costa Rica

September 2013

293Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery men1ioned by Ph.D. Mathias Kondolf

1 INTRODUCTION

In their analysis of environmental damages related to the construction of the border road

Nº 1856 along the frontier between Costa Rica and Nicaragua, Dr. Mathias Kondolf and his
colleagues presented 54 sites where they claim there is direct flow of sediment from the

border road into the San Juan River (Ko ndolf et al., 2012) (hereinafter "the Kondolf
Report").

The aim of this report is to carry out a detai led analysis of all those 54 points mentioned
by the Kondolf Report based upon field work, helicopter flights and navigations on the San

Juan River, in order to verify whether there c an be found any indicators to confirm or deny
Dr. Kondolf’s statement regarding each ofthose 54 sites. For this task, the coordinates

provided by Nicaragua to Costa Rica were used as reference of the location of the sites.

In another study we present an inventory of all water courses and slopes related to the
construction of the border road Nº 1856, including an estimation of the quantity of sediment
produced by each of those slopes per year (Mende et al., 2013). Based on these data we

present an estimation about the maximum quantity of sediment which could reach the San
Juan River per year at each of the sites mentioned by t he Kondolf Report. Thiswas

calculated by addingup the values of sedim ent production of all slopes with potential
drainage to the corresponding sites listed by Dr . Kondolf. It is important to mention that

these numbers represent the worst case scenario because only under extraordinary
circumstances all of the produced sediment would reach the San Juan River.

It must be noted that 7 of the sites mentioned by the Kondolf Report are actually located
on Nicaraguan territory. Therefore, those site s have been assigned a 0 value for sediment

input because there is no sediment delivery coming from Costa Rica to the San Juan River
from them. This does not prec lude that those sites may contribute sediment to the San

Juan River, but this was not possible to assess because we were unable to undertake field
work on the Nicaraguan territory. In the case of two Kondolf sites (Nº 36 and 49) erosive
water courses have been found which produc e certain amounts of sediment being

transported to the San Juan River. In these cases it is not possible to estimate the
maximum sediment production because the measurement of the volume eroded by a

specific water course would require a complex analysis which has not been possible to
execute in the frame of this study.

In order to have a well-founded base to assign proportional va lues of maximum
sediment input to the San Juan River, we compare the absolute values of estimated

sediment production with the to tal sediment load transported by the San Juan River at
each of the 54 sites listed by Dr. Kondolf. This information has been extracted from the

hydrological model of the San Juan River System carried out by the “Instituto
Costarricense de Electricidad - ICE” under the leadership of Dr. Federico Gomez-Delgado

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

294 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery men2ioned by Ph.D. Mathias Kondolf

(Gomez-Delgado, 2013). The percentage value of the maximum sediment input induced by
the border road at a spec ific site listed by Kondolf in relation to the total sediment

transported by the San Juan River at this poi nt gives a reasonable basis to estimate
whether any of the 54 sites has the actual potential to pr oduce any damage to this river

system.

This report contains two main parts. The first part comprises an overview map exhibiting
the spatial distribution of the 54 sites mentioned by the Kondolf Report as well as a set of
13 detail maps showing the local conditions of those sites. The detail maps are based upon

a land use map elaborated by Astorga & Mende (2013) and also contain the spatial
distribution of water courses and slopes along the border road Nº 1856 (Mende & Astorga,

2013).

The second part of this Report contai nsa data sheet for each of the 54
locations specified in the Kondolf Report in order to give a sound basis of information about
their local conditions. These data sheets contain the following information:

1. GPS – Coordinates of the site given in decimal degree units as presented by the

government of Nicaragua to the Internat ional Court of Justice on July 2013
(Annex I from the note HOL-CAG-146 dated 29 of July 2013).

2. Estimation of the Maximum Sediment Production at the site based upon the

inventory of slopes (Mende et al., 2013).
3. Sediment transported at the site in the San Juan River, derived from the

hydrological model of the San Juan River (Gomez-Delgado et al., 2013).

4. Percentage of the Maximum Sediment Production versus Total Sediment Flow in
the San Juan River.

5. A short description of the specific characteristics of the site.

6. Reference to the ID codes of slopes and water courses as included within the

inventory of water courses and slopes of the Border Road Nº 1856 (Mende et al.,
2013).

7. A detail map showing the local conditions of the site.

8. Representative photographs of the site in order to provide direct visual
information about the actual situation at the site.

Finally a summary of the results of this re port is provided including some conclusions

about the importance of the 54 Kondolf sites for the San Juan River System.

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

295Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery 3entioned by Ph.D. Mathias Kondolf

Overview map: Spatial distribution of the 54 sites

specified in the Kondolf Report

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Deli5ery mentioned by Ph.D. Mathias Kondolf

Detailed maps - Land Use, Slopes and Water Courses

along the Border Road Nº 1856 in addition to the Spatial

Distribution of the 54 sites specified in the Kondolf Report

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery19entioned by Ph.D. Mathias Kondolf

Data Sheets for the 54 sites

specified in the Kondolf Report

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

312 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by Ph.D20Mathias Kondolf

Kondolf Point: PK 1

X-Coordinate: - 84.35485800 Y-Coordinate: 10.99093000

Maximum Sediment Production at this site: 740 t/year (estimation)

Sediment transported at this site in the San Juan River:3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.022%

Description:

Fill Slope without any drainage, water flow over the road leads to gully erosion.

Related to Slope: T-8 Related to Water Cource: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by Ph21. Mathias Kondolf

Kondolf Point: PK 2

X-Coordinate: -84.34441200 Y-Coordinate: 10.97827500

Maximum Sediment Production at this Site: 360 t/year (estimation)

Sediment transported at this site in the San Juan River:3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.011%

Description:

A water course (C-8) has been closed by landfill, water flowing through this landfill has provoked sinking of the road
structure; during heavy rain, water may flow over the ro ad. Nevertheless only very small amounts of sediment have

reached the San Juan River.

Related to Slope: T-17 Related to Water Course: C-8

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

314 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by Ph22. Mathias Kondolf

Kondolf Point: PK 3

X-Coordinate: -84.34750000 Y-Coordinate: 10.966488

Maximum Sediment Production at this Site: 0 t/year (estimation)

Sediment transported at this site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Probably related to the T-24 slope and/or the C-10 slope, but there is no indication that s ediment from those features

could reach the San Juan River, distance to the San Juan River: 350 m.

Related to Slope: T-24 (?) Related to Water Course: C-10 (?)

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

315Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by Ph.23 Mathias Kondolf

Kondolf Point: PK 4

X-Coordinate: -84.351123 Y-Coordinate: 10.954566

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Broken road bridge with little sediment input to the water co urse, by far the major part of the sediment plume reaching

the San Juan River is caused by erosion within the upperwatershed of the water course. This can clearly be seen in
the aerial photograph in the right upper side, as this water course exhibits a heavy sediment load already upstream the

road bridge and the area of open soil related to the border road.

Related to Slope: none Related to Water Course: C-12

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

316 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by Ph24. Mathias Kondolf

Kondolf Point: PK 5

X-Coordinate: -84.350615 Y-Coordinate: 10.950459

Maximum Sediment Production at this Site: 260 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.008%

Description:

Drainage channel, part of the sediment eroded on the slopeswithin the vicinity may be transported to the San Juan

River. Mitigation measures have been performed at this site.

Related to Slope: T-29, T-30, T-31 Related to Water Course: C-13

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by Ph25. Mathias Kondolf

Kondolf Point: PK 6

X-Coordinate: -84.348509 Y-Coordinate: 10.949374

Maximum Sediment Production at this Site: 1200 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.035%

Description:

Drainage channel, part of the sediment eroded on the slopes within the vicinity may be transported into the San Juan

River. Mitigation measures have been performed at this site.

Related to Slope: T-30, T-31, T-32a, T-32b Related to Water Course: C-14

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

318 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P26D. Mathias Kondolf

Kondolf Point: PK 7

X-Coordinate: -84.345042 Y-Coordinate: 10.949253

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Provisional bridge over smaller water course with slight erosion downstream of the bridge.

Related to Slope: none Related to Water Course: C-16

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P27D. Mathias Kondolf

Kondolf Point: PK 8

X-Coordinate: -84.339647 Y-Coordinate: 10.948089

Maximum Sediment Production at this Site: 340 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.010%

Description:

Slope (T-37) with mitigation measures.

Related to Slope: T-37 Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

320 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P28D. Mathias Kondolf

Kondolf Point: PK 9

X-Coordinate: -84.336418 Y-Coordinate: 10.950686

Maximum Sediment Production at this Site: 0 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Site located on Nicaraguan territory.

Related to Slope: none Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P29D. Mathias Kondolf

Kondolf Point: PK 10

X-Coordinate: -84.336028 Y-Coordinate: 10.945655

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Drainage culvert with slight erosion.

Related to Slope: none Related to Water Course: C-18

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

322 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P30D. Mathias Kondolf

Kondolf Point: PK 11

X-Coordinate: -84.330133 Y-Coordinate: 10.943617

Maximum Sediment Production at this Site: 0 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Site located on Nicaraguan territory.

Related to Slope: none Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P31D. Mathias Kondolf

Kondolf Point: PK 12

X-Coordinate: -84.334792 Y-Coordinate: 10.941062

Maximum Sediment Production at this Site: 4000 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.119%

Description:

T-38 Slope with further mitigation measures to be carried out.

Related to Slope: T-38 Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

324 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P32D. Mathias Kondolf

Kondolf Point: PK 13

X-Coordinate: -84.3345 Y-Coordinate: 10.938104

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Provisional drainage tube in an acceptable state, no indication of erosion or sedimentation to the San Juan River.

Related to Slope: none Related to Water Course: C-20

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P33D. Mathias Kondolf

Kondolf Point: PK 14

X-Coordinate: -84.332474 Y-Coordinate: 10.932826

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Provisional bridge in an acceptable state, no indication of erosion or sedimentation to the San Juan River.

Related to Slope: none Related to Water Course: C-22

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

326 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by Ph.34 Mathias Kondolf

Kondolf Point: PK 15

X-Coordinate: -84.330911 Y-Coordinate: 10.931832

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

A water course has been closed by a landfill, water is infilt rating through this landfill but until now no severe damage
can be seen; some sediment flow in direction of the San Juan River is notable, but it has not reached the river due to

the plain located between the border road and the river serving as a buffer.

Related to Slope: Related to Water Course: C-23

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by Ph.D35Mathias Kondolf

Kondolf Point: PK 16

X-Coordinate: -84.327579 Y-Coordinate: 10.926409

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Exact location has no relation to any slope or water course; it could be related to the water course C-26, which is

crossed by the road by means of a pr ovisional bridge without any erosion orsedimentation towards the San Juan
River.

Related to Slope: none Related to Water Course: C-26 (?)

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P36D. Mathias Kondolf

Kondolf Point: PK 17

X-Coordinate: -84.323897 Y-Coordinate: 10.918903

Maximum Sediment Production at this Site: 300 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,362,000 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.009%

Description: Drainage pathway collecting the sediments from the slope T-46 with gully erosion. Mitigation works
carried out.

Related to Slope: T-46 Related to Water Course: C-29

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by Ph.37 Mathias Kondolf

Kondolf Point: PK 18

X-Coordinate: -84.305245 Y-Coordinate: 10.915977

Maximum Sediment Production at this Site: 5580 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.157%

Description:

Río Infiernillo water course located in the proximity of seven surrounding slopes . Nevertheless, as can be seen in the
photograph, the most important part of the sediment plume r eaching the San Juan River is caused by erosion within

the upper watershed of the Río Infiernillo.

Related to Slope: T-56, T-57a, T-57b, T-58a, T-58b,
T-59, T-60 Related to Water Course: C-35

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P38D. Mathias Kondolf

Kondolf Point: PK 19

X-Coordinate: -84.297602 Y-Coordinate: 10.914443

Maximum Sediment Production at this Site: 2,160 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.061%

Description:

Wide area with open soil and high slope angles. Mitigation works carried out.

Related to Slope: T-61 Related to Water Course: C-36

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by 39.D. Mathias Kondolf

Kondolf Point: PK 20

X-Coordinate: -84.283903 Y-Coordinate: 10.909981

Maximum Sediment Production at this Site: 0 t/year

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Site located on Nicaraguan territory.

Related to Slope: none Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

332 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P40D. Mathias Kondolf

Kondolf Point: PK 21

X-Coordinate: -84.289629 Y-Coordinate: 10.90672

Maximum Sediment Production at this Site: 2,070 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.058%

Description:

Location characterized by deep gully erosion and landslides.

Related to Slope: T-65 Related to Water Course: C-37

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by Ph.41 Mathias Kondolf

Kondolf Point: PK 22 and PK 23

X-Coordinate (PK 22): -84.28725 Y-Coordinate (PK 22): 10.899889

X-Coordinate (PK 23): -84.287094 Y-Coordinate (PK 23): 10.899421

Maximum Sediment Production at this Site: < 1 t/year (rough estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

For the points PK 21 and PK 22 up to now there could not be collected any field data so fare, because during field work
very bad weather conditions did not permit any data collection at this site. Based on satellite images sediment input to

the San Juan River cannot be proven. As PK 21 and PK 22 are lo cated very close to each other they may refer to the
same site.

Related to Slope: none Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

334 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P42D. Mathias Kondolf

Kondolf Point: PK 24

X-Coordinate: -84.280593 Y-Coordinate: 10.90006

Maximum Sediment Production at this Site: 0 t/year

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Site located on Nicaraguan territory.

Related to Slope: none Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

335Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P43D. Mathias Kondolf

Kondolf Point: PK 25

X-Coordinate: -84.283927 Y-Coordinate: 10.89442

Maximum Sediment Production at this Site: 2,250 t/year (estimation)

Sediment transported at this Site in the San Juan River:3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.063%

Description:

Fill slope with gully erosion and landslides.

Related to Slope: T-68 Related to Water Course: C-40

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

336 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P44D. Mathias Kondolf

Kondolf Point: PK 26 and PK 27

X-Coordinate (PK 26): -84.281868 Y-Coordinate (PK 26): 10.893188

X-Coordinate (PK 27): -84.282023 Y-Coordinate (PK 27): 10.893287

Maximum Sediment Production at this Site: 4,500 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.126%

Description:

Location PK 26 y PK 27 probably refer to the same site, characterized as a fill slope with gully erosion and landslides.

Related to Slope: T-72 Related to Water Course: C-42

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P45D. Mathias Kondolf

Kondolf Point: PK 28

X-Coordinate: -84.280862 Y-Coordinate: 10.89337

Maximum Sediment Production at this Site: 3,400 t/year (estimation)

Sediment transported at this Site in the San Juan River:3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.095%

Description:

Related to the cut slope T-73 characterized by deep gully erosion and landslides.

Related to Slope: T-73 Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

338 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P46D. Mathias Kondolf

Kondolf Point: PK 29

X-Coordinate: -84.279346 Y-Coordinate: 10.892837

Maximum Sediment Production at this Site: 5,000 t/year (estimation)

Sediment transported at this Site in the San Juan River:3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.141%

Description:

Location related to fill slope T-74 passing by a little valley with a water course (C-43).

Related to Slope: T-74 Related to Water Course: C-43

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

339Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by P47D. Mathias Kondolf

Kondolf Point: PK 30

X-Coordinate: -84.278523 Y-Coordinate: 10.892642

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River:3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Related to the cut slope T-75, at present there is not visible any sediment flow in direction of the San Juan River.

Related to Slope: T-75 Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

340 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 48 Ph.D. Mathias Kondolf

Kondolf Point: PK 31

X-Coordinate: -84.274959 Y-Coordinate: 10.89224

Maximum Sediment Production at this Site: 50 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.001%

Description:

Related to fill slope T-77 and water course C-44b. Slight sediment flow towards the San Juan River.

Related to Slope: T-77 Related to Water Course: C-44b

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 49 Ph.D. Mathias Kondolf

Kondolf Point: PK 32

X-Coordinate: -84.273831 Y-Coordinate: 10.892122

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Related to cut slope T-78, there is no sign for any sediment flow in direction of the San Juan River.

Related to Slope: T-78 Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

342 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 50 Ph.D. Mathias Kondolf

Kondolf Point: PK 33

X-Coordinate: -84.272108 Y-Coordinate: 10.891831

Maximum Sediment Production at this Site: 90 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.002%

Description:

Related to water course C-44 and T-79 and T-80 slopes, slight sediment flow.

Related to Slope: T-79, T-80 Related to Water Course: C-44

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 51 Ph.D. Mathias Kondolf

Kondolf Point: PK 34

X-Coordinate: -84.268405 Y-Coordinate: 10.891704

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Small river (C-45) without any bridge, there is no sign for any sediment flow in direction of the San Juan River

Related to Slope: none Related to Water Course: C-45

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

344 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 52 Ph.D. Mathias Kondolf

Kondolf Point: PK 35

X-Coordinate: -84.267486 Y-Coordinate: 10.891516

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

There is not visible any source of sediment at this site.

Related to Slope: none Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 53 Ph.D. Mathias Kondolf

Kondolf Point: PK 36

X-Coordinate: -84.263719 Y-Coordinate: 10.890958

Maximum Sediment Production at this Site: erosive water cause, estimation not possible at this moment

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: No data

Description:

At this site the road is interrupted for the reason of the destruction of larger drainage tube.

Related to Slope: none Related to Water Course: C-46

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 54 Ph.D. Mathias Kondolf

Kondolf Point: PK 37

X-Coordinate: -84.252381 Y-Coordinate: 10.889064

Maximum Sediment Production at this Site: 890 t/year (estimation)

Sediment transported at this Site in the San Juan River:3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.025%

Description:

Cut slope T-81 with gully erosion.

Related to Slope: T-81 Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 55 Ph.D. Mathias Kondolf

Kondolf Point: PK 38

X-Coordinate: -84.251092 Y-Coordinate: 10.888361

Maximum Sediment Production at this Site: 390 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.011%

Description:

Cut slope with gully erosion.

Related to Slope: T-82 Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

348 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 56 Ph.D. Mathias Kondolf

Kondolf Point: PK 39

X-Coordinate: -84.247971 Y-Coordinate: 10.887251

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

There is not visible any source of sediment at this site.

Related to Slope: none Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

349Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 57 Ph.D. Mathias Kondolf

Kondolf Point: PK 40

X-Coordinate: -84.221807 Y-Coordinate: 10.867978

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Sediment flow is predominantly related to a farm house and its animals, and has no relation to the border road.

Related to Slope: T-84 Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

350 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned b58Ph.D. Mathias Kondolf

Kondolf Point: PK 41

X-Coordinate: -84.224737 Y-Coordinate: 10.802815

Maximum Sediment Production at this Site: 30 t/year (estimation)

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.001%

Description:

Sediment production is caused by erosion within the upper watershed of the water course, with minimal input of erosion
products coming from slopes related to the border road.

Related to Slope: T-92, T-93 Related to Water Course: C-61

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

351Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned59y Ph.D. Mathias Kondolf

Kondolf Point: PK 42

X-Coordinate: -84.203566 Y-Coordinate: 10.799494

Maximum Sediment Production at this Site: 0 t/year

Sediment transported at this Site in the San Juan River: 3,559,500 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Site located on Nicaraguan territory.

Related to Slope: none Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

352 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 60 Ph.D. Mathias Kondolf

Kondolf Point: PK 43

X-Coordinate: -84.188654 Y-Coordinate: 10.790028

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 7,753,350 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Provisional drainage tube, acceptable present no indication of erosion or sedimentation to the San Juan River.

Related to Slope: none Related to Water Course: C-67

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

353Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned61y Ph.D. Mathias Kondolf

Kondolf Point: PK 44

X-Coordinate: -84.176205 Y-Coordinate: 10.786282

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 7,753,350 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Drainage tube in an acceptable stno indication of erosion or sedimentation to the San Juan River.

Related to Slope: none Related to Water Course: C-70

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

354 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 62 Ph.D. Mathias Kondolf

Kondolf Point: PK 45

X-Coordinate: -84.156595 Y-Coordinate: 10.786223

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 7,753,350 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Provisional drainage tube, acceptable present no indication of erosion or sedimentation to the San Juan River.

Related to Slope: none Related to Water Course: C-76

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned63y Ph.D. Mathias Kondolf

Kondolf Point: PK 46

X-Coordinate: -84.132591 Y-Coordinate: 10.783828

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 7,753,350 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Drainage tube with slight erosion downstream the road.

Related to Slope: none Related to Water Course: C-80

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

356 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 64 Ph.D. Mathias Kondolf

Kondolf Point: PK 47

X-Coordinate: -84.123554 Y-Coordinate: 10.764318

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 7,753,350 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Provisional drainage tube, acceptable present stano indication of erosion or sedimentation to the San Juan River
related to the road. Slight sediment input to the San Juan River is caused by a settlement at the edge of the river.

Related to Slope: none Related to Water Course: C-85

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

357Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned65y Ph.D. Mathias Kondolf

Kondolf Point: PK 48

X-Coordinate: -84.087589 Y-Coordinate: 10.771606

Maximum Sediment Production at this Site: 0 t/year

Sediment transported at this Site in the San Juan River: 7,753,350 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Site located on Nicaraguan territory.

Related to Slope: none Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned by66h.D. Mathias Kondolf

Kondolf Point: PK 49

X-Coordinate: -84.084951 Y-Coordinate: 10.761729

Maximum Sediment Production at this Site: erosive water cause, estimation not possible at this moment

Sediment transported at this Site in the San Juan River: 7,753,350 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: No data

Description:

Site where the Caño Cureña (C-86) as well as another smaller water course (C-87) with erosive features flow into the San
Juan River. Nevertheless, as seen in the last two photographs on the following page, during the day of the helicopter

overflight the San Juan River exhibited a considerably higher sediment load in comparison with the incoming water course.

Related to Slope: T-114, T-115 Related to Water Course: C-86, C-87

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 67 Ph.D. Mathias Kondolf

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

360 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 68 Ph.D. Mathias Kondolf

Kondolf Point: PK 50

X-Coordinate: -83.995491 Y-Coordinate: 10.760629

Maximum Sediment Production at this Site: 40 t/year (estimation)

Sediment transported at this Site in the San Juan River: 7,753,350 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.006%

Description:

Most probably related to a fill slope site (T-153); sediment input to the San Juan River is buffered by the plain area between
the fill slope and the river.

Related to Slope: T-152 Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

361Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentione69by Ph.D. Mathias Kondolf

Kondolf Point: PK 51

X-Coordinate: -83.985908 Y-Coordinate: 10.761695

Maximum Sediment Production at this Site: 0 t/year

Sediment transported at this Site in the San Juan River: 7,753,350 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Site located on Nicaraguan territory

Related to Slope: none Related to Water Course: none

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned70y Ph.D. Mathias Kondolf

Kondolf Point: PK 52

X-Coordinate: -83.990118 Y-Coordinate: 10.754811

Maximum Sediment Production at this Site: < 3 t/year (estimation)

Sediment transported at this Site in the San Juan River:7,753,350 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Provisional drainage tube (C-98), some erosion and slight sediment flow.

Related to Slope: none Related to Water Course: C-99

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 71 Ph.D. Mathias Kondolf

Kondolf Point: PK 53

X-Coordinate: -83.969122 Y-Coordinate: 10.736112

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 7,753,350 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Provisional bridge over a small river (C-100) without any indicator for erosion or sediment flow into the San Juan River;
the water of the C-100 exhibits a by far much lower degree of turbidity in comparison with the San Juan River.

Related to Slope: none Related to Water Course: C-100

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

364 Annex 5

Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned 72 Ph.D. Mathias Kondolf

Kondolf Point: PK 54

X-Coordinate: -83.918261 Y-Coordinate: 10.710488

Maximum Sediment Production at this Site: < 1 t/year (estimation)

Sediment transported at this Site in the San Juan River: 8,949,300 t/year

Maximum Sediment Production in relation to Sediment transported in the San Juan River: 0.000%

Description:

Bridge over the Caño Negro (C-109), river edges stable and non-erosiv e, no visible indicators of sediment flow into the San
Juan River.

Related to Slope: none Related to Water Course: C-109

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery me73ioned by Ph.D. Mathias Kondolf

1 CONCLUSIONS

The above data on the 54 sites specified in the Kondolf Reportare summarizedin
Tables 1 and 2.

Table 1 gives an overview of all 54 sites regarding their ma ximum sediment production
and the relation of this value in comparison with the sediment load at the corresponding

site in question. In addition, Table 2 represents this data grouped by ranges of Maximum
Sediment Production and the corresponding percentage in relation to the sediment
transported in the San Juan River.

As determined in the study, 7 of the 54 sites (13%) indicated by Dr. Kondolf were

actually located in Nicaragua ra ther than in Costa Rica. Thos e sites were therefore not
assigned an absolute or proportional value of sedi ment input in this study. Additionally, in

the case of 23 sites (42.6% of all sites), where Dr. Kondolf detect ed a direct flow of
sediment from the border road into the San Juan River, it has not been possible to find any
indicator or evidence to confirm this observa tion. In these cases photographs can prove

that the border road does not af fect in any way the San Juan River System. Therefore, in
all, 30 sites (55.6%) of the 54 indicated by Dr. Kondolf lack factual basis.

5 sites lay in the range between 1 and 100 t/year of Maximum Sediment Production

corresponding to 0.001 to 0.003% of the sediment transpor ted in the San Juan River.
These percentage values by themselves prove that these 4 sites can be fully ignored
because the San Juan River is accustomed to transport extremely high sediment volumes.

7 sites (13%) fall in the range between 100 and 1000 t/year of Maximum Sediment

Production corresponding to 0.001 to 0.025% of the sediment transported in the San Juan
River. In the case of smaller river systems with much lower sediment loads, an additional

sediment input within this r ange could provoke damages to some degree, but not with
respect to the San Juan River due to its extr emely high level sediment load, as shown by
Gomez-Delgado et al. (2013).

The range between 1000 and 5600 t/year of Maximum Sediment Production (0.025 to

0.160% of the sediment transpor ted in the San Juan River) counts for 9 sites (16.7%).
Again, in the case of ot her river systems characterized by much lower sediment

transportation rates in comparison to the San Juan River, sediment input of this dimension
could generate serious problem s. In the case of the San Juan River System the
percentage values of 0.025 to 0.160% show that this ri ver can handle much higher

amounts of sediment and therefore there will be no significant damage to this river system
as a whole. There are a sma ll number of localised sites which have been impacted. For

this reason it is recommended that Costa Rica continues with the so far successful actions
and measures to mitigate erosion and sedimentation.

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

366 Annex 5

Maximum Sediment Sediment transported Maximum Sediment Production in relation to
Kondolf Site 1 2
Production in the San Juan River Sediment transported in the San Juan River

1 740 t/year 0.022 %

2 360 t/year 0.011 %
3 0 t/year 0.000 %

4 < 1 t/year 0.000 %

5 260 t/year 0.008 %

6 1,200 t/year 0.035 %

7 < 1 t/year 0.000 %

8 340 t/year 3,362,000 t/year 0.010 %

9 0 t/year (Mojón II to Río 0.000 %
10 < 1 t/year Infiernillo) 0.000 %

11 0 t/year 0.000 %

12 4,000 t/year 0.119 %

13 < 1 t/year 0.000 %

14 < 1 t/year 0.000 %

15 < 1 t/year 0.000 %

16 < 1 t/year 0.000 %
17 300 t/year 0.009 %

18 5,580 t/year 0.157 %

19 2,160 t/year 0.003 %

20 0 t/year 0.047 %

21 2,070 t/year 0.058 %

22 < 1 t/year 0.000 %

23 < 1 t/year 0.000 %

24 0 t/year 0.049 %
25 2,250 t/year 0.063 %

26 4,500 t/year (includes 27) 0.126 %

27 See Nº 26 0.126 %

28 3,400 t/year 0.095 %

29 5,000 t/year 3,559,500 t/year 0.141 %

30 < 1 t/year (Río Infiernillo to Río 0.000 %
San Carlos)
31 50 t/year 0.001 %

32 < 1 t/year 0.000 %
33 90 t/year 0.002 %

34 < 1 t/year 0.000 %

35 < 1 t/year 0.000 %

36 No data !! No data !!

37 890 t/year 0.025 %

38 390 t/year 0.011 %

39 < 1 t/year 0.000 %
40 < 1 t/year 0.000 %

41 30 t/year 0.001 %

42 0 t/year 0.000 %

43 < 1 t/year 0.000 %

44 < 1 t/year 0.000 %

45 < 1 t/year 0.000 %

46 < 1 t/year 0.000 %
47 < 1 t/year 0.000 %
7,753,350 t/year
48 0 t/year (Río San Carlos to 0.000 %

49 No data !! Río Sarapiquí) No data !!

50 40 t/year 0.001 %

51 0 t/year 0.000 %

52 < 3 t/year 0.000 %

53 < 1 t/year 0.000 %

8,949,300 t/year
54 < 1 t/year (Río Sarapiquí to Delta 0.000 %

Costa Rica)

Table 1: Resume of the collected data for the 54 sites mentioned by Kondolf et al. (2012): sites marked in

light green refer to those locations where no sediment input could be detected, sites marked in light

orange are those where a possible sediment input to the1San Juan River has been found), sites
marked in grey are those located in Nicaragua; ( ): based upon the data from Mende & Astorga (2013);
2
( ): based upon the data from Gomez-Delgado et al. (2013).

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Border Road Nª 1856 – Evaluation of the 54 Sites of Purported Direct Sediment Delivery mentioned b75Ph.D. Mathias Kondolf

Maximum Sediment Maximum Sediment Production in Number of Sites mentioned by
1 relation to Sediment transported in the San
Production 2 Kondolf et al (2012)
Juan River

Sites located in 0.000 % 7
Nicaragua

0 - 1 t/year 0.000 % 23

1 -100 t/year 0.001 – 0.003 % 5

100 – 1000 t/year 0.003 – 0.025% 7

1000 – 5600 t/year 0.025 – 0.160% 9

No data / excluded ( ) - - - - - 3

Sum 54

Table 2: Data for the 54 sites mentioned by Kondolf . (2012) grouped based on ranges of Maximum Sediment
Production and the according percentage in relation to Sediment transported in the San Juan River; ( ): based on data
2 3
from Mende & Astorga (2013) ; ( based on data from Gomez-Delgado et al. (2013); ( ): site 27 has been excluded
because its sediment production is included in the value of site 26.

2 REFERENCES

Astorga, A. & Mende, A. (2013): Ruta 1856 Route 1856: Analysis of the Change in Land

Use. San José, Costa Rica.

Gomez-Delgado, F., Leitón-Montero, J. J. & Aguilar-Cabrera, C.A. (2013). Report on

hydrology and sediments for th e Costa Rican river basins draining to the San Juan

River. San José, Costa Rica: Instituto Costarricense de Electricidad.

Kondolf, G. M., Hagans, D., Weaver, B & Weppner, E. (2012): Environmental Impacts of

Juan Rafael Mora Porras Route 1856, Costa Rica, on the Río San Juan, Nicaragua.

Mende, A. & Astorga, A. (2013): Inventory of Slopes and Wate r Courses related to the

Border Road Nº 1856 between Mojón II and Delta Costa Rica. San José, Costa Rica.

Dr. Andreas Mende, Dr. Allan Astorga & Dr. Olivier Chassot (September 2013)

368 ANNEX 6

Dr. Andreas Mende and Dr. Allan Astorga

Inventory of Slopes and Water Courses related to the Border Road Nº 1856
between Mojón II and Delta Costa Rica

September 2013

369370 Annex 6

Inventory of Slopes and Water Courses

related to the Border Road Nº 1856

between Mojón II and Delta Costa Rica

Elaborated by: Presented to:

Dr. Andreas Mende Ministry of Foreign AffairsCosta Rica
International Expert in Geographic Information
Systems and Remote Sensing

In cooperation with:
Dr. Allan Astorga
International Expert in Environmental Geology and Land
Management

San José - Costa Rica
October 2013

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Inventory of Slopes and Water Courses related to the Border Road Nº 1856 between Moj1n II and Delta Costa Rica

1 INTRODUCTION

This report provides a complete inventory of all cut slopes, fill slopes, and watercourse

intersections (crossings) along Route 1856 betw een the Mojón II, where the border road

first approaches the San Juan River, and Delta Costa Rica, where it ends.

Applying data on erosion depths and rates of land surface lowering due to sheet, rill,

landslide and gully erosion reported in UCR (2013), by Oreamuno Vega, M. Eng. and

Roberto Villalobos Herrera at the University of Costa Rica, we estimated the sediment

yields from all the cut and f ill slopes that exist along the bor der road between Mojón II and

Delta Costa Rica. The sediment yields were, in turn, passed to Federico Gómez Delgado,
Juan José Leitón Montero and Carl os Aguilar at the Costa Rica n Institute of Electricity,

Centre for Engineering Studies, Department of Hydrology. They used the yields, together

with calculations of sediment yields due to sheet and rill erosion of the road bed and other

disturbed areas, to estimate overall erosion and sediment delivery from Route 1856 to the

San Juan River system (ICE 2013).

2 METHODOLOGY

The inventory of cut and fill slopes, and wa tercourse intersections and crossings was
undertaken between April and A ugust 2013. It is based upon extended field work,

navigation on Costa Rican rivers and helicopter over flights, complemented by examination

of high resolution satellite images.

The following guidelines were used as a basis for building the inventory:

 A unique identificat ion code was assigned to each feature ( C-1, C-2 etc. for

watercourse intersections/crossings and T-1, T-2 etc. for cut and fill slopes
(Spanish Talud)), in order to create a complete register and uniform nomenclature

to be used in this and all future studies.

 Attribute data for slopes and waterc ourses were collect ed and entered on

specially designed data record sheets in order to guarantee standardized and
complete data records (see Figures 1 and 2).

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Figure 1: Data sheet used for the collection of field data in the case of slopes.

 Attribute data have been stored in an A CCESS database especially designed for

this project and purpose. Second degree normalization of all information in the

database has been performed to maximize the capacity for analysis. The data in

the database are spatially referenced within an ArcMAP GIS environment. This

was achieved using an OLE DB Connecti on, based upon uniqu e identification

codes for each slope and watercourse.

 The locations of each feature were estab lished in the field using a high precision

GPS, with an average accuracy of 1 m. In the case of slopes, the GPS

coordinates of the start and end points of the feature we re recorded, whereas for

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Inventory of Slopes and Water Courses related to the Border Road Nº 1856 between Mojón3II and Delta Costa Rica

watercourses the intersection point(s) with the Border Road were recorded. In the

case of bridges with a length greater t han 5 m, the start and end points of the

structure were recorded using the GPS.

 The present states of all slopes and watercourses were documented using digital

photographs. Photograph numbers and descriptions are included in the ACCESS

data base.

Figure 2: Data sheet used for the collection of field data in the case of water course intersections and

crossings.

3 DATA COLLECTION

This section reports the data sets collected for slopes and watercourses (see the record

sheets used for field data collection in Figures 1 and 2).

Administrative data for each feature comprise the Unique Identification Code for each

feature, the date of t he field visit, a short description of the location and the name of the

person executing field data collection, together with the GPS coordinates.

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For water course intersections a nd crossings, records include the Type Of Structure

(options: Closed Land Fill, Land Fill with Drainag e Tube, Land Fill with Bridge, Land Fill
with Tree-Trunks, Bridge without Land Fill, Without any Construction) and the Present

Technical State (options: Closed, Provisional, Improved, Appropriate, Broken, Without any

Construction). In addition, the presence/absence of Sedimentary/Erosive Processes and

the potential Use of Land Fills for the crossing are recor ded. Free text fields for

descriptions of geological a nd/or geomorphological featur es and any general comments

complete the record.

For slopes, records include the Type of Slope (options: fill or cut slope), the average

and maximum height of the slope and which side of the road the feature is on (options: left

or right with respect to the downstream dire ction of the adjacent San Juan River). Slope
heights were estimated visually in the fiel d so that data collection could be completed

within a reasonable time span.

Specific data for slopes include Erosion Features (options: None, Sheet Erosion, Rills,
Gullies, Land Slides ) and Geology - Stratigraphic Unit ( options: Ophiolite Complex of

Tiricias, Turbidites of Eocene/Paleocene age, Volcan ic and Volcaniclastic rocks of Tertiary

age, Volcanic Rocks of Quat ernary age, Volcaniclastic Ro cks of Quaternary age, Coarse

Volcaniclastic Breccias, Land Fill).

Field observations also included estimating the Proportion of the Feature covered by

each type of Erosion (option: percentage of the total area of the slope ). It was observed

that the areas affected by each type of eros ion did not overlap, so the sum of the

percentages of the attribute classes ( None, Sheet Erosion, Ril ls, Gullies, Land Slides)

always add up to 100% of the total area of the slope.

Finally, the presence of any Mitigation Measures was noted ( options: None,

Geotextiles, Drainage Control, Stabilization by Terraces, Sowed Vegetation, Natural

Vegetation, Sediment Traps ). As in the case of waterc ourses, free text fields for
descriptions of geological and /or geomorphological featur es and other comments in

general complete the record.

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Inventory of Slopes and Water Courses related to the Border Road Nº 1856 between Mojó5 II and Delta Costa Rica

4 SPATIAL DISTRIBUTION OF SLOPES AND WATER COURSES

In Figure 3 we present an overview map showing the locati ons of all slopes and water

course intersections along the Road between Mojón II and Delta Costa Rica. Tables 1 and
2 provide summary information on the spatia l distribution of sl opes and watercourses

grouped into four segments of the Road:

(1) Mojón II to Río Infiernito (13.8 km),

(2) Río Infiernito to Río San Carlos (27.6 km),

(3) Río San Carlos to Río Sarapiquí (43.6 km) and

(4) Río Sarapiquí to Delta Costa Rica (22.6 km).

The map in Figure 3, together with the information in Tables 1 and 2, reveal a clear

pattern in the spatial distribution and density of slopes and watercourse intersections, and

this is discussed below.

The number and density of watercourse inte rsections are highest in Segment 1 (34

watercourses, 2.5 intersections kilometre). Segment 1 also contains the greatest length

and highest proportion of slopes (length 9.4 km, which is 68% of the length of the Road
between Mojón II and Río Infiernito). Segment 2 also exhibits relati vely high watercourse

numbers and densities (34 watercourses, 1.3 intersections per kilometre). In Segment 2,

slopes are found along 7.9 km of the Road, which is 29% of the length of the Road in this

segment.

In Segment 3 there are 43 watercourses, but the intersections are more widely spaced

because this segment is longer (43.6 km), yielding just 1 intersection per kilometre. Slopes

are found along 6.7 km of the Road in this segment, which constitutes 15% of the 43.6 km

length of the Road in this segment.

There are only 10 watercourses in Segment 4, from the Sar apiquí River to Delta Costa

Rica, meaning that the density of intersections is only 0.4 per kilometre. Similarly, there are
only 10 slopes in this low relief segment, occupying just 5% of the length of the Road.

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Inventory of Slopes and Water Courses related to the Border Road Nº 1856 between Mo6ón II and Delta Costa Rica

Figure 3: Overview map with the locations of all

slopes and water course intersections along the 1856 Road between

Mojón II and Delta Costa Rica

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Inventory of Slopes and Water Courses related to the Border Road Nº 1856 between Mojón II and Delta8Costa Rica

Road Section Section Slopes Slopes (total Slopes (percentage of
Length (km) (number) length) segment road length)

Section 1 - Mojón II to 13.8 km 63 9.4 km 68 %
Río Infiernito

Section 2 - Río
Infiernito to Río San 53 7.9 km
Carlos 27.6 km 29 %

Section 3 - Río San
Carlos to Río Sarapiquí 43.6 km 64 6.7 km 15 %

Section 4 - Río

Sarapiquí to Delta 8 1.1 km
Costa Rica 22.6 km 5 %

Sum 107.6 km 188 25.1 km

Table 1: Spatial distribution of slopes along the bord er road Nº 1856 in function of 4 established road

segments.

Section Water Courses Number of Water
Road Section
Length (km) (number) Courses per Kilometre
Section 1 - Mojón II to
Río Infiernito 13.8 km 34 2.5

Section 2 - Río
Infiernito to Río San 27.6 km 35 1.3
Carlos

Section 3 - Río San 43.6 km 43 1.0
Carlos to Río Sarapiquí

Section 4 - Río
Sarapiquí to Delta 22.6 km 10 0.4
Costa Rica

Sum 107.6 km 122

Table 2: Spatial distribution of water courses along t he border road Nº 1856 in function of 4 established road

segments.

In conclusion, both the numbers and densities of watercourse intersections, and the

lengths and proportions of slopes decrease with distance from Mojón II. The spatial

distributions of these features are such that they are highly conc entrated in segments 1

and 2. Segment 3 has a lower but moderate concentration of watercourse and slope

features, while these are rare in Segment 4.

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Inventory of Slopes and Water Courses related to the Border Road Nº 1856 betwee9 Mojón II and Delta Costa Rica

5 DETAILED MAP SET SHOWING SLOPES AND WATER COURSES

ALONG ROUTE 1856

To provide detailed cartographic information regarding all watercourse intersections and
slopes along the Route 1856 between Mojón II and Delta Costa Rica, we made a set of 16

detailed maps at a scale of 1:15.000. Thes e maps show the extents of all slopes and

locations of all watercourse intersections along the Road. This map set is based on the

land use change maps produced earlier by Astorga & Mende (2013).

Dr. Andreas Mende & Dr. Allan Astorga (October 2013)

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Inventory of Slopes and Water Courses related to the Border Road Nº 1856 between Moj10 II and Delta Costa Rica

Detailed Set of 16 Maps showing Slopes and Water Courses along

Route 1856 between Mojón II and Delta Costa Rica

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Inventory of Slopes and Water Courses related to the Border Road Nº 1856 between Mojón II a27 Delta Costa Rica

6 PRESENT CONDITION OF SLOPES AND WATERCOURSE
INTERSECTIONS

In this section we use statistical treatment of the base data to provide an overview of the

present condition of watercourse intersections and slopes along Route 1856.

6.1 W ATERCOURSE INTERSECTIONS

According to the inventory, there are 121 watercourse intersections along the Road

between the Mojón II and De lta Costa Rica, includ ing those at San Carlos and Sarapiquí

Rivers, which are exceptionally large and which are, therefor e, excluded from further

statistical treatment.

Water courses Water courses
Type Of Structure (number) (%)

Closed Land Fill 16 13.4 %

Land Fill with Drainage Tube 48 40.3 %
Land Fill with Bridge 35 29.4 %

Land Fill with Tree-Trunks 3 2.5 %
Bridge without Land Fill 1 0.8 %

Without any Construction 16 13.4 %

Sum 119 100.0%

Table 3: Statistical data regarding the type of structures us ed for crossing of water courses in the case of the
border road.

The structural conditions of the watercourse intersections are summarized in Table 3.

The results show that 84% of watercourses (excluding the Sa n Carlos and Sarapiquí) are

crossed by means of a variety of generally acceptabl e structures including 48 Land Fills

with Drainage Tubes, 35 Land Fills with Bridges and 1 Bridge without Land Fill . There are

16 watercourse intersections where construc tion of any type a crossing has not yet

commenced (see). At 16% of watercourse intersec tions, different technical solutions have

been invoked, including 16 that have been closed by land fills and 3 where tree-trunks

(rather than culverts have been installed to allow water to pass beneath the Road.

The present operational conditions of the cr ossings are summarized in Table 4. For 26

watercourses (22%), the presen t state is entirely acceptable This includes watercourses

where there is an appropriate crossing solution or no impac t due to construction of the

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Road. At another 26 crossi ngs (22%), technical impr ovements have been made and,

although further corrective works may be necessary in future, the crossings will continue to

be in an acceptable condition in the medium-term.

Present Technical State Water courses Water courses
(number) (%)
Closed 16 13.4 %

Provisional 42 35.3 %

Improved 26 21.8 %
Appropriate 10 8.4 %

Broken 9 7.6 %

Without any Construction 16 13.4 %
Sum 119 100.0%

Table 4: Statistical data regarding the present technical state of structures used for crossing of water courses
in the case of the border road.

42 crossings (35%) are currently in a prov isional state and techni cal improvements are

recommended within the near future. This recommendation also applies to the 16 (13%) of

crossings that are closed and the 9 (8%) where the crossing structure is broken. Technical

improvements are not time crit ical at these crossings, but should be undertaken once civil

engineers have reviewed the watercourses and designed appropriate permanent crossing

solutions.

In conclusion, conditions at crossings along Route 1856 can at present be described as

typical during a construction period. Techni cal improvements have been made at some

crossings, and these will be exte nded to other crossings that ar e in a provisional condition

so that all crossings reach an acceptable condition in the future.

6.2 S LOPES

According to the inventory, there are 188 slopes (139 cut slopes 49 fill slopes) along

Route 1856 between Mojón II an d Delta Costa Rica (for more detailed data see Appendix

A). Based on the slope inventory (as described in section 3, above), the overall length of

these slopes is about 25.1 km and the total area of the slopes is estimated as 124,350 m . 2

According to the field surveys, the area pres ently affected by Sheet Erosion is around

63,200 m , which represents approximately 51% of the total area of the slopes (compare

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Table 5). Extensive areas of Rills (26,250 m 2 or ~21%) and Gullies (20,160 m 2or ~16%)

2
were also inventoried. Landslides were observed to occupy 12,640 m (~10%) of the total
2
area. Mostly as a result of the re-established dense vegetation, 2,100 m (2%) of observed

slopes do not show identifiable erosion processes.

2
Types of Erosion Slopes (Area m ) Slopes (Area %)
None 2.100 m 2 2 %
2
Sheet Erosion 63.200 m 51 %
2
Rills 26.250 m 21 %
Gullies 20.160 m 2 16 %

Land Slides 12.640 m 2 10 %
2
Sum 124.350 m 100.0%

Table 5: Statistical data regarding the types of erosion present at the slope s identified along the border road

between Mojón II and Delta Costa Rica.

Mitigation Measures Slopes (number) Slopes (%)

Mitigation Measures (in general) 53 28.2 %
Geotextiles 10 5.3 %

Drainage Control 18 9.6 %
Stabilization by Terraces 9 4.8 %

Sowed Vegetation 14 7.4 %
Natural Vegetation 20 10.6 %

Sediment Tramps 14 7.4 %
Sum 188

Table 6: Statistical data regarding the mitigation measur es so fare done on the slopes along the border road
between Mojón II and Delta Costa Rica.

As listed in Table 6, mitigation measures have so far been undertaken on 53 (28%) of

the slopes, with a focus on drainage control ( 18 slopes, ~10%) and re-establishment of

natural vegetation (20 slopes, ~11%). Sowed vegetation (principally different kinds of

grass) as well as sediment traps had been deployed at 14 slopes (~7%) to reduce the

sediment yield from the slope. Also, geotextiles (10 slopes, ~5%) and terracing (9 slopes,

~5%) have been used to stabilize slopes, most ly situated within the Segment 1 (between

Mojón II and the Infiernito River).

As is the case with watercourse intersection s, the present condition of the slopes along

the border road between Mojón II and Delta Costa Rica can be co nsidered to be typical of

a road under construction. Mitigation measures have been undertaken to stabilize some of

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the slopes and these works should be continued to control the runoff and reduce sediment

yields along Route 1856.

7 ESTIMATION OF SEDIMENT YIELDS DUE TO EROSION AT SLOPES
ALONG ROUTE 1856 BETWEEN MOJÓN II AND DELTA COSTA RICA

The UCR (2013) report presents the results of field monitoring of erosion and land

surface lowering on cut and fill slopes encompa ssing the effects of sheet erosion, rills,

gullies and landslides. The main findings of the report are summarized in Table 7.
Nevertheless some clarifications are necessary . The erosion per year used for landslides

are based on the results from the UCR (2013) r eport obtained for cut slopes because they

were unable to record landslides in fill slopes (approp riate fill slopes were absent in their

study area). The highest figure of 1.48 m/year was assigned to fill slopes because these

are more unstable than cut slopes. The second cl arification involves the 0.24 m/year figure
used for sheet and rill erosion in fill slopesThe 0.24 m/year figure is based on the 0.20

m/year average erosion rate calculated for gu lly erosion in fill slopes by the UCR (2013)

report, with an added 20% as a margin of safety in the approximation. As explained in

detail in the UCR (2013) report, the 0.20 m/year rate is obt ained by distributing the effects

of gully erosion (which is triggered by overland flow) over the area of the fill slope in which

they were found. It is considered that this can approximate the effects of sheet and rill
erosion because these are both distributed processes triggered by flowing water.

Based on this data we calculated the total sedi ment yield from all the slopes included in

the inventory of slopes along Route 1856 (for details see Appendix A). The first step was to
identify the area occupied by each of the different erosion types (sheet erosion, rills, gullies

and landslides), using the percentages observed in the field and listed in the database. The

sediment yield for each slope was then found by multiplying the resulting surface areas the

appropriate erosion depth, as listed in Table 7, and summing the yields for all the types of

erosion present on that slope. The resulting estimates of average annual sediment yield

may be found in Appendix A.

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Erosive feature Erosion of 1 m per Year (m)

Sheet Erosion 0.095

0.17
CUT SLOPES Rills
0.21
Gullies

Landslides 0.5

Sheet Erosion 0.24

Rills 0.24
FILL SLOPES
Gullies 0.75

Landslides 1.48

Table 7: Average erosion rate per square meter for the different types of slopes and erosive features based upon
the study from Oreamuno & Villalobos (2013).

The total average annual sediment production for all the slopes along the Route 1856

between Mojón II and Delta Costa Rica is the su m of the sediment pr oduction of all 188
3 -1 -1
slopes which is around 36 590 m y or 61 100 t y using the transform ratio 1:1.67 from

the ICE Report (2013).

It is important to mention that this val ue should be regarded as a ‘worst case’ scenario

because it is based on the highest values moni tored for sediment yield from slopes in

segment 1, which has a high number of slopes and the steepest gradients. Also, the effects

of mitigation measures already installed on 53 of the slopes , which will reduce actual

yields, are not taken into account in these calculations.

The average annual yield of sediment from slopes along the Road was reported to Dr.

Federico Gomez-Delgado and his colleagues at ICE, who used t hese data in their

assessment of sediment input from Route 1856 to the San Juan River.

8 REFERENCES

Astorga, A. & Mende, A. (2013): Route 1856: Analysis of the Change in Land Use.-

Technical Report to the Ministry of Foreign Affairs. San José, Costa Rica.

Gomez-Delgado, F., Leitón-Montero, J. J. & Aguilar-Cabrera, C.A. (2013). Report on

hydrology and sediments for th e Costa Rican river basins draining to the San Juan

River. San José, Costa Rica: Instituto Costarricense de Electricidad.

Dr. Andreas Mende & Dr. Allan Astorga (October 2013)

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Oreamuno, R. & Villalobos, R. (2013): Systematic Field moni toring of Erosion and

Sediment Yield along Route 1856.- Universidad de Costa Rica. San José, Costa Rica.

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Appendix A: Overview about the most important data collected

for Cut and Fill Slopes along the 1856 Road between

Mojón II and Delta Costa Rica

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408 ANNEX 7

Note from Ana Lorena Guevara Fernández, Vice-Minister of the Environment,
Costa Rica, to Enrique Castillo Barrantes, Minister of Foreign Affairs, Costa
Rica

Report on the progress in the Environmental Management Plan of Route Juan

Rafael Mora Porras, executed by the Ministry of the Environment and Energy

Reference DVM-293-2013,

8 October 2013

English Translation

409410 Annex 7

San José, 8 October 2013

DVM-293-2013

Enrique Castillo Barrantes
Minister of Foreign Affairs
Ministry of Foreign Affairs

Honourable Minister:

I am pleased to address you to send my greetings and to refer to the progress achieved in
complying with that set forth in the Environmental Management Plan of Route Juan Rafael Mora

Porras, executed by the Ministry of the Environment and Energy ( Ministerio de Ambiente y
Energía), within the framework of Executive Decree N°36440-MP and the General Emergency Plan,

a situation and process triggered by Nicaragua’s violation of Costa Rican sovereignty.

In conformity with Appendix N°3 of the aforementioned plan, I am detailing below the
achievements thus far:

1) To minimize the possible effects of slopes caused by the construction of the road and its
effect on water resources, we hired the company Corporación de Desarrollo Forestal de la

Zona Norte (CODEFORSA) , which is currently implementing a plan to recover the forest
cover in areas with slopes of Route 1856. Thi s project has addressed 12 slope areas in
total, in which vetiver grass has been planted. In addition, the entity in charge of

supervising the construction of Route 1856, CONAVI, has placed geoblankets in areas with
pronounced cuts.

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Since the beginning of 2012 a process was initiated to recover forest cover on the right bank of
San Juan River, using native species such as “ sotacaballo” (Zygia longifolia), used traditionally by

the inhabitants to stabilize soil next to bodies of water. Other species planted include: Ceibo
(Vochysia guatemalensis), almendro (Dipteryx panamensis), javillo (Hura crepitans), chilamate
(Ficus insípida), among others. To date approximately 27,000 trees of native species have been

planted, and these are between 1 and 3 metres high, depending on the species. At the end of
September 2013 a second phase of the reforestation project began on the bank of San Juan River,

and it is expected to include 25,000 more trees, to reach a total of 52,000 trees.

412 Annex 7

Group of volunteers receive technical instructions for tree planting

Demonstration of the planting method

413Annex 7

Volunteers perform recovery of vegetation cover on the bank of San Juan River, on Costa Rican

territory

Current state of plantations initiated in 2012. Some trees are over 2 m tall.

414 Annex 7

Volunteers during the planting process of the second phase of reforestation, initiated in
September of this year.

The planted areas receive periodic maintenance consisting of mowing, application of fertilizer,
pruning, fence maintenance, and labelling. All of this care is provided over the course of two years

to guarantee that the trees continue growing on their own after that period.

Other actions indicated by the Environmental Management Plan include the construction of
sediment traps, step drains and ditches. This activity has been managed by the Consejo Nacional
de Vialidad (CONAVI), since it is in charge of the construction of the road.

415Annex 7

Placement of silt fence in slope areas

Slopes covered with geoblanket to prevent runoff

416 Annex 7

Protective barriers to prevent runoff

Ditches created to channel runoff water

417Annex 7

Placement of concrete pipes at small stream passages

Step drain to reduce the speed of rainwater

418 Annex 7

Finally, I report that this Ministry has implement ed a Plan for Prevention, Control and Protection
to improve surveillance in the area. The employees of the Sistema Nacional de Áreas de
Conservación (SINAC) are responsible for the implementation of this plan, with the support of the

Ministry of Public Saf ety ( Ministerio de Seguridad Pública ). Through monitoring and control
activities it has been possible to: obtain an updated registry of the inhabitants in the region;

detecting illegal activities such as illegal hunting, felling of forests and of forbiddentypes of
timber, seizure of timber; and dismantling of new construction at natural heritage sites of the

Government.

Similarly, the construction of 3 MINAE surveillance stations has begun, on three strategic points

along Route 1856, for better control and protection of the Border Wildlife Corridor Refuge
(Refugio de Vida Silvestre Corredor Fronterizo).

Regards,

Ana Lorena Guevara Fernández

Vice-Minister of the Environment

C Mr. René Castro Salazar, MINAE Minister

419420 ANNEX 8

Consejo Nacional de Vialidad (CONAVI),

Program for the Consolidation and Continued Improvement of Route No 1856

Reference DIE-02-13-3107

25 October 2013

English Translation

421422 Annex 8

Translation into English

(CONAVI logo)
Executive Directorate
Tel. (506) 2202-5563 Fax: (506) 2253-3584
Email: [email protected]
DIE-02-13-3107
P age | 1

25 October 2013

PROGRAM FOR THE CONSOLIDATION AND CONTINUED IMPROVEMENT OF ROUTE N° 856,
JUAN RAFAEL MORA PORRAS

The Ministry of Public Works and Transport (Ministerio de Obras Públicas y Transportes, MOPT) and Consejo
Nacional de Vialidad (CONAVI) continue the works for the consolidation of Route N° 856, Juan Rafael Mora
Porras, and to give attention to certain points that require complementary works so as to mitigate the effects of
the rain. All works seek to continue the consolidation of the route and, where circumstances require it, perform

remediation works. All of these works constitute measures of compensation or environmental mitigation, with
the goal of adequately managing the sediment that may be generated due to erosion and the adequate
channelling of surface run-off.

During February, March and April the following works were performed:

General Information

Region : Huetar Norte

Province : Alajuela
Type of Work : Mitigation works

Construction Company : MECO S.A.
Resident Engineer (Company): Jonathan Granados Castillo, Eng.

Technical Director (Company): Benjamín Meneses Monastel, Eng.
Project Engineer (CONAVI): José Mena Carmona, Eng.

Length : 15 km
Abbreviated bidding: 2012LA-000072-0DI00

Contract signing date : 5-feb-2013
Date of Order to begin works : 11-feb-2013

Date of completion : 12-abril-2013
Project status : Completed

Contract amount : ¢669.900.000,00
Original term of the construction works : 60 business days

Physical progress 100%
Financial progress 93.13%

423Annex 8

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Geographic location of the project

The works were performed according to Abbreviated Bidding No. 2012LA -000072-0DIOO, located in sections
2, 3 and 4 (mountain and wetlands area) of Route 1856 (Juan Rafael Mor a Porras), in provinces 02 and 04:

Alajuela and Heredia; cantons 210 and 410: San Carlos and Sarapiquí; districts 13, 11 and 02: Cutris, Pocosol

and La Virgen.

424 Annex 8

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Description of the works

Work was carried out in the Tiricias sector, and the project spanned the approximate distance of 15 km. The

figure below depicts this sector.

Station 0+000.
Crossing of Tiricias

Area of the
mitigation works

The stations for this project are as follows: from the crossing of Tiricias (Est. 0+000) to the Southeast the

values are positive; and from the crossing of Ti ricias to the Northwest the values are indicated preceded by a

minus sign (-).

Works performed:

Placement of sediment control barriers

Placement of geoblanket for erosion control

Excavation and filling of slopes on embankments

Placement of culverts with a 90 cm diameter, with the corresponding headwalls
Construction of reinforced concrete top ditches, class X, 10 cm thick

Excavation of channels and construction of sediment traps

425Annex 8

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Executive Directorate
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P age | 4

Construction of concrete energy dissipators, 15m long

The following table shows the amounts invested in carrying out the mitigation works, which were

performed with CONAVI budget.

ITEM UNIT COST

1 Placement of sediment control barriers (Siltfence barrier) m 13.447.244,98
2 Placement of geo blanket for erosion control (Coconut fibre blanket) m2 93.836.827,17

3 Excavation and filling of slopes on embankments (Common excavation) m3 115.767.909,03
4 Excavation and filling of slopes on embankments (Embankment construction) m3 124.566.092,44
Placement of culverts with a 90cm diameter, with the corresponding headwalls

5 (Reinforced concrete pipe, Class III C-76, 0,90m diameter) m 29.892.432,32
6 Construction of reinforced concrete top ditches, Class X 10cm thick m2 21.559.648,78
7 Excavation of channels and construction of sediment traps m3 4.888.838,64

9 Structural reinforced concrete, Class X, 180kg/cm2: for dissipators and headim3s 38.281.898,46
8 Construction of concrete energy dissipators, 15m long 13.628.284,50
9 Item 110,06 13.628.284,50

10 Construction of concrete dissipators, Class X m2 202.505.265,33
TOTAL 672.002.726,15

The discrepancy between the total in the table above and the amount approved under the contract is due to
adjustments made in the process of settling the contract, and once the process was underway.

Pictures of the project:

Picture 1. Creation of slopes, placement of coconut fibre, construction of ditches and

placement of siltfence

426 Annex 8

Translation into English

(CONAVI logo)
EExecutive Directorate
Tel. (506) 2202-5563 Fax: (506) 2253-3584
Email: [email protected]
DIE-02-13-3107
P age | 5

Picture 2. Creation of slopes, placement of coconut fibre, construction of ditches and
placement of silt fence

Picture 3. Creation of slopes, placement of coconut fibre, building of top ditches

Picture 4. Construction of dissipators

427Annex 8

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DIE-02-13-3107
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Picture 5. Creation of slopes, construction of ditches and top ditches

Picture 6. Placement of pipes, construction of headwalls, construction of ditches

Picture 7. Placement of coconut fibre, construction of ditches

428 Annex 8

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TeEmail: [email protected].cro584

DIE-02-13-3107
P age | 7

Picture 8. Construction of lined channels, placement of coconut fibre, building of ditches

Picture 9. Placement of coconut fibre, building of ditches

Picture 10. Creation of slopes, placement of coconut fibre, construction of ditches, placement

of ballast and placement of silt fence

429Annex 8

Translation into English

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DIE-02-13-3107
P age | 8

Picture 11. Creation of slopes, placement of coconut fibre, building of ditches and placement
of siltfence

Picture 12. Placement of coconut fibre, construction of ditches, placement of silt fence

Please find below the comparative tables reflecting the situation before and after the work performed, with the
corresponding geographic location.

430 Annex 8

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P age | 9

Point 1

Stations (-) 7+760 (-) 7+400 (-) 7+350
Lambert GPS Coordinates N 329945, E 496508
Description: Direction toward Marker IIRight side: creation of banks and plament of geoblanket.

Excavation and lining for transversal channels with surfacdepth wetland water and
concrete pipes

BEFORE AFTER

431Annex 8

Translation into English

(CONAVI logo)
ExecutiveTel. (506) 2202-5563 Fax: (506) 2253-3584
Email: [email protected]
DIE-02-13-3107
P age | 10
Point 2

Stations (-) 7+250 (-) 7+200
Lambert GPS Coordinates N 330352 E 496887
Description: Direction toward Marker II. Right side: creation of banks and placement of geoblanket.
Excavation for transversal channels with surface depth wetland water and lined ditch.

BEFORE AFTER

432 Annex 8

Translation into English

(CONAVI logo)
ExecutiveTel. (506) 2202-5563 Fax: (506) 2253-3584
Email: [email protected]
DIE-02-13-3107
P age | 11
Point 3

Stations (-) 7+140
Lambert GPS Coordinates N 330329 E 496942
Description: Left side, Right side - creation of slopes and placement of geoblanket
Left side - excavation of ditches, construction of lined ditch

BEFORE AFTER

433Annex 8

Translation into English

(CONAVI logo)
ExecutiveTel. (506) 2202-5563 Fax: (506) 2253-3584
Email: [email protected]
DIE-02-13-3107
P age | 12
Point 4

Stations (-) 6+750
Lambert GPS Coordinates N 330052 E 497114
Description: Left side, Right side, creation of slopes and placement of geoblanket.
Left side, Right side, excavation for ditches, construlined ditch, 2 drainpipes with

dissipators

BEFORE AFTER

434 Annex 8

Translation into English

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P age | 13

Point 5

Stations (-) 6+350
Lambert GPS Coordinates N 329855 E 497430
Description: Left side, construction of bank, placement of geoblanket and lined ditch

Right side; refine slope, place geoblanket and lined ditch

BEFORE AFTER

Point 6

Stations (-) 4+576
Lambert GPS Coordinates N 328515 E 498489
Description: Left side, fill slope
BEFORE AFTER

435Annex 8

Translation into English

(CONAVI logo)
Executive Directorate
Tel. (506) 2202-5563 Fax: (506) 2253-3584
Email: [email protected]
DIE-02-13-3107
P age | 14

Point 7

Stations (-) 0+622
Lambert GPS Coordinates N 325345 E 498072
Description: Right side, over 80 m: define slope, place geoblanket, construction of headwalls on existing
passage, line channel exit

BEFORE AFTER

436 Annex 8

Translation into English

(CONAVI logo)
EExecutive Directorate
Tel. (506) 2202-5563 Fax: (506) 2253-3584
Email: [email protected]
DIE-02-13-3107
P age | 15

Point 8

Stations (-) 0+300
Description: Drain passage, 90cm diameter, with surface depth wetland water, h eadings, and line
channel exit

BEFORE AFTER

Point 9

Stations 0+480
Lambert GPS Coordinates N 325177 E 499060

Description: Right side, construction of a step drain and lining of the exit channel

BEFORE AFTER

437Annex 8

Translation into English

(CONAVI logo)
ExecutiveTel. (506) 2202-5563 Fax: (506) 2253-3584
Email: [email protected]
DIE-02-13-3107
P age | 16
Point 10

Stations 0+550 to 0+804
Lambert GPS Coordinates N 325163 E 499126
Description: Right Side, Construction of drainage channel

BEFORE AFTER

Point 11

Stations 1+109
Lambert GPS Coordinates N 324868 E 499477
Description: Ditch passage and headwalls, 1.5 m diameter

BEFORE AFTER

438 Annex 8

Translation into English

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P age | 17

Point 12

Stations 1+030 1+090
Description: Left side, digging of channel

BEFORE AFTER

Point 13

Stations 1+195 - 1+365 - 1+407
Lambert GPS Coordinates N 324757 E 499503

Description: Left side, slope of 250x20m, 250m of top ditches, 500m of siltfence, 80m of dissipator (4 for
top ditches), Left side embankment, construction of lined ditch , digging of ditch, Right side
lined ditch

BEFORE AFTER

439Annex 8

Translation into English

(CONAVI logo)
Executive Directorate
Tel. (506) 2202-5563 Fax: (506) 2253-3584
Email: [email protected]
DIE-02-13-3107
P age | 18
Point 14

Stations 2+600 - 2+657 - 2+755 - 2+890
Description: Right side, Improve bank, lined ditch, remove landslides and cut into terraces

BEFORE AFTER

Point 15

Stations 2+960

Description: Right Side, create slope, material for use in other activities

BEFORE AFTER

440 Annex 8

Translation into English

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P age | 19

Point 16

Stations 3+604
Description: Right side, create slope, material for use in other activities

BEFORE AFTER

Point 17

Stations 3+690 3+720 3+830 4+000
Description: Left side. Dissipators, top ditches, ditches, protection with silt fence
Left side, construction of lined ditch and dissipator
Right Side construction of lined ditch and dissipator, digging to fill bank with cut material
Left side, embankment and filling

Right side, Landslide

BEFORE AFTER

441Annex 8

Translation into English

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P age | 20

Point 18
Stations 4+185
Lambert GPS Coordinates N 322071 E 500667
Description: Ditch, top ditch, coconut fibre geoblanket. Creation of slope, left and right sides.
Right side, cut slope and fill bank

BEFORE AFTER

Point 19
Stations 4+330
Lambert GPS Coordinates N 321987 E 500774
Description: Drain passage
Excavation for pipes

Filling for pipes
Pipes with an internal diameter of 1.5 metres
Heading for tube with a diameter of 1.5 metres
Class A concrete for skirtboard

BEFORE AFTER

442 Annex 8

Translation into English

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Executive Directorate
TEEmail: [email protected].cro584
DIE-02-13-3107
P age | 21

Point 20
Stations 6+704 - 7+000
Description: Digging of loose material
Creation of slopes

Coconut fibre geoblanket for erosion control
Sediment barrier

BEFORE AFTER

Point 21

Stations 7+050

Lambert GPS Coordinates N 321779 E 500975
Description: Digging of loose material
Creation of slopes
Coconut fibre geoblanket for erosion control
Sediment barrier

BEFORE AFTER

443Annex 8

Translation into English

(CONAVI logo)
Executive Tel. (506) 2202-5563 Fax: (506) 2253-3584
Email: [email protected]
DIE-02-13-3107
P age | 22

Point 22
Stations 7+350 - 7+750
Description: Digging of loose material
Creation of slopes
Coconut fibre geoblanket for erosion control

Sediment barrier

BEFORE AFTER

444 Annex 8

Translation into English

(CONAVI logo)
Executive Directorate
Tel. (506) 2202-5563 Fax: (506) 2253-3584
Email: [email protected]
DIE-02-13-3107
P age | 23
Works currently being carried out include the cleaning and conservation o f works built last year a nd during

February, March and April. New sectors of the route will be covered, but with specific emphasis of the sectors
identified in Section N° 2; Río Pocosol – Río Infiernito, of this report. Complementary and road conservation
works are supervised by Engineer José Mena Carmona.

Point N°1: Slope with pending strengthening measures

Location
North Lambert projection:
E: 499554
N: 324579

Benching was performed at this point to create the slope and prevent landslides. A coconut fibre blanket is being pl aced
to control sediment, in addition to the use of hydroseeding and top ditches to control the surface runoff on this slope,
making it impermeable and eliminating the displacement of sediment. A silt fence will also be placed as precaution, so
that it will retain sediment in the event that it is displaced.

445Annex 8

Translation into English

(CONAVI logo)
EExecutive Directorate
Tel. (506) 2202-5563 Fax: (506) 2253-3584
Email: [email protected]
DIE-02-13-3107
P age | 24
Point N°2: Río Infiernito, slopes to be protected and created

Location
North Lambert Projection:
E: 502973
N: 321544

Landslides are being removed in this sector, due to the instability of the slopes, in addition to cleaeing of th

lined ditch to recover its adequate hydraulic function.

Additional works to be performed during the following months

Description:

The following works will be performed after concluding the intervention at the points indicated by the technical
team, which mainly consist of hydraulic improvement of several points in this sector, namely: improvement of

water passages through the construction of drains with the corresponding protection s (headings, buttresses,
skirt-boards), construction of lined ditch, construction of step drains and placement of Silt Fence. There are
also some works to clean channels and ditches.

446 Annex 8

Translation into English

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Executive Directorate
TeEmail: [email protected].cro584

DIE-02-13-3107
P age | 25
Point A: (Cleaning of ditch, removal of landslide)

North Lambert coordinates:

E: 499892
N: 323218

A landslide was removed at this point, caused by an inadequate slope structure. The lined ditch was also
cleaned to maintain its adequate hydraulic function.

Hydro-seeding will be used in this sector to treat this slope, to improve its stability. A lined ditch will also be
built at certain points affected by the landslide. See pictures below:

447Annex 8

Translation into English

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TEmail: [email protected].cro3584

DIE-02-13-3107
P age | 26

Point B (Construction of Drain): North Lambert Coordinates:
E: 499560

N: 324228

A drain with a 1,50m diameter will beplaced in this sector, with the corre sponding protection (headings,
buttresses, skirt-boards), and a 10m transversal section of the road. See picture below:

Point C (Construction of Drain): North Lambert Coordinates:
E: 499650

N: 323870

A drain with a 1,50m diameter will be placed here, with the corresponding protections (headings, buttresses,
skirt-boards), and a 10m transversal section of the road. See pictures below:

448 Annex 8

Translation into English

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TeEmail: [email protected].cro584

DIE-02-13-3107
P age | 27

Point D (Repair of hole in log bridge): North Lambert coordinates:
E: 499777
N: 323555

This sector requires the repair of a hole in Tucas bridge. See picture below:

Point E (Construction of Drain): North Lambert coordinates:

E: 499986
N: 323171

A drain with a diameter of 1m will be placed here, with the corresp onding protections (headings, buttresses,
skirt-boards), and a 10m transversal section of the road. See picture below:

449Annex 8

Translation into English

(CONAVI logo)
EExecutive Directorate
Tel. (506) 2202-5563 Fax: (506) 2253-3584
Email: [email protected]
DIE-02-13-3107
P age | 28

Point F (Repair of hole in log bridge): North Lambert Coordinates:

E: 500256
N: 322867

This sector requi res the repair of a hole the log bridge, and cleaning of the channel (since logs are

obstructing the course of the river).

450 Annex 8

Translation into English

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TeEmail: [email protected].cro584

DIE-02-13-3107
P age | 29
Point G (Cleaning of channel and ditch): North Lambert Coordinates:
E: 500445
N: 322614

This sector requires cleaning of the drain structure connecting with the channel and cleaning of the lined ditch
on the right side. See pictures below:

Point H (Construction of drain): North Lambert Coordinates:
E: 321839

N: 500887

A drain wit h a 1,50m diameter will be placed in this sector, with the corresponding protection (headings,
buttresses, skirt-boards), and a 10m transversal section of the road.

Point I (Construction of step drain): North Lambert Coordinates:
E: 321689

N: 501233

A step drain will be built in this sector to prevent undermining due to rain water circulating on the ditch, which
could cause damages to the existing pavement structure. See pictures below:

451Annex 8

Translation into English

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TeEmail: [email protected].cro584

DIE-02-13-3107
P age | 30

Point J (Construction of lined ditch and placement of Silt Fence):

North Lambert coordinates:

E: 501394
N: 321653

A lined ditch will be built at this point, along 330m, not continuous, and a silt fence will be placed to control the

displacement of sediment. See pictures below:

452 ANNEX 9

Professor Colin Thorne

‘Report on the Risk of Irreversible Harm to the Río San Juan relating to the
Construction of the Border Road in Costa Rica’

4 November 2013

453454 Annex 9

CASE
CONCERNING

C ONSTRUCTION
OF
A
R OAD
IN
C OSTA
R ICA
ALONG
THE
S AN
JUAN
R IVER

(N ICARAGUA
v.
C OSTA
R ICA )

Report
on
the
Risk
of
Irreversible
Harm
to
the
Río
San
Juan
relating
to
the

Construction
of
the
Border
Road
in
Costa
Rica

Prepared
by

Colin
Thorne

Nottingham,
UK

Professor
and
Chair
of
Physical
Geography

University
of
Nottingham

4
November
2013

455Annex 9

Table
of
Contents

1.
INTRODUCTION
.....................................................................................................................................
3

2.
MY
QUALIFICATIONS
...........................................................................................................................

3.
TERMS
OF
REFERENCE
........................................................................................................................

4.
METHODOLOGY
.....................................................................................................................................

5.
CONTRIBUTION
OF
SEDI MENT
FROM
THE
ROAD
T O
THE
RÍO
SAN
JUAN
..........................
7

5.1
O VERVIEW
............................................................................................................................
...............................
7

5.2
IS
THERE
EVIDENCE
OF
A
SURGE
IN
SEDIMENT
LOAD
IN
THE R ÍO
SAN
JUAN
SINCE
D ECEMBER
2010?
8

-‐1
5.3
IS
THE 1
M
Y
RATE
OF
LAND
LOWERING
ESTIMATED
IN
THE
2012 K
ONDOLF
R EPORT
REASONABLE ?

13

5.4
A RE
CALCULATED
DELIVERY
RATES
FOR
R OAD – DERIVED
SEDIMENT
BASED
ON
THE
RESULTS
OF
FIELD

MONITORING
SUFFICIENT
TO
CAUSE
“ SIGNIFICANT ”
OR“IRREVERSIBLE ”
DAMAGE
TO
THE
R ÍO
S AN
JUAN ?
..
20

5.5
P OTENTIAL
FOR
R OAD -DERIVED
SEDIMENT
TO
IMPACT
THE
R ÍO S AN
JUAN
...................................
....
22

5.5.1
Introduction
.........................................................................................................................
.....................
22

5.5.2
Estimated
annual
load
of
Road -‐related
sediment
supplied
to
the
Río
San
Juan
.............
23

5.5.3
Average
annual
sediment
load
in
the
lower
Río
San
Juan
since
December
2010
...........
24

5.5.4
Input
of
Road-‐derived
sediment
to
the
Río
San
Juan
........................................................
.......
25

5.5.5
Potential
impact
on
sedimentation
in
the
lower
Río
San
Juan
..............................................
25
5.5.6
Inputs
of
Road-‐derived
sediment
are
not
just
insignificant,
they
are
undetectable
......
26

6.
RESPONSE
TO
NEW
EVIDENCE
SUBMITTED
BY
NICARAGUA
...............................................
27

7.
MY
OBSERVATIONS
OF
M ITIGATION
WORKS
ON
THE
ROAD
IN
MAY
2013
....................
37

8.
CONCLUSIONS
ON
THE
R ISK
OF
IRREVERSIBLE
HARM
TO
THE
RIVER
.............................
41

9.
REFERENCES
.......................................................................................................................................
42

10.
STATEMENT
OF
INDEPENDENCE
AND
TRUTH
........................................................................
43

456 Annex 9

1. Introduction

1. I
am
Colin
Thorne,
Professor
of
Physical
Geography
at
the
University
of
Nottingham.
I

have
been
requested
by
Costa
Rica
to
prepare
an
independent
expert
report
for
the

International
Court
of
Justice
(the
Court)
in
connection
with
the
Request
for
New

Provisional
Measures
submitted
by
Nicaragua
on
11
October
2013
(the
Request)
in

the
Case
Concerning
Construction
of
a
Road
in
Costa
Rica
along
the
San
Juan
River

(Nicaragua
v
Costa
Rica)
(the
Road
Case).

2. I
am
instructed
to
form
an
independent
expert
opinion
on
the
matters
set
out
in
the

Terms
of
Reference
below.

2. My
Qualifications

3. I
hold
the
Chair
of
Physical
Geography
at
the
University
of
Nottingham,
UK.
I
have

BSc
and
PhD
degrees
in
Environmental
Science
from
University
of
East
Anglia,
UK.
I

have
over
35
years
professional
experience
in
matters
relating
to
rivers,
river

sedimentation
and
river
morphology.
My
research
concentrates
on
fluvial
hydraulics

and
sediment
transport
in
natural,
modified
and
managed
rivers,
particularly
with

respect
to
the
implications
for
erosion,
sedimentation,
flood
risk
and
the
river

environment.

4. I
have
previously
submitted
an
independent
expert
report
in
the
Certain
Activities

Case:
“Assessment
of
the
physical
impact
of
works
carried
out
by
Nicaragua
since

October
2010
on
the
geomorphology,
hydrology
and
sediment
dynamics
of
the
San

Juan
River
and
the
environmental
impacts
on
Costa
Rican
territory”,
which
is

Appendix
1
to
Costa
Rica’s
Memorial
in
the
Certain
Activities
Case
(the
First
Report).
I

also
submitted
a
second
independent
expert
report
in
the
Certain
Activities
Case,

relating
to
Costa
Rica’s
Request
for
Provisional
Measures,
dated
24
September
2013.

That
report
is
entitled
“Report
on
the
Impact
of
the
Construction
of
two
New
Caños

on
Isla
Portillos”
and
dated
10
October
2013
(the
Second
Report).

457Annex 9

3. Terms
of
Reference

5. I
am
instructed
to
form
an
independent
expert
opinion
on
allegations
of
fact
made
in

the
Request
that
pertain
to
delivery
of
sediment
derived
from
erosion
of
the
Road

(including
slopes
adjacent
to
the
Road
and
disturbed
areas)
and
the
degree
to
which

the
Road
poses
an
imminent
risk
of
irreversible
harm
to
the
Río
San
Juan.

6. In
the
Request,
Nicaragua
makes
various
statements
concerning
the
risks
posed
to

the
Río
San
Juan
by
the
Road.
Specifically:

(i) Page
1,
paragraph
2,
final
sentence,

‘Costa
Rica’s
road
works
have
caused
a
surge
in
the
San
Juan
River’s
sediment

load
requiring
Nicaragua
to
take
active
efforts,
including
dredging,
to
maintain

the
capacity
and
quantity
of
the
river’s
waters.’

(ii) Page
2,
paragraph
3,

‘construction
by
Costa
Rica
of
a
160
km
road
running
along
the
margin
of
the
San

Juan
River.’

(iii) Page
2,
paragraph
5,
sentences
four
to
six,

‘They
(the
team
sent
by
Nicaragua
to
inspect
the
River
in
October
2012)

confirmed
that
Costa
Rica
had
not
taken
measures
to
stop
or
even
mitigate
the

serious
harm
caused
to
the
San
Juan
de
Nicaragua
River.
Furthermore
in

anticipation
of
the
second
heavy
rainy
season
since
the
construction
of
the
Road

began,
Nicaragua
sent
the
same
team
on
a
second
mission
in
May
2013.
The

second
mission
underscored
the
urgent
need
for
mitigation
measures
previously

presented
by
Nicaragua
to
the
Court.’

(iv) Page
3,
paragraph
2,

‘As
the
rainy
season
enters
into
its
heaviest
stage
washing
even
greater

quantities
of
sediment
and
run-‐off
into
the
river’s
waters,
Costa
Rica
still
has
not

provided
the
necessary
information
to
Nicaragua,
nor
has
it
taken
the
necessary

actions
along
the
160
km
road
to
avoid
or
mitigate
the
irreparable
damage
that

is
being
inflected
[sic]
on
the
river
and
its
surrounding
environment,
including

458 Annex 9

navigation
and
the
health
and
wellbeing
of
the
population
living
along
its

margins.’

7. I
have
been
asked
to
consider
the
accuracy
of
these
statements,
bearing
in
mind

what
has
already
been
set
out
in
Nicaragua’s
pleadings
in
the
Road
Case
(including
in

the
Report
of
Professor
Kondolf
(the
2012
Kondolf
Report,
referred
to
in
paragraph
9

below),
and
with
a
particular
view
to
the
risk
of
irreversible
harm
to
the
San
Juan

River.

8. I
have
also
been
asked
to
review
and
comment
upon
the
documents
submitted
by

Nicaragua
to
the
Court
on
1
November
2013
in
support
of
its
Request.
These
are:

(a) Confirmation
of
Urgent
Measures
to
Mitigate
Erosion
&
Sediment
Delivery

from
Rte
1856,
Costa
Rica,
into
the
Río
San
Juan,
Nicaragua,
a
report
by
Dr

Kondolf
dated
12
October
2013
(Annex
1);

(b) Continued
Impacts
of
Erosion
from
Rte
1856,
Costa
Rica
to
the
Río
San
Juan,

Nicaragua,
a
further
report
by
Dr
Kondolf
dated
30
October
2013
(Annex
2);

and

Nicaragua
caused
by
Costa
Rican
Route
1856
Construction,
Poor
Design
and

Lack
of
Maintenance.
Photos
taken
May
20-‐22,
2013
(Appendix
A),
which

accompanies
Annex
2.

My
primary
comments
on
these
documents
are
set
out
in
Section
6
below.

4. Methodology

9. In
this
report
I
collate
and
present
the
relevant
outcomes
to
date
of
work
performed

in
two
ongoing
scientific
and
engineering
studies
that
I
requested
be
undertaken
in

February
2013
and
for
which
I
continue
to
provide
technical
leadership.
These

reports
are:
Report
on
hydrology
and
sediments
for
the
Costa
Rican
river
basins

draining
to
the
San
Juan
River.
Costa
Rica
Institute
of
Electricity,
Centre
for

Engineering
Studies,
Department
of
Hydrology,
San
José,
Costa
Rica
(the
ICE
Report),

which
has
been
submitted
as
Attachment
CR-‐1;
and
Systematic
Field
monitoring
of

459Annex 9

Erosion
and
Sediment
Yield
along
Route
1856.
University
of
Costa
Rica,
Faculty
of

Engineering,
School
of
Civil
Engineering
(the
UCR
Report),
which
has
been
submitted

as
Attachment
CR-‐2.
These
studies
have
been
undertaken
to
provide
data
to
inform

my
review
of
the
Report
prepared
by
G.
Mathias
Kondolf
entitled,
Environmental

Impacts
of
Juan
Rafael
Mora
Porras
Route
1856,
Costa
Rica,
on
the
Río
San
Juan,

Nicaragua,
December
2012
(the
2012
Kondolf
Report),
which
is
Annex
1
to

Nicaragua’s
Memorial
in
the
Road
Case.

10. I
also
draw
upon
observations
and
knowledge
gained
through
research
undertaken

in
preparing
a
report
that
will
accompany
Costa
Rica’s
Counter
Memorial
in
the
Road

Case
that
has
included:

(a) participating
in
two
site
visits
to
the
Road,
on
15
and
16
February,
and

7
May
2013.
On
the
first
occasion
I
drove
along
and/or
viewed
from
the
air
the

entire
length
of
the
Road.
On
the
second
occasion
I
drove
to
and
reviewed

from
the
air
the
first
41
km
of
the
Road
between
Marker
II
and
Boca
San

Carlos.
During
both
site
visits
I
undertook
field
observations,
spoke
to

engineers
and
scientists
engaged
in
mitigation
works
and
took
ground
and

aerial
photographs;

(b) requesting,
formulating
and
supervising
scientific
and
technical
studies

performed
by
qualified
Costa
Rican
scientists
and
engineers,
to
elicit
the
data

and
information
needed
to
evaluate
the
potential
for
construction
of
the
Road

to
impact
the
Río
San
Juan;

February
14
and
17,
May
6
and
9-‐10,
and
July
30-‐31,
during
which
we

discussed
approaches
and
methodologies
to
be
employed
in
performing
the

work,
reviewed
progress
and
discussed
the
results
of
archive-‐based,
field,

remote-‐sensing,
GIS-‐based
research,
and
computer
modelling;
and

(d) reviewing
and
challenging
the
preliminary
findings
of
the
team
and
requesting

additional
analyses
where
appropriate.

460 Annex 9

11. Where
I
rely
on
information
and
data
contained
in
the
ICE
and
UCR
Reports,
or
any

other
reports
prepared
in
the
course
of
the
investigations
and
activities
referred
to
in

paragraph
10
above,
I
indicate
that
I
am
doing
so.

5. Contribution
of
sediment
from
the
Road
to
the
Río
San
Juan

5.1
Overview

12. In
my
opinion,
Nicaragua’s
estimates
of
the
contribution
of
sediment
to
the
San
Juan

River
from
the
Border
Road
have
been
over-‐estimated
and
indeed
are
massively

overstated.
In
my
view,
the
contribution
of
sediment
from
Road
to
the
River
cannot

be
said
to
pose
any
risk
of
significant,
let
alone
irreversible,
harm
to
the
River.

13. My
opinion
is
based
on
the
outcomes
of
scientific
studies
(reported
in
detail
in

below)
which
indicate
that:

(a) there
has
been
no
measurable
surge
in
the
San
Juan
River’s
sediment
load

since
construction
of
the
Road
(see
section
5.2
below);

(b) the
estimate
for
rate
of
land
surface
lowering
due
to
erosion
of
cut
and
fill

-‐1
slopes
along
the
Road
made
in
the
2012
Kondolf
Report
(1
m
yis
a
significant

overestimate
(see
section
5.3
below);

nowhere
near
sufficient
to
cause
significant,
let
alone
irreversible,
damage
to

the
Río
San
Juan
(see
section
5.4
below);
and

(d) even
if
the
additional
input
of
sediment
from
the
Road
estimated
in
the
2012

Kondolf
Report
was
accurate
(which
it
is
not),
there
would
still
be
no
impact
on

navigation
in
the
lower
Río
San
Juan
that
would
require
Nicaragua
to
take

active
efforts
including
dredging
(see
section
5.5
below).

14. At
the
outset,
it
is
important
to
bear
in
mind
that
the
Río
San
Juan
drains
a
large

catchment
that
produces
a
significant
but
highly
variable
amount
of
sediment
every

year
and
to
recognise
that
the
River
has
a
the
capacity
to
process
that
sediment

annually.
This
is
explained
further
in
paragraph
16
below.
For
these
reasons,

461Annex 9

1
comparisons
with
streams
like
the
Clearwater
River
in
the
United
States
are
inapt.

Furthermore,
given
these
particular
characteristics
of
the
Río
San
Juan,
analogies

with
fish
species
such
as
salmon
are
also
inapt,
because
the
species
of
fish
occupying

2
the
San
Juan
are
naturally
adapted
to
high
and
variable
concentrations
of
sediment.

5.2
Is
there
evidence
of
a
surge
in
sediment
load
in
the
Río
San
Juan
since

December
2010?

15. To
ascertain
whether
there
is
evidence
to
support
Nicaragua’s
assertion
that
there

has
been
a
surge
in
the
San
Juan
River’s
sediment
load
since
construction
of
the

Road,
I
examined
available
records
of
measured
Suspended
Sediment
Concentration

(SSC)
in
the
Río
San
Juan
–
Río
Colorado
system
prior
to
and
following
construction
of

the
Road.

16. The
Río
San
Juan
drains
a
large
catchment
(~40,000
km 2 )
that
includes
areas
of
high,

steep
and
naturally
unstable
terrain
(including
active
volcanoes),
and
which
receives

abundant
but
highly
variable
amounts
of
rainfall
distributed
unevenly
throughout

the
basin
and
the
year.
The
physical
attributes
of
its
basin
dictate
that
it
transports
a

heavy,
but
highly
variable
sediment
load.
SSC
records
from
Station
6901-‐03
at

3
La
Trinidad
between
January
1974
and
March
1976,
and
Station
6911-‐04
at
Delta

Colorado,
between
December
2010
and
June
2013,
demonstrate
both
the
high

concentrations
and
variability
of
sediment
in
the
River.
These
records
represent

periods
prior
to
and
since
construction
of
the
Road.
SSCs
measured
at
these
two

stations
should
be
comparable
because
over
90%
of
the
flow
and
sediment
that

1

Cf
Annex
2,
p.
8.

2

Cf
Annex
2,
pp.
2
and
8.

3

These
data
are
used
because
they
are
the
only
suspended
sediment
records
available
to
the

technical
team
for
the
Río
San
Juan
under
pre -‐Road
conditions.
I
am
instructed
that
these

measurements
were
made
jointly
by
Costa
Rica
and
Nicaragua
and
their
source
is:
Governments
of

Nicaragua
and
Costa
Rica
(1977).
Central
American
Hydrological
Project
[PHCA),
with
the
assistance

of
the
United
Nations
Development
Programme,
San
Juan
River
H ydroelectric
and
Navigation

Project,
December
1977,
volume
1,
page
69.
These
data
were
cited
in
Nicaragua's
Counter
Memorial

in
the
Navigational
Rights
Case ,
“the
sediment
load
immediately
downstream
from
the
Sarapiquí

River,
measured
at
the
beginning
of
t he
seventies,
was
10.2
million
metric
tons
per
year.”
See

Nicaragua
Counter-‐Memorial,
Navigational
Rights
Case,
para.
1.1.8.

462 Annex 9

passes
through
the
La
Trinidad
also
passes
through
the
Delta
Colorado
Station.

Station
locations
are
shown
in
Figure
1
below
and
records
are
listed
in
Table
1.

Figure
1.
Gauging
stations
and
mean
annual
discharges
in
the
Río
San
Juan
-‐
Colorado

system
with
La
Trinidad
and
Delta
Colorado
Stations
highlighted
(from
the
ICE
Report).

Table
1.
Suspended
sediment
records
for
the
Río
San
Juan
–
Colorado
(from
the
ICE
Report).

Ave.
Annual

Station
No.
of
Sampling
Suspended

code
Name
Basin
River
samples
period
load

-‐1
(t
yr )

01-‐03
La
Trinidad
San
Juan
San
Juan
12
1974-‐1976

7
995
000

a
11-‐04
Delta
Colorado
San
Juan
Colorado
31
2010-‐2013

5
981
000

a
Note:
this
is
the
average
annual
suspended
load
in
the
Río
Colorado
downstream
of
the
Delta.

17. To
allow
comparison,
these
records
are
plotted
together
on
a
single
graph,
with

rating
curves
for
SSC
as
a
function
of
discharge
for
each
station
and
period
being

added
using
regression
(Figure
2).

463Annex 9

Figure
2.
Measured
suspended
sediment
concentrations,
rating
curves
and
95%
confidence

intervals
for
pre-‐Route
1856
[La
Trinidad
(01-‐03),
January
1974
to
March
1976]
and
post-‐
Route
1856
[Delta
Colorado
(11-‐04),
December
2010
to
June
2013]
periods.
Continuous

lines
are
SSC
Rating
Curves
(based
on
best-‐fit
regression).
Dotted
lines
indicate
the
95%

confidence
intervals
for
each
regression
curve
(from
the
ICE
Report).

18. If
additional
sediment
from
the
Road
had
caused
a
surge
in
the
rate
of
sediment

transport
in
the
Río
San
Juan,
this
would
reflect
in
Figure
2
through
increases
in
the

SSCs
measured
since
2010
and
a
corresponding
upward
shift
in
the
2010-‐2013

suspended
sediment
rating
curve
compared
to
that
for
1974-‐1976.
It
is
clear
from

Figure
2
that
this
is
not
the
case.

-‐1
19. On
the
contrary,
the
highest
measured
concentration
(SSC
>
600
mg
l )
was
actually

observed
during
the
period
prior
to
construction
of
the
Road
and
the
distribution
of

27
of
the
31
post-‐Road
measured
concentrations
in
Figure
2
coincides
with
that
of

the
pre-‐Road
data.
Not
only
is
there
no
statistically
significant
difference
between

the
pre-‐
and
post-‐Road
suspended
sediment
rating
curves,
Figure
2
reveals
them
to

be
practically
identical.
This
suggests
that
any
differences
between
pre-‐
and
post-‐

Road
SSCs
measured
at
these
stations
are
the
result
of
random
chance.

20. Additionally,
the
high
degree
of
natural
variability
in
the
relationship
between

discharge
and
suspended
sediment
concentration
means
that
the
95%
confidence

intervals
on
the
rating
curves
are
wide
apart.
Not
only
is
natural
variability
similar

during
the
pre-‐
and
post-‐road
periods,
but
the
two
uncertainty
bands
are
also
close

464 Annex 9

to
coinciding.
This
illustrates
that
variability
in
measured
SSCs
has
not
changed

significantly
between
pre-‐
and
post-‐Road
periods
and
that
differences
between

measured
values
are
probably
due
to
random
chance.

21. As
discharge
is
measured
on
a
semi-‐continuous
basis
at
these
hydrometric
stations,

the
suspended
sediment
rating
curve
can
be
integrated
with
the
discharge
record
to

calculate
the
mean
annual
suspended
sediment
load.
This
approach
was
used
to

calculate
the
mean
annual
suspended
sediment
loads
transported
by
the
Río
San

Juan
at
La
Trinidad
between
1974
and
1976;
7
995
000
t
yr,
and
by
the
Río
Colorado

at
Delta
Colorado
between
2010
and
2013:
5
981
000
t
yr -
(as
listed
in
Table
1).

22. The
average
discharges
measured
at
the
La
Trinidad
and
Delta
Colorado
stations

listed
in
Table
2
are
1
123
ms and
1
026
m
s ,
respectively.
This
suggests
that,
on

average,
~91%
of
the
discharge
in
the
Río
San
Juan
approaching
Delta
Costa
Rica

passes
to
the
Río
Colorado,
while
~9%
passes
to
the
lower
Río
San
Juan.
As
the

suspended
load
is
distributed
throughout
the
River’s
flow,
it
is
reasonable
to
assume

that
the
suspended
sediment
load
is
similarly
divided.

23. On
this
basis
the
suspended
load
measured
in
the
Río
Colorado
at
the
Delta
Colorado

station
may
be
adjusted
to
represent
that
in
the
Río
San
Juan
upstream
of
the
Delta

by
multiplying
it
by
the
reciprocal
of
0.91.
Applying
this
adjustment,
the
average

annual
suspended
load
in
the
Río
San
Juan
between
December
2010
and
June
2013

-‐1
was
approximately
6
573
000
t
yr .
It
follows
that
the
mean
annual
suspended
load

-‐1
in
the
lower
Río
San
Juan
during
this
period
was
about
592
000
t
yr

24. In
considering
these
figures,
it
must
be
borne
in
mind
that
they
are
based
on
small

numbers
of
samples
made
over
short
(two
to
three-‐year)
periods
of
observation.
The

95%
confidence
intervals
of
the
regression
relationships
used
to
generate
the

suspended
sediment
rating
curves
reflect
not
only
uncertainty
due
to
the
small

number
of
data
points,
but
also
the
high
degree
natural
variability
inherent
to
the

way
that
SSCs
vary
with
discharge
in
the
Río
San
Juan.

25. Recognising
this,
uncertainty
analyses
were
performed
on
the
data
for
both
stations

to
produce
95%
confidence
intervals
for
the
calculated
mean
annual
suspended

465Annex 9

sediment
loads
in
the
Río
San
Juan.
The
results
are
listed
in
Table
2
and
illustrated
in

Figure
3.

Table
2.
Mean
annual
suspended
sediment
loads
in
the
Río
San
Juan
–
Colorado

(from
the
ICE
Report)

Mean
Annual
Suspended
Sediment
Load
(t
yr )
-‐1
River
Period

Best
Estimate
95%
Confidence
Interval

San
Juan
1974
-‐
1976
7
995
000
5
405
000
-‐
10
585
000

San
Juan
2010
-‐
2013
6
573
000
5
181
000
-‐
7
966
000

Colorado
2010
-‐
2013
5
981
000
-‐-‐

Lower
San
Juan
2010
-‐
2013
592
000
-‐-‐

-‐1 1974
–
1976

2010
-‐
2013

in
the
San
Juan
River
(t
y
Annual
Suspended
Sediment
Load

La
Trinidad

Delta
Colorado

Figure
3.
Mean
annual
suspended
sediment
loads
in
the
Río
San
Juan
based
on

measurements
at
La
Trinidad
(1974-‐1976)
and
Delta
Colorado
(2010-‐2013).
Vertical
black

lines
indicate
95%
confidence
intervals.
Note
that
the
loads
based
on
measurements
at

Delta
Colorado
station
have
been
adjusted
to
represent
the
Río
San
Juan
on
the
basis
that
at

the
Delta
suspended
load
is
divided
in
the
same
proportion
as
discharge
(from

the
ICE
Report).

26. In
comparing
the
suspended
sediment
loads
transported
annually
by
the
River
during

the
two
periods
of
observation,
the
first
point
to
note
is
that
the
best
estimate
of
the

mean
for
2010-‐2013
is
noticeably
lower
than
that
for
1974-‐1976.
This
is
unsurprising,

because
the
post-‐Road
period
has
been
drier
than
usual.
For
example,
measured

data
for
the
hydrometric
El
Bum
station
(69-‐578)
indicate
that
mean
annual
rainfall

in
the
hydrological
year
1975-‐1976
was
3
651
mm,
compared
to
only
2
267
mm
in

the
hydrological
year
2011-‐2012.
Lower
rainfall
produces
less
catchment
runoff
that

generates
less
erosion
and,
therefore,
a
smaller
suspended
load.

466 Annex 9

27. However,
it
is
instructive
to
consider
that
the
difference
between
the
mean
annual

suspended
loads
falls
within
the
confidence
intervals
on
those
means
(listed
in

Table
2).
As
the
over-‐lapping
confidence
intervals
in
Figure
3
confirm,
the
high
levels

of
measurement
uncertainty
and
natural
variability
in
annual
suspended
sediment

loads
mean
that
there
is
no
statistically
significant
difference
between
mean
annual

suspended
sediment
loads
for
periods
prior
to
and
following
construction
of
the

Road.

28. The
point
is
that,
notwithstanding
the
difference
in
calculated
loads,
analysis
of
the

measured
data
indicates
that
they
are
not
significantly
different.
Statistically,
there
is

a
95%
probability
that
the
two
sample
means
come
from
the
same
population
of

annual
suspended
sediment
loads,
a
population
that
is
characterised
by
a
very
high

degree
of
inter-‐annual
variability.
It
must,
therefore,
be
concluded
that
the

difference
between
them
is
statistically
insignificant.

29. The
data
reveal
that
measurement
uncertainty,
together
with
natural
fluctuations
in

rainfall,
discharges,
catchment
sediment
yields
and
SSCs,
mean
that
suspended

sediment
loads
are
likely
to
vary
inter-‐annually
between
about
5
and
10.5
million

tonnes.
Using
longer
measurement
records
with
more
measurements
would

probably
reduce
the
confidence
interval
on
the
mean
annual
suspended
load

somewhat,
but
the
range
of
expected
loads
would
remain
wide
because
high
natural

variability
is
a
property
of
the
River,
not
the
data.

30. The
significance
of
this
finding
is
that
it
demonstrates
that
no
possibility
exists
for

using
measured
loads
to
prove
the
existence
of
a
surge
in
sediment
transport
in
the

Río
San
Juan,
unless
that
surge
produces
a
truly
exceptional
annual
suspended
load
–

meaning
something
greater
than
around
10.5
million
tonnes.

-‐1
5.3
Is
the
1
m
yrate
of
land
lowering
estimated
in
the
2012
Kondolf
Report

reasonable?

31. In
the
2012
Kondolf
Report,
Dr
Kondolf
concludes
that
‘landslide/gully
erosion

averages
1
m
deep
(i.e.,
lowering
of
the
land
surface
by
1
m
on
average’
(2012

Kondolf
Report,
page
46).
Using
this
estimate,
Dr
Kondolf
concludes
a
sediment
input

467Annex 9

of
87
000
to
109
000
m y
(2012
Kondolf
Report,
page
46).
This
estimate
is
repeated

in
Annex
2
(on
page
2).
It
is
an
estimate
for
all
sediment
delivered
from
slopes
and

other
disturbed
areas
along
the
Road
to
the
River,
whether
by
mass
wasting

or
gullying.
In
the
2012
Kondolf
Report
erosion
of
the
road
bed
itself
is
dismissed
as

being
less
than
10%
of
that
from
slopes
and
in
Annex
1
Dr
Kondolf
notes
that
most
of

the
road
bed
is
now
gravelled,
which
will
further
reduce
erosion
of
the
road
itself,

especially
in
relation
to
erosion
of
cut
and
fill
slopes.

32. To
establish
whether
rate
at
which
the
land
surface
is
being
lowered
by
erosion
of

cut
slopes,
fill
slopes
and
other
disturbed
areas
along
the
Road
adopted
in
the
2012

Kondolf
Report
(1
m
y -‐)
(taken
from
the
2012
Kondolf
Report,
page
46)
is

conservative,
or
even
reasonable,
a
team
from
the
University
of
Costa
Rica
has,
since

8
June
2013,
been
monitoring
erosion
at
nine
of
the
most
active
sites
for
sheet

erosion,
rill
(micro-‐channel)
erosion,
landslides
and
gullying
along
the
Road
between

Marker
II
and
the
Río
Infiernito
(Figure
4).

Figure
4.
Location
of
monitored
sites
(from
the
UCR
Report).

33. The
monitoring
results
reported
here
come
from
the
two
largest
rotational

landslides
observed
along
the
Road;
the
three
large
gullies;
the
slope
which

displayed
most
intense
rill
(micro-‐channel)
erosion;
and
a
sediment
trap
that
collects

sediment
eroded
from
a
steep
stretch
of
road
bed
and
cut
slope
which
only

468 Annex 9

experiences
sheet
erosion
(Figures
5
and
6).
Hence,
it
is
reasonable
to
assume
that

the
recorded
rates
of
land
surface
lowering
represent
‘worst
case’
scenarios
for

Road-‐related
erosion
to
date.

(a)
(b)

Figure
5.
Sediment
trap
#2
on
(a)
8
June
and
(b)
22
July
2013
(from
the
UCR
Report).

Figure
6.
Rill
erosion
monitoring
site
on
a
cut
slope,
with
rills
numbered
and
1
metre
grid

overlaid
for
scale
(from
the
UCR
Report).

34. Based
on
field
measurements,
the
rate
of
land
surface
lowering
due
to
sheet
erosion

of
the
road
bed
and
cut
slopes
varies
between
about
0.061
and
0.095
m
y -.
The

range
in
the
rates
is
due
to
differences
in
the
amount
of
soil
lost
between
re-‐surveys

of
features
made
during
relatively
dry
(June
-‐
July)
and
relatively
wet
(July
-‐
August)

periods
in
2013.
Based
on
these
direct
measurements
it
is
concluded
that
using

469Annex 9

-‐1
0.095
m
y
to
represent
the
average
annual
rate
of
lowering
of
the
land
surface
due

to
sheet
erosion
is
conservative.

35. On
the
monitored
cut
slopes
where
landslides
were
observed,
they
occupied
10%
to

13%
of
the
overall
area
of
the
slope
and
had
lowered
the
land
surface
in
those
areas

by
between
0.11
and
0.38
metres.
It
is
reasonable
to
assume
that
the
slopes
were

created
when
the
Road
was
under
construction
in
2011,
in
which
case,
they
have

now
existed
for
at
least
two
years.
This
implies
average
rates
of
lowering
of
the
land

-‐1
surface
due
to
landslides
of
between
0.06
and
0.19
m
y
when
averaged
over
the

entire
areas
of
the
slopes
affected.

36. Gullies
on
cut
slopes
were
the
rarest
erosion
feature
observed
by
UCR
along
the

Road
between
Marker
II
and
the
Río
Infiernito,
while
rills
were
the
most
common.

The
worst
gully
monitored
in
the
study
had
a
maximum
depth
of
3
metres
and
a

2
surface
area
of
13.1
m ,
meaning
it
covered
only
just
over
2%
of
the
slope
in
which
it

had
formed.
The
total
volume
of
soil
eroded
to
create
this
gully
was
approximately

3
6
m .
When
this
volume
is
divided
by
the
total
area
of
the
slope,
the
average

lowering
of
the
land
surface
due
to
erosion
by
this
gully
is
0.01
m.
If
it
is
again

assumed
that
the
slope
was
created
when
the
Road
was
under
construction
in
2011,

-‐1
this
implies
a
rate
of
lowering
of
the
land
surface
due
to
gullying
is
0.005
m
yhen

averaged
over
the
entire
area
of
the
slope
affected.

37. The
majority
of
slopes
along
the
Road
between
Marker
II
and
the
Río
Infiernito

experience
rill
erosion.
At
the
rill
study
site,
there
were
26
rills,
the
largest
of
which

had
a
maximum
width
of
0.3
metres
and
a
maximum
depth
of
0.6
metres.
Based
on

spatial
analysis
of
all
the
rills
in
the
sample
area,
and
with
the
conservative

assumption
that
they
all
had
widths
and
depths
equal
to
that
of
the
largest
rill,
UCR

concluded
that
rill
erosion
has
lowered
the
land
surface
of
the
slope
by
an
average
of

0.12
metres.
Again
assuming
that
the
slope
was
created
when
the
Road
was
under

construction
in
2011,
this
implies
an
average
rate
of
lowering
of
the
land
surface
due

to
rilling
of
around
0.06
m
y
when
averaged
over
the
entire
area
of
the
slope.
As

the
UCR
study
site
was
the
most
intensely
rilled
slope
observed,
this
represents
the

‘worst
case’
example
of
rill
erosion
in
their
study
area.

470 Annex 9

38. Fill
slopes
in
the
studied
area
do
not
feature
erosion
due
to
deep
landslides,
with

mass
wasting
limited
to
much
less
damaging
shallow
slips
and
soil
falls.
Rill
erosion
is

observed
on
fill
slopes,
and
the
rate
monitored
on
the
most
intensively
rilled
cut

slope
may
be
conservatively
used
to
represent
rill
erosion
of
fill
slopes
as
well.

39. Gully
erosion
on
fill
slopes
was
observed
by
UCR
to
cover
about
4%
to
10%
of
the

monitored
fills,
lowering
the
surface
of
these
slopes
by
between
0.06
and
0.10
m

when
averaged
over
the
area
of
fill
slope
affected.
In
contrast
to
erosion
of
road

cuts,
the
monitored
gullies
had
formed
in
about
six
months.
Therefore,
the

estimated
average
annual
rate
of
land
surface
lowering
due
to
gully
erosion
of
fill

slopes
is
higher
than
that
for
cut
slopes,
being
between
0.12
and
0.20
m
y -‐.

40. Table
3
below
summarises
the
observed
average
erosion
depths
and
average
annual

rates
of
land
surface
lowering
mentioned
above.
As
this
summary
lists
the
highest

values
of
eroded
area/area
of
feature,
average
eroded
depth,
and
average
annual

rates
of
land
surface
lowering
for
each
erosion
type,
the
data
listed
are
likely
to
over-‐

estimate
actual
average
values
for
the
Road
between
Marker
II
and
the
Río
Infiernito

and,
in
this
respect,
they
are
conservative.

Table
3.
Summary
of
erosion
monitoring
results
(from
the
UCR
Report).

Eroded
Average
erosion
Average
rate
of
land

Type
of
Erosion
depth

surface
lowering

feature
type
Area/Area
of

Feature
(%)
(m)
(m
y )

Cut
Slope
Landslide
13
0.38
0.19

Cut
Slope
Gully
2
0.01
0.005

Cut
Slope*
Rill
50
0.12
0.06

Road
bed
and

Sheet
100
0.02
0.095

Cut
Slope

Fill
Slope
Gully
9
0.10
0.20

*these
findings
may
also
be
conservatively
applied
to
rills
on
fill
slopes.

41. The
UCR
further
recommend
using
average
erosion
depths
for
landslides,
gullies
and

rills
on
cut
slopes
in
place
of
estimated
annual
rates
of
land
surface
lowering
when

calculating
Road-‐related
erosion
and
potential
sediment
yield
to
the
Río
San
Juan,
as

doing
so
is
even
more
conservative.
For
sheet
erosion,
the
maximum
rate
observed

471Annex 9

(i.e.
0.095
m
y
during
the
wet
season)
is
recommended.
Finally,
0.20
m
y
is
the

most
conservative
value
for
gullies
in
road
fills
and
UCR
suggests
that
this
should
be

used.
These
rates
should
all
over-‐estimate
actual
average
erosion
to
date,
but

considering
that
the
last
two
years
have
been
drier
than
average,
they
could
be

exceeded
in
future.
This
will
only
be
the
case
if
erosion
risks
are
unmitigated,
leaving

the
slopes
exposed
to
potentially
heavier
rainfall.
As
discussed
in
Section
7
below,

and
reported
in
Attachments
CR-‐3
and
CR-‐6,
work
to
mitigate
erosion
risks
has

begun
and
will
continue
as
necessary.

42. In
the
2012
Kondolf
Report,
rates
of
land
surface
lowering
due
to
erosion
were

estimated
using
visual
observations
of
the
Road
made
at
a
distance
from
the
air
and

from
a
boat
during
a
single,
two-‐day
visit
to
the
area
in
October
2012,
together
with

consideration
of
published
studies
of
sediment
budgets
in
the
Pacific
Northwest
of

North
America
and
the
team’s
observations
of
road-‐related
erosional
impacts

elsewhere
(2012
Kondolf
Report,
page
46).
In
his
Report,
Dr
Kondolf
states
that,
‘we

conservatively
estimated
that
that
landslide
and
gully
erosion
is
occurring
on
40-‐50%

of
the
steep
disturbed
land
(21.8
to
27.3
ha)
and
that
this
landslide/gully
erosion

averages
1
m
deep
(i.e.,
lowering
the
land
surface
by
1
m
on
average)
(2012
Kondolf

Report,
page
46).

43. Monitoring
of
landslide
and
gully
erosion
reported
by
UCR
above
suggests
that
the

rate
of
land
surface
lowering
estimated
in
the
2012
Kondolf
Report
is
probably
too

high
by
a
factor
of
five.
Further,
UCR
field
monitoring
indicates
that
landslides
and

gullies
on
average
cover
around
10
to
15%
of
the
slopes
with
these
features,
so
the

40
to
50%
estimate
of
the
area
of
the
Road
on
which
this
erosion
is
occurring
which

is
adopted
in
the
2012
Kondolf
Report
would
also
appear
to
be
significantly
too
high.

44. In
my
experience,
including
my
inspections
of
the
Road
in
February
and
May
2013,
of

-‐1
land
surface
lowering
due
to
landslides
and
gullies
averaging
1
m
y
is
too
high
and
it

is
unlikely
to
be
accurate.
Also,
the
assumption
that
landslides
and
gullies
cover
40
to

50%
of
slopes
and
other
disturbed
areas
overstates
the
extent
of
these
features.

Conversely,
the
monitored
rates
and
areas
affected
as
summarised
in
Table
3
are

entirely
reasonable
and,
in
my
opinion,
more
reliable.

472 Annex 9

45. Recognising
this,
the
average
annual
sediment
yield
due
to
landslide
and
gully

erosion
between
Marker
II
and
Boca
San
Carlos
(i.e.
the
upstream
41.6
km
of
the

Road
that
runs
adjacent
to
the
River)
estimated
by
Dr
Kondolf
(reported
on
page
46

of
the
2012
Kondolf
Report)
of
218
400
to
273
000
m
is
likely
to
be
too
high.

46. In
Annex
2,
which
is
discussed
further
in
Section
6
below,
Dr
Kondolf
emphasizes
the

impact
of
‘mass
wasting’
which
he
describes
as
involving
‘the
movement
of
larger

volumes
of
earth
by
gravity,
often
along
failure
plains
determined
by
differences
in

material,
such
as
the
boundary
between
a
volume
of
fill
material
and
the
existing

slope
upon
which
it
was
placed.’
(Annex
2,
page
9.)
I
agree
in
principle
with
this

description.
Dr
Kondolf
also
states
that,
on
his
inspection
in
October
2013,

‘[s]ignificant
cutslope
and
fillsope
[sic]
mass
wasting
as
also
locally
evident’
(Annex
2,

page
14).
However,
the
‘mass
wasting’
Dr
Kondolf
is
said
to
have
observed
in

October
2013
has
not
caused
him
to
revisit
his
estimates
of
sediment
input
to
the

Road,
which,
as
noted
in
paragraph
31
above,
includes
all
sediment
input,
whether

from
mass
wasting
or
otherwise.

47. All
forms
of
mass
wasting
(including
landslides)
are
driven
by
gravity.
In
short
the

weight
of
the
slope
becomes
greater
than
its
strength
and
it
falls
down.
Failure
may

be
triggered
by
any
of
the
processes
listed
as
triggering
landslides
in
the
UCR
Report,

on
page
14.
Essentially
there
is
a
range
of
mechanisms
by
which
slopes
retreat
due

to
mass
wasting,
with
landslides
being
the
largest
in
scale
and
shallow
slides
being

the
smallest.
In
the
studies
made
by
UCR
and
ICE,
which
yield
the
estimates
for

sediment
input
described
in
Table
3
above,
all
mass
wasting
is
treated
as
being
by

landslides.
As
a
result,
the
estimates
for
sediment
input
are
conservative,
because

landslides
are
the
largest
in
scale
of
the
potential
events
which
result
in
mass

wasting.
Furthermore,
it
is
clear
that
these
estimates
take
account
of
all
potential

sediment
input
from
the
Road
to
the
River,
including
by
mass
wasting.
The
potential

for
this
sediment
input
to
cause
damage
to
the
San
Juan
River
is
discussed
further
in

Section
5.4
below.

473Annex 9

5.4
Are
calculated
delivery
rates
for
Road–derived
sediment
based
on
the
results
of

field
monitoring
sufficient
to
cause
“significant”
or
“irreversible”
damage
to
the

Río
San
Juan?

48. To
investigate
whether
sediment
eroded
from
the
Road
could
pose
any
risk
to
the

Río
San
Juan,
the
ICE
Report
took
up
the
results
of
erosion
monitoring
reported
in

the
UCR
Report
to
estimated
sediment
delivery
rates
from
the
Road
to
the
River.
The

work
was
performed
in
two
steps.
First,
the
data
in
Table
3
were
adopted
to

represent
average
annual
rates
of
land
surface
lowering,
as
recommended
in
the

UCR
Report.
ICE
then
used
the
length
and
steepness
of
the
road
bed,
and
the
areas

of
cut
slopes,
fill
slopes
and
other
disturbed
ground
along
the
full
length
of
the
Road

adjacent
to
the
River
between
Marker
II
and
Delta
Costa
Rica
to
convert
annual

average
rates
of
land
surface
lowering
into
annual
eroded
volumes.

49. The
results
are
summarized
for
each
of
the
five
main
river
basins
draining
from
Costa

Rica
to
the
Río
San
Juan
between
Marker
II
and
Delta
Costa
Rica,
in
Table
4.

Table
4.
Estimated
average
annual
erosion
rates
for
the
Road
(from
the
3 ICE -‐1eport).
-‐1
Road
length

Annual
rate
by
volume
(m
yr )

Annual
rate
by
mass*
(t
yr )

Basin

(km)

Road
Slopes
Total

Road
Slopes
Total

Major
Costa
Rican
river
basi ns
draining
directly
to
the
San
Juan
River
between
Marker
II
and
Delta
CR

Infiernito
38

12
260
28
000
40
260

20
450
46
750
67
250

San
Carlos
11

2
060
600
2
660

3
450
1
000
4
450

Cureña
28

5
220
7
560
12
780

8
700
12
650
21
350

Sarapiquí

3

560
160
720

950
250
1
200

Chirripó

22

4
100
260
4
360

6
850
450
7
300

Costa
Rican
area
that
drains
directly
to
the
San
Juan
River
between
Marker
II
to
and
Delta
Colorado

Total
102

24
200
36
580
60
780

40
400
61
100
101
550

*
To
convert
eroded
volumes
to
masses,
a
bulk
density
of
1.67
t
m
was
assumed.
This
value
is
widely
used
to

represent
the
bulk
density
of
silt -‐sand
soils.

50. Second,
ICE
applied
a
sediment
delivery
ratio
to
estimate
the
proportion
of
the

eroded
sediment
reaching
the
Río
San
Juan.
The
2012
Kondolf
Report
estimated
this

delivery
ratio
to
be
0.4
(2012
Kondolf
Report,
page
46).
However,
considering
the

small
size
of
many
of
the
micro-‐basins
draining
either
directly
to
the
Río
San
Juan
or

to
the
five
major
Costa
Rican
tributaries,
and
bearing
in
mind
the
relatively
fine
grain

474 Annex 9

size
of
most
of
the
eroded
sediment
(found
to
be
mostly
silt
in
the
UCR
Report),
ICE

concluded
that
Dr
Kondolf’s
estimate
was
probably
low
and
they
used
a
higher

estimate
of
0.6
instead.

51. I
concur
with
ICE’s
selection
of
0.6
as
being
reasonable
but
more
conservative
than

Dr
Kondolf’s
assumption
of
0.4.
The
results
of
applying
this
higher
delivery
ratio
are

listed
in
Table
5
and
shown
in
Figure
7.

Table
5.
Average
annual
inputs
of
Road-‐derived
sediment
to
the
Río
San
Juan

(from
the
ICE
Report)

Road
length

Input
by
volume
(m 3
yr )

Input
by
mass*
(t
yr )
‐1
Basin

(km)

Road
Slopes
Total

Road
Slopes
Total

Major
Costa
Rican
river
basins
draining
directly
to
the
San
Juan
River

Infiernito
38

7
360
16
800
24
160

12
250
28
050
40
300

San
Carlos
11

1
240
360
1
600

2
050
600
2
650

Cureña
28

3
140
4
540
7
680

5
200
7
600
12
800

Sarapiquí

3

340
100
440

550
150
700

Chirripó

22

2
460
160
2
620

4
100
250
4
350

Costa
Rican
area
that
drains
directly
to
the
Río
San
Juan
between
Marker
II
to
and
Delta
Colorado

Total
102

14
540
21
960
36
500

24
150
36
650
60
800

-‐3
*
To
convert
eroded
volumes
to
masses,
a
bulk
density
of
1.67
t
m
was
assumed.
This
value
is
widely
used
to

represent
the
bulk
density
of
silt -‐sand
soils.

Figure
7.
Estimated
annual
inputs
of
eroded
sediment
to
the
Río
San
Juan
from
the
Road

along
the
five
main
basins
between
Marker
II
and
Delta
Colorado
(from
the
ICE
Report).

475Annex 9

52. The
results
indicate
that
delivery
of
sediment
eroded
from
slopes
along
the
Road
in

the
San
Carlos,
Sarapiquí
and
Chirripo
reaches
of
the
Río
San
Juan
is
negligible.
Input

of
the
slope-‐derived
sediment
in
the
Infiernito
stretch
of
the
Road
is
more
of
an

issue,
which
is
consistent
with
Dr
Kondolf’s
decision
to
focus
his
attention
on
that

stretch
in
the
2012
Kondolf
Report.

53. However,
the
estimated
average
annual
input
sediment
eroded
from
the
Infiernito

reach
of
the
Road
is
around
24
000
my ,
which
is
an
order
of
magnitude
less
than

that
estimated
by
Dr
Kondolf
for
the
first
41.6
km
of
the
Road
between
Marker
II
and

Boca
San
Carlos
(87
000
–
109
000
my ).
Indeed,
the
estimated
input
for
the
entire

length
of
the
Road
alongside
the
River
between
Marker
II
and
Delta
Costa
Rica

(36
500
m 3 y )
is
only
a
third
to
a
half
of
that
estimated
on
page
46
of
the
2012

Kondolf
Report.

54. The
average
annual
rates
of
additional
sediment
delivery
listed
in
Table
5
and

graphed
in
Figure
7
represent
conditions
since
December
2010
and
up
to
June
2013.

The
results
indicate
that
during
this
period
additional
sediment
eroded
from
the

Road
has
been
delivered
to
the
Río
San
Juan
in
the
Infiernito
and,
to
a
lesser
degree,

the
Cureña
reaches,
but
at
rates
insufficient
to
have
any
significant
impact
on
the

River
or
its
surrounding
environment.
This
is
due
to
the
relatively
large
size
and

power
of
the
Río
San
Juan
and
its
inherent
capacity
to
accommodate
and
process

additional
sediment
without
perturbing
either
reach-‐scale
channel
morphology

(which
is
geologically-‐controlled)
or
in-‐stream
and
riparian
habitats
and
ecosystems

(which
are
well
adapted
to
high
and
variable
sediment
loads).

5.5
Potential
for
Road-‐derived
sediment
to
impact
the
Río
San
Juan

5.5.1
Introduction

55. The
purpose
of
this
Section
is
to
examine
whether
the
additional
Road-‐derived

sediment
supplied
to
the
Río
San
Juan
could
cause
‘irreparable
damage
that
is
being

inflected
[sic]
on
the
river
and
its
surrounding
environment,
including
navigation
and

the
health
and
wellbeing
of
the
population
living
along
its
margins’
and
whether

‘Costa
Rica’s
road
works
have
caused
a
surge
in
the
San
Juan
River’s
sediment
load

476 Annex 9

requiring
Nicaragua
to
take
active
efforts,
including
dredging,
to
maintain
the

capacity
and
quantity
of
the
river’s
waters.’.
In
summary,
the
evidence
does
not

support
either
of
these
statements.

5.5.2
Estimated
annual
load
of
Road-‐related
sediment
supplied
to
the
Río

San
Juan

56. According
to
the
data
and
calculations
presented
in
the
2012
Kondolf
Report

(page
46),
the
average
total
quantity
of
sediment
supplied
to
the
Río
San
Juan
by
the

Road
annually
is
87
000
to
109
000
m3
y-‐1.
As
explained
in
paragraph
31
above,
this

estimate
includes
all
potential
sources
of
sediment
input
considered
significant
in
the

2012
Kondolf
Report
(a
finding
not
revisited
in
Annex
2),
including
surface
erosion

and
mass
wasting.

57. Dr
Kondolf’s
estimate
is
based
on
a
3-‐day
fieldtrip
during
October
2012,
during
which

he
observed
the
Road
from
a
helicopter
and
boat
on
the
Río
San
Juan,
but
made
no

measurements
of
erosion
or
sediment
delivery.
It
should
be
noted
that
Dr
Kondolf’s

figure
applies
only
the
first
41.6
km
of
the
Road
between
Marker
II
and
Boca
San

Carlos.
He
made
no
estimate
of
erosion
from
the
remaining
~60
km
between
Boca

San
Carlos
and
Delta
Costa
Rica,
nor
did
he
suggest
that
his
estimate
for
the
first

41.6
km
could
be
upscaled
to
apply
to
the
entire
length
of
the
Road
between
Marker

II
and
Delta
Costa
Rica.
In
my
opinion,
to
upscale
his
estimate
would
be

unreasonable
because,
as
Dr
Kondolf
noted,
43
of
the
54
locations
where
he

allegedly
observed
Road-‐derived
sediment
to
have
entered
the
Río
San
Juan
are

within
the
first
41.6
km,
with
only
11
along
the
remaining
length
of
the
Road.
Having

inspected
the
entire
length
of
the
Road,
I
conclude
that
Dr
Kondolf
did
not
upscale

his
estimate
based
on
the
entire
length
of
the
Road
because
to
do
so
would
grossly

exaggerate
the
total
input
of
Road-‐derived
sediment.
On
this
basis,
the
upper
bound

of
Dr
Kondolf’s
estimated
range
seems
likely
to
be
close
to
what
he
would
have

estimated
for
the
entire
Road.

58. As
reported
in
section
5.4
above
the
Costa
Rican
technical
team’s
estimate
for
the

total
quantity
of
Road-‐derived
sediment
delivered
to
the
River
by
volume
is

477Annex 9

3
-‐1
36
500
m y ,
which
is
only
a
third
of
the
upper
bound
of
the
range
estimated
by

Dr
Kondolf.

59. As
stated
earlier,
based
on
wide
experience
in
both
field
observation
and
erosion

-‐1
monitoring,
my
view
is
that
Dr
Kondolf’s
use
of
1
m
y
as
the
average
rate
of

lowering
of
the
land
surface
due
to
landsliding
and
gullying
is
certainly
an
over-‐

estimate.
My
observations
along
the
entire
length
of
the
Road
likewise
indicate
to

me
that
Dr
Kondolf’s
estimate
that
40
to
50%
of
slopes
are
covered
by
landslides
and

gullies
is
also
an
over-‐estimate.

60. Notwithstanding
this,
to
determine
whether
the
input
of
Road-‐derived
sediment

could
impact
the
environment
of
the
Río
San
Juan
and
navigation
in
the
lower
Río

San
Juan,
I
have
been
instructed
to
proceed
on
the
basis
of
Dr
Kondolf’s
estimate
of

average
annual
sediment
delivery
of
road-‐derived
sediment,
which
is
two
to
three

times
higher
than
the
estimate
made
in
the
ICE
Report.
This
exercise
does
not
imply

acceptance
of
Dr
Kondolf’s
estimate,
which,
for
the
reasons
I
have
explained,
I

consider
to
be
a
significant
over-‐estimate.

5.5.3
Average
annual
sediment
load
in
the
lower
Río
San
Juan
since

December
2010

61. Sediment
loads
in
the
River
are
expressed
by
mass
(tonnes)
rather
than
volume

(cubic
metres).
Hence,
it
is
necessary
to
convert
Dr
Kondolf’s
estimate
from
a
volume

per
year
to
a
mass.
As
noted
in
Tables
4
and
5
above,
a
cubic
metre
of
sediment
has

a
mass
of
about
1.67
tonnes.
This
is
typical
for
closely-‐packed,
quartz
sand
grains,

though
it
may
be
a
little
high
for
soil
(which
has
a
higher
porosity).
Hence,
it
is
in
that

respect
conservative.
Assuming
that
each
cubic
metre
of
soil
has
a
mass
of

1.67
tonnes,
the
average
annual
load
of
Road-‐related
sediment
input
to
the
Río
San

-‐1
Juan
is,
according
to
Dr
Kondolf,
157
180
to
182
030
t
yr

62. For
comparison,
the
Costa
Rican
technical
team
estimates
the
rate
of
input
of
Road-‐
-‐1
related
sediment
to
be
60
800
t
yr ,
based
on
their
measurements
which
are

described
as
reported
in
Attachment
CR-‐1
and
CR-‐2.

478 Annex 9

63. ICE
monitor
sediment
transport
at
multiple
gauging
stations
within
the
basin
of
the

Río
San
Juan,
including
the
Delta
Colorado
(Station
691104)
on
the
Río
Colorado

immediately
downstream
of
the
Delta
(see
Figure
1).
According
to
their
records,
and

as
explained
in
the
ICE
Report,
the
average
annual
total
sediment
load
(that
is

suspended
load
plus
bed
load)
carried
by
the
Río
San
Juan
between
December
2010

-‐1
and
June
2013
was
around
9
133
000
t
yr .
In
the
ICE
Report,
it
is
estimated
that
at

-‐1
-‐1

the
Delta,
8
470
000
t
yrss
to
the
Río
Colorado
and
663
000
t
yr to
the
lower
Río

San
Juan.

5.5.4
Input
of
Road-‐derived
sediment
to
the
Río
San
Juan

64. The
sediment
derived
from
erosion
related
to
the
Road
as
estimated
by
Dr
Kondolf,

makes
up
1
or
2%
of
the
total
sediment
load
carried
by
the
Río
San
Juan
which
is

obviously
too
small
a
proportion
to
have
an
significant
impact
on
the
River.

65. Assuming
that
10%
of
the
additional
sediment
enters
the
lower
Río
San
Juan

suggests
that
the
average
annual
input
of
Road-‐derived
sediment
to
the
lower
Río

-‐1
San
Juan
is
15
718
to
18
203
t
ywhich
constitutes
2
or
3%
of
the
total
load
in
the

lower
Río
San
Juan
downstream
of
the
Delta.

5.5.5
Potential
impact
on
sedimentation
in
the
lower
Río
San
Juan

66. The
lower
Río
San
Juan
is
approximately
30
km
long
and
it
has
an
average
channel

2
width
around
90
m,
giving
it
a
bed
area
of
about
2.7
million
m .
Using
Dr
Kondolf’s

3 -‐1
estimate
of
sediment
delivery
to
the
Río
San
Juan
(87
000
to
109
000
m y ),

conservatively
assuming
that
10%
of
this
enters
the
lower
Río
San
Juan
(8
700
to

3 -‐1
10
900
m y ),
and
supposing
that
all
of
the
Road-‐related
sediment
were
deposited

on
the
bed
of
the
lower
Río
San
Juan
(with
none
at
all
deposited
on
the
floodplains

and
in
the
wetlands
or
passing
through
to
the
Caribbean
Sea,
which
is
extremely

conservative),
the
average
increase
in
the
rate
of
aggradation
of
the
bed
would
be

3
to
4
mm
y

67. It
is
immediately
obvious
that
the
addition
of
even
the
quantity
of
additional
Road-‐

derived
sediment
estimated
by
Dr
Kondolf
to
the
total
annual
sediment
load
of
the

lower
Río
San
Juan
could
not
have
impeded
navigation
or
required
Nicaragua
to
take

479Annex 9

active
efforts,
including
dredging,
to
maintain
the
capacity
and
quantity
of
the
River’s

waters.

5.5.6
Inputs
of
Road-‐derived
sediment
are
not
just
insignificant,
they
are

undetectable

68. It
should
be
recalled
that
the
annual
load
of
the
Río
San
Juan
is
not
constant
year-‐on-‐

year
but
is
different
every
year
because
it
responds
to
natural
variability
in
rainfall,

runoff,
erosion
and
channel
evolution.

69. As
reported
in
Section
5.2
above,
monitoring
of
suspended
sediment
load
in
the
Río

Colorado
immediately
downstream
of
the
Delta
between
2010
and
2012
revealed

that
while
the
average
annual
load
of
suspended
sediment
was
5
981
000
t
y -,
the

95%
confidence
interval
on
the
average
value
was
between
5
181
000
and

10
585
000
t
y due
to
uncertainty
and
natural
variability
in
the
measured
data.
This

means
that
there
is
a
95%
probability
that
the
suspended
load
carried
in
any
year
will

be
between
5
181
000
and
10
585
000
t,
but
there
is
a
5%
chance
that
it
could
be
still

higher
or
lower
than
this.
Variability
in
annual
bedload
is
unknown,
but
is
likely
to
be

similar
or
greater
than
that
in
the
suspended
sediment
load.
It
follows
that
using

variability
in
suspended
load
to
represent
that
in
total
load
(i.e.
suspended
sediment

plus
bed
loads)
is
conservative.

70. Observed
variability
in
suspended
loads
indicates
that
the
annual
total
sediment
load

of
the
Río
Colorado
will
be
within
about
+/-‐
20%
of
the
mean
value
95%
of
the
time.

71. As
around
90%
of
the
discharge
in
the
Río
San
Juan
passes
to
the
Río
Colorado,
it

follows
that
the
95%
confidence
interval
on
the
mean
annual
sediment
load
of
Río

San
Juan
must
also
be
around
+/-‐
20%.
Similarly,
as
100%
of
the
discharge
passing

through
the
lower
Río
San
Juan
comes
from
the
Río
San
Juan,
the
95%
confidence

interval
on
its
annual
sediment
loads
is
also
likely
to
be
about
+/-‐
20%.

72. The
increase
of
1
or
2%
predicted
based
on
Dr
Kondolf’s
estimated
range
for
delivery

of
road-‐derived
sediment
to
the
Río
San
Juan
falls
well
within
the
range
of
natural

variability
of
sediment
loads
in
the
River
represented
by
a
confidence
interval
of

480 Annex 9

+/-‐
20%,
meaning
that
even
if
such
a
change
in
load
were
to
occur
it
would
be

indiscernible
and
statistically
undetectable
in
records
of
measured
loads.

73. The
bed
of
the
lower
Río
San
Juan
is
formed
in
mobile
sand,
self-‐organised
into

ripples
and
dunes
with
amplitudes
ranging
from
centimetres
up
to
a
metre
or
more,

respectively.
The
bed
also
features
pools
and
bars
that
cause
in-‐channel
depths
to

vary
from
several
metres
to
a
metre
or
less.
It
follows
that
a
change
in
the
rate
of

-‐1
sedimentation
by
3
or
4
mm
y
(which
is
one
and
a
half
to
two
times
the
diameter
of

a
single
sand
grain)
would
be
imperceptible
in
the
field
and
immeasurable
using
even

high
precision
sonar
equipment.

6. Response
to
new
evidence
submitted
by
Nicaragua

74. As
mentioned
in
paragraph
8
above,
I
have
been
asked
to
review
and
comment
upon

the
opinions
expressed
in
Annex
1,
Annex
2
and
Appendix
A
submitted
to
the
Court

by
Nicaragua
on
1
November
2013.

75. At
the
outset,
I
note
that
the
material
dealt
with
in
Annex
1
is
largely
repeated
in

Annex
2.
Annex
1
records
observations
from
a
site
visit
in
May
2013.
Those
same

observations
are
repeated
and
elaborated
in
Annex
2
at
pages
9-‐12.
Annex
1
also

repeats
the
list
of
‘recommended
urgent
measures’
which
is
set
out
in
Kondolf’s

2012
Report
and
which
are
listed
in
the
Request.
For
these
reasons,
I
will
focus
my

responses
on
the
material
contained
in
Annex
2.

76.
On
page
of
Annex
2
(paragraph
two),
it
is
reported
that
in
May
2013
Dr
Kondolf

‘documented
multiple
“deltas”
of
sediment
eroded
from
the
road,
and
carried
by

local
streams
or
newly
eroded
gullies
into
the
river.’
Having
examined
the

photographs
in
Appendix
A,
I
am
unsure
of
the
basis
on
which
Dr
Kondolf
can
be
so

certain
that
all
of
the
deltas
documented
in
the
photographs
were
composed

entirely
or
even
predominantly
of
‘sediment
eroded
from
the
road’.
My
doubts
stem

partly
from
the
fact
is
that
the
Road
is
not
even
visible
in
many
of
the
photographs

and
there
are
certainly
plenty
of
other
potential
sources
of
sediment
on
the
Costa

Rican
side
of
the
River;
some
natural,
others
anthropogenic
but
unrelated
to
the

Road
in
either
case.
But
there
is
a
much
more
compelling
reason
for
me
to
question

481Annex 9

the
causal
link
between
the
Road
and
the
deltas
that
is
made
so
easily
in
Annex
and

Appendix
A.
As
noted
in
paragraph
10
above,
I
also
participated
in
an
overflight
of

the
Road
in
May
2013,
and
I
also
noticed
multiple
deltas
of
sediment.
However,

many
of
the
deltas
I
noticed
were
along
the
bank
line
of
the
Río
San
Juan
on
the

Nicaraguan
side.
Several
of
them
appeared
quite
a
lot
larger
and
considerably
more

prominent
than
those
documented
in
Appendix
A
(Figures
8-‐10
show
some

examples).
These
deltas
are
composed
of
sediment
eroded
from
Nicaraguan
territory

and
deposited
in
the
Río
San
Juan
by
Nicaraguan
tributaries.
They
cannot
be
deltas
of

sediment
eroded
from
the
Road.

(a)

482 Annex 9

(b)

Figure
8.
Prominent
sediment
delta
observed
in
the
Río
San
Juan
from
a
helicopter
in
Costa

Rican
airspace
on
7
May
2013
(a)
close
up
and
(b)
wide
angle
view
showing
clearly
that
this

delta
is
on
the
left
(Nicaraguan)
bank
of
the
River.
Route
1856
is
clearly
visible
on
the
right

(Costa
Rican)
side
of
the
River
(both
photographs
by
author).

(a)

483Annex 9

(b)

Figure
9.
Large
sediment
delta
observed
in
the
Río
San
Juan
from
a
helicopter
in
Costa
Rican

airspace
on
7
May
2013
(a)
close
up
and
(b)
wide
angle
view
showing
clearly
that
this
delta

is
also
on
the
far
(Nicaraguan)
bank
of
the
River.
Route
1856
is
clearly
visible
on
the
near

(Costa
Rican)
side
of
the
River
(both
photographs
by
author).

484 Annex 9

485Annex 9

Figure
10.
Photographs
taken
from
Costa
Rican
air
space
on
7
May
2013.
These
show
that

deltas
of
sediment
occur
at
most
of
the
left
bank
tributaries
of
the
Río
San
Juan.
The
deltas

are
unrelated
to
the
Road
and
are
formed
by
sediment
delivered
to
the
Río
San
Juan
by

streams
drain
catchments
entirely
within
Nicaraguan
territory.

77. I
do
not
agree
with
the
view
that
that
sediment
deltas
in
the
Río
San
Juan
are

exclusively
or
perhaps
even
predominantly
caused
by
deposition
of
sediment
eroded

from
the
Road.
On
the
contrary,
deltas
are
part
of
the
natural
sediment
transfer

system.
They
form
when
local
rainstorms
produce
sediment-‐laden
runoff
from

486 Annex 9

tributaries,
the
coarse
fraction
of
which
is
deposited
in
the
lower
course
of
the

tributary
channel
and
around
the
tributary
confluence
with
Río
San
Juan.
As

Dr
Kondolf
notes,
that
deposition
is
temporary
–
deltaic
sediments
are
re-‐eroded
and

transported
downstream,
diffusing
into
the
receiving
river’s
sediment
load
during

the
next
significant
sediment
transport
event
in
the
main
river.
The
limited
size
and

wide
spacing
of
the
tributary
deltas
I
observed
in
the
Río
San
Juan
in
May
2013

means
that
they
do
not
harm
the
River.
Indeed,
to
the
contrary,
tributary
bars
and

deltas
are
beneficial
to
the
aquatic
and
riparian
ecosystems
because,
for
example,

they
provide
fresh
habitats
and
open
niches
for
pioneer
plant
species
–
for
example,

as
illustrated
in
photographs
1018,
1043
and
1046
in
Appendix
A.

78. In
reviewing
the
impacts
of
road
construction
in
rivers
other
than
the
Río
San
Juan,

Annex
2
makes
reference
on
page
7
(paragraph
2)
to
ecological
impacts
that
stem

from
‘The
combination
of
hydrological
effects
and
increased
erosion
and

sedimentation
from
road
construction
that
result
in
significant
increases
of
sediment

loading
to
rivers
and
streams,
which
in
turn,
have
been
documented
to
cause
a
range

of
serious
environmental
problems’.
And
in
paragraph
5
on
page
7,
‘The
delivery
of

massive
volumes
of
sediment
to
rivers
has
resulted
in
significant
ecological
damage’.

These
statements
are
entirely
general
in
their
terms
and
are
only
relevant
to
road

construction
that
delivers
increases
in
sediment
loading
that
may
justifiably
be

described
as
massive
or
at
the
very
least
significant.
As
explained
in
Section
5
above,

even
if
we
accept
Dr
Kondolf’s
upper
bound
estimate
that
109
000
m 3
y
of
sediment

eroded
from
the
Road
has
been
delivered
to
the
Río
San
Juan
(an
estimate
which
I

believe
to
be
too
high
by
a
factor
of
3,
and
which
incorporates
all
sediment
input
to

the
River
considered
significant
in
the
2012
Kondolf
Report,
and
which
is
restated
in

Annex
2),
this
contributes
about
2%
to
the
sediment
load
carried
annually
by
the
Río

San
Juan.
In
no
sense
can
such
an
increase
be
described
as
massive
or
even

significant.
Considering
uncertainty
in
the
sediment
load
associated
with
natural

variability
in
the
annual
load
such
an
increase
is
not
only
negligible,
it
is
indiscernible.

79. On
page
8
(paragraph
3)
Dr
Kondolf
alludes
to
the
finding
reported
by
Reid
and

Dunne
(2003)
that
‘road-‐related
sediment
can
dominate
the
sediment
budget
in

many
rivers’.
As
a
general
proposition
and
in
the
abstract,
I
agree
with
this

487Annex 9

statement.
But
Reid
and
Dunne
were
not
referring
to
the
Río
San
Juan.
In

Attachment
CR-‐1,
ICE
have
constructed
a
sediment
budget
specific
to
this
River:
the

Río
San
Juan.
The
result
is
depicted
in
Figure
11
(reproduced
from
Attachment
CR-‐1),

which
illustrates
that
the
contribution
of
road-‐related
sediment
is
tiny
in
the
context

of
this
River.
Road-‐related
sediment
may
dominate
the
sediment
budget
in
many

rivers,
but
the
Río
San
Juan
is
not
one
of
them.

Figure 11. Increases in average annual sediment loads input to the San Juan – Colorado River
system due to construction of Route 1856 are illustrated by the red lines in this version of the
sediment balance diagram. Inputs of road -derived sediment are specified numerically: for

example, the lar-1st change in average annual sediment load input to the San Juan River is
+40 300 t y from CR5 (the Infiernito Basin). The narrow width of the red band is correctly
scaled and accurately portrays that cumulative sediment inputs from Route 1856 are so small
relative to pre-construction loads that they are not only difficult to see but inconsequential and
practically undetectable (from Attachment CR-1 – the ICE Report).

80. On
page
11
(paragraph
2)
of
Annex
2,
Dr
Kondolf
reports
suspended
sediment

concentrations
in
three
samples
of
muddy-‐water
in
plumes
in
the
River,
which
had

entered
the
River
following
a
15
minute
downpour.
The
samples
had
SSCs
of
364,

459
and
483
grams
per
cubic
metre.
Dr
Kondolf
describes
these
SSCs
as
‘high’.
He

also
took
two
samples
of
River
water,
both
of
which
had
SSCs
of
8
grams
per
cubic

metre.
In
Attachment
CR-‐1,
ICE
report
not
five
SSC
samples,
but
2,409.
Table
6

488 Annex 9

(reproduced
from
Attachment
CR-‐1)
lists
the
sources
of
SSC
data
for
the
Rio
San
Juan

and
its
Costa
Rican
tributaries
and
these
data
shown
graphically
in
Figure
12.
The
full

results
may
be
found
in
Appendix
A
of
Attachment
CR-‐1.

Table
6.
Properties
of
the
sediment
gauging
stations
in
the
Costa
Rican
basins

draining
to
the
San
Juan
River
(from
Attachment
CR-‐1,
the
ICE
Report).

Note:
1
gram
per
cubic
metre
=
1
part
per
million
(ppm)

Figure
12.
Suspended
sediment
concentration
as
a
function
of
discharge
for
2
409
samples

taken
from
the
Río
San
Juan
and
Costa
Rican
tributaries.
Note:
Station
14-‐01
in
the
legend

refers
to
Delta
Colorado
(Station
11-‐04)
in
Table
6
(from
Attachment
CR-‐1,
the
ICE
Report).

489Annex 9

81. The
SSCs
measured
in
this
larger
data
set
vary
from
less
than
10
ppm
(or
grams
per

cubic
metre
–
the
two
measures
of
SSC
are
equivalent)
to
more
than
10
000
ppm.

While
the
background
SSC
in
the
River
as
measured
by
Dr
Kondolf
was
indeed
low,

the
concentrations
in
the
plume
of
muddy-‐water
are
not
high
in
the
context
of
SSC’s

routinely
observed
in
runoff
draining
to
the
Río
San
Juan,
or
even
in
the
River
itself.
I

am
not
surprised
that
a
15-‐minute
rainstorm
in
May
produced
a
striking
contrast

between
SSCs
in
local
runoff
and
the
receiving
water
because
under
these

circumstances
the
source
of
sediment
is
localised
to
the
area
of
the
rainstorm
while

discharge
and
background
SSCs
in
the
River
are
at
their
lowest.
However,
the
volume

of
muddy
water
is
a
tiny
fraction
of
even
the
lowest
discharge
in
the
Río
San
Juan

and
turbulent
mixing
would
ensure
that
the
relatively
high
SSC
decreases
to

background
levels
within
a
short
distance
downstream
and
a
short
time
after
the

rainstorm
ends,
as
the
plume
of
local
runoff
diffuses
into
the
far
greater
flow
in
the

receiving
water.

82. With
two
exceptions,
Annex
2
adopts
a
descriptive
approach
in
presenting
a

literature
review
of
the
impacts
of
road
building
on
rivers
other
than
the
Río
San

Juan
(much
of
which
is
similar
or
even
identical
to
material
presented
previously
in

the
2012
Kondolf
Report),
together
with
textual
commentary
and
a
virtual
tour
of

the
case
in
point,
both
of
which
extend
only
to
41
km
of
the
Road
between
Marker
II

and
the
Rio
Infiernito.
The
five
suspended
sediment
samples
constitute
one

exception
to
this
approach.
The
other
exception
is
the
reported
results
of
Dr
Rios’

sampling
of
the
periphyton
at
nine
sites,
in
late
May
2013.
On
page
13
(paragraph
1)

Annex
2
makes
clear
that
four
samples
came
from
the
deltas
assumed
by
Dr
Kondolf

to
be
composed
of
sediment
eroded
from
the
Road
on
the
south
(Costa
Rican)
bank

of
the
River.
The
text
is
less
clear
concerning
the
nature
of
the
sample
sites
on
the

north
(Nicaraguan)
bank.
We
are
told
these
were,
‘five
sites
draining
relatively

undisturbed
landscapes’.
What
we
are
not
told
is
whether
those
sites
were
on
any
of

the
multiple
deltas
I
observed
at
the
Nicaraguan
side
of
the
River
earlier
that
month.

If
they
were
then
it
would
be
a
fair
to
compare
them;
if
they
were
not
then
the

comparison
between
samples
taken
at
the
north
and
south
banks
is
inapt.

490 Annex 9

83. Putting
the
evidence
together,
I
can
find
nothing
to
support
the
statement
made
in

paragraph
4
on
page
2
of
Annex
2
that
Dr
Kondolf
and
his
team
‘already
see

extensive,
severe
environmental
damage’.
As
regards
the
case
in
point,
irreversible

damage
to
the
Rio
San
Juan,
this
statement
seems
at
odds
with
the
photographs
in

Annex
A,
let
alone
the
evidence
provided
in
this
report,
which
is
supported
by
data

provided
in
Attachments
CR-‐1
and
CR-‐2.
In
the
same
paragraph,
the
statement
that,

‘There
is
no
question
that
when
intense
rains
associated
with
tropical
storms
and

hurricanes
occur,
the
damage
will
be
widespread
and
severe.’
Indeed,
it
would.
The

scale
at
which
such
events
cause
damage
simply
dwarfs
that
of
the
Road.
For

example,
in
1998
Hurricane
Mitch
is
reported
to
have
destroyed
not
41
but
1300
km

of
road
in
Costa
Rica
alone,
though
not
in
the
region
of
the
Rio
San
Juan.
The
fact
is

that
if
this
region
were
to
suffer
a
tropical
storm
or
a
hurricane
not
only
would
this

be
devastating,
it
would
also
be
unprecedented.
In
the
circumstances
that
this

particular
region
has
never
been
hit
by
a
hurricane
or
tropical
storm
(as
to
which
see

the
United
States
National
Oceanic
and
Atmospheric
Administration
(NOAA)
map

which
is
provided
as
Attachment
CR-‐8,
which
indicates
that
no
hurricane
or
tropical

storm
has
been
recorded
in
the
area
to
date),
it
cannot
be
said
that
there
is
any

serious
or
imminent
risk
of
the
kind
of
damage
such
an
event
would
inflict
upon
the

region.
In
the
concluding
part
of
paragraph
4
on
page
2
of
Annex
2,
Dr
Kondolf
makes

reference
to
irreversible
harm
done
to
salmon
by
massive
mining
in
California
and

extensive
logging
in
the
Pacific
Northwest.
This
contrasts
with
statements
in
the

2012
Kondolf
Report
that
attribute
the
demise
of
pacific
salmon
populations
in
the

USA
to
road
building
alone,
which
was
not
the
case.
But
there
are
no
salmon
in
the

Rio
San
Juan
and
in
any
case
construction
of
a
Road
that
increases
the
impermeable

area
in
the
Costa
Rican
basins
draining
to
the
Rio
San
Juan
by
0.05%
cannot
be

compared
to
the
catchment-‐wide
practices
of
hydraulic
mining
and
clear-‐cut
forestry

that
occurred
in
California
and
the
Pacific
Northwest.

7. My
observations
of
mitigation
works
on
the
Road
in
May
2013

84. During
my
first
visit
to
the
Route
1856
in
February
2013,
I
inspected
mitigation
works

under
construction
at
several
points
along
the
Road
between
Marker
II
and
the
Río

Infiernito,
including
speaking
to
senior
engineers
from
Conservando
Mejorando
y

491Annex 9

Construyendo
la
Red
Vial
Nacional
-‐
CONAVI
( http://www.conavi.go.cr/ ).
An
engineer

from
the
lead
contractor
MECO
( http://constructorameco.com )
was
present,
as
was
an

engineer
with
the
contractor
responsible
for
materials
Durman

(http://www.durman.com/inicio .htm ).

85. During
my
second
visit
to
the
Road
in
May
2013,
I
focused
particularly
on
the

41.6
km
stretch
between
Marker
II
and
Boca
San
Carlos
including
inspection
of

mitigation
works
performed
since
my
February
visit.
I
did
so
based
on
the
focus
on

this
stretch
in
the
2012
Kondolf
Report,
my
own
observations
of
eroding
cut
and
fill

slopes
in
this
stretch
in
February
2013,
and
my
conclusion
that
there
were
very
few

eroding
slopes
along
the
Road
between
Boca
San
Carlos
and
the
Delta.
I
was

accompanied
in
the
field
by
Mr
Carlos
Pereira
who
was
at
that
time
leading
the

mitigation
effort
on
behalf
of
CONAVI.
I
also
took
the
opportunity
to
inspect
some
of

the
sites
proposed
for
erosion
monitoring
by
the
University
of
Costa
Rica
(see
the

UCR
Report
for
a
full
account).

86. Before
and
after
photographs
of
a
representative
selection
of
the
mitigation
sites
I

visited
are
included
below
in
Figures
13-‐18.

(a)
(b)

Figure
13.
The
Road
near
Marker
II
(a)
prior
to
mitigation
work
on
15
February
2013
and
(b)
on
7

May
2013
with
mitigation
measures
in
place:
note
in -‐board
drainage
channel
and
extensive

biodegradable,
erosion
control
matting.
Photographs
by
author.

492 Annex 9

(a)
(b)

Figure
14.
View
down
a
large
gully
in
a
fill
prism
created
by
concentrated
runoff
from
the
Road

draining
to
Costa
Rican
territory
to
the
west
of
Marker
II
(a)
in
February
when
it
was
actively
eroding

and
(b)
in
May
when
the
gully
had
been
back -‐filled
and
stabilized
using
a
culverted
cross -‐drain
and

concrete
drainage
channel,
with
coconut
matting
used
to
protect
the
surrounding
fill
slope
from

sheet
and
rill
erosion.
Photographs
by
the
author.

(a)
(b)

Figure
15.
Road
near
Tiricias
(a)
on
15
February
when
failure
of
geotextile
slope
protection
had

allowed
concentrated
out -‐board
runoff
from
the
Road
to
create
two
gulli es
and
in-‐board
runoff
was

undercutting
a
cut
slope
(b)
on
7
May
2013
after
construction
of
concrete -‐lined
out-‐board
and
in

board
ditches.
Photographs
by
author.

(a)
(b)

Figure
16.
Road
between
Marker
II
and
Río
Infiernito
(a)
on
15
February
2013
showing
network
of

gullies
on
outboard
slope
and
sediment
accumulated
as
a
run -‐out
deposit
on
flat
terrace
surface

separating
foot
of
slope
from
the
bank
of
the
Río
San
Juan
(b)
on
7
May
2013
showing
mitigation

works
including
concrete
channels
and
drop
structures
to
convey
runoff
from
the
road
bed
and
silt

fences
to
protect
the
slope
from
sheet
and
rill
erosion
a nd
prevent
road-‐derived
sediment
reaching

the
terrace.
A
sediment
trap
has
also
been
constructed
at
the
downstream
termination
of
the
gully

system,
though
this
cannot
be
easily
identified
in
the
photograph.
Photographs
by
author.

493Annex 9

(a)
(b)

Figure
17.
Road
near
Río
Infiernito
(a)
on
15
February
when
surface
unmanaged
runoff
from
the
road

bed
and
surrounding
slopes
disturbed
during
construction
had
caused
sheet
and
rill
erosion
of
bare

soil
surfaces.
(b)
same
stretch
of
road
on
7
May
2013
after
protection
of
the
road
surface
using

crushed
rock,
installation
of
silt
fences
to
prevent
sheet
and
rill
erosion
while
directing
down -‐slope

surface
runoff
into
concrete -‐lined
outboard
and
inboard
ditches.
Photographs
by
author.

(a)
(b)

Figure
18.
Road
near
Río
Infiernito
(a)
on
15
February
when
unmanaged
runoff
from
the
path

cleared
in
preparation
for
construction
of
the
road
bed
had
caused
sheet
and
rill
erosion.
(b)
The

same
area
road
on
7
May
2013
after
installation
integrated
measures
to
manage
runoff
involving

regrading,
silt
fences,
and
concrete -‐lined
outboard
ditch.
Photographs
by
author.

87. Based
on
the
observations
of
the
Road
on
15
February
and
7
May
2013
that
are

reported
above
it
may
be
concluded
that,
during
the
intervening
period,
substantial

engineering
works
were
performed
by
MECO
(overseen
by
CONAVI)
at
multiple

locations
along
the
Road
between
Marker
II
and
Boca
San
Carlos,
of
which
those

illustrated
in
Figures
13-‐18
are
a
representative
sample.
I
also
observed
extensive

areas
of
reforestation
undertaken
by
local
contractors.

88. I
have
also
reviewed
Consejo
Nacional
de
Vialidad
(CONAVI),
Program
for
the

Consolidation
and
Continued
Improvement
of
Route
No
1856,

494 Annex 9

Reference
DIE-‐02-‐13-‐3107,
25
October
2013
(Attachment
CR-‐3);
Report
from
Ana

Lorena
Guevara
Fernández,
Vice-‐Minister
of
the
Environment,
Costa
Rica,
to
Enrique

Castillo
Barrantes,
Minister
of
Foreign
Affairs,
Costa
Rica,
Reference
DVM-‐293-‐2013,

8
October
2013
(Attachment
CR-‐5);
and
Comisión
de
Desarrollo
Forestal
de
San

Carlos
(CODEFORSA),
Consulting
Services
for
the
Development
and
Implementation

of
an
Environmental
Plan
for
the
Juan
Rafael
Mora
Porras
Border
Road,
Report
of

Activities
to
the
Ministry
of
Foreign
Affairs
of
the
Republic
of
Costa
Rica,
January

2013
(Attachment
CR-‐6).
These
reports
detail
the
continuing
work
to
reduce
any

erosion
risk
presented
by
the
Road.
I
do
not
agree
with
the
recommendation
in
the

opening
sentence
of
paragraph
4
on
page
2
of
Annex
2
that,
‘If
work
continues
on
Rte

1856,
its
impact
will
be
devastating
to
areas
directy
affected
and
to
downstream

receiving
waters’.
On
the
contrary,
I
believe
that
mitigating
work
should
continue
in

order
to
minimise
the
risk
of
future
erosion
should
heavier
rainfall
occur.

89. Based
on
my
experience
with
engineered
and
biotechnical
erosion
mitigation
works

in
other
areas
experiencing
heavy
rainfall,
including
Ethiopia,
Bangladesh
and
the

USA,
my
opinion
is
that
the
measures
taken
by
Costa
Rica
have
reduced
and
will

continue
to
reduce
the
risk
that
significant
erosion
might
occur
during
heavy

rainstorms,
compared
to
conditions
immediately
following
construction
of
the
Road.

Consequently,
I
do
not
agree
with
the
conclusion
drawn
in
paragraph
3
on
page
2
of

Annex
2
that,
‘erosion
control
and
drainage
works
have
been
ineffective’.

90. It
is
my
understanding
that
the
measures
I
observed
in
May
2013
are
part
of
ongoing

efforts
intended
to
reduce
erosion
risks
stemming
from
the
way
the
Road
was

constructed
in
2011
and
that
they
are
not
intended
to
provide
a
permanent
solution

to
erosion
issues.
Given
that,
my
experience
suggests
that
with
appropriate

inspection
and,
where
necessary,
maintenance
or
repair,
the
mitigation
works
will

significantly
reduce
local
erosion
rates
for
the
next
year
or
two,
allowing
time
for
the

work
necessary
to
design,
contract
and
build
permanent
works
to
progress.

8. Conclusions
on
the
risk
of
irreversible
harm
to
the
River

91. There
is
no
scientific
justification
for
‘active
efforts,
including
dredging,
to
maintain

the
capacity
and
quantity
of
the
river’s
waters’
in
the
lower
Río
San
Juan
on
the

495Annex 9

pretext
of
having
to
remove
Road-‐derived
sediment.
Sediment
transfer
and

deposition
calculations
based
on
measured
data
and
conservative
assumptions

demonstrate
that,
even
using
the
range
of
sediment
contributions
by
the
Road
to
the

River
given
in
the
2012
Kondolf
Report
(which
are
almost
certainly
too
high
by
a

factor
of
2
to
3,
and
which
incorporate
all
sediment
input,
including
from
mass

wasting),
the
additional
amount
of
Road-‐derived
sediment
entering
the
lower
Río

San
Juan
is
probably
just
2%
or
3%
of
its
total
load.
Sediment
continuity
dictates
that

even
if
all
of
this
sediment
were
to
be
deposited
on
the
bed
of
the
channel,
it
would

raise
the
bed
of
the
river
by
only
3
or
4
mm
per
year.
In
fact,
deposition
is
spread

over
a
much
wider
area
of
floodplain,
wetlands
and
wash
lands
and
an
unknown
but

significant
percentage
of
the
load
is
discharged
to
the
Caribbean
Sea.
Hence
the

estimates
of
increase
sediment
load
and
bed
deposition
are
necessarily
over-‐

estimates.
They
are
in
any
case
well
within
the
error
margin
for
sediment

measurements
and
calculations,
and
are
small
in
comparison
to
inter-‐annual

fluctuations
that
are
the
product
of
natural
variability.

92. Similar
investigations
and
calculations
could
be
performed
with
respect
to
the
other

potential
impacts
of
the
Road
on
the
Río
San
Juan
mentioned
in
the
Request.
In

summary,
due
to
very
small
relative
contribution
of
sediment
in
comparison
to
the

heavy
and
highly
variable
sediment
load
in
this
River,
the
Road
cannot
possibly
pose

a
risk
of
imminent,
irreversible
harm
to
the
morphology,
environment,
or
ecology,
all

of
which
are
well-‐adapted
to
the
heavy
load
and
highly
variable
sediment
regime
of

the
Río
San
Juan.

9. References

ICE
(Costa
Rican
Institute
of
Electricity)
2013.
Report
on
hydrology
and
sediments
for

the
Costa
Rican
river
basins
draining
to
the
San
Juan
River.
Federico
Gómez
Delgado,

Juan
José
Leitón
Montero
and
Carlos
Aguilar
Cabrera,
Centre
for
Engineering
Studies,

Department
of
Hydrology,
San
José,
Costa
Rica
(Attachment
CR-‐1).

UCR
(University
of
Costa
Rica)
2013.
Systematic
Field
monitoring
of
Erosion
and

Sediment
Yield
along
Route
1856.
Rafael
Oreamuno
Vega,
M.
Eng.
and
Roberto

496 Annex 9

Villalobos
Herrera,
Universidad
De
Costa
Rica,
Facultad
De
Ingeniería,
Escuela
De

Ingeniería
Civil
(Attachment
CR-‐2).

10. Statement
of
independence
and
truth

93. The
opinions
I
have
expressed
in
this
Report
represent
my
true
and
complete

professional
opinion.
Where
I
have
relied
on
information
or
facts
supplied
to
me
by

those
instructing
me,
I
have
noted
this
in
my
Report.

94. I
understand
that
my
overriding
duty
is
to
the
Court,
both
in
preparing
this
Report

and
in
giving
oral
evidence,
if
required.
I
have
complied
and
will
continue
to
comply

with
that
duty.

95. I
have
set
out
in
my
Report
what
I
understand
from
those
instructing
me
to
be
the

questions
in
respect
of
which
my
opinion
as
an
expert
is
required.
I
have
done
my

best,
in
preparing
this
Report,
to
be
accurate
and
complete.
I
have
mentioned
all

matters
that
I
regard
as
relevant
to
the
opinions
that
I
have
expressed.
I
consider

that
all
the
matters
on
which
I
have
expressed
an
opinion
are
within
my
field
of

expertise.
I
have
drawn
the
attention
of
the
Court
to
all
matters,
of
which
I
am

aware,
which
might
adversely
affect
my
opinion.

96. In
preparing
this
Report,
I
am
not
aware
of
any
conflict
of
interest
actual
or
potential

which
might
impact
upon
my
ability
to
provide
an
independent
expert
opinion.
I

confirm
that
I
have
not
entered
into
any
arrangement
where
the
amount
or
payment

of
my
fees
is
in
any
way
dependent
on
the
outcome
of
this
proceeding.

97. I
have
not,
without
forming
an
independent
view,
included
anything
which
has
been

suggested
to
me
by
others,
including
those
instructing
me.

98. At
the
time
of
signing
this
Report
I
consider
it
to
be
complete
and
accurate

assessment
of
the
information
available
to
me,
subject
to
any
qualifications
noted

herein.
I
will
notify
those
instructing
me
if,
for
any
reason,
I
subsequently
consider

that
the
Report
requires
any
material
correction
or
qualification.

497Annex 9

99. I
understand
that
this
Report
will
be
the
evidence
that
I
will
give,
if
required,
under

oath,
subject
to
any
correction
or
qualification
I
may
make
before
swearing
to
its

veracity.

100. The
substance
of
all
facts
and
instructions
given
to
me
which
are
material
to
the

opinions
expressed
in
this
Report
or
upon
which
those
opinions
are
based
are

reflected
in
my
Report.

101. I
confirm
that
I
have
made
clear
which
facts
and
matters
referred
to
in
this
Report

are
within
my
own
knowledge
and
which
are
not.
Those
that
are
within
my
own

knowledge
I
confirm
to
be
true.
The
opinions
I
have
expressed
represent
my
true
and

complete
professional
opinion.

………………………………………

Professor
Colin
Thorne

2
Parker
Gardens

Nottingham,
UK

4
November
2013

498 ANNEX 10

Costa Rica, Centro Científico Tropical

Environmental Diagnostic Assessment (EDA), Route 1856 Project – Ecological
Component

November 2013

499500 Annex 10

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501Annex 10

Environmental Diagnostic Assessment (EDA)
Route 1856 Project – Ecological Component

i. Acknowledgments

Acknowledgements are extended to Oscar Lücke and Biologist Raquel Gomez for their
collaboration throughout the length of this study. Likewise to Jorge Mairena and Biologist Fatima

Reyes for the invaluable a ssistance and collaboration during the extent of the project. Thanks to
Monika Springer (University of Costa Rica) for the use of the sampling equipment and tools of
the aquatic bio-monitoring laboratory, AquaBiolab S.A.

Acknowledgements are also extended to the work team of the Basic Studies Department of the
Costa Rican Electrical Institute, to the Hydrology Department of the University of Costa Rica, to
the National Conservation Areas System and to the National Highways Council for information

provided on the area where the project is located.

Thanks to Freddy Rodríguez, Ulises Aleman, Sergio Balladares, Rafael Orozco, Edwin Leitón
and Fidel Gonzales; to Aero Diva, Maquenque Ecolodge, Laguna Lagarto Lodge, El Manzano
Hotel, Delta Cabins and the Office of National Security for their assistance with fieldwork.

Finally, grateful recognition to Laura Mairena, Roger Zelaya, and all members of the Tropical
Science staff, for their support with the logistic, administrative and financial coordination of the
project.

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Environmental Diagnostic Assessment (EDA)
Route 1856 Project – Ecological Component

ii. Professional team, Ecological Component, EDA - Route

1856 Project.

This document was coordinated and prepared by the TROPICAL SCIENCE CENTER, with the

participation of the following professional specialists:

Professional

Professional Specialist Field Association, Signature
SETENA
membership

Geography Colegio: CIA-6450
Oscar Lücke Sánchez, MSc. __________________
Technical Coordinator SETENA: CI-235-12

Natural Sciences for
Development and
Olivier Chassot Labastrou, Environmental Colegio: 1967 __________________
Ph.D. Management SETENA: CI-157-12

Technical Coordinator

Ana Luisa Báez Rojas Sustainable Tourism Colegio: 1202 __________________

Biology and Natural Colegio: 844
Guisselle Monge Arias, Ph.D. Resources __________________
Management SETENA: CI-146-13

Colegio: CIA-4377
Rafael Bolaños Montero Forestry and Land __________________
Use SETENA: CI-001-98

Colegio: 1695
Bernald Pacheco Cháves Aquatic Biology __________________
SETENA: CI-214-08

Digital Cartography
Andreas Mende, Ph.D. and Geographic __________________
Information Systems

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Environmental Diagnostic Assessment (EDA)
Route 1856 Project – Ecological Component

iii. Table of Contents

1 ! EXECUTIVE SUMMARY ....................................................................................................... 13 !
2 ! INTRODUCTION ................................................................................................................... 15 !

2.1 ! Background....................................................................................................................! 15

2.2 ! Scope of Study ...............................................................................................................!15

2.3 ! Objetives.....................................................................................................................!... 16
2.3.1 ! General Objective .................................................................................................... 1!

2.3.2 ! Specific Objectives ................................................................................................... !6

2.4 ! Methodology ..................................................................................................................! 16

2.5 ! Time frame for the Ecological Component of the EDA ................................................... 18 !
2.6 ! Terms of Reference ........................................................................................................ 18!

2.7 ! Limitations...................................................................................................................!... 19

3 ! PROJECT DESCRIPTION .................................................................................................... 20 !

3.1 ! Geographic Location....................................................................................................... 20 !
3.2 ! Political and Administrative Location .............................................................................. 20 !

3.3 ! Estimated Project Area and Influence Areas .................................................................. 20 !

3.4 ! General Description of the Activity .................................................................................. 22 !
3.5 ! Environmental Aspects ................................................................................................... 23 !

3.6 ! Environmental Risk Control System ............................................................................... 30 !

3.6.1 ! Risk of Cutting Down Trees which are in Danger of Extinction ................................ 30 !

3.6.2 ! Risk of Slope Erosion and Slope Instability .............................................................. 30 !
3.6.3 ! Risk of Altering Natural Drainage Systems .............................................................. 30 !

3.6.4 ! Risk of Obstructing Waterways ................................................................................ 30 !

3.6.5 ! Risk of Eroded Sediments Depositing on Bodies of Water ...................................... 31 !

4 ! DESCRIPTION OF THE PHYSICAL ENVIRONMENT ......................................................... 32 !
4.1 ! Geology of the Study Area .............................................................................................. 32 !

4.1.1 ! Regional Tectonic Framework ................................................................................. 32 !

4.1.2 ! Regional Geology..................................................................................................... 32!

4.1.2.1 ! Ophiolites of Tiricias .......................................................................................... !3
4.1.2.2 ! Sarapiquí Arch ...................................................................................................!33

4.1.2.3 ! Quaternary Deposits.......................................................................................... 33 !

4.1.3 ! Seismic Activity .......................................................................................................! 33

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4.2 ! Geomorphology .............................................................................................................. 3!

4.2.1 ! Morphologies of Tertiary Vulcanism of the Extreme North of Costa Rica (Bergoeing
et al., 1997) .......................................................................................................................... 34
4.2.2 ! Morphologies of Alluvial Quaternary Cones in Northern Costa Rica (Bergoeing et al.,

1997) 34 !
4.2.3 ! Sedimentary Quaternary Morphologies ................................................................... 34 !

4.3 ! Soils.........................................................................................................................!...... 35

4.4 ! Climate.......................................................................................................................!.... 35

4.4.1 ! Micro-climates..........................................................................................................!35
4.4.2 ! Rainfall ...............................................................................................................!..... 36

4.4.3 ! Temperature.............................................................................................................!36

4.4.4 ! Solar Brightness .......................................................................................................!36

4.4.5 ! Dry Months..............................................................................................................! 36
4.5 ! Hydrology/ Hydrography ................................................................................................. 36 !

5 ! DESCRIPTION OF THE BIOLOGICAL ENVI RONMENT ..................................................... 38 !

5.1 ! Introduction .................................................................................................................!... 38
5.1.1 ! Terrestrial Environment ............................................................................................ 39 !

5.1.1.1 ! Protection Status (Protected Areas) .................................................................. 39 !

5.1.1.2 ! Life Zones........................................................................................................!. 42

5.1.1.3 ! Natural Associations and Land Cover ............................................................... 44 !
5.1.1.4 ! Current Plant Cover by Natural Association ...................................................... 46 !

5.1.1.5 ! Indicator species by natural ecosystem. ............................................................ 58 !

5.1.1.6 ! Endemic species with reduced or threatened populations. ............................... 59 !

5.1.1.7 ! Fragility of Terrestrial Ecosystems. ................................................................... 65 !
5.1.1.8 ! Impacted flora species ....................................................................................... 68 !

5.1.2 ! Aquatic Environment (inland water bodies). ............................................................. 68 !

5.1.2.1 ! Aquatic Fauna ................................................................................................... !4

5.1.2.2 ! Characterization of the Riparian System. .......................................................... 87 !
5.1.2.3 ! Indicator Species. .............................................................................................. !7

5.1.2.4 ! Endemic Species with Reduced or Threatened Populations ........................... 106 !

5.1.2.5 ! Fragility of the Inland Aquatic Environment. .................................................... 109 !

6 ! ENVIRONMENTAL DIAGNOSTIC ...................................................................................... 113 !
6.1 ! Comprehensive environmental suscept ibility map vs.Project components. ................. 113 !

6.2 ! Identification of impacts and environmental risks ......................................................... 131 !

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6.2.1 ! Activities susceptible of causingenvironmental impacts ......................................... 131 !

6.2.2 ! Impacted or potentially impacted environmental factors ........................................ 131 !
6.2.3 ! Identificationof environmental impacts ................................................................... 131 !

6.2.4 ! Description of identified Environmental impacts .................................................... 132 !

6.2.4.1 ! Terrestrial flora and fauna ............................................................................... 132 !
6.2.4.2 ! Aquatic flora y fauna ........................................................................................ 134 !

6.2.4.3 ! Landscape ....................................................................................................... 1!4

6.3 ! Assessment of Environmental impacts and corective measures .................................. 135 !

6.3.1 ! Methodology........................................................................................................... 13!
6.3.2 ! Impact Assessment ................................................................................................ 139 !

6.4 ! Risk analysis and contingency plans ............................................................................ 141 !

6.4.1 ! Sources of environmental risk ................................................................................ 141 !

6.4.2 ! Environmental risk evaluation ................................................................................ 143 !
6.5 ! Environmental control measures .................................................................................. 144 !

6.5.1 ! Environmental control measures for the identified impacts .................................... 144 !

6.5.1.1 ! Control measures for terrestr ial flora and fauna .............................................. 144 !

6.5.1.2 ! Aquatic flora and fauna .................................................................................... 148 !
6.5.1.3 ! Paisaje............................................................................................................! 150

6.6 ! Environmental Management Plan – Environmental Adequacy Plan (PAA) .................. 150 !

7 ! Conclusions y recommendations ........................................................................................ 156 !

7.1 ! Conclusions .................................................................................................................. !56
7.1.1 ! Terrestrial Biology .................................................................................................. 15!

7.1.2 ! Aquatic Biology ...................................................................................................... 15!

7.1.3 ! Tourism .................................................................................................................! 159
7.1.4 ! Ecological Connectivity .......................................................................................... 160 !

7.2 ! Recommendations ........................................................................................................ 161 !

8 ! REFERENCES .................................................................................................................... 164 !

9 ! ANNEXES ........................................................................................................................... 1!0
9.1 ! BioSketches of consultants participating in the realization of the EDA -Ecological

Component ............................................................................................................................ 170
9.1.1 ! Geography and Land Use Planning Expert ............................................................ 170 !

9.1.2 ! Sustainable Tourism Expert ................................................................................... 171 !

9.1.3 ! Biology and Management of Natural Resources Expert ........................................ 172 !

9.1.4 ! Land Use Expert .................................................................................................... 173 !

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9.1.5 ! Aquatic Biology Expert ........................................................................................... !74

9.1.6 ! Geographic Information Systems Expert ............................................................... 175 !
9.1.7 ! Connectivity Expert ...............................................................................................! 176

9.2 ! Impact assessment of the implementation of the Route 1856 project on the development
of tourism activities in the San Juan River ............................................................................. 177 !

9.3 ! Analysis of the structural connectivity in the landscape of Route 1856 ........................ 203 !

9.4 ! Threatened species potentially found in the Border Biological Corridor Mixed Wildlife
Refuge and Maquenque Mixed Wildlife Refuge. ................................................................... 225 !

9.5 ! Limited and threatened species to be used in local reforestation. ................................ 234 !

9.6 ! Tree species observed in the area of Las Crucitas, San Carlos. .................................. 236 !
9.7 ! Taxa richness and abundance of individuals of aqua tic macroinvertebrates collected at

study sites along Route 1856, Juan Rafael Mora Porras, July - August, 2013. Upstream (Abj)
and downstream (Arb) of the road. ( *) less common taxa or with limited distribution in the
country................................................................................................................................... 242

Chart Index

Chart 1: Activities conducted during the Project construction stage. .......................................... 23 !
Chart2: Hydrographic Watersheds in the Study Area ................................................................. 36 !

Chart3: Natural Associations recognized in the study area.. ...................................................... 48 !

Chart4: Area occupied by natural assocaitions recognized in the DIA. ...................................... 55 !

Chart5: Common or outstanding tree species in palustrine or lacustrine wetlands. ................... 56 !
Chart6: Common tree spe cies in forest associations. ................................................................. 58 !

Chart7: Main threatened species within the Route 1856 study area. .......................................... 62 !

Chart8: Endemic tree species reported for the study area. ......................................................... 63 !

Chart9: Tree species at risk. .....................................................................................................!. 64
Chart10: Species officially under ban. ......................................................................................... 65!

Chart11: Variation in number of species and trees in condition different from forest (in the
Biological Border Corridor) in 0,25 ha plots, for tr ees thicker than 10 cm DBH. .................. 66 !

Chart12: Fragility of terrestrial ecosystems characterized for this study. .................................... 67 !

Chart13: Area impacted for each ecosystem within the project area. ......................................... 68 !

Chart14: List of aquatic fauna recorded for the project area and surroundings. ......................... 74 !
Chart15: List of aquatic macroinvertebrate taxa for the project area and surroundings. ............ 8!

Chart16: Listof phytoplancton species recorded for the San Juan tributaries. ............................ 85 !

Chart17: Description of sites and sampling points along Route 1856. ........................................ 90 !

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ERoute 1856 Project – Ecological Component

Chart18: BMWP-CR’ index values and water quality at sampled sites along Route 1856, 2013. 99 !

Chart19: Water quality classification according to BMWP -CR Index. ....................................... 100 !
Chart20: Species of aquatic fauna recorded for the project a rea included, included in some

conservation category ........................................................................................................ 106 !
Chart21: Modified matriz for impact identification related to Route 1856. ................................. 132 !

Chart22: Evaluation criteria for the MIIA. .................................................................................. 136 !

Chart 23: Matrix of Importance of Environmental Impacts(MIIA) for the Route 1856project in
Costa Rica territory. ........................................................................................................... 140

Chart24: Matrix of Importance of Environmental Impacts (MIIA) for the Route 1856 project on
Nicaraguan territory............................................................................................................ 142!

Chart25: Environmental risk evaluation for the Route1856 project. .......................................... 143 !

Chart26: Environmental Adequacy Plan (PAA). ........................................................................ 152 !

Map Index

Map 1: Geographic Location of the Project ................................................................................. 21 !

Map 2: Road Design Location (1 of 6). ....................................................................................... 24 !

Map 3: Road Design Location (2 of 6). ....................................................................................... 25 !

Map 4: Road Design Location (3 of 6). ....................................................................................... 26 !
Map 5: Road Design Location (4 of 6). ....................................................................................... 27 !

Map 6: Road Design Location (5 of 6). ....................................................................................... 28 !

Map 7: Road Design Location (6 of 6). ....................................................................................... 29 !

Map 8: Conservation Areas and Protected Areas. ...................................................................... 41 !
Map 9: Life Zones........................................................................................................................ !3

Map10: Map ofEcosystems (1 of 6). ........................................................................................... 49 !

Map11: Map of Ecosystems (2 of 6). .......................................................................................... 50 !

Map12: Map of Ecosystems (3 of 6). .......................................................................................... 51 !
Map13: Map of Ecosystems (4 of 6). .......................................................................................... 52 !

Map14: Map of Ecosystems (5 of 6). .......................................................................................... 53 !

Map15: Map of Ecosystems (6 of 6). .......................................................................................... 54 !

Map16: Location of Great Green Macaw nests. .......................................................................... 61 !
Map17: Location of water bodies registered for the area of study (1 of 4). ................................. 70 !

Map18:Location of water bodies registered for the area of study (2 of 4). .................................. 71 !

Map19:Location of water bodies registered for the area of study (3 of 4). .................................. 72 !

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ERoute 1856 Project – Ecological Component

Map 20:Location of water bodies registered for the area of study (4 of 4). ................................. 73 !

Map21: Location of sampled bodies of water with classif ication of water quality according to
BMWP-CR’ Index, along the study area of Route 1856. .................................................... 101 !

Map 22: Location of sampled bodies of water with classification of water quality according to
BMWP-CR’ Index, along the study area of Rou te 1856..................................................... 102 !

Map23: Location of sampled bodies of water with classification of water quality according to
BMWP-CR’ Index, along the study area of Route 1856. .................................................... 103 !

Map24: Environmental Diagnostic Section 1. ........................................................................... 114 !

Map25: Environmental Diagnostic Section 2. ........................................................................... 115 !
Map26: Environmental Diagnostic Section 3. ........................................................................... 116 !

Map27: Environmental Diagnostic Section 4. ........................................................................... 117 !

Map 28: Environmental Diagnostic Section 5. .......................................................................... 118 !

Map29: Environmental Diagnostic Section 6. ........................................................................... 119 !

Map 30: Environmental Diagnostic Section 7. .......................................................................... 120 !
Map31: Environmental Diagnostic Section 8. ........................................................................... 121 !

Map32Environmental Diagnostic Section 9. ............................................................................. 122 !

Map33: Environmental Diagnostic Section 10. ......................................................................... 123 !

Map34:Environmental Diagnostic Section 11. .......................................................................... 124 !
Map35: Environmental Diagnostic Section 12. ......................................................................... 125 !

Map36:Environmental Diagnostic Section 13. .......................................................................... 126 !

Map37: Environmental Diagnostic Section 14. ......................................................................... 127 !

Map38:Environmental Diagnostic Section 15. .......................................................................... 128 !

Map 39: Environmental Diagnostic Section 16. ........................................................................ 129 !
Map40: Environmental Diagnostic Section 17. ......................................................................... 130 !

Glossary

Agarradores: “clingers”, organisms found in bodies of water with strong currents, which often
have adaptations (long, strong nails, hooks, suction cups) to hold on to the surroundings.

Auto-trophs: organisms that have the ability to synthesize all elements essential to their
metabolic needs based on non -organic substances, such that they do not need other living
organisms for their nourishment.

Bailey bridge: portable pre -fabricated metal bridge, designed primarily for military use, which is
used in many countries as a provisional bridge while a permanent structure is being built.

Bentonic: relative to the community formed by organisms that inhabit the bot tom of aquatic
ecosystems; adjective: bentonic.

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Bentonic macro-invertebrate: non -vertebrate animal that lives all or part of its life cycle in the
bottom or in the substratum of the bottom layer found in bodies of fresh water, whose body size
allows direct visual observation without the use of instruments.

Bio-indicator: organism selected for its degree of sensibility or tolerance to diverse types of
contamination or its effects. It measures or quantifies the magnitude of stress and degree of

ecological response to it.
Biological Corridor: a territory that offers connectivity among landscapes, eco -systems and

habitats, natural or modified, assuring the presence of biological diversity and ecological
processes.

Boundary marker or landmark : artificial structur e used commonly to define the limits of
properties and territories.

Branchiae: gills, respiratory organs of aquatic animals which allow extraction of oxygen diluted
in the water, and transference of carbon dioxide (CO2) to the environment.

Caudal: current, quantity of water that moves through a section of a river during a given unit of
time.

Caño: channel, water course that runs through muddy, flooded terrain, or through palustrine or

lacustrine wetlands, whose depth and appearance change as a function of the level of water.
“Climbers”: organisms that live in the submerged part of aquatic plants.

Collectors: organisms that collect fine particles deposited in water surfaces.

Community: group of organisms of all species that co -exist in a defined space calle d a biotope
which offers the required environmental conditions for their survival.

Density: number of organisms in an area or defined volume.

Detriment: slight or partial destruction of something

Detritus: residues, generally solid and permanent, that resu lt from the decomposition of organic
sources (vegetal and animal); dead matter.

Diversity: related to the number or richness of species, as well as the equality or relative
abundance of individuals between speciae.

Divers: organisms that dive and swim to f eed themselves; often they spend time holding on to

submerged objects.
Egg-laying: fish, reptiles and amphibians release eggs to the environment.

Endemic Species: taxon that is limited to a reduced geographic area, not found in a natural

state anywhere else in the world.
Epi-lithic: organism that develops on the surface of hard substrata.

Extinction: disappearance of all the individuals of a species or a taxonomic group; a species is

extinguished when the last individual of the species dies.
Filters: organi sms that feed off particulate, fine, and very fine organic matter in suspension,

which are collected by the organism with the use of mouth brushes or silk nets.

Forest: natural vegetation of a forest ecosystem of an extension greater than 2 hectares.

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Environmental Diagnostic Assessment (EDA)
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Forested: a section covered by natural tree vegetation, with variable surfaces, whether smaller

or larger than 2 hectares.

Fragmenters: organisms that chew large pieces of vascular plants to feed themselves.
Habitat: area where organisms live and grow in natura l fashion.

Interstitial Space: space or crevice between two bodies or between parts of a body.

Lacustrine: that exists or develops in waters of little or no movement (Gomez 1984 in Kappelle
2008).

Lentic: System of stagnant continental waters with little m ovement and exchange; as an
example, lakes formed by emerging waters, lakes, ponds, swamps and marshes (Mata and

Quevedo 2005 in Kappelle, 2008).

Monitoring: systematic use of biological responses to evaluate changes in the environment for
the purpose of implementing conservation and control programs.

Morbility: proportion of organisms that become sick in a site over a specified period of time.

Mortality: number of individuals within a population that die within a specified period of time.
Palustrine: referring to stagnant or slow moving shallow waters with emergent vegetation at

least in 30% of the area (Gomez 1984, in Kappelle 2008).
Phytoplancton: group of aquatic organisms that are plankton auto- thropic, have photosynthetic

capacity and live dispersed in water.

Plancton: group of organisms, mainly microscopic, that inhabit salty or fresh waters, whose
movement is passive.

Population: group of organisms, or individuals of the same species that co -exist in a given
space and time, and share certain biologica l properties which produce a high reproductive and
ecological cohesion in the group.

Predators: herbivores and other organisms that feed on other organisms.

Richness: number of species that are part of a community.

River: natural course of water that flows continuously, has a defined stream, constant
throughout the yearly cycle, that flows into the sea, a lake, or another river (in which case it is
considered an affluent or tributary course).

“Scrapers”: organisms that feed on peri -phyton algae and microbes that adhere to rocks and
other substrata.

Sediment: solid accumulated material on the terrestrial surface (lithosphere) derived from the
action of phenomena and processes that act on the atmosphere, hydrosphere and biosphere

(winds, temperature variations , meteorological precipitations, circulation of surface or
underground waters, displacement of masses of water in marine or lacustrine environments,
chemical agents or the action of live organisms.

Slope: slanting surface, inclined surface of land or arti ficial inclined structure that is part of an
engineering work.

Skaters: organisms that live in the aerial phase on the surface film of water and skate on this
surface.

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“Sprawlers”: organisms that live in habitats, or micro -habitats with less current and wh ich crawl

on the surface of the bottom substratum, on rocks, sediment, leaves and wood.

Swimmers: organisms that live in permanent submersion and are capable of swimming with
movements such as those of fish; organisms spend time holding on to rocks, roots of aquatic
plants and other submerged objects.

Taxa: plural of taxon (Latin).

Tributary: body of water, also called affluent that does not run its course to the sea, but
empties into a river, at a point known as the confluence of both.

Trophic level: each one of the groups of species or organisms of an eco -system that coincide
by the place they occupy in the system of energy and nutrients circulation, that is to say, those
that occupy an equivalent place in the food chain.

Wetland: area covered with water g enerally containing natural and semi -natural vegetation and

very often rich in diversity of organisms.
“Yolillal” patch or extension : basal tropical eco -system that generally grows close to the

coasts and is frequently inundated, and is dominated by the pa lm known as ”Yolillo” (Raphia
taedigera) (Kappelle 2008).

Acronyms

RNVSMM: Refugio Nacional de Vida Silvestre Mixto Maquenque

DBH: Diameter at Breast Height (1.30 meters )

TSC:Tropical Science Center

BBC: Border Biological Corridor

ICE: Costa Rican Electrical Institute

IGN: National Geographic Institute.
RSJ: San Juan River, on the Costa Rica- Nicaragua border.

UCR: University of Costa Rica.

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1 EXECUTIVE SUMMARY

The Ministry of Foreign Affairs of the Government of Costa Rica commissioned the services of
the Tropical Science Center (TSC) to conduct an Environmental Diagnostic Assessment of the
road project known as Route 1856, taking into account factors such as the TSC´s 15 years of

work experience in the area, its knowledge of ecosystems and its internatio nal scientific
reputation.

The Project consisted in the construction of a gravel road that starts in the locality of San
Jeronimo near the town of Los Chiles and stretches all the way east to a site known as Delta
Siete (better known locally as Delta Costa Rica). The Project has a length of 159,7 km. with
101,5 km. (63,6%) of this length being mostly access and connecting roads that have been

present in the area for more than 30 years. The remaining 57,4 km. (35,9%) of the Route is a
new road designed to co nnect those existing roads along the border between Costa Rica and
Nicaragua in close proximity to the San Juan River.

The study was planned according to legal requirements for such a study under Costa Rican law,
taking into account that these studies ar e the appropriate instrument for environmental
assessment applied to works that have already been executed, in order to determine their

environmental conditions and impact, and to define the necessary measures to achieve
environmental harmony within a syst ematic normative framework.

The environmental implications of the Route are defined on the basis of technical scientific
criteria through the application of a national legal instrument that supports the definition of public
policies in the area of environm ental intervention of the Project.

The methodology included an exhaustive review of other research conducted in the region by
the TSC, as well as other work done by scientists and institutions with recognized prestige such
as the public universities. Furth ermore, field work was also conducted through five field visits of

several days’ duration and an observation flight over the project area . Information was obtained
from the legally established protected areas in the region, along with data generated by the
Great Green Macaw Project of the TSC, satellite images and aerial photographs, among other.

The Environmental Diagnostic Assessment was based on the legal requirements described in
the “Technical Guide for Environmental Diagnostic Studies” formulated by t he National Technical
Environmental Service (SETENA) of the Ministry of the Environment (MINAE) through

Resolution No. 2572- 2009 of November 2, 2009. Four months were dedicated to the formulation
of the study in its ecological component, a process that was recorded in detail in a video of the
current conditions of the Route. The study covered the stretch from a point known as Border
Marker 2 in the vicinity of Las Tiricias de Cutris in San Carlos, all the way to Delta Costa Rica, at

the site of the splittin g of the Colorado and San Juan Rivers.

This study recognizes a limitation in the fact that it was not possible to analyze the larger context
of the study area due to the fact that the Government of Nicaragua did not allow the scientists
conducting this study to enter the Nicaragua area of the San Juan River. Due to the above, it
was not possible to conduct sampling and analyze the San Juan River, specifically in the mouths
of rivers and channels where they empty into the San Juan River.

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Concretely, the stud y describes the general aspects of the Project that include geographic
location, definition of the Project area and areas of influence, general description of the work,
risks and system of control of environmental risks.

Several sections of the study offer detailed description of the environment wherein the specific
physical and biological conditions (aquatic and terrestrial) of the study area are described and

inventoried.
A section on “Environmental Diagnostic” follows where environmental impacts and risk s are

identified and characterized along with the activities that have potential to create environmental
impacts, and this leads to an evaluation of the same and proposed corrective measures. A
matrix of importance of the impacts (MIIA) of the project is presented where 11 specific impacts

are identified, of which 8 impacts were considered irrelevant and 3 were deemed moderate
according to the official SETENA methodology. Also, 5 sources of environmental risk were
identified along the whole length of the Ro ute (159,7 km.) that require the introduction of
preventive and mitigating measures.

As an integral part of the Environmental Diagnostic Assessment, an “Environmental Adequacy
Plan” (PAA) is proposed which consists in a matrix that includes the environmental aspect, the

impacts identified, the corrective or compensatory measures, the environmental goals and
indicators of environmental performance, the location and frequency of sampling to be
conducted, the interpretation and feedback required, and the organ ization that should be

responsible for the execution of the above.
Finally, the study presents a section on conclusions and r ecommendations intended to facilitate

the practical application of the study results on the construction works, which is ultimately aimed
at improving the quality of life of the inhabitants and ecosystems in the region of the study.

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2 INTRODUCTION

2.1 Background

In the context of the conflict between Costa Rica and Nicaragua due to actions taken by

Nicaragua in the Costa Rican territory of Isla Portillos on November 2010, along with other
actions displayed by that country, the Government of Costa Rica, in accordance with a National
Emergency Decree, has developed a series of civil works in its territory that include the
construction of a road along the northern frontier known as Route 1856 - the Juan Rafael Mora

Porras road.
In response to claims made by the Government of Nicaragua regarding supposed impacts on its

territory originated by the construction of Route 1856, the Ministry of Fo reign Relations has
convened a national and international technical group for the purpose of conducting an
exhaustive assessment of the environmental conditions existing along the Route and the
potential environmental impacts of the construction.

As part of the effort to conduct an environmental analysis of the Route 1856 project, the Ministry
commissioned the services of the Tropical Science Center, given its reputation, technical

expertise in the subject, and more than 20 years of experience in research p rojects in the area,
with the purpose of conducting an Environmental Diagnostic Assessment with emphasis in the
ecological component.

For such purpose, the TSC met with members of a technical team formed by representatives of
the Ministry of Foreign Rela tions, the Instituto Costarricense de Electricidad, the Ministry of the
Environment and Energy and other government advisors.

According to the legal norms of Costa Rica, diagnostic environmental studies, known as EDA,

constitute an excellent instrument for environmental evaluation that applies to activities and
works already conducted, in order to establish their environmental assessment and to define,
within a systematic organizing framework, the series of environmental measures that are needed
in order to achieve environmental equilibrium .

2.2 Scope of Study

The Environmental Diagnostic Assessment (EDA)- Ecological Component, is intended to
establish the environmental effect of the Route 1856 project based on scientific criteria and to

develop an instrument t hat supports the definition of public policies regarding the environmental
actions of the project.

This diagnostic study aims to organize and plan, within the same system, the technical and
environmental actions that have been applied, are applicable, and should be applied in the
future regarding this project.

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2.3 Objetives

2.3.1 General Objective

To formulate the Ecological Component of the Environmental Diagnostic Assessment (EDA),

based on the analysis and recommendations defined by the field research and document ary
evidence concerning the eventual impacts on the physical and biological environment within the
area of the Route 1856 project . This was accomplished through the identification and
assessment of the corrective environmental measures that were applied during the construction
process, as well as those that will be applicable in the short and m id term, in order for the project

to be an environmentally viable operation.

2.3.2 Specific Objectives

¥ To formulate a general description of the physical environment in the study area where
Route 1856 is located.

¥ To collect and consolidate information on the ecosystems of the region, specifically in the
area between Border Landmark 2 and the site known as Delta 7 (Delta Costa Rica).

¥ To prepare qualitative and quantitative an alyses of the possible environmental impacts
generated by construction activities related to Route 1856.

¥ To provide technical scientific foundations that guide the Government of Costa Rica
towards decision making in the design and construction of Route 185 6.

2.4 Methodology

Regarding the methods utilized to formulate the biological component, a bibliographical review
was conducted of studies and research performed in the past by members and other associates
of the TSC in the region, along with five field visitsby professional team members, and an aerial

observation flight, all intended to validate aspects of the characterization of the local ecosystems
and the possible environmental factors impacted by work done on Route 1856.

Despite the limited biological inf ormation available on the area, previous work and 15 years of
field experience by experts Guisselle Monge and Olivier Chassot, as part of the Lapa Verde
Program which the TSC develops in the area of the Route project , served to verify and
consolidate field information. Likewise, the experience of various consultants in different relevant

scientific fields was considered in the formulation of the biological component of the
Environmental Diagnostic Assessment (see Annex 9.1).

In order to collect the necessar y information to characterize the green coverage and ecosystems
present in the area, different studies were analyzed. Even though some of these studies
recognize the existence of different natural associations or eco -systems in the border area, no
maps wer e identified to characterize and differentiate these systems in all of Route 1856.

Instead, only some limited areas were identified. For this reason, the information on this topic is
partial, due in part to the fact that in previous years access to the for ests and wetlands of the
area was extremely difficult. On the other hand, some of the information that identifies these
natural wild lands stretches through extensive areas from the border territory of Rio San Juan for

some dozens of kilometres inland.

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National forest cover maps offer quantitative information but do not define natural associations

as such. Similarly, there are maps of protected areas in the study area, and it is possible to
locate some conspicuous ecosystems such as wetlands but not for th e whole of the study area,
due to the geography of the Route.

To determine predominant natural associations along the Route 1856, aerial photography were
analyzed to distinguish among the different types of vegetation, and field verification was carried

out later for adjustments in the classification. Primary and secondary forests were determined,
as well as their location and general physiographic condition. Furthermore, a generalized slope
map was used resulting in the differentiation of two topographic conditions and two distinct and
remarkable types of forest associations along Route 1856.

Wetland areas existing within the project´s Direct Influence Areas (DIA) are also located on the
map mentioned before. Such wetlands constitute different types of ec ological associations.

Using the natural cover map, impacted surface in each type of vegetation was quantified.

With respect to the characterization and description of the aquatic fauna in the region, the
analysis done covered species identified in pre vious studies such as textbooks, technical
reports, theses and scientific articles.

For the field work, ten bodies of water along Route 1856 were selected in order to study and
identify the aquatic macro -invertebrate community abundance and the richness of the taxa, as
well as to evaluate the quality of the water applying the BMWP -CR index. These macro -

invertebrates were selected as bio -indicators of the quality of the aquatic habitat. Criteria applied
for the selection of the sampling sites were:

¥ Geographic location

¥ Land Use

¥ Type of Plant Coverage

¥ Access, Size and Depth

¥ Type of Stream Current
¥ Substrate Availability

Priority was given to tracts where it was deemed probable that environmental impacts existed

due to the construction works of Route 1856. Most o f these sites corresponded to tracts with
steep, unstable slopes and non -consolidated landfills, such as is the case, as an example, of the
stretch between Infiernito River and the site of Boca San Carlos on the San Carlos river.

Finally, the structure an d guidelines of the present study are based on the Technical Guide for
the Environmental Diagnostic Assessment established by the National Technical Environmental
Secretariat (SETENA) of the MINAE based on Resolution No. 2572 -2009-SETENA of November

2, 2009.

Such document states that “the EDA is an instrument of environmental assessment similar to an
Environmental Impact Study (EslA) but instead of being based on predictions, it is based on
samples and measurements conducted by an assessment team on an acti vity, work or project
that has been built and is functioning, which does not have an environmental license and whose

owner (developer) is interested in obtaining such licence”.
According to the resolution mentioned, the Environmental Diagnostic Assessment addresses the

accomplishment of the following technical objectives:

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1. To identify and quantify the eventual environmental impacts and risks that a specified

activity or project is creating for the environment and the population.

2. To define and establish the necessary measures to eliminate, prevent, attenuate or
compensate such significant impacts, for which purpose it must propose a
corresponding Environmental Adequacy Program (PAA), as well as a Contingency
and Accidents Prevention Program, for cases require d or defined by official

authorities.
The SETENA also indicates that the EDA is formulated only on significant negative impacts,

since its aim is to eliminate, prevent, diminish or compensate negative impacts, and for that
purpose operational impacts are evaluated through measurement techniques, making use of
environmental measures to avoid, prevent, attenuate or compensate them within a financial
equilibrium that does not attempt against the activity that is being evaluated.

2.5 Time frame for the Ecological Component of the EDA

The preparation of the Ecological Component study began with the signing of a contract

between the Chancery of the Government of Costa Rica and the Tropical Science Center on
May 22 of 2013. Starting with the mutual agreement among the actors, the TSC defined a 4 -
month period for the development of the Ecological Component and a video that would collect
images of the present conditions of Route 1856. For the stated purpose, available bibliography

was analyzed, terrestrial and aerial vis its within the project area were conducted, and the San
Juan river was visited by the study´s professional team.

2.6 Terms of Reference

The analyses performed for the Ecological Component of Route 1856 were based on the
environmental guidelines established in Costa Rica by the Ministry of the Environment and
Energy (MINAE) according to Ministerial Resolution N o 2572-2009-SETENA, as well as
o
Executive Decree N 32966 – MINAE, which includes as one of its annexes the Guide for the
Formulation of Instruments for En vironmental Impact Assessment. This diagnostic study will
also adjust to the terms and procedures standardized in Costa Rica for the evaluation of projects

being proposed, as well as projects in operation.
These analyses placed emphasis on the road design ated as Route 1856, whose initial

construction occurred during the period 2011 -20123, although for the purpose of the present
evaluation includes only the area between Border Marker 2 (Mojon 2) to the site known as Delta
7 (also known as Delta Costa Rica), which refers basically to the section of Route 1856 that runs
along the San Juan river all the way to the point where the San Juan bifurcates into the Colorado

River.
This EDA-Ecological Component is part of a series of technical reports being developed b y

different Costa Rican institutions as part of an interdisciplinary effort to contribute to the
improvement of road design and construction works.

Even though the study follows a line of development according to the guidelines established in
Costa Rica n legislation for the f ormulation of an EDA, two supplementary analysis were
developed in order to extend the applications of this study. The first report corresponds to an

“Impact Assesment of the Implementation of the Route 1856 on the Development of To urism
Activities in the San Juan River ” (See Annex 9.2). The second report is an analysis of structural
connectivity in the landscape of Route 1856 (See Annex 9 .3). Since the Route is critically

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located on the Costa Rica -Nicaragua border, it is of utmost importance to analyze its potential
impacts on the conservation of connectivity, based on the identification of priority sites and
critical links for connectivity.

2.7 Limitations

The results and evaluations done are limited only to the section of the Route 1 856 that begins in

Border Landmark 2, close to the site of Tiricias de Cutris de San Carlos, all the way to Delta
Costa Rica, across the bifurcation of the Colorado and San Juan rivers.

It is important to note that it was not possible to analyze the result s of this study in a larger
context within the study area due to the fact that the Government of Nicaragua denied
permission to the scientific team to visit the San Juan river. For this reason it was not possible to

conduct sampling and analysis within the river, especially in the mouths of rivers and channels
that empty into the San Juan and that were included in this study.

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3 PROJECT DESCRIPTION

3.1 Geographic Location

Route 1856 is located in the northern territory of Costa Rica, in the provinces of Alajuela and
Heredia. The area that corresponds to the study area is located between the following points:

Beginning: Border landmark 2 (Mojon 2), 1215724 North and 526412 East.

End: Site known as Delta 7 or Delta Costa Rica, between coordinates 1190664 North
and 460768 East (See map 1).

The design of the Route is contained in 4 topographical sheets at a scale of 1:50,000 by the
National Geographic Institute (IGN), which are labelled from northwest to southeast from Border
Landmark 2 to Delta Costa Rica, as follo ws:

¥ Pocosol 3348-IV

¥ Infiernito 3348-III
¥ Cutris 3348-II
¥ Trinidad 3448-III

3.2 Political and Administrative Location

Along the design of Route 1856 contained in this study, several important provincial, county and
district boundaries were identified for purposes of an adequate institutional coordination,

decision making, and environmental technical follow -up as required by the Project:
Alajuela (Province 02): San Carlos County and Pocosol, Cutris and Pital districts

Heredia (Province 04): Sarapiquí County and t he Cureña, Puerto Viejo and Llanura del
Gaspar districts.

3.3 Estimated Project Area and Influence Areas

The study area includes an important segment of tropical evergreen lati -foliated forest and
swampy lati -foliated forest (World Bank and CCAD, 2001; Vreugde nhill et al., 2002), with

different degrees of human intervention evident, as well as different agriculture and livestock
systems in place, in the Northern Caribbean watershed of Costa Rica. In these ecosystems
standout perhumid forests rich in trees, epip hytes, palm trees and humid forests that have an
average rainfall of 1500 and 3500 mm yearly (Hartshorne, 2002; Chassot et al., 2006a). The

territorial framework of the study is determined by the conceptual reference known as the Water
and Peace Biosphere Reserve (Moreno and Muller, 2007) and the Biological Corridor San Juan-
La Selva (Chassot et al., 2006a).

The study area covers part of the San Carlos and Sarapiquí counties, both of them
demonstrating the largest extension of natural land cover on the nort hern Caribbean territory of
Costa Rica. Such areas constitute a mosaic of lands in a natural state and some showing human

intervention, and some anthropic use areas that act as buffer zones for those in a natural state
(Chassot, 2010).

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The terrestrial buffer zone areas involve some landscape elements that defend the protected

wild lands from external threat and also include human communities that cause some type of
direct impact on protected wild lands (Groom et al, 1999, V ilhena et al., 2004)

Due to the physical and biological characteristics of the region of Route 1856, the ecological
analyses contain terrestrial as well as aquatic components. Taking into account the influence of
civil works conducted during the construction of the Route, as well as the national legislation on

the matter, the Project Area (AP) has been identified as the 50 meters of the right of way of the
Route.

On the other hand, the Direct Influence Area (DIA) has been defined as the first 1000 meters
from the right margin of the San Juan river towards Cos ta Rican territory (see Map 1).

Finally, the Indirect Influence Areas (AII) has no uniform extension but is defined by the physical
and biological conditions as esti mated by each professional member of the team, and, where
possible, the conditions of San Juan river were assessed, subject to the access limitations

mentioned above.

3.4 General Description of the Activity

The Route 1856 Project consists of the construction of a gravel road that starts at the site known
as San Jerónimo de Los Chiles and continues to the site called Delta 7 (Delta Costa Rica). The
Project is 159.7 km. in length. Approximately 63.6% (101.5 km.) of the Route´s extension is
made up of pre-existing roads and connections in existence over 30 years. The remaining 35.9%

(57.4 km.) are new roads that join the existing pathways.
As indicated in section 2.7, the study focuses only on the design of the Route that runs parallel

to the San Juan river, which amounts to 108.2 km. of the total route .

The main purpose of the Route was the consolidation of a new terrestrial pathway that would
communicate all settlements located between Border Landmark 2 and Delta Costa Rica. This
project took advantage primarily of the network of existing roads that run parallel to the San Juan
River and built a smaller percentage of roads required to provide continuity to the network.

For the development of this main activity, and as is common in these types of projects, it was
necessary to carry out several important secondary actions. Among these were the cleaning of

terrain, building up retention slopes, placement of drains and water conduits, and laying a base
and rolling surface on the road, among others.

Chart 1 shows the m ain and secondary components that were part of the activities conducted
during the construction of Route 1856.

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Chart 1: Activities conducted during the Project construction stage.

No Component Description

1 Clearing and cleaning of new sites At specific sites along the right of way of the Route.

In sections of the right of way where topography and the
Land movement, retention slopes slope did not permit normal traffic. This was done with the
2 and land fills use of heavy machinery (backhoes, heavy trucks,

excavators, etc.)

Installation of systems to control the speed of superficial
3 Erosion control measures runoff and sediment control structures.

4 Installation of drainage systems Drainage systems and temporal bridges where placed on
and temporal bridges most rivers and ducts along the Route

Road filling, base layer and rolling Commonly needed on any road to permit the transit of
5
surface vehicles.

In order to better appreciate the Project Area, a series of 6 maps (1 :50,000 scale) help to

visualize the design of Route 1856 and the land uses in the area (Maps 2, 3, 4, 5, 6 and 7) .

3.5 Environmental Aspects

In the previous chapter, a general description was provided of the environment in which the
Route project is located a nd of its construction characteristics, taking into account that large part

of the project operates in a totally rural environment. For that reason it is important to establish in
greater detail the environmental aspects related to the construction and ope ration of the project.
This will allow a greater approximation to an environmental intervention in accordance to the

characteristics of the project.

The environmental aspects will correspond with all the actions related to the 1856 Route, which
implies some degree of interaction on some environmental component. On the other hand, what
is understood as environmental effect is the degree of alteration of the environment, resulting

from the previously identified environmental aspects.

Following are the enviro nmental aspects and their relation to activities of the Route:
1. Clearing and cleaning of land on sites of road design: this activity is related to the

elimination of forest or plant cover along some sections of the Route where no roads
were present.

2. Soil movements, building of retention slopes and fills: could generate instability of slopes
in some sites where the degree of slope is high. Likewise with the generation of

increased surface runoff, laying of sediments in nearby bodies of water and the impact
on the scenery in some sections of the Route.

3. Installation of drainage systems and temporal bridges: this fa ctor could be associated to
the affectation of aquatic eco systems on isolated, specific points and the modification of

natural drainage systems in th e area.

4. Placement of land fills, sub- surface layers and rolling surface: this activity is associated to
the possible laying of sediments in some bodies of water close to the Route.

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Starting with the previously stated, four activities have been identified which are associated with

possible environmental impacts. Each one of them will be described in greater detail in the
section that deals with Identification and Evaluation of Environmental Impacts.

3.6 Environmental Risk Control System

According to the activities conducted for the Project, some sources of environmental risk were
identified and measures implemented in order to avo id the alteration of the terrestrial and
aquatic environment. These are presented below.

3.6.1 Risk of Cutting Down Trees which are in Danger of Extinction

The possibility of cutting down trees that are in danger of extinction due to the land clearing and

cleaning activities in some sites of the Route, was minimized as a result of the tree inventory
performed by the National Highway Council (CONAVI) during the construction of the project. It
should be pointed out that currently there is a reforestation plan that is being implemented by
CODEFORSA since 2012 that has planted some 26,000 trees native to the zone along the strip

of land that surrounds the Route.

3.6.2 Risk of Slope Erosion and Slope Instability

This risk appears as a consequence of an inadequate design of d rainage systems and a lack of
proper protection of slopes along the road. This can be prevented with adequate drainage
construction in different sections of the slopes to avoid runoff on the face of the slope, the
generation of furrows or grooves, bumps an d destruction of terraces. This risk has also been

controlled with the placement of geo- textiles and, even better, with the planting of grasses on the
slopes with the idea of diminishing the direct impact of r ainfall on the exposed surface.

3.6.3 Risk of Altering Natural Drainage Systems

There is a risk present of modifying the natural drainage patterns of the different bodies of water
along the Route, particularly the drainage systems of still waters and wetlands along specific
sections. Based on the previously mentioned, a partial control is conducted of the structures to
avoid the natural action of the drainage which existed before the construction of the Route.

Greater control must be established of the correct func tioning of different waterways.

3.6.4 Risk of Obstructing Waterways

There is risk of obstructing rivers, creeks and channels in some sections of the Route,
specifically in points where temporal structures in poor condition were laid to facilitate movement
across such bodies of water. The possibility of col lapse and the falling of trees, steel beams and
construction materials could cause artificial obstruction of waterways, generate floods and

changes in the natural drainage system and erosion along the margins.
To avoid this situation, a periodic monitoring effort has been conducted of Route 1856 by

COSEVI, promoting an adequate preventive control of the structures along the way.
Nevertheless, it is necessary to establish more rigorous preventive and corrective measures.

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3.6.5 Risk of Eroded Sediments Depositing on Bodies of Water

Due to the high rate of rainfall in the area of the Route, the high grade of weathering of the
geological materials that are part of the ground, and the absence of forest cover in some specific
sites, the existence of the potential risk o f eroded sediments depositing on the different bodie s of

water has been identified.

As a preventive measure runoff control systems have been put into place, as well as sediment
traps along the Route. These measures must be complemented with monitoring syst ems to
verify the control of sediments in suspension.

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4 DESCRIPTION OF THE PHYSICAL ENVIRONMENT

4.1 Geology of the Study Area

4.1.1 Regional Tectonic Framework

Costa Rica is located on the southwestern margin of the Caribbean Tectonic Plate and is part of
the mature intra-oceanic arch of southern Central America, of Superior Cretacian age (Astorga
et al., 1991). Some of the tectonic characteristics with strong influence in the Northern area of

Costa Rica are described by Astorga et al. (1991):
a. The North American Tr ench, where the Cocos Plate slides under the Caribbean Plate,

and which includes the subduction of the submarine range named Dorsal Asysmic
Cocos, in the South Pacific of Costa Rica.

b. The Hess Scarp, interpreted as the trace of a fault, with a possible tran s-current
movement, with activity present mainly during the pre -Cenozoic period (Bowland 1984;
Astorga et al, 1991) and which separates the Rising of Nicaragua and the Colombia
Watershed (Mann and Burke, 1984 in Astorga et al., 1991)

c. The Nicaragua Depressi on (McBirney and Williams, 1965 in Astorga et al, 1991) which
extends to the trans-arch region of northern Costa Rica and which belongs to a system of

trenches (graben) belonging to the Late Neogene (Mann and Burke, 1984 in Astorga et
al, 1991), whose orig in is associated (Mann, 1990 in Astorga et al, 1991) with an
extension of the trans -arch area due to subduction, subsidence among dextral trans -
current faults disposed along the borders and by combination of both processes.

Astorga (1991) classifies two g enerations of sedimentary watersheds for Costa Rica, according
to the geodynamic evolution and the interaction among the previous and other tectonic

characteristics. The first generation is formed by watersheds of intra- oceanic island arches
which contain the morpho-tectonic units corresponding to the Trincher, Arco Externo and Arco
Interno, with ages that go from the Superior Cretaceous to the present. It includes the Northern
Limón watershed as a trans -arch watershed, which presents two generations of nor mal faults,

one aged in the Oligocene - Miocene and another one in the Miocene Superior -Pliocene.
The second generation is formed by the watersheds superimposed on the arch of islands,

originated by local tectonic phenomena during the Late Tertiary (Astorg a, 1991), mainly by trans-
tensive mechanisms associated to trans -current faults, which makes the San Carlos watershed
a second generation watershed of the extensional type. Nevertheless, this watershed does not
show important deformation structures that ca n be correlated with the deformation phases

defined by Gursky (1988) for the northwest of Costa Rica, and thus it is considered a marginal
watershed, tectonically passive, of the Northern Costa Rica Segment.

4.1.2 Regional Geology

Geologically, the area under s tudy is formed mainly from volcanic and volcano -clastic rocks of
the Superior Tertiary period, which have been named the “Sarapiqui Arch” (Astorga 1992). This
arch has a basement of serpentinized ophiolites of Cretacian age.

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The exogenous processes have or iginated a sedimentation process of materials coming from

the Sarapiquí Arch, and it is thus that the San Carlos watershed as well as the Northern
Caribbean watershed, have a filling of Quaternary deposits.

4.1.2.1 Ophiolites of Tiricias

The Ophiolites of Tiricias are formed from serpentinized peridotitic rocks which are considered to
be the base of the Sarapiquí Arch (Astorga 1992). A small upcrop of these serpentine rocks
described by Astorga (1992), 6 km. west of the site of Tiricias, close to the border of Nica ragua,

has been correlated with the presence of serpentine rocks at 1920 meters deep in the Tonjibe
well, perforated by the Costa Rican Petroleum Refinery (RECOPE). The existence of these
serpentine rocks in the surface, as well as in great depth, leads to the interpretation of the
existence of a rock base of Mesozoic oceanic cortex in this section of the trans -arch, with a

tectonic emplacement by accretion (Astorga 1997), with a minimal age of Superior Albiano
(Astorga 1991). Tournon and Bellon (2009) cons ider that due to their texture and composition
these ophiolites are typical peridotites of the mantle, similar to those of the Santa Elena
Peninsula in Guanacaste, which leads them to interpret their origin as part of the proto -

Caribbean base layer.

4.1.2.2 Sarapiquí Arch

The Sarapiquí Arch is probably a remnant of a volcanic arch with volcanic activity during the pre -
Pliocene (Astorga 1991). Gazel et al. (2005) assign a Miocene age between 22.2 and 11.3 Ma to
it with a composition of olvinic and riolitic basalts r epresented by lavic faces, pyroclastic d eposits
and sub-volcanic bodies.

4.1.2.3 Quaternary Deposits

Quaternary deposits of the San Carlos graben are formed by volcano -clastic deposits and
marginal volcanites (Astorga, 1991). This sedimentation process starts duri ng the Pliocene with

a concise clastic marine sedimentation (Astorga 1991).

The trans-arch watershed of Northern Limón is filled with marine clastic sediments, which pro -
grade towards the Colombia watershed, without major tectonic distortions (Astorga, 19 91). It is
possible that the formation of the delta of the San Juan River mouth occurred during the
Superior Miocene.

4.1.3 Seismic Activity

The Northern Caribbean region is a region of low seismic activity. Nevertheless, in 2012 and
after the Sámara Earthquake of September 5, 2012, 9 earth tremors were recorded along the

Colorado River, close to the Nicaraguan border, with magnitudes (Mw) of 3.1 up to 3.9
(Barquero 2013)

The alignment of the epicenters of such seismic activity coincide with the Colorado River, w ith a
northwestern to southeastern orientation, which suggests the presence of an active fault. This
recent sismic activity could accelerate exogenous processes and increase the sedimentation

rate towards the San Juan River.

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4.2 Geomorphology

The design of the Route includes morphologies of volcanic ranges of the Tertiary period, related
to the Sarapiquí Arch. These ranges contrast with the lowlands of San Carlos, which are

composed of sediments of the Quaternary period and are found in the San Carlos and North ern
Caribbean watersheds.

Within the Quaternary morphologies neighbouring the San Juan river, coexist fans or alluvial
cones which provide materials of volcanic composition and whose morphologies mix with those
of the lowlands in the area.

4.2.1 Morphologies of Tertiary Vulcanism of the Extreme North of Costa Rica (Bergoeing
et al., 1997)

On the southern margin of the San Juan river, on the northern limit of the tectonic trench or

graben of Nicaragua, a volcanic range of the Tertiary Period arises with an altitu de of 250
meters above sea level (m.a.s.l) which contrasts with the lowlands that do not surpass the
altitude of 50 m.a.s.l.

According to Bergoeing et al. (1997), such morphologies lead to a multi -convex model due to the
alterations caused by volcanic mate rial.

4.2.2 Morphologies of Alluvial Quaternary Cones in Northern Costa Rica (Bergoeing et
al., 1997)

A series of coalescent dejection cones mark the limits between the Central Volcanic Range and

the lowlands of San Carlos. Such cones are cut across by a fault w ith steep slopes that marks
the southern limit of the Nicaragua graben. From this boundary and extending for some 50 km. a
series of fans or alluvial cones of volcanic composition, with a red clay matrix, have developed.
These cones began to form during th e Median to Superior Pleistocene, evolving towards a

series of glacis during the Upper Pleistocene -Holocene, where they mix with the pre -existing
lowlands.

The alluvial cones described possess a multi -convex model, proper to lowland soils in tropical
environments (Bergoeing et al. 1997). In the lowlands are also found paleo -meandric
morphologies which were probably active during the Superior Pleistocene (Bergoeing et al.
1997).

4.2.3 Sedimentary Quaternary Morphologies

Bergoeing et al., 1997, divide the sedimenta ry deposits of the lowlands in the San Carlos and

Northern Caribbean watersheds into Quaternary deposits of the Upper Pleistocene and
Quaternary deposits of the Holocene. The Upper Pleistocene deposits are found closer to the
morphologies of the Tertiary volcanic activity, so that they could be interpreted as a product of
the erosion of volcanic remainders.

Within the Holocene deposits is found the delta of the San Juan river, which divides into two
arms due to the fluvial terrace built up by the sediments of the San Juan river, starting in the

Upper Pleistocene and on to the Holocene (Bergoeing, 1997)

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4.3 Soils

The region of Route 1856 contains soils of the Ultisol class (Vasquez 1985) corresponding to the
class of oldest and most weathered soils in the country. These are common in the Northern

region (Sarapiquí, San Carlos, Cutris), in the southern region (Perez Zeledón, Buenos Aires and
the border region of Panamá) as well as in the lower altitudes of the Talamanca Mountain
Range, both Pacific and Atlantic si des.

In terms of mineral content, there is a predominance of clays in the order of 1:1 (mainly
Caolinite) and oxides of Fe and Al. Although these materials are fine, the formation of H bridges
in the 1:1 facilitates that particles stick together creatingmore developed structures. These in

turn are covered by oxides and constitute a type of particle of larger size which is known as
“pseudo-arena”.

4.4 Climate

According to data of the Meteorological Institute, the Northern Zone is the third most rainy region
in the country with a rainfall rate greater than 3,200 mm. annual average. According to
Bergoeing (2008) the region belongs to a structural unit known as the Nicaragua Trench, which

extends from Nicaragua to the Southern Caribbean region of Costa Rica.

This region belongs to the rainfall regime of the Caribbean Coast, which has a rainy season that
stretches throughout the year, with a decrease in rainfall during the months of February, March
and April. It is a region of diverse rainfall conditions with an int eraction among the climatic
elements and the geographic conditions of the region, among them extensive lowlands, low

altitude mountain ranges, wetlands and lagoons, including the influence of the exten sive lake of
Nicaragua.

4.4.1 Micro-climates

In general, the climate of this region is determined by atmospheric systems of large magnitude
such as the Inter -tropical Convergence Zone (ICZ), the Eastern Waves and the modified cold
fronts from the North, which are sources of instability. Also influential are the hurr icanes in the
Caribbean Ocean, particularly those that come close to, or even penetrate , the Central American

Isthmus.

The ICZ determines in large measure the general climate of the country during the period of May
to December, particularly on the Pacific Watershed, originating frequent and abundant rainfall
(Chassot et al. 2006).

In correlation with these conditions of the humid tropical region, the temperature averages 29 º C
(Holdridge 1987). This environmental condition combined favours a high relative humidity all
year round. In high places, such as Tamborcito mountain (101 m.a.s.l.) or the top of El Recreo

range, the climate is colder and windy.

Relative humidity is 85% on average during a great part of the year, with a few exceptional
colder days (22 º C). The most humid period extends from July to October (Chassot and Monge
2002) with an average humidity of 90%. The wind factor displays two behaviours during the
year: prevalent winds from February to May are westerly, related to equatorial currents fr om the

Pacific region. From June to November easterly winds are dominant, with low velocities. During
hurricane events on the Caribbean Ocean, the winds follow the direction of the large air masses

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that move from the West to th e Caribbean with gusts of 50 km/hour. Between December and
January, the dominant winds are from the North.

4.4.2 Rainfall

In the project area the average a nnual rainfall varies between 2300 millimeters and 4400

millimeters.

4.4.3 Temperature

The average annual temperature for the plains areas ap proximates 26 to 27 º C and the higher
elevations such as the Chaparron Mountain and Las Crucitas, the median annual temperature

may be as low as one degree centigrade.

4.4.4 Solar Brightness

The average sunlight hours can reach up to a maximum of 5 hours. The w hole region is
influenced by large nuclei generated by evaporation.

4.4.5 Dry Months

According to existing information in the historical records of the National Meteorological Institute ,
a dry season is not present as such in the area. Rather, a partial decrease in rainfall during a

period of 3 months, February through April, is identified.

4.5 Hydrology/ Hydrography

Costa Rica has 34 important hydrographic watersheds, with 17 of them on the Caribbean side
and 7 of them emptying in the San Juan river. The main river s in the area of the 1856 Route are

the Sarapiquí, the San Carlos and the San Juan rivers, with the latter being the receptor of the
waters of the previous two. The San Carlos and Sarapiquí rivers are among the most important
ones in the country´s hydrogra phic system.

Chart2: Hydrographic Watersheds in the Study Area

Major Medium Area
watershed watershed Minor watershed (hectares)

Río San Carlos 3783.4

Río Tres Amigos 27.9

Quebrada Rosalía 1035.9

Caño Boca Tapada 1694.1

Río San Juan Río San Carlos Caño Canacas 1033.4

Caño Cerritos Gemelos 186.8
Caño El Jardín 2436.0

Caño La Mona 916.8

Caño Pataste 4353.2

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Major Medium Area
watershed watershed Minor watershed (hectares)

Caño Recreo 906.4

Caño Sucio 4672.5

Río Toro 872.8

Río Sarapiquí Río Sarapiquí 1611.3

Quebrada Grande 168.0

Río Cureñón-Caño
14271.2
Cureña

Río San Juan 1389.3

Quebrada – Caño 8562.5
Río San Juan Copalchí

Caño Tambor 7636.1

Caño El Chile 254.2

Caño Cureñita 3881.7

Source: Chassot et al., 2006.

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5 DESCRIPTION OF THE BIOLOGICAL

ENVIRONMENT

5.1 Introduction

During recent years, the country´s legal framework has been characterized by its attempts to
regulate in a more integral manner the relationship between humans and their environment, and

to organize the appropriate use of available nat ural resources. In this sense, Article 50 of the
Political Constitution is aimed at the promotion of sustainable development; that is to say,
development which is compatible with the environment. This article states:

“The Government shall procure the gre atest wellbeing to inhabitants of the country, by
organinzing and encouraging production and equitable distribution of richness. Every person
has the right to a sound, ecologically balanced environment. Is therefore entitled to denounce

any acts that vio late the law and to claim compensation for damage caused. The Government
shall guarantee, defend and preserve that right. The law shall determine the corresponding
responsibilities and penalties” (Article ammended by Law No. 7412, on May 24, 1994, publish ed
in La Gaceta No. 111, June 10, 1994).

In the area of Route 1856, different technical studies have underscored the importance of
promoting and consolidating activities that support the conservation of native forest patches, as
well as the importance of promoting recovery actions that assure the permanence of the

biological routes that are travel paths for different species, among them thGreat Green Macaw
Ara ambiguus, a species that is currently under threat of extinction. For this reason Costa Rica
has acquired a number of national and international commitments that lead the country to take
appropriate measures, within its means, to preserve the environment and protect bi -national

species and habitats.
In addition to the standard norms, the geographic a rea of Route 1856, has specific norms that

reinforce the legal and political commitments assumed by the State of Costa Rica to foster
conservation and sustainable management in that region. Among these stands out the
Agreement on Border Territories signed by the governments of Costa Rica and Nicaragua on the
15 of December, 1990, which establishes the International System of Prot ected Areas for Peace
(SIAPAZ).

As part of the system a number of actions have been implemented for the integrated

management of n atural protected areas in Southeastern Nicaragua and the northern region of
Costa Rica; one of these is the establishment of the El Castillo -San Juan-La Selva Binational
Biological Corridor as one single biological unit (Chassot e t al., 2006).

On the other hand, the Mesoamerican Biological Corridor (CBM) is a regional initiative that is
intended to maintain the ecological connectivity between North and South America, with the goal
of preserving migration routes and the transmission of genetic flux through t he Central American
isthmus (CBM 2002). The Atlantic Humid Tropical Forest of Northern Costa Rica contains the

last remnant of lowland habitat with potential of maintaining continuity of the Mesoamerican
Biological Corridor between Costa Rica and Nicaragua , the largest gap on the Atlantic route
between Honduras and Colombia (Chassot et al., 2005; Villate et al. 2008).

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The El Castillo-San Juan-La Selva corridor arises as a management strategy that responds also
to a territorial organizational and zoning sche me that maintains the connectivity of the
Mesoamerican corridor. The importance of the northern territory of Costa Rica, in addition to the

presence of wetlands of high biological value, it contains the last remnant of very humid tropical
forest where the mountain almond tree (Dipteryx panamensis) is a dominant species. It is also
home to numerous threatened species, among them the emblem species: jaguar (Panthera
Onca), the sea cow (Trichechus manatus) and the Great Green Macaw , a species that is highly

dependent on the almond tree as a source of nourishment and substratum for nesting. (Chassot
et al. 2006).

The San Juan River is an important navigation route. It is the river that empties Lake Cocibolca
(Lake Nicaragua). Within the interest areas, along the superior branch and up to the confluence
with the San Carlos River, it is narrow, deep, without islands and with some rapids. After it joins

the San Carlos River, it broadens its course (Chassot and Monge, 2002), it becomes shallow,
islets appear and it ends in a delta when it reaches the Caribbean Ocean. The main input for its
waters comes from the tributary watersheds of the right margin,that is the San Carlos, Sarapiquí

and Chirripó rivers. These rivers provide 65% of the total volume of the San Juan Ri ver. Indeed,
the San Juan River, before receiving the waters of the San Carlos River, carries approximately
474 m 3/s and after receiving the waters of the San Carlos it goes up to 833 m /s, a volume that
increases to1308 m 3/s with the addition of the Sarapi quí waters, (Chassot and Monge, 2002); it
3
later increases again by 191 m /s with the added waters of the Chirripó river.

5.1.1 Terrestrial Environment

The region adjacent to the San Juan River, on the Costa Rican margin, has been a territory
marked by migratory processes and intermittent colonization. Until the 1950s, the area where
Route 1856 is located was dominated by subsistence agriculture and domestic use. The weak

agriculture production of the local farmers is complemented by fishing and hunting in
neighbouring areas. The poor soils in the area have frustrated any attempts to develop the
productive capacity of the land.

Presently, the main productive activities in the region are cattle raising and agriculture (basic
grains, root crops, palm and citric crops ). During the last couple of decades, cattle farms have

begun to change to exotic monoculture plantations (mainly Melina and Teca).

All of the above mentioned activities and events have occurred through the years inside the
National Wildlife Refuge Border Corridor. Families that have lived within the refuge for more than
40 years have been given rights to the property and its use. (Chassot et al., 2006)

5.1.1.1 Protection Status (Protected Areas)

The establishment of the Natural Protected Areas system in Costa Rica began in 1955. Because
of the problems of landscape fragmentation resulting from the expansion of the agricultural

frontier, the small size of protected areas, and given the need to plan these areas with an
integrated perspective, in 1988 it became necessary to create the system of protected areas
through the establishment of the National Conservation System (SINAC) in 1999. This required

the integration of the three main directing offices within the Ministry of Natural Resources,
Energy and Mines: the For estry, Wildlife and National Parks offices; offices which were in charge
of protected areas under different management categories. This integration process was legally
consolidated in 1998, with the approval of the Biodiversity La w No. 7788 (Mena et al., 1998).

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Presently, the country is divided administratively into 11 conservation areas, responsible for

directing the management of protected areas within its geographic area. In this manner, within
the study area of Route 1856, there are three conservation a reas: the Arenal Huetar Norte
Conservation Area (ACAHN), the Central Volcanic Range Conservation Area (ACCVC), and the
Tortuguero Conservation Area (ACTo), (See Map 8).

The protected area Costa Rica -Nicaragua Border CorridorNational Wildlife Refuge, create d by

Executive Decree No. 22962 -MIRENEM, 1994) is found within the ACAHN, ACCVC and ACTo
conservation areas. The corridor includes all of the border strip from the Pacific to the Atlantic
Coast, with a width of 2 kilometers (Rio San Juan -Amigos de la Tierra Project, 2000). This is the
only protected area that is directly affected by the design of Route 1856 which is included in the

route design between Border Mark 2 and Delta Costa Rica.
Other important conservation designations are found within the Natio nal Wildlife Refuge Costa

Rica-Nicaragua Border Corridor such as the Northeastern Caribbean Ramsar Wetland (created
by Ramsar convention in March 1996), the Maquenque Ramsar Wetland (Ramsar convention of
October 2010) and the Water and Peace Biosphere Rese rve (created by UNESCO in
September 2007).

The Northeastern Caribbean Wetland located on the northern Caribbean Coast of Costa Rica,

has lagoons, swamps and flooded forests with “yolillo” palm ( Raphia taedigera).
The Maquenque Wetlands contains a complex o f lakes and palustr ine ecosystems common to

an ecoregionof very humid tropical forest s and characterized by high bio diversity where it
sustains a number of threatened species such as the Great Green Macaw (Ara ambigu us),
vulnerable species such as the Mana tee (Trichecus manatus ) and other signal species such as
the Jaguar ( Panthera Onca ) and the Gaspar fish ( Atractosteus tropicus ) (Tropical Science

Center, 2008).

The Water and Peace Biosphere Reserve holds great natural riches that include wetlands,
navigable rivers, tropical wet forests and great water springs (Moreno and Muller, 2007).

Finally, the Maquenque Mixed National Wildlife Refuge (created by Executive Decree No.
32405-MINAE 2005), is located south of the Indio Maiz Biological Reserve, next to the National
Wildlife Refuge Costa Rica -Nicaragua Border Corridor, less than 2 km. from the Route 1856
design, and contains the largest area and best representation of the lowland forests in the

Caribbean slope of Costa Rica.

The San Juan -La Selva Biological Corridor (246,608 hectares) fills the conservation gap
between Southeastern Nicaragua and the lowlands of the northern region of Costa Rica,
preserving the connection between eco- systems in the Central Volcanic Range and the La Selva
Biological Station (12 5,691 hectares) in Northern Costa Rica, with Barra del Colorado National

Wildlife Refuge (102,165 hectares) and the Tortuguero National Park (29,068) along the
Caribbean Coast of Costa Rica, and, in turn, with the extensive complex that includes the Indio
Maiz Biological Preserve (306,980 hectares), Punta Gorda (54,900 hectares) and Cerro Silva
(339,400) in Southeastern Nicaragua.

The central conservation unit of the San Juan -La Selva Biological Corridor is the Maquenque
Mixed National Wildlife Refuge, whic h contains the largest area of the corridor with the largest

percentage of forest cover. The main goals of this initiative is the preservation of the movement
routes documented for wildlife that connects key habitats to prevent isolation or loss of species
and the preservation of the ecosystem functions.

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The corridor initiative is promoted by the Local Council of the San Juan -La Selva Biological

Corridor with support from the Tropica l Science Center through its administrative and logistical
resources. The Local Council is integrated by a number of state and civil society institutional
representatives (Chassot and Monge, 2002).

5.1.1.2 Life Zones

Two life zones are found within the study area: the very humid basal transition pre -montane
forest and the very humid tropical forest (see Map 9), with annual rainfall that varies between

2.300 and 2.800 mm.. Furthermore, there is an extended rainy period of 10 months on average,
and an average tempera ture of 27 º C with some variability during the months of April and
December, with maximum temperatures of 29 º C (Holdridge 1987).

The pre -montane very humid forest is the life zone that covers the western part of the study
area. This forest is of low to median height, semi -perenifoliar, with two to three strata, with some

canopy species such as oaks (Quercus), with short stems that divide into ascending branches,
long, heavy and twisted, that end in broad umbrella -like tops. The soil is covered by ferns,
begonias, araceas and creeper plants, and by a thick cover of mantle in a state of
decomposition.

The more common epiphytes, bromeliads and ferns, are small. A thin layer of fern grows on tree
trunks and herbaceous vines are common on the ground surface o r near the ground, as well as

tree vines, which are thick an d very common (Holdridge 1987).
The very humid tropical forest is the most representative life zone in Northern Costa Rica where

it covers 61% of the territory in the lowlands of Sarapiquí and San Carlos. It is the life zone that
provides the main connecting habitat between the southern part of the Atlantic watershed of
Nicaragua and the Central Volcanic Range of Costa Rica. It is characterized by very high
rainfall.

Canopy trees generally grow to 30-40 meters in height, and have round broad tops and trunks

that are relatively short and smooth. Tree buttress wings are common but small. The cortex is for
the most part of grey or brown colour, of moderate thickness and flaky or containing fissures and
the leaves often form bunches at the extreme end of the branches. There are epiphytes but
these are not very conspicuous. Herbaceous climbing vines are abundant and most of the trees

are covered by a dense layer of moss (Holdridge 1987).
Central American flora and fauna reflect in their diversity and richness of species a characteristic

interphase between the biotas of the Neo -tropical zone of South America and the Neo -Artic
North America. The biological diversity present in the study area is exceptionally diverse,
reflecting the general bio -geographic situation ofCentral America and as a consequence of
strong altitudinal differences ranging between 30 and 3,000 meters above sea level

(temperature gradients); different rainfall patterns and variations in th e type of soils (Chassot et
al. 2005).

Possibly, the San Juan- La Selva Corridor is the biological corridor with the greatest biological
diversity in Central America, with an important number of endemic plant species. The climate in
most of the northern par t of Costa Rica is that of the Atlantic watershed. It is generally

determined by atmospheric systems of large magnitude, as are the Inter -tropical Convergence
Zone (ICZ), the Eastern Waves and the modified cold fronts from the North, which are waves
that create instability (Chassot et al., 2005) .

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The ICZ determines to a great extent the general climate of the country during the period of May
to December, particularly on the Pacific Watershed, creating freq uent and abundant rains. The
general macro-climate of the Northern Caribbean is humid tropical to very humid, characterized
mainly by rainfall throughout the year, without a well -defined dry season which only lasts with a

few weeks. More specifically, for the regions closer to the northern border, there are local effects
such as the wind breezes that move towards and away from the San Juan River (Chassot et. al.
2005).

5.1.1.2.1 Project Area Bioclimate
According to the life zones map of Costa Rica (Bolaños and Watson , 1993) and observing the

relationship between the existing vegetation with ecosystems present at the site, two life zones
are found along the extension of the project area. Most of the Route extension analysed (92
km.²) belongs in the life zone category o f Very Humid Tropical Forest (between Infiernito River
and the Delta), while some 13 km. ² located between Border Marker 2 and Infiernito River are

located within the Very Humid Pre -montane transition to Basal Forest, which corresponds with a
less rainy bio-climate.

These life zones belong to the Tropical Latitudinal Region, and to the Province of Perhumid
Humidity (very humid). In consequence both zones are very humid, with a pluvial precipitation
rate that exceeds more than double the evapotranspiration po tential of the area. These bio -

climatic characteristics denote that the expected natural vegetation for these conditions
corresponds with dense forests, exuberant and diverse in species, under natural unperturbed
conditions.

Climatically, it means that the life zone known as Very Humid Pre -montane transition to Basal
Forest has an annual median inferior precipitation rate of 4000 mm. (within the study area

between 3500 and 4000 mm., approximately), while in the very humid tropical forest there is
greater pr ecipitation, with an annual median superior rate of 4000 mm. which increases
gradually from West to East, reaching 5000 mm. annually in the area of Kilometer 0 of the
Route. However, based on field observations, it is possible to conclude that the section between

Infiernito river and the mouth of the San Carlos river shows and irregular precipitation pattern
with increases and reductions according to the local physiography.

It is a well known fact that the areas located within the Very Humid Tropical Forest life zone are
very restrictive environments for the establishment of many different activities of land use. They
are fragile areas which at the same time are rich in bio -diversity. The median annual bio-

temperature along the Route shows little variation, given the minimal altimetric fluctuation. For
this area of the Project, this factor varies between 24 and 25 º C annually.

5.1.1.3 Natural Associations and Land Cover

Costa Rica is one of the 20 countries in the world with the highest biodiversity, with more than
10,000 known species of plants. This number places the country in an estimated 12 thposition in
terms of the absolute number of species of plants. Likewise, there are many diverse natural

associations present in the country (Janzen 1983).

In the study are a of Route 1856, various ecosystems or ecological associations are known,
among them: forest associations (secondary, primary and intervened forests), wetland systems,
riparian systems and “yolillo” palm associations.

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In the last years, and because of the extension of agricultural lands, m any of the primary forest

ecosystems in the border territory have been altered and/or destructed and later converted into
secondary forests. Even so, these forests present a high vegetal diversity.

Regarding the wetland systems, there exist in the area an important quantity of rivers, creeks,
channel and lagoons where a typical vegetation of lacustrine and palustrine wetlands is found.
The wetlands are ecosystems that depend on aquatic regimes, natural or artificial, perm anent or

temporal, lentic or lotic, fresh or salt water, including marine extensions up to the posterior limit
of marine fanerogams or corral reefs, or, in their absence, up to six me ters of depth in low tide
(CCT 2008).

Lacustrine systems are aquatic habi tats that present the following general characteristics: they
are located in topographical depressions or in conditions of natural or artificially dammed
drainage, with a depth of less than 2 meters, which may contain vegetation such as emerging,

floating plants, moss and lichens, and the water is fresh. On the other hand, the palustrine
system includes all wetlands of interior lands with the following characteristics: they may have
plant cover or not (such as is the case with Yolillales), the vegetation ma y show a dominance of
trees, bushes and busy vegetation, and/or emergent vegetation, moss and lichens; the depth

levels in depressions do not exceed two meters and the water is fresh water with some sediment
in suspension. Swamps proliferate among them, wi th herbal and gramineal vegetation, marshes
with palm vegetation (“Yolillales”) and swamps of flooded forests (Bravo and Ocampo 1993).

Finally, the area has aquatic and river margin environments that drain the bodies of water and
keep water in slow or rapi d motion and which can be characterized as fluvial corridors. The main

ones are the Remolino Grande lagoon (lacustrine wetland), Maquenque lagoon (palustrine
wetland), Tambor lagoon (also Tamborcito, a lacustrine wetland), Canacas lagoon (palustrine)
and Colpachí lagoon (lacustrine); all of them of biological, scenic and eco -touristic interest. The
majority of them connect with the San Juan River through the Cureña, Cureñita, Tamborcito and

Colpachí channels. The water in these environments is mildly turbid with light penetration of no
more than one meter in apparently meso -trophic state due to plant decomposition (Mata, 2005).

Riparian eco -systems are characterized by a marked presence of species such as the
“sotacaballo” ( Zygia confusa ), “gavilan” ( Pentaclethra macroloba ), “poponjoche” ( Pachira
acuatica), and “Caobilla” ( Carapa guianensis ). The following pioneering species are also
common: “guarumo” ( Cecropia spp.) and “balsa” ( Ochroma pyramidale ). In associations or eco -

systems known as “Yolillales”, the dominant plant is the “Yolillo” palm tree ( Raphia taedigera),
(CCT 2008).

5.1.1.3.1 Characterization

The border strip that limits with the San Juan River, specially its right margin, has been
subjected to alteration in forest areas, and small isolated human settlemen ts have been

established for many decades, in part due to the presence of a navigable river. According to
Moreno and Muller (2007), and Chassot (2010), the penetration of settlers in this area began in
mid-19 thCentury, from both bordering countries. Moreno and Muller state that “ the confluence
of Nicaraguan and Costa Rican population opened up the way for exchange and development of

practices for the extraction of rubber, wood, and “raicilla”, with lumber being one of the main
natural resources extracted in the region.”

That is the reason why the forests along the San Juan River were for a long time object of
selective extraction of some of its wood, or cut down in order to develop pastures for cattle or
subsistence agriculture. The presence of secondary f orests with several decades of growth
indicates that such sites have been abandoned after a few years of use. On the right margin of

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the river, due to the ease of extraction of products through fluvial means, this process occurred
repeatedly, unlike in the inner territory south of the river, where wood extraction was connected
to the penetration of roads from the interior of the country starting in the final two decades of the
20thCentury.

In that regard, the organization Friends of the Earth (Amigos de la Tierra) (2000), indicates that

in this border territory many families settled a long time ago: “many have been in possession of
these lands for over 60 years and they have established farms, edifications and roads.”

Ever since the 1980s the push of the ag ricultural frontier from the northern regions of the country
is beginning to transform this border forest area into pecuarian productive units mainly, despite
the difficult access, transforming slowly the diverse natural forest eco- system into agro -
pecuarian activities.

Nevertheless, not all sites in the area are adequate for agro -pecuarian activities, so that in some

areas the process of forest substitution did not proceed or actually fell back. Presently, a border
zone is observable with areas where agr o-pecuarian activities are dominant and other areas
where the natural forest eco -system dominates the landscape, the latter conditioned by the less
than favourable topographic conditions and fertility of the land.

In general terms, along the path designate d for Route 1856 flat or slightly undulating terrain is

dominant, although there are short stretches where these undulations are accompanied by local
steep slopes with solid ground that use to be covered, and may still be covered, by forests with
significant biodiversity.

On the other hand, towards the eastern sector of the Route, flat or slightly concave roads are
dominant, and in some sections these contain wetlands. These wetlands are small compared

with those located towards the east of the area under s tudy. However, because of their small
size, they are more open to alterations and transformations and are of great importance for the
capacity to contribute to biological diversification due to their distinct bio -physical conditions.

5.1.1.4 Current Plant Cover by Natural Association

The lowlands of the Northern Caribbean territory of Costa Rica constitute one of the priority sites
for biodiversity conservation in Mesoamerica. However, the landscape has suffered a strong

process of fragmentation that threatens con nectivity among natural protected areas in Costa
Rica and the southeast of Nicaragua (Chassot and Monge 2006).

Wetlands are under strong threat worldwide due to replacement activities and modification of the
landscape, despite the fact that they are dete rminant units in the ecosystems that regulate water
dynamics. On the other hand, wetlands are the home of a large quantity of flora and fauna,

especially birds that use these environments as part of their biological and ecological
requirements and as such can serve as indicators of the quality of eco -systems (CCT 2008).

In 1992, COSEFORMA estimated that only 5% of the original forest in the region remained
intact; forest extractive activities during the last decade have significantly reduced this
percentage. The present use of the land in this area consists of a variety of non sustainable uses
of the forests, alternating with cattle -raising and pineapple production, palm tree and root crops

in small scale. Some of the land cover types present in the area (Ch assot and Monge, 2006)
are:

a. High Altered Forests: It has poorly defined strata. Some common species are “caobilla”
(Carapa guianensis), “roble coral” ( Terminalia amazonica ), “jicaro” (Lecythys ampla),
“manú” ( Minquartia guianensis ), “fruta dorada” ( Virola hoshnyi), “pilón” (Hieronyma

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oblonga) and “areno” ( Qualea paraensis ); there are few palm trees in the understory

layer.

b. Riparian Forest: This forest is characteristic of the region with very large trees that
border the channels that connect with the lagoon s. Among these, the following stand out:
“Cativo” (Prioria copaifera), which forms pure clusters mainly at the entrance to Tambor
Channel, accompanied by “caobilla” ( Carapa guianensis ) and Ficus. The lowest layer in

this type of forest contains large numbe rs of Geonoma palms, as well as Heliconia; the
canopy has a large quantity of bromeliads and orchids.

c. Yolillo patches: Raphia taedigerra and Coroso oleifera, known as “Yolillo” form large
patches that may extend for several hectares and can be associated with “gavilán”
(Pentaclethra macroloba) and “sangrillo” ( Pterocarpus officinalis ).

d. Lagoon vegetation: Aquatic plants found in lagoons include Hymenocallis litoralis
(Amarillidaceae), Urospata grandis (Araceae), Aeschunomene sensitiva (Pailionacaeae),

Nepsera acuatica (Melastomatacea), Ludwigia sedoides (Onagaraceae) and Ciperaceae.

5.1.1.4.1 Recognized Natural Associations

Along the study area, studies recognize the presence of various ecosystems and ecological
associations, particularly some types of wetlands, where as forest associations in inland areas
are not recognized and are generally known simply as forests.

Within the wetland eco -systems in this area, the TSC (2008) points to the Maquenque lagoon
(palustrine wetland) and the Remolinito Grande lagoon (lacustrin e wetland). The Maquenque

lagoon has been greatly altered by human activity and is being used mostly as pasture lands, it
has almost no permanent water surface, only when it floods due to heavy rainfall.

Several Yolillo associations are identified which ar e palustrine wetlands without permanent water
surfaces, covered by a particular type of palm tree (Raphia taedigera). In addition, in the area
close to the direct impact area of the project (2 to 6 km. from the Route), other important
wetlands are located such as the Tambor and Colpachí lagoons, as well as the Canacas Yolillo

patch. These wetlands, although permanently flooded, are shallow, reaching at most a depth of
2.5 meters.

Of the different natural eco -systems identified partially within the area of R oute 1856, the
Maquenque Mixed National Wildlife Refuge has been subjected to the most research and
analysis. In 2008 the TSC described the importance of the sector as follows: The Maquenque

Refuge contains a series of complex lagoons that represent the we tlands of the region and are
an important part of the hydrological system, characterized by the presence of three great rivers:
San Juan, San Carlos and Sarapiquí rivers, which create natural limits to a large section of the
protected area, underscoring th e importance of the conservation of a unique eco- system that

protects a large number of species in danger or threatened by adverse effects that in many
cases are generated by human activities.”

Also, in the management plan proposed for the border biologica l corridor, Amigos de la Tierra
(2000) points among the ecosystems of national importance, apart from wetlands and yolillales,
to the less altered tropical forests, in reference to the forest association found between the
Tiricias and Cureña sector, as the most important remnant forests in the Huetar Norte region,

considered the ecosystems with the highest biodiversity index in the country (up to 140 species
of trees per hectare).

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The TSC (2008) states that the area of the study has an estimated 354 species of trees, in
addition to 107 species of vines and 380 species of epiphytes. This information refers to the area

of the Maquenque Refuge, which covers a area of the Route 1856 study, but stretches
extensively to the South of the border.

Chart3: Natural Associations recognized in the study area..

Association or
Presence in the DIA Presence in the IIA
Ecosystem

Palustrine wetland - !

Lacustrine wetland Limited !

Yolillal ! !
Riverine Systems ! !

Forest associations
! !
(4 types)

Source: Centro Científico Tropical, 2008.

In the case of forest associations, the TSC (1996) classifies three types of associations for a
region close to Route 1856: the flat lands primary forest, the primary forest on slopes, and the

secondary forest. T hese forest associations show important differences in their floristic
composition, diversity of species and bio -mass volume, among other aspects.

5.1.1.4.2 Plant Cover by Natural Association

At the time of this study, no quantitative data was found on the natural associations existing

along Route 1856. Due to the latter, the study conducted a classification effort of the main
associations present in the area of direct influence (DIA), according to some studies that offered
partial numbers. The methodology used was as follows.

5.1.1.4.3 Description of natural associations and its indicator species

The different natural associations are divided into primary forest on sloping terrain, secondary
forest on slopes, primary forests on flat lands or plains, and secondary flat lanSee Maps 10,
11, 12, 13, 14, 15 and Chart 4). It is important to point to the fact that 47% of the DIA shows

cover that is not natural, that is, it is altered lands, use d basically for cattle pastures since many
years ago.

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Chart4: Area occupied by natural assocaitions recognized in the DIA .

Natural Association Area in ha Proportion (%)

Primary forest on slopes 3.525,2 33,7

Secondary forest on slopes 202,0 1,9

Primary forest on plains 1.524,5 14,6

Secondary forest on plains 134,7 1,3

Yolillalo patch 149,7 1,4
Lacustrine Wetland 17,9 0,2

Palustrine Wetland 0,0 0,0

Altered Areas 4.921,3 47,0

Total 10.475,2 100,0

Source: Own Autorship.

a. Yolillo patch (Yolillal)

This ecosystem evolves on flat or concave flat terrain, which remains almost permanently
flooded. It is characterized by homogeneous floristic composition, where the dominant species is

the Yolillo palm ( Raphia taedigera) although in the less flooded areas are often found other
species such as the Corozo palm ( Coroso oleifera) and trees such as the “Gavilan”
(Pentaclethra macroloba ) and “Sangrillo” ( Pterocarpus officinalis ). The Yollilo patches are

palustrine sytems, but are separated from them because this association does not keep a visible
water surface as happens in various of the palustrine wetlands. It is a natural association not
found in abundance with the study area (1,4%).

b. Riverine systems

There exist in the area numerous rivers of different dimensions, as well as channels and creeks.

It is difficult to characterize arboreal indicator species, or those typical of these wetland
ecosystems, because they depend on the characteristics of the terrain loca ted on their margins,
so that in the majority of cases, the species are as diverse as the adjoining forests.

Nevertheless, some species are very common along the borders of these ecosystems:

“Sotacaballo” ( Zygiua confuse ), “gavilan” ( Pentaclethra macrolob a), “Caobilla” ( Carapa
guianensis), “fruta dorada” ( Virola spp), and in the eastern sector of the Route is found “Cativo”
(Prioria copaifera). Also common are pioneering species such as the “guarumo” ( Cecropia spp)

“Jobo” ( Spondias mombin), “Guabillo” ( Inga spp), “Chilamate” ( Ficus insipida ) and “B alsa”
(Ochroma pyramidale).

c. Lacustrine and palustrine wetlands

Both types of natural associations maintain common plant species, due to the fact that they are
lakes with a respective water surface. In their surro undings, in the case of lakes, Forestry Law

No. 7575 establishes an area of 50 meters in width as a protection zone around the water
surface, which in a natural manner constitutes a forest of diverse species.

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In the study area, these natural associations are few and occupy only 0,2% of the section
analyzed. Arboreal indicator species or species typical of these natural associations depend on
the characteristics of the terrain, in such a way that in the majority of cases the species found

are as diverse as the surrounding forests. Some of the more common species are found in the
following chart:

Chart5: Common or outstanding tree species in palustrine or lacustrine wetlands.

Common Name Scientific Name Common Name Scientific Name

Sota de Suampo Zygia confusa Aceituno Simarouba amara

Roble Coral Terminalia Amazonia Croton Croton smithianus

Gavilán Pentaclethra macroloba Colpachi Croton schiedeanus

Fruta Dorada Virola sebifera Manga Larga Laetia procera

Pejibayito Maranthes panamensis Cedrillo Tapirira guianensis

Eschweilera
Repollito costaricensis Fruta dorada Virola koschnyi

Eschweilera
Repollito panamensis Palma Conga Welfia regia

Botarrama Vochysia ferruginea Tamarindo Dialum guianense

Cespedesia
Mouriri Mouriri gleasoniana Tabacón de Suampo
macrophylla
Maquengue
Socratea exorrhiza Baco Couma macrocarpa
Amargo

Nace blanco Byrsonima crispa Cedro María Calophyllum
brasiliense

Cucaracho,
Laurel Muñeco Cordia bicolor Chiricano* Vantanea barbourii

Swartzia
Gallinazo Jacaranda copaia Maquenque maquenqueana

Sthryphnodendron
Vainillo Miconia Miconia punctata
microstachyum
Guabo Inga alba Hirtella Hirtella media

Carey* Elaeoluma glabrescens Casearia Casearia arborea

Source: Centro Científico Tropical. 2008, citing to: Salas, 2007 / *Species with some degree of vulnerability .

d. Forest associations

The forests in this region present a very high floristic diversity, which leads to the dominance of
some species in certain areas, depending mainly on physical and climatic factors s uch as rainfall
differences, soil conditions and topography.

In the following paragraphs the different recognized forest associations are described, as well as

the common species observed during field work. These are common to various associations but
they vary in terms of abundance or dimensions of the trees, so they are presented jointly. Four

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distinct types of natural forest associations are described which jointly cover some 51,4% (5,386

hectares) of the DIA.

i. Primary forest on flat lands
This type corr esponds to forest associations that evolved over plain or flat terrain and up to

slightly undulating terrain (0 -5% slope). In some cases these terrains have drainage problems.
The forest is tall and dense and its canopy may reach 40 to 45 meters in height. It has less
diversity of species as the primary forest found on sloping lands, but its trees have a greater
volume equivalent to 150 m ³/ha taking into account trees with 30 cm. In DBH height. It contains

some 420 trees greater than 10 cm/ha (CCT, 1996).

The same source indicates that at least for this sector the most outstanding species is the yellow
almond, which represents 50% of the volume. In similar manner, this species, along with
“Tamarindo” and “Caobilla” turn out to be the most common trees. This is an ecosystem that still
provides important cover (14,6% of the study area), despite the fact that much land was

deforested to introduce cattle grazing.
ii. Primary forest on sloping terrain

These forest associations are locate on hillsides and sloping terrain, with slopes of 5 to 80 %.

This is the most abundant natural association since it occupies more than one -third of the total
area analyzed (see Chart 2.). Its basic character is one of well -drained soils and low fertility with
clay texture soils and very high susceptibility to hydric erosion.

The forest is characterized by a medium height, with a canopy that reaches 35 to 40 meters, is
quite dense and very diverse in tree species. According to CCT (1996) this type of forest when
not altered contains some 115 me³ /ha (30 cm. in DBH), with some 660 trees per hectare, at 10

cm.DBH). The most common species is the “tamarindo”, while the largest in volume is the
“almendro Amarillo”. Palm trees are very abundant.

However, the volume, number of species and trees found in this type of forest is drastically
reduced when it has been exploited for lumber, with only half of the trees reaching girths beyond
10 cm..

iii. Secondary forest on flat l ands

These associations are forests of secondary growth which have evolved over flat lands, or
almost flat, in conditions similar to those described for primary forests. Their development,
density, height and species are very variable because they depend on the years of forest

recovery. Observations in the area suggest that these forests are few and young (5 to 20 years)
with tree heights that do not go beyond 20 meters. This study quantified only 135 hectares of
this type of association.

No information was obtained on the number of trees per hectare for this association, but in
relation to the primary f orest, it is estimated that this forest is less dense than the secondary

forest on sloping terrain , with some 350-500 trees/ha with DBH greater than 10 cm.
iv. Secondary forest on sloping terrain

Much like the previous type of forest, this ecosystem is v ery variable in structure and

composition, but slightly more abundant (1.9%) than the secondary f orest on flat land with
respect to area, and in some cases there are older units observable where it is possible to find
trees reaching 30 meters in height and approximately 30 years old.

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These forests are dense, with up to 600 trees/ ha (thicker than 10 cm. in DHB) and they also
display an important amount of tree species, depending on age and development.

Chart6: Common tree species in forest associations .

Common Name Scientific Name Common Name Scientific Name

Almendro
amarillo Dipteryx panamensis Aceituno* Simarouba amara

Roble Coral Terminalia Amazonia Algodoncillo* Croton smithianus

Gavilán Pentaclethra macroloba Pilón Hieronyma oblonga

Fruta Dorada Virola spp Manga Larga* Laetia procera

Almendro papayo Lecythis ampla Cedrillo Tapirira guianensis

Pterocarpus
Caobilla Carapa guianensis Sangrillo officinales

Tamarindo Dialium guianense Palma Conga Welfia regia

Botarrama Vochysia ferruginea Chaperno Lonchocarpus sp

Cespedesia
Ceiba Ceiba pentandra Tabacón macrophylla

Palmito Amargo Socratea exorrhiza Chilamate Ficus insipida

Calophyllum
Cebo Vochysia guatemalensis Cedro María
brasiliense

Botarrama Vochysia ferruginea Anonillo* Rollinia microsepala
Gallinazo* Jacaranda copaia Chumico Pouruma aspera

Sthryphnodendron
Vainillo Manga larga blanco* Casearia arborea
microstachyum

Guabo Inga alba Guanacaste blanco Enterolobium
schomburgkii

Escobo Terminalia bucidoides Peine de mico Apeiba
membranacea

Guácimo Luehea seemannii
colorado Ajillo Balizia elegans

Guarumo* Cecropia spp Balsa* Ochroma
pyramidale

Source: field observations, current s*: most abundant species in secondary forests

5.1.1.5 Indicator species by natural ecosystem.

As a result of deforestation during the last decades, the disappearance of natural cover, which
implies the disappearance of habitats, has led to the decrease in number of many animal and
plant species, among them species of high com mercial value for the lumber industry, including

important seed trees such as the mountain almond ( Dipteryx panamensis) (Chassot et al. 2001)

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Along the path of Route 1856 can be found complexly related wetlands associated with the

lower watershed fo the Sa n Juan River: Tamborcito, Tambor, Maquenque, Remolino Grande
and Colpachí wetlands. These contain a large quantity of aquatic plant species as well as birds
commonly found in wetlands such as the “jabirú” (Jabiru mycteria). The vegetation in these
lagoons is very valuable since it has a species composition that is only found in Caño Negro.

These wetlands are the habitat of fish and mammals such as “gaspar” ( Atractosteus tropicus )
and the Manatee or Sea Cow ( Trichechus manatus ), both of them endangered speci es. In
addition to the lagoons, “yolillo” patches are found along the Route which are often subjected to

burning and drainage by human actors (Monge et al. 2002).
Some indicator species of the natural ecosystem described are:

a. Great Green Macaw: this region is the priority nesting area f or the Great Green Macaw
(Ara ambiguus) (Powell et al. 1999) and it is key to the survival of the species, included in

the CITES Appendix I.

b. Manatee: Trichechus manatus has been observed in the wetlands by farmers throughout
the region, who are familiar with the sites where this species plays and reproduces in the
Tambor lagoon. This species is also found in the river bottom grasses of San Juan River.

c. Gaspar: Atractosteus tropicus is a living fossil that has a natural breedin g ground in the
lagoons system of the Maquenque Refuge which empties in San Juan River.

d. Jaguar: Panthera onca has been observed by neighbors in the region and its tracks are
commonly found specially in the neighbourhood of the Tamborcito and La Cureña

mountains. Frequently, there are reports of cattle being depredated specially along the
Border Corridor. Local residents have observed jaguars crossing the San Juan River into
the Indio-Maiz Biological Reserve.

e. Almendro: Dipteryx panamensis produces food for m any species, among them the
Great Green Macaw , a species that depends on this tree for nourishment (80%), as well
as nesting (90%).

f. Pinillo: Podocarpus guatemalensis is considered a threatened species. It is represented
by a number of specimens of great si ze which can be found in the forested hillsides close

to the Tambor lagoons.

5.1.1.6 Endemic species with reduced or threatened populations.

The current crisis that threatens species with extinction is born with colonization and occupation
of territories by human beings, who create forest fragmentation as one of the greatest negative
impacts. In the southeastern part of Nicaragua and the northern zone of Costa Rica, forest
fragmentation into patches, is a serious threat to ecological connectivity as well as to thegenetic

quality of biodiversity (Chassot et. al. 2001, Chassot et. al. 2002, Chassot et. al. 2006, Monge et.
al. 2000). Many species of flora and fauna depend on the conditions of these forest remnants,
among them the Great Green Macaw (Ara ambiguus ).The f ollowing are among the
representative emblematic species of the flora and fauna found in the study area:

Ara ambiguus

The Great Green Macaw , Ara ambiguus, is the second largest psitacid in the New World. Its
distribution is limited to low humid lands, main ly the forests of the Atlantic coast from Honduras

all the way to Colombia, and an isolated Pacific population in Guayaquil, Ecuador. It is

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recognized internationally as a threatened species, and in Costa Rica it is included in Appendix I
of the Convention on Commerce of Endangered Species (CITES).

Its historical reproductive area in Costa Rica has been reduced by 90%, mainly due to
uncontrolled lumber extraction and deforestation to introduce pasture lands during the second
half of the 20 thCentury, and is currently limited to the northern region of Costa Rica, with

greatest concentration in the area between the San Carlos, San Juan, Sarapiquí rivers, and the
northern slopes of the Central Volcanic Range.

The Bi -National El Castillo -San Juan -La Selva Biolog ical Corridor (Nicaragua -Costa Rica)
constitutes the last viable habitat of less developed land s that can maintain the Great Green
Macaw and a unique biodiversity area, by connecting more than twenty protected areas (Monge
et al. 2003).

Dipteryx panamensis

The mountain almond Dipteryx panamensis is a Fabacea (Leguminosae) whose distribution is

limited to the lower parts of the Atlantic Coast of Nicaragua (South), Costa Rica, Panama and
Colombia (Flores 1992). This is a tree that rises from the canopy foun d in humid and very humid
forests where the median annual temperature varies between 24º and 30º, and the median
annual precipitation is greater than 3500 mm. with elevations between 20 and 1000 meters

above sea level (masl).
It is considered to be abundan t in the northern region of Costa Rica (Flores 1992). Despite the

fact that it is a slow -growth tree in a natural environment, observations show that growth
response is greater in forest clearings, in forest borders and in grasslands with important
incidence of sunlight. The almendro tree reaches great height and always stands out in the

canopy, a condition that the Great Green Macaw uses to its advantage to build its nests in a safe
spot (see Map 16) in the wholes left by fallen branches (Flores 1992).

Of the more than 100 known Great Green Macaw nests that are currently potentially active, only
3 of them (3%) are located in the influence area of Route 1856, so that the impact of this project
on the Great Green Macaw population is considered irrelevant.

The almendro wood is extremely hard, nevertheless its use was not attractive until the mid
1980s due to its extremely difficult and costly extraction. As new technology led to the

development of steel saws with carbon content, and the use of diamond -point saws, these great
trees have begun to disappear from the landscape, thanks to the high mechanical resistance
and quality of its wood, which have turned the species into a highly priced lumber. The almond
tree constitutes 90% of nesting sites of the Great Green Macaw. Likewise, the tree provides 80%

of the parrot´s nourishment showing a dependent relationship between the two species: almond -
Great Green Macaw (Monge et al. 2003; Madriz 2004).

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Chart7: Main threatened species within the Route 1856 study area .

Class Common Name Scientific Name

Mammals Oso caballo Myrmecophaga tridactyla

Mono congo Alouatta palliata

Mono colorado Ateles geoffroyi

Nutría Lutra longicaudis

Jaguar Panthera onca

Manatí Trichechus manatus

Cariblanco Tayassu pecari

Danta Tapirus bairdii

Birds Galán sin ventura Jabiru mycteria

Águila solitaria Harpyhaliaetus solitarius

Águila crestada Morphnus guianensis

Águila arpía Harpia harpyja

Aguilillo blanco y negro Spizastur melanoleucus

Cacao Daptrius americanus
Halcón pechirrufo Falco deiroleucus

Pato cantil Heliornis fulica

Lapa verde Ara ambiguus

Lapa roja Ara macao

Momoto pico quilla Electron carinatum

Reptiles Cocodrilo Crocodylus acutus

Tortuga lagarto Chelydra serpentina

Fishes Gaspar Atractosteus tropicus

Source: Chassot et al. (2005).

a. Mammals

The tapir ( Tapirus bairdii ) and wild pigs persist in extensive flooded forested areas and Yolillo

patches. The “tepezcuintle” ( Agouti paca), the mountain goat ( Mazama americana ) and the
“cariblanco” pig (Tayassu tajacu) are common. Manatee ( Trichechus manatus ) and “jabalí”
(Tayassu pecari) populations have decreased dramatically.The following mammals found in the

region are included in Appendix I of CITES: Alouatta palliate, Ateles geoffroyi, Lutra longicaudis,
Panthera onca, Puma concolor, Trichechus manatus, and Tapirus bairdii (see threatened
species).

Mammals reported in Appendix II of the CITES list are: Cebus capucinus, Myrmecophaga

tridactyla, Bradypus variegates, Leopardus pardalis, Leopardus wiedii, Herpailurus yaguarondi,
Tayassu pecari, Tayassu tajacu.

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b. Birds

The following species in the study area are included in Appendix I of CITES (species that are
threatened or that may be affected by commercial interests): Harpia harpyja, Falco peregrinus,
Ara ambiguus, Ara macao, Falco deiroleucus, Spizastur melanoleucus, Daptrius americanus,
Morphnus guianensis, Jabiru mycteria, Heliornis fulica, Electron carinatum .

c. Fishes

The region is part of the icthious watershed of the San Juan River. The San Juan watershed,

which includes the San Carlos and Sarapiquí rivers, is a diverse and rich area in terms of fresh
water fish. This is related to the hydrographic structure whe re large rivers, streams and lagoons
connect to the San Juan River, the Caribbean Ocean and Lake Cocibolca. This explains the
presence of the bull shark ( Carcharrinus leucas ), “pargos” (Lutjanidae) and “roncadores”

(Haemulidae).

The following are common: p oecilides, characids (particularly Astyanax fasciatus ) and the
cyclids, “mojarras” and “guapotes”. The poecilides minnows are the most abundants: among
them the most common is Alfaro cultratusy . “Guapotes” are common ( Ciclasoma doviiy ,
Ciclasoma loiselle ), the “guapote tigre” ( Ciclasoma managuense ) and the “vieja” ( Ciclasoma

nicaraguense).

d. Reptiles and amphibians

The following are found in Appendix I of CITES:Chelidra serpentina , Crocodylus acutus .
Appendix II includesDendrobates pumilio, Dendrobates auratusandPhyllobates lugubris.

e. Flora

According to Friends of the Earth (2000), in the Border Corridor (2 km. wide): “populations of
nine species of trees are under threat of extinction, several flora species are threatened,
including at least four endemic species”. Of these four endemic tree species found along the
Corridor, three are reported to be found within the central section of the 1856 Route, al though

others are not dismissed.
Chart8: Endemic tree species reported for the study area.

Scientific Name Common Name

Dussia macroprophyllata sangregao

Sclerolobium costarricense tostado

Vochysia allenii botarrama

Source: Poyecto Río San Juan-Amigos de la Tierra(2000).

CCT (2008) mentions that “regarding the flora, the area houses an estimated 354 species of
trees, of which 28 are considered threatened and ten are endemic”. The previously stated
information refers to the Maquenque Refuge, which includes only a section of the Route 1856
study, but covers an extensive area to the S outh.

A study conducted in the area that represents the forest ecosystems between Border Marker 2

and the mouth of the San Carlos river, on the strip adjoining the San Juan River, (between 2 and
5 km. from the river), adjoining the Infiernito river, for an estmated area of 4,500 hectares, of
which some 3,000 are forested, 221 species of trees were identified, and it was estimated that
with further study, the number could reach 300 species for this region (CCT , 1996).

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This same source found that in this region there are 24 tree species considered threatened, rare
species or in danger of extinction and only one species was considered endemic to the country.
It is interesting that a large quantity of tree species are threatened or in danger of extinction.

These are basically commercial species found in the Costa Rica -Nicaragua border region, thus
turning this area into a refuge for endangered species. Following is a list of tree species under
different categories of threat.

Chart9: Tree species at risk.

Species Common Name Status Cause Altitude

1 Aspidosperma spruceanum amargo, caretigre limited

2 Tabebuia guayacan corteza, guayacán threatened HL 100 - 600

3 Ceiba pentandra ceiba threatened 50 - 300

4 Copaifera aromatica camíbar threatened HL 0 - 350

5 Cynometra retusa guapinol negro very limited 0 - 150

6 Prioria copaifera cativo threatened HL 0 - 150

7 Sclerolobium costarricense tostado endangered HL 50 - 700

8 Terminalia amazonia roble coral threatened 30 - 300

9 Terminalia oblonga surá, guayabón threatened 20 - 400

10 Dalbergia melanocardium bálsamo threatened 100 - 900

11 Dalbergia glomerata granadillo threatened 0 - 500

12 Dipteryx panamensis* almendro threatened

13 Dussia macroprophyllata sangregao threatened HL 0 - 600

14 Hymenolobium cola de pavo endangered HL 30 - 700
mesoamericanum

15 Platymiscium pinnatum cachimbo, cristobal endangered HL 0 - 600

16 Humiriastrum diguense chiricano alegre threatened HL 0 - 700

17 Vantanea barbourii chiricano triste threatened HL 0 - 800

18 Povedadaphne quadriporata ira rosa rare

19 Couroupita guianensis bala de cañon rare

20 Lecythis ampla olla de mono threatened HL 50 - 300

21 Ruptiliocarpon caracolito caracolito threatened 200 - 650
22 Carapa guianensis caobilla decreased 50 - 250

23 Cedrela fissilis* cedro real endangered HL 50 - 500

24 Cedrela odorata cedro amargo threatened HL 0 - 1200

25 Trichilia pittieri rare

26 Minquartia guianensis manú threatened HL 0 - 500

27 Podocarpus guatemalensis* cipresillo, pinilloendangered HL 50 - 1500

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Species Common Name Status Cause Altitude

28 Elaeoluma glabrescens carey threatened 50 - 300

29 Sideroxylon capiri danto amarillo threatened HL 0 - 900

30 Christiana africana piedra rare

31 Vochysia allenii botarrama rare/ E HL

32 Qualea paraensis areno threatened HL 100 - 850

Source: Centro Científico Tropical, 2008 , citing: Jiménez, 1993; Jiménez, 1997; Jiménez, com. pers., 2001; Sánchez -
Vindas et al., 1987; Quesada et al., 1997; Holdridge et al., 1997; Zamora et al., 2000. *: according to UICN.Status: E:
endemic,Cause HL: hábitat lossCI: intensive hunting or over fishing CO: polution

Despite the high degree of threat that weighs over a large number of lumber species in the
Northern Territory, only 5 species were identified whose use has been banned.

Chart10: Species officially under ban.

Species Common Name

Cedrela fissilis* Cedro real

Dipteryx panamensis** Almendro

Hymenolobium mesoamericanum* Cola de pavo

Podocarpus guatemalensis* Cipresillo, pinillo

Sclerolobium costarricense* Tostado
o
Source: * totally banned due to its critically endangered status, according N 25700-MINAE, 2008. ** In
CITES, Appendix III.

5.1.1.7 Fragility of Terrestrial Ecosystems .

The construction of Route 1856 could attract settlers to the region, generating pressure on the

existing services and i nfrastructure, as well as on the region´s natural protected areas. If this
becomes the case, it could imply that natural segments in wild lands could suffer greater
vulnerability due to the impact on natura l connecting areas, and to contamination due to h uman

activities.

The region where Route 1856 is located contains some characteristics common to frontier rural
areas along the Costa Rica -Nicaragua border. It has always been a region of difficult access; in
much of the territory access has been through fluvial means. In the case of Costa Rica, where

most of the means of collective use - infrastructure and services - have historically been provided
by the state, especially after the second half of the 20 thCentury, border regions have suffered an

almost total abandonment, remaining as “no man´s land”, where the benefits of infrastructure
and services are relative.

Tropical rainforests are fragile to a large extent due basically to their weak ecological
equilibrium. Moreover, many of these forests evolve on poor soils and are susceptible to erosion

when altered by human action. Nevertheless, primary forests ecosystems (not altered) are more
fragile when considering their susceptibility to sever damage when exploi ted for commercial

purposes, or worse, when cut down completely. Among the primary forest ecosystems present
in the area, the primary forest on sloping terrain is the most vulnerable, due to the fact that the

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elimination of plant cover leads to very strong erosion. Biodiversity in these ecosystems is

negatively affected when important numbers of trees and minor plant species disappear,
although the structure, volume of biomass and economic value of lumber species is also

affected, as well as species of faun a that are harder to quantify and value.

In the Route 1856 project area, there are few unaltered primary forests, since most of them were
subjected to lumber extraction during past decades. The CCT (1996) cites a study conducted
during the period mentioned in an area neighbouring the Route area, Crucitas sector and the

Infiernito river, where an analysis of 3,000 hectares of forest concluded that only 6% of the forest
had not been altered, where no trees had been cut or only 2 trees /hectare had been taken out.

In the same study, forest cover, volume and number of trees and species were analyzed and a
comparison was made between altered sites (where lumber extraction had take place) and

unaltered sites (primary). The study emphasized that the volume of lumbe r per hectare was
drastically reduced when comparing primary for ests in flat terrain (150 m ³/ha, with trees larger
than 30 cm. DBH) and altered forests (43 m ³/ha with trees larger than 30 cm. DBH). Similarly,

the number of specimens and species were decima ted and the structure of ecological
association was extremely altered.

In that regard, an analysis conducted of forests within the study area (between San Carlos and
Sarapiquí rivers) shows interesting data on the reduction in the number of tree species, o f 27%

when comparing primary forests with those that were altered for commercial lumbering purposes
in adjoining sites (see Chart 11).

Chart11: Variation in number of species and trees in condition different from logical Border Corridor)
in 0,25 ha plots, for trees thicker than 10 cm DBH.

o o
Forest Category N Species N Trees

Primary (not intervened) 63 189

74 198

70 180

65 199

65 160

Average 67 185

Primary intervened 55 121
53 118

48 124

46 119

47 108

Average 49 118

Secundary (25 years) 45 167

36 141

Average 40 154

Source: plot data from Proyecto Río San Juan-Amigos de la Tierra (2000).

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This shows in some way the susceptibility of these ecosystems, since this degradation of the
composition of the ecosystem remains for many decades and in some areas with sparse forest

this impoverishment of the forest may become irreversible.

Since this study does not have quantitative information and location for the non -altered primary
forest ecosystems, it i s assumed that forests characterized as primary are for the most part
altered forests. It was possible to observe that between the area of Tiricias and the Infiernito

river there is a non- altered primary forest, as well as forests on slopes located between Infiernito
and Chorreras. There are some forest remnants that are not altered between the Project and the
area of direct influence.

In the case of secondary forest ecosystems, they are considered of medium fragility given that in
their characteristic stat e of immaturity they represent more simple ecosystems and that with

elimination of plant cover, the natural processes tend to return to zero. Therefore, when a
secondary forest is eliminated, a secondary forest may be generated, whereas, it is difficult to
guarantee the restoration of a primary forest. In Chart 10 fragility is qualified for the distinct

ecosystems described here.

Even though wetlands generally are fragile ecosystems, especially when there are human
activities occurring in their surroundings , such as the process of settlements, roads, or farming
activities, it is concluded that for the area and its natural associations, Yolillo patches present the

most fragility because they are susceptible to being turned into pasture lands.
Chart12: Fragility of terrestrial ecosystems characterized for this study .

Ecosystem Fragility

Palustrine wetland Medium

Lacustrine wetland Medium

Yolillal patch High

Riverine systems (its protective riverbank) Medium

Primary forest on sloping terrain High

Primary forest on flat land High

Secondary forest on sloping terrain Medium
Secondary forest on flat land Medium

Source: CCT, 2013.

5.1.1.7.1 Ecosystems and tree species i mpacted by human activities in the a rea of Route
1856

The ecosystems that we re identified and determined to have been impacted by the construction
of Route 1856 were evaluated through a geographic information system using ecosystem cover s

(see Chart 13).

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Chart13: Area impacted for each ecosystem within th e project area.

Natural Ecosystem Area Proportion (%)
(hectares)

Primary forest on sloping terrain 59,6 17,0

Secondary forest on sloping 9,4 2,7
terrain

Primary forest on flat land 8,8 2,5

Secondary forest on flat land 5,5 1,6

Forest plantation (mature) 1,1 0,3

Yolillo patch 0,7 0,2

Lacustrine wetland 0,1 0,0

Agriculture and livestock uses 265,1 75,7

Total 350,2 100,0

Source: Map of ecosystems, this study.

Relevantly, 75% of the impacted project area was identified as used foragricultureand lives tock
activities, and was characterized by open pasture lands without trees. This translates into a low
percentage of natural areas intervened by the construction of the road and a low general impact.

To complete the information described previously, Annex 9.4 offers a list of threatened species

present in the Biological Border Corridor and the Maquenque Wildlife Refuge. Annex 9.5
contains a list of threatened species and species with low numbers , to be used in local
reforestation projects. Finally Annex 9.6shows a total list of tree species observed in the area of

Las Crucitas, San Carlos.

5.1.1.8 Impacted flora species

It has not been possible to determine the impacted flora species, nor to provide a geo -reference
for them, due to the lack of a prior inventory of the existing tree species.

5.1.2 Aquatic Environment (inland water bodies).

The description of the aquatic environment is divided into four main components: aquatic fauna,

riverine system description, threatened species and environmental fragility. Each one has
specific characteristics that differentiate them in terms of the methods applied and the definition
of the direct and indirect influence area.

Regarding the influence areas, for the aquatic component, the direct influence area of the

Project (DIA) was defined as all the area contained in the Route, the San Juan River basin and
all the bodies of water such as creeks, rivers, channels that traverse Route 1856. The area of
indirect influence (IIA) is defined as upstream waters for the bodies of water that are crosscut by

the Route, where it is possible that displacement of migratory aquatic species pr esent in the
region takes place.

In terms of the description of the aquatic environment, the project area was divided into three
sections: 1) From Border Landmark 2 to the mouth of the San Carlos river; 2) From the mouth of

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the San Carlos river to the Sarapiquí river confluence with the San Juan River; 3) from the
mouth of the Sarapiquí river to the site called Delta Costa Rica.

Border Landmark 2 - Mouth of the San Carlos river

This stretch starts in Border Landmark 2 of Route 1856 and ends at the point where the San
Carlos river empties into the San Juan River. In this stretch 28 tributary streams were identified
that empty into the San Juan River (see Map 17 and 18 ). Most of these are steams, channels or
small creeks. The larger affluent s are the Infiernito river, Caño Jardín and Caño Trinidad.

This stretch was identified as the most impacted due to the presence of several unstable

slanting retention wall that could create sedimentation, erosion and sediment plumes in the San
Juan and its tributaries.

Mouth of the San Carlos - the Mouth of Sarapiquí River

This stretch starts on the left margin of the mouth of the San Carlos river and ends where the
Sarapiquí River e mpties into the San Juan River. In this stretch nine water courses were
identified (see Maps 18, 19 and 20), 4 of them creeks without a name, and the remaining five,
the largest, are known as Caño Cureña, Cureñita, Tambor, Tamborcito, and C olpachí. Along

this stretch are found several sites with steep slopes and eroded retention walls, also red clay
soils, which suggested a category of low impact.

Mouth of the Sarapiquí - Delta Costa Rica

This stretch begins in the Sarapiquí River and ends at the site of D elta Costa Rica on the San
Juan River margin. No impacts were registered in this stretch. An extended segment of this
stretch is flat and with few unstable retaining walls. Three bodies of water were identified along
the stretch (see Map 20), one without n ame, a second one being a channel known as Caño

Tigre and the third one the Maria river.

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5.1.2.1 Aquatic Fauna

a. Vertebrates

Chart 14 presents a list of all species of fish (74), mammals (4), amphibians (7), reptiles (10) and

birds (42) that have been reported in the available literature about the study area. The chart
includes the family, common name, scientific name and th e distribution of the species.

b. Macroinvertebrates

Aquatic macroinvertebrates are defined as those that can be observed without instruments and
whose life cycle includes partial involvement with an aquatic environment. The

macroinvertebrate aquatic communit y is composed of diverse invertebrate groups such as
worms, leeches, molluscs, crustaceans, acaroids and mainly juvenile states of several orders of
insects. In Chart 15 presents a list of aquatic macro -invertebrates taxa that have been collect in

previous studies close the project area. It reports 93 genera, 73 families, 21 orders, 9 claes and
5 phyla.

c. Phytoplancton

Phytoplancton is formed by live organisms of vegetal origin (algae) that live in a body of water,
floating on a water column or remained adhe red to diverse substrate such as vascular plants, on
other algae and on animals. Algae are autotrophic organisms capable of performing

photosynthesis. Their importance is fundamental given the fact that they are the most important
primary producers in aquatic ecosystems.

Chart 16 presents a list of some genera and species that have been reported in previous studies
conducted in eight tributary rivers of the San Juan River which includes the San Carlos and

Sarapiquí rivers (upstream and in the mouth). The study reported 65 genera and 54 species
belonging to the following groups: Chlorophyta (28), Bacillariophyta (21) Cyanophyta (9),
Euglenophyta (3), Dinophyta (2), and Cryptophyta (2).

Chart14: List of aquatic fauna recorded for the project area and surroundings.

Common
Family Species Name Distribution in the area

Fishes
Anguillidae Anguilla rostrata Anguila Ríos de la zona norte

Atherinidae Atherinella chagresi ** Sardina Vertiente atlántica

Tributarios del sistema
!! Atherinella hubbsi Sardina fluvial del río San Juan, lago
Nicaragua

!! Atherinella milleri Sardina Cuenca del río San Juan
Lago Nicaragua, río San
!! Atherinella sardina Sardina Juan *

Carangidae Caranx latus Jurel Vertiente atlántica,
Tortuguero
!! Oligoplites palometa Pez cuero Río San Juan, río Sarapiquí

Madrecazón, Lago de Nicaragua, río San
Carcharhinidae Carcharhinus leucas Juan, río San Carlos, río
Tiburón Toro Puerto Viejo y río Sarapiquí

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Common
Family Species Distribution in the area
Name
Barra de Colorado, San
Centropomidae Centropomus parallelus Calva Juan, Río Infiernillo, lago de
Nicaragua

!! Centropomus pectinatus Gualaje Vertiente atlántica
Atlántico

!! Centropomus undecimalis Robalo Vertiente atlántica
Sardina,
Plateada, Vertiente Atlántica (ubicua),
Characidae Astyanax aeneus
Colirroja, lago de Nicaragua
Golosa
Lago de Nicaragua, río San
Astyanax nasutus Sardina Juan y sus tributarios, río
!! lagunera
Colorado, Tortuguero
Sardina Vertiente Atlántica, lago de
!! Bramocharax bransfordii picuda Nicaragua, río San Juan

Characidae Brycon guatemalensis Machaca, Vertiente Atlántica, río San
Sabalete Carlos, río Sarapiquí
Bryconamericus Sardina de Vertiente Atlántica, río San
!!
scleroparius quebrada Juan
Lago de Nicaragua, sistema
!! Carlana eigenmanni Sardinita fluvial del río San Juan

Hyphessobrycon Vertiente Atlántica,
!! tortuguerae Sardinita tributarios del río San Juan,
río Tortuguero
Sardinita,
Vertiente Atlántica, río
!! Roeboides bouchellei Alma seca, Sarapiquí
Changuito
Lago de Nicaragua, río San
Cichlidae Amphilophus citrinellus Mojarra Juan hasta río Matina.

Amphilophus labiatus Mojarra Lago de Nicaragua, río San
!! Juan *
Zona norte, vertiente
!! Asthatheros alfari Mojarra
atlántica, Río Puerto Viejo
Cholesca,
!! Asthatheros longimanus Carate, Río San juan y tributarios,
lago de Nicaragua
Pecho rojo
Lago de Nicaragua y
!! Asthatheros rostratus Masamiche sistema fluvial del río San
Juan hasta el río Matina

Vertiente Atlántica, lago de
!! Archocentrus centrarchus Mojarra Nicaragua, río San Juan y
sus tributarios

Archocentrus Congo,
!! Zona norte y atlántica
nigrofasciatus Carate, Burra

Archocentrus Vertiente atlántica entre el
!! septemfasciatus Mojarra sistema del río San Juan y
cuenca del río Banano

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Common
Family Species Distribution in the area
Name
Cholesca, Lago de Nicaragua, zona
!! Herotilapia multispinosa Mojarrita norte y vertiente atlántica

Lago de Nicaragua, sistema
Moga fluvial del río San Juan y
!! Hypsophrys nicaraguensis amarilla tributarios hasta la cuenca
del río Matina

Lago de Nicaragua y los
Cichlidae Neetroplus nematopus Moga tributarios del río San Juan.

Vertiente atlántica, zona
Parachromis dovii Guapote, norte río Puerto Viejo de
!! Lagunero Sarapiquí y lago de
Nicaragua

!! Parachromis friedrichsthalii Guapote Río San Juan *
Guapotito,
Zona norte, Vertiente
!! Parachromis loisellei Guapote atlántica
amarillo
Guapote
Lago de Nicaragua,
!! Parachromis managuensis tigre, vertiente atlántica y río San
Guapote
barcino Carlos

!! Theraps underwoodi Vieja, moga Vertiente atlántica, zona
verde, Tuba norte, río Sarapiquí
Pis pis,
Vieja maculicauda Palometa, Vertiente atlántica, zona
!! norte
Vieja
Lago de Nicaragua, río San
Juan, río Colorado, boca del
Clupeidae Dorosoma chavesi Sabalete
río Sarapiquí, lago Caño
Negro y Tortuguero,
Guarasapa, Vertiente atlántica, zona
Eleotridae Dormitator maculatus
Pipón norte
Pez perro,
!! Eleotris amblyopsis Guabina, Vertiente atlántica, zona
Lucia norte

Vertiente atlántica, zona
!! Eleotris pisonis Pez perro norte, río San Juan

!! Gobiomorus dormitor Guavina, Vertiente atlántica, zona
Bocón norte, río Sarapiquí
!! Hemieleotris latifasciatus Guavinita Río San Juan y zona norte

Mojarra Lago de Nicaragua, río San
Gerreidae Eugerres plumieri prieta,
mojarra fina Juan

Gobiesocidae Gobiesox nudus Chupapiedra Río Sarapiquí
Vertiente atlántica, zona

Gobiidae Awaous banana Lamearena norte, río Sarapiquí, río San
Carlos
Chupapiedra, Vertiente atlántica, zona
!! Sycydium altum
Tití norte

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Common
Family Species Distribution in the area
Name
Gymnotidae Gymnotus cylindricus Barbudo Río San Juan *

!! Gymnotus maculosus Madre de Tributarios del río San Juan,
barbudo ríos San Carlos y Sarapiquí
Río Sarapiquí, río San
Haemulidae Pomadasys crocro Roncador Carlos

Lago de Nicaragua, río San
Juan y tributarios, San
Lepisosteidae Atractosteus tropicus Gaspar, Gar Carlos, Tortuguero y lago
Caño Negro

Lago de Nicaragua y los
tributarios del río San Juan
Megalopidae Megalops atlanticus Sábalo Real en la zona norte, río Puerto

Viejo, río Sarapiquí, río San
Carlos y río Peñas Blancas.
Mugilidae Agonostomus monticola Tepemachín Zona norte, río San Carlos

Vertiente Atlántica, río San
!! Joturus pichardi Bobo Carlos, río Sarapiquí

Pimelodidae Rhamdia guatemalensis Barbudo Vertiente Atlántica
!! Rhamdia nicaraguensis Barbudo Vertiente Atlántica

Vertiente Atlántica,
!! Rhamdia rogersi Barbudo tributarios del río San Juan

Poeciliidae Alfaro cultratus Olomina Vertiente atlántica
Pepesca Vertiente Atlántica, lago de
!! Belonesox belizanus gaspar Nicaragua, río Tortuguero

!! Brachyrhaphis holdridgei Olomina Vertiente Atlántica, río San
Carlos
Vertiente Atlántica, río San
!! Brachyrhaphis parismina Olomina
Juan
!! Gambusia nicaraguensis Olomina Vertiente atlántica

!! Neoheterandria umbratilis Olomina Lago de Nicaragua,
vertiente atlántica
Poeciliidae Phallichthys amates Olomina Zona norte y atlántica

Phallichthys tico Olomina Lago de Nicaragua y en
!! tributarios del río San Juan.

!! Poecilia gillii Olomina Vertiente atlántica
!! Poecilia mexicana Olomina Vertiente atlántica

!! Poecilia sphenops Olomina Río San Juan *
Vertiente atlántica,

!! Priapicththys annectens Ω Olomina tributarios del lago
Nicaragua
Pez sierra, Río San Juan, lago de
Pristidae Pristis pectinata Peje peine Nicaragua *

Pez sierra, Río San Juan, lago de
!! Pristis perotteti Peje peine Nicaragua *

!! Pristis pristis Pez sierra, Afluentes del río San Juan
Pejesierra en la zona norte

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Common
Family Species Distribution in the area
Name
Río Sarapiquí, lago de
Rivulidae Rivulus isthmensis Olomina Nicaragua, vertiente
atlántica

Anguila de
Synbranchidae Synbranchus marmoratus pantano, Zona norte
anevila

Syngnathidae Pseudophallus mindii Pez pipa Zona norte y atlántica
Mammals

Nutria, Perro Vertiente del caribe, río
Mustelidae Lontra longicaudis de agua Sarapiquí

Trichechidae Trichechus manatus Manatí, Vaca Vertiente del caribe, río San
marina Juan
Tapiridae Tapirus bairdii Tapir, Danta Vertiente del caribe

Didelphidae Chironectes minimus Zorro de Vertiente del caribe
agua

Amphibians
Bufonidae Bufo haematiticus !! Vertiente atlántica

Vertiente atlántica, parte alta
!! Bufo valliceps !! de la cuenca del río San
Juan

Leptodactylidae Leptodactylus !! Vertiente atlántica
melanonotus
Vertiente atlántica, parte alta
!! Leptodactylus labialis !! del río San Juan

Eleutherodactylus Vertiente atlántica, río San
!! bransfordii !! Juan

Ranidae Rana taylori !! Vertiente atlántica
!! Rana vaillanti !! Vertiente atlántica

Reptiles

Iguana,
Iguanidae Iguana iguana Iguana verde Vertiente atlántica

Lago de Nicaragua, cuenca
Colubridae Thamnophis marcianus !! del río San Juan

Thamnophis proximus Cuenca del río San Juan y
!! !! río Colorado
Culebra de
Tretanorhinus
Dipsadidae nigroluteus*** manglar Vertiente atlántica
quilada
Tortuga
Kinosternidae Kinosternon leucostomum Vertiente atlántica
amarilla
Tortuga
Chelydridae Chelydra serpentina lagarto Vertiente atlántica

Geoemydidae Rhinoclemmys funerea Tortuga Vertiente atlántica
negra del río

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Common
Family Species Distribution in the area
Name
Vertiente atlántica, lago de
Emydidae Chrysemys ornata Tortuga Nicaragua, cuenca del río
resbaladora San Juan

Crocodylidae Caiman crocodilus Caiman, Vertiente atlántica, río San
Lagarto Juan
Cocodrilo,
Vertiente atlántica, río San
!! Crocodylus acutus Lagarto Juan
negro
Birds

Martín
Alcedinidae Ceryle alcyon pescador Vertiente del Caribe
norteño

Martín
!! Ceryle torquata pescador Vertiente del caribe
collarejo

Martín
!! Chloroceryle aenea pescador Vertiente del caribe
enano

Martín
!! Chloroceryle amazona pescador Vertiente del caribe
amazónico
Martín

!! Chloroceryle inda pescador Vertiente del caribe
vientrirrufo
Anatidae Anas acuta Pato rabudo Vertiente del caribe

!! Anas clypeata Pato cuchara Vertiente del caribe

Cerceta
!! Anas crecca aliverde, Vertiente del caribe
Zarceta
Cerceta
!! Anas cyanoptera Vertiente del caribe
castaña
Cerceta
!! Anas discors aliazul, Vertiente del caribe

Zarceta
Porrón
!! Aythya affinis menor Vertiente del caribe

!! Aythya callaris Porrón Vertiente del caribe
collarejo

!! Cairina moschata Pato real, Vertiente del caribe
Pato perulero

Pijije común,
!! Dendrocygna autumnalis Piche Vertiente del caribe

Pijije
!! Dendrocygna viduata cariblanco, Vertiente del caribe
Piche careto

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Common
Family Species Distribution in the area
Name

!! Oxyura dominica Pato Vertiente del caribe
enmascarado

Pato aguja,
Anhingidae Anhinga anhinga aninga Vertiente del caribe

Garza
Ardeidae Agamia agami Vertiente del caribe
pechicastaña

!! Ardea herodias Garzón Vertiente del caribe
azulado
Avetoro,
Ardeidae Botaurus pinnatus Puncus, Vertiente del caribe

Mirasol
Garcilla
verde,
!! Butorides striatus Vertiente del caribe
Chocuaco,
Martín peña
Garceta
!! Casmerodius albus Vertiente del caribe
grande
!! Egretta caerulea Garceta azul Vertiente del caribe

!! Egretta thula Garceta Vertiente del caribe
nivosa
Garceta
!! Egretta tricolor Vertiente del caribe
tricolor
Garza tigre,
!! Tigrisoma fasciatum Martín peña, Vertiente del caribe
Pajaro Vaco

Garza tigre,
!! Tigrisoma lineatum Martín peña, Vertiente del caribe
Pajaro Vaco

Garza tigre,
!! Tigrisoma mexicanum Martín peña, Vertiente del caribe
Pajaro Vaco

Ciconiidae Jabiru mycteria Jabiru Vertiente del caribe
Cigüeñon,

!! Mycteria americana Garzón, Vertiente del caribe
Guairón
Perrito de Vertiente del caribe,

Heliornithidae Heliornis fulica agua, Corredor Biológico San
Toboba Juan - La Selva

Cormorán,
Pato
Phalacrocoracidae Phalacrocorax olivaceus chancho, Vertiente del caribe

Pato de agua

Zambullidor

Podicipedidae Podilymbus podiceps Piquipinto, Vertiente del caribe
Pato de agua

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Family Species Common Distribution in the area
Name
Zambullidor

!! Tachybaptus dominicus Enano, Vertiente del caribe
Patillo, Pato
de agua

Rallidae Amaurolimnas concolor Rascón café Vertiente del caribe
Rascón
!! Aramides cajanea cuelligrís Vertiente del caribe

Agujeta
Scolopacidae Limnodromus scolopaceus silbona, Vertiente del caribe
Piquilarga

Tringa solitaria Andarríos Vertiente del caribe
!! solitario

Threskiornithidae Eudocimus albus Ibis blanco, Vertiente del caribe
Coco
Mesembrinibis Ibis verde,
!! cayennensis Coco negro Vertiente del caribe

Plegadis chií Ibis Vertiente del caribe
!! cariblanco
Ibis morito,
!! Plegadis falcinellus Vertiente del caribe
Coco negro

Source: (Fishes: Bussing, 1976 *; Bussing, 1998; Rojas, 2002 **; Espinoza, 2008; INBIO, 201mmals: Carillo et
al., 2002; Amphibians and Reptiles: Savage, 2002; Birds: Style & Skuth 1989).

Chart15: List of aquatic macroinvertebrate taxa for the project area and surroundings .

Phylum – Class Order Family Taxon ***

Arthropoda
Arachnida Trombidiformes Fam. indet.

Insecta Coleoptera Curculionidae

Dryopidae *** Dryops

Elmoparnus

Dytiscidae ***

Elmidae Cylloepus

Heterelmis

Macrelmis

Microcylloepus

Neoelmis

Phanocerus

Gyrinidae Gyrinus

Hydrophilidae *** Tropisternus

Hydroscaphidae

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Phylum – Class Order Family Taxon ***

Psephenidae Psephenus

Ptilodactylidae Anchytarsus

Scirtidae ***

Staphilinidae ***

Diptera Blephaceridae Paltostoma

Ceratopogonidae

Chironomidae Chironomus

Xestochironomus

Chironominii

Orthocladinae

Tanypodinae

Culicidae *** Anopheles

Culex

Diptera Empididae

Muscidae

Psychodidae *** Maruina

Simulidae * Simulium

Tabanidae ***

Tipulidae Hexatoma

Limonia

Ephemeroptera Baetidae Americabaetis
Baetodes

Callibaetis

Camelobaetidius

Cloeodes

Caenidae Caenis

Heptagenidae *** Stenonema

Leptohyphidae Asioplax

Epiphrades

Leptohyphes

Tricorythodes

Vacuperinus

Leptophlebiidae Farrodes

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Phylum – Class Order Family Taxon ***

Terpides

Thraulodes

Traverella

Ulmeritoides

Polymitarcyidae

Hemiptera Gerridae

Veliidae Rhagovelia

Belostomatidae *

Hebridae Hebrus

Naucoridae *** Cryphocricos

Limnocoris

Hemiptera Mesoveliidae *** Mesovelia

Nepidae *** Ranatra

Notonectidae *** Buenoa ?

Odonata Aeshnidae *

Calopterygidae Hetaerina

Coenagrionidae Acanthagrion

Argia

Leptobasis

Telebasis

Megapodagrionidae *** Heteragrion
Platystictidae *** Palaemnema

Protoneuridae ***

Gomphidae Agriogomphus

Desmogomphus

Erpetogomphus

Phyllocycla

Phyllogomphoides

Libellulidae Brachymesia

Brechmorhoga

Dythemis

Erythemis

Erythrodiplax

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Phylum – Class Order Family Taxon ***

Macrothemis

Miathyria

Nephepeltia

Pantala

Perithemis

Tramea

Protoneuridae *

Trichoptera Calamoceratidae Phylloicus

Helicopsychidae *** Helicopsyche

Glossosomatidae *** Protoptila

Culoptila

Hydropsychidae Leptonema

Macronema

Macrostemum

Smicridea

Hydroptilidae Alisotrichia

Zumatrichia ?

Leptoceridae Nectopsyche

Oecetis

Triplectides

Limnephilidae
Odontoceridae

Philopotamidae Chimarra

Polycentropodidae Polycentropus

Megaloptera Corydalidae *** Corydalus

Chloronia

Plecoptera Perlidae Anacroneuria

Lepidoptera Crambidae * Petrophila

Blattodea Blaberidae *** Epilampra?

Malacostraca Decapoda Palaemonidae Macrobrachium**

Macrobrachium carcinus **

Macrobrachium acanthurus **

Macrobrachium olfersi **

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Phylum – Class Order Family Taxon ***

Atyidae ** Potimirin

Pseudothelphusidae

Isopoda

Ostracoda Podocopida Candonidae

Ord. indet. Fam. indet.

Mollusca

Bivalvia Unionoida Unionidae

Gastropoda Basommatophora Ancylidae ***

Lymnaeidae *

Physidae

Planorbidae ***

Mesogastropoda Cyclophoridae

Neotaenioglossa Hydrobiidae

Naticidae

Monoplacophora Ord. indet. Fam. indet.

Nematoda

Clase indet. Ord. indet. Fam. indet.

Annelida

Clitellata Rhynchobdellida Glossiphoniidae

Haplotaxida Naididae *

Fam. indet.

Platyhelminthes

Turbellaria Tricladida Planariidae ***

Source: Fenoglio et al., 2002 *; Lara, 2006 **; Springer, 2008 ***; Salvatierra et al., 2013.

Chart16: Listof phytoplancton species recorded for the San Juan tributaries.

Division / Species Division / Species Division / Species

Cyanophyceae Navicula cuspidata Dictyosphaerium sp.

Anabaena sp. Navicula sp. Gonium sp.

Anabaenopsis raciborskii Nitzschia acicularis Kichneriella obesa

Anabaenopsis sp. Nitzschia palea Kirchneriella lunaris

Chroococcus giganteus Nitzschia sigmoidea Kirchneriella sp.

Chroococcus limneticus Nitzschia sp. Micrasterias foliacea

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Division / Species Division / Species Division / Species

Chroococcus sp. Pinnularia dactylus Micrasterias furcata

Chroococcus turgidus Pinnularia mayor Micrasterias radiosa

Gomphosphaeria sp. Pinnularia nobilis Monoraphidium skujae

Lyngbya contorta Pinnularia sp. Monoraphidium sp.

Lyngbya limnetica Pleurosigma sp. Oocystis lacustris

Merismopedia elegans Rhizosolenia sp. Oocystis sp.

Merismopedia sp. Rhopalodia sp. Pandorina sp.

Microcystis aeruginosa Stauroneis acuta Pediastrum duplex

Microcystis sp. Surirella biseriata Pediastrum simplex

Oscillatoria sp. Surirella linearis Pediastrum tetras

Spirulina sp. Surirella sp. Pseudostaurastrum lobulatum

Surirella turgida Scenedesmus acuminatus

Bacillariophyta Synedra rupens Scenedesmus quadricauda

Achnanthes sp. Tabellaria sp. Scenedesmus sp.

Amphipleura lindheimeri Terpsinoe musica Shroederia sp.

Asterionella sp. Spirogyra sp.

Aulacoseira ambigua Chlorophyta Staurastrum sp.

Aulacoseira distans Actinastrum sp. Tetraedron regulare

Aulacoseira granulata Ankistrodesmus bernardii Tetraedron sp.

Aulacoseira islandica Ankistrodesmus sp. Tetrastrum sp.

Aulacoseira subarctica Botryococcus braunii Treubaria sp.
Cyclotella pseudostelligera Chlamydomonas sp.

Cyclotella sp. Chlorella sp. Euglenophyta

Bacillariophyta Chlorophyta Euglenophyta

Denticula sp. Chlorolobion braunii Euglena acus

Eunotia asterionelloides Chlorolobion sp. Phacus sp.

Eunotia sp. Chodatella sp. Trachelomonas sp.

Fragilaria crotonensis Closterium sp.

Fragilaria pinnata Coelastrum sp. Cryptophyta

Fragilaria sp. Cosmarium connatum Cryptomonas sp.

Fragilaria ulna Cosmarium margaritiferum Rhodomonas sp.

Gomphonema sp. Cosmarium sp.

Melosira italica Crucigenia sp. Dinophyta

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Division / Species Division / Species Division / Species

Melosira sp. Desmidium aptogonum Gymnodinium sp.
Navicula cryptocephala Desmidium sp. Peridinium sp.

Source: Chow, (s.f.).

5.1.2.2 Characterization of the Riparian System .

The fluvial and riparian systems are intimately and directly related to the terrestrial environ ment

(Peterjohn and Correl, 1984; Talley et al. 2006). T he riverbank area contains the inter phase
between liquid and solid, a characteristic of the most productive ecosystems (Doppelt et al.
1993; Pringle 2006). The riverbank vegetation is an important com ponent of a watershed
because it provides a significant percentage of the nutrients that reach the river´s alimentary

network and the load of epirreica water (epi -continental) and hiporreica ( underground coastal
current).

Even under extreme conditions and extensive periods of dry climate these corridors always
maintain a prosperous vegetation. They are very valuable systems for the surrounding
environment (Laurance 2004; Mata and Quevedo 2005). It is of basic importance to regulate

strictly any variation t hat must be effected on the normal flux of the channels, streams and
creeks in the study area (Chassot et al. 2006, 2010).

Riparian ecosystems of the study area are characterized by a marked presence of species such
as the “sotacaballo” (Zygdia confuse), “gavilan” (Pentaclethra macroloba), “poponjoche” ( Pachira
acuatica) and “caobilla” ( Carapa guanensis ). Also common are pioneering species such as the

“guarumo” ( Cecropia spp ) and the “balsa” ( Ochroma pyramidale ). In the ecosystems or
associations of “Yolillo” the dominant tree is the Yolillo palm ( Raphia taedigera) (CCT, 2008).

The riparian forest is characteristic of the region, with very large trees that border the channels
leading to the lagoons, with a very attractive species called “cativo” ( Prioria co paifera) which
forms very pure hoops above all at the entrance to Caño Tambor. These are accompanied by

“caobilla” and ficus. The undergrowth here is constituted by mas ses of palm trees of the genus
Geonoma as well as Heliconia. The canopy has a great quan tity of bromeliads and orchids.

5.1.2.3 Indicator Species.

An indicator species is an organism that has been selected for its sensibility or tolerance to
diverse types of contamination and alteration or to its effects within the organism´s habitat. The
response of biological indicators is founded on their capacity to respond in an integrated manner

to the effects of eventual or permanent perturbances in the environme nt where they grow and
develop.

In aquatic environments generally there is no assessment of the con dition of a species, instead it
is performed on groups of organisms or the structure of the community; outstanding among
these are the aquatic macro -invertebrates (Res and Jackson 1963; Segnini 2003). The structure

of a community depends on the compositio n and abundance of the species that form it. In
general terms it is safe to say that the structure of the aquatic community reflects the historical
factors and environmental conditions that prevail there (Resh and Jackson, 1993).

Aquatic macroinvertebrates are considered to be appropriate bio -indicators of the quality of
water, followed by algae, fish and macrophytes, due to the fact that they are sensitive to the

contamination and respond rapidly to changes in structure of the community; they are easily

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identified and sampled; they are abundant and have a cosmopolitan distribution; they are
relatively sedentary and thus are representative of the area where they are collected, and can be
used to estimate biotic index es (Roldan 2003; Segnini 2003).

Biotic indexes are fast and simple methods that are utilized habitually in biological monitoring to

evaluate the quality of water using aquatic macro -invertebrates as bio -indicators (Roldan 2003).
Used in Costa Rica, the BMWP -CR (Biological Monitoring Working Party modified for Costa
Rica) assigns points to the families according to the tolerance of different groups to

contamination. The total value of the index is obtained by adding the points for each family,
independently of abundance or diversity (MINAE- S 2007).

The collection of aquatic macro -invertebrates to determine the structure of the aquatic
community and calculate the BMWP -CR index is done through a standardized sampling
methodology of multi -habitat macro-invertebrates with the use of a “D” net and a net l ight of 0,5

mm. (Photograph 1).

At each sampling site the types of micro -habitats and substrata are identified to collect
organisms and the collection is done over a total effort of 1 hour. All collected material is
identified and stored in plastic contai ners and preserved in 70% alcohol.

The collected organisms are identified with the use of taxonomic keys (Merritt et al ., 2008;
Springer et al. 2010; Pacheco Chaves 2010; Oceguera -Figueroa and Pacheco Chaves 2012) up

to the maximum taxonomic level possible (mostly up to the level of genera). The material
identified is deposited in the aquatic insect collection of the Zoology Museum of the University of
Costa Rica.

Photograph1: Collection of aquatic
macroinvertebrates acuáticos with “ D”
net. Route 1856, 2013.

5.1.2.3.1 Description of study sites
In order to assess the effects of the construction of Route 1956 on the aquatic ecosystems that

cut across the road and empty into San Juan River, 10 lotic bodies of water (creeks, channels
and rivers) were selected, the structure of the communities was characterized and the quality of

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water was evaluated calculating the MWP -CR index (MINAE-S, 2007) making use of the aquatic

macro-invertebrates group as indicator species.

In each of the bodies of water two sampling points were located, one upstream (no direct
influence) where the road crosses the body of water, and another one downstream (direct
influence) for a total of 20 sampling points.

Data on the sampling locations is identified as geograp hic coordinates (decimal degrees, Datum
WCS 84). The type of water course of all rivers identified and sampled along the Route project is
low- taking into account their location in the watershed - and all rivers end in the San Juan River.

Chart 17 describes the sites and points sampled for the study.

5.1.2.3.2 Structure of aquatic macroinvertebrates communities

The Project area is represented by 73 genera, 58 families and 21 orders (see Annex 9.4) of a
total of 957 collected specimens, whose distribution and abundanc e is determined by the kind of
habitat in the region. The most abundant orders and families were Ephemeroptera (Baetidae,

Lepthophlebiidae and Leptohyphidae), Hemiptera (Notonectidae) and Diptera (Chironomidae).
The families with the greatest diversity of genera were Baetidae (Ephemeroptera), Gerridae
(Hemiptera) and Elmidae (Coleoptera) with 5 genera each (see Annex 9.4)

Some of the macro -invertebrate genera collected in this study were species within the different
categories of the Red List of the Interna tional Union for Conservation of Nature (IUCN). Among
them are found lobsters ( Machrobrachium genus) and dragon flies (most genera, except

Agriogomphus). It should be clarified that identification of most organisms did not reach the level
of species, given the difficulties implied in such a process.

Several of the collected organisms were found in larval stage and for these there are no
taxonomic keys a the species level; moreover, there are larval stages that have not been
described so that the determinat ion of whether the collected specimen belongs in the red list is a

difficult task.
Of the total macro-invertebrate taxa collected, at least 23 could be considered as not common or

of restricted distribution in the country (based on comparisons of the mate rials found in the
Aquatic Entomology collection of the Zoology Museum of the University of Costa Rica). This
number corresponds to a third part of the collected taxa, which is a considerable fraction,
demonstrating that this region of the country has not been sampled extensively or at least not as

much as other regions.

In general, the aquatic community of most sites sampled had a very low diversity and richness of
taxa. This results is probably due to three reasons: stream size, turbidity -sedimentation and type
of substrate. In rivers of low areas, turbidity values are high as a consequence of sediment drag
from medium and upper parts of the watershed, which turns river bottom substrates unstable

(Minshall, 1984; Williams and Felmate, 1992; Roldan and Ramirez, 1984). Sediments such as
clay and fine sand can alter the movement of water, the quality of nutrients, the availability of
oxygen and interstitial spaces, significantly altering the habitat in a substrate (Minshall, 1984)

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589Annex 10

. . .
on

branchesh

Murky water

.asture and cattle pastures on sunny.
cological Component underwater roots.
E cloudy.
– Comments logs, underwater roots and branches and

condition: sunny.

Weather Underwater pasture and scrublands Weather condition:
.
Environmental Diagnosis Assessment (EDA)
Weather condition:

PreCsleebnaocntehroomctelre,ar waterrsflaemargins.tCaf tfeisrh, leaf litterPreUnbdoetataerrgpinass.ture, riparian forest and then cattle pasture

openings openings

Exposure openings
Large Large Shadow with
Solar Radiation

90
el

bstrate Clay Clay
Su Grav

Slow Slow Slow

Water Speed

2013
: 4 0,25 m : 4 m : 1: >1 m
Depth W : W D 0,5 m W D
D

Waterway Width

, , , CENTRO CIENTÍFICO TROPICAL

asl asl
masl

/Altitude 35 m 36 m 29
Coordinates 10,-8939°N,°W 10,-9007°N,°W 10,9-466°N,7°W

Photographs

Location Upstream Upstream
Downstream

Description of sites and sampling points along Route 1856

17: te 1 2
Si Caño
Trinidad
Chart

590 Annex 10

Underwater Underwater
. .

cattle pastures on
Clean rock surface. Weather condition:

then
Murky water Murky water
and . .

roots roots
cological Component
E
– Comments underwater roots.

and cattle pastures on both margins.
, riparian forest

Weather condition: sunny.
le. Pasture and
Environmental Diagnosis Assessment (EDA)

asture and cattle pastures on both margins.e, scrublands
PrMubrkythwmar ins. Prepsesnucnenyo.f fish and underwater PrpseWeather condition: sunny.r

osed osed
xposed

Exposure
100% Exp 100% E 100% Exp
Solar Radiation

bstrate Clay Mud Clay
Su Gravel Pebblesel

Slow Slow
Modera
Water Speed

2013
: 2: >1 m : 1 m :,5 m
Depth W D W D 0,5 m W D 0,5 m

Waterway Width

, , , CENTRO CIENTÍFICO TROPICAL

asl asl
masl

/Altitude 40 m 32 m 31
Coordinates 10,-5486°N,°W 10,-4813°N,°W 10,-4830°N,°W

Photographs

Location Upstream
Downstream Downstream

te 3
Si

591Annex 10

.ipon both

underwater roots..

logs and y.

cological Component
E
– Comments
brancy.s,

condition: cloud

le.f litter,orest and scrubland fish and underwater roots. Murky water
Environmental Diagnosis Assessment (EDA)
condition: cloud Weather . Clear water. Forest on both margins. Weather

PrCleWareawtahteerr PreClmargins. surface. Pastures and riPrebsraecnnoccnhedeiotsifonta:dspuonlneys., fish, leaf litter, logs and underwater

Exposure openings
Shadow with Large openings Large openings
Solar Radiation

bstrate Clay Clay Clay
Su Pebblesvel

Slow Slow Slow
Moderate
Water Speed

m m
2013
: 3 : 3 m : 10,15m
Depth W D 0,5 m W : 0,25 W D
D

Waterway Width

, , , CENTRO CIENTÍFICO TROPICAL

asl asl
masl

/Altitude 26 m 33 m 31
Coordinates 10,-3293°N,°W 10,9-294°N,7°W 10,9-335°N,3°W

Photographs

Location Upstream Upstream
Downstream

te 4 5
Si

592 Annex 10

. .

Clean
.
Weather

Murky water
and branches

on both margins. Clear water
.

on both margins.

cological Component underwater roots. underwater roots
E
– Comments
logs,y.

Forest on both margins. Weather condition:
y. Clean rock surface. Forest
lea. litter,
Environmental Diagnosis Assessment (EDA)
condition: cloud
Sand and clay falling from riverbed.

PreSsueceeroleapfalsitttuerreaanndd scrPresence ofter Prerock surface. litter and underwater roots

Exposure openings
Large openings Shadow with Large openings
Solar Radiation

bstrate Clay Sand Sand
Su BloPebblesel Gravel

rate

Fast Fast Fast
Mode
Water Speed

2013
: 1 m : 2 m : 1,5 m
Depth W : 0,25 m W : 0,25 m W : 0,15 m
D D D

Waterway Width

, , , CENTRO CIENTÍFICO TROPICAL

asl
masl masl

/Altitude 29 m 17 22
Coordinates 10,-1358°N,°W 10,-9144°N,°W 10,-9238°N,°W

Photographs

Location Upstream
Downstream Downstream

te 6
Si

593Annex 10

. . .

as well on both

and branches and branches and branches
y.

on both margins

condition: cloud

cological Component underwater rootscloud underwater roots underwater roots
E
– Comments Weather
logs, logs, logs,
Weather

condition: rainy.

Clean rock surface. Submerged pastures and
leClean rock surface. Forest lea. litter, le.f litter,pastures and cattle pastures
Environmental Diagnosis Assessment (ED.) on both margins.
Weather

Presence ofotdeerd vegetation. PreCsleenacrewoafter Presemargins.

Exposure openings
Shadow with Large openings Large openings
Solar Radiation

bstrate Sand Sand Mud
Su Pebblesel Gravel

Fast Fast Slow

Water Speed

2013
: 1 m : 1 m : 6 m
Depth W : 0,15 m W : 0,15 m W D > 1 m
D D

Waterway Width

, , , CENTRO CIENTÍFICO TROPICAL

asl asl
masl

/Altitude 55 m 30 m 30
Coordinates 10,-9171°N,°W 10,-4,,27780°W 10,-7121°N,°W

Photographs

Location Upstream Upstream
Downstream

te 7 8
Si

594 Annex 10

. . .

and branches and branches and branches

y. y.

y.
underwater roots underwater roots underwater roots
cological Component
E
– Comments logs, logs, logs,

condition: cloud condition: cloud

condition: cloud
leaf litter, leaf litter, leaf litter,
Weather Weather
fi.h,merged pastures and cattle pasturefi.h,merged pastures, trees and cattle fis.,uus eornged pastures, trees and cattle pastures on
Environmental Diagnosis Assessment (EDA)
Weather

PreMsmargins.woafter PrMurky watergins. PreMsboth margins.er

osed

Exposure openings
100% Exp Shadow with Large openings
Solar Radiation

bstrate Mud Mud Mud
Su

Slow Slow Slow
Moderate Moderate
Water Speed

2013
: 6 m : 20 m : 20 m
Depth W D > 1 m W D > 1 m W D > 1 m

Waterway Width

, , , CENTRO CIENTÍFICO TROPICAL

asl asl asl

/Altitude 35 m 31 m 27 m
Coordinates 10,-7136°N,°W 10,-0299°N,°W 10,-0269°N,°W

Photographs

Location Upstream
Downstream Downstream

te 9
Si Caño
Jardín

595Annex 10

Weather
Submerged
Murky water.

leaf litter.
Murky water.

cological Component
E
– Comments

undery.ter roots and
Environmental Diagnosis Assessment (EDA)
rain

Prepsaesdsioti,fotnfries:ehcsloaaunndddy.Pastures, trees and cattle pastures on both margins.

openings openings
Exposure Shadow with Shadow with
Solar Radiation

bstrate Mud Mud
Su

Slow Slow

Water Speed

2013

Depth : 2: > 1 m : 2: > 1 m
W D W D

Waterway Width

, , CENTRO CIENTÍFICO TROPICAL

asl asl

/Altitude 26 m 36 m
Coordinates 10,-0774°N,°W 10,-0854°N,°W

Photographs

Location Upstream
Downstream

te
Si 10 Río
Marías

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Determination of the type of substrate in a stream bed is most important since the establish ment
of marginal flora and aquatic fauna depends on it. The sandy alluvi al and clay substrata are

normally found in the lower parts of watersheds, where current is slow. These types of substrate
are very poor in bentonic fauna, since they are a very unstable medium for their establishment
(Roldan and Ramirez, 2008). The fauna that is dominant in these types of environment is

constituted by organisms adapted to low oxygen levels and high quantities of solids such as
diptera and some predators such as odonata, coleoptera and hemiptera (Williams and Felmate,
1992).

Graph 1 display s the richness of taxa, which was greater in the sample points located up stream

from Route 1856, in 6 of the sites sampled. Of these, sites 3 and 5 presented the highest values.
In Graph 2 it can be seen that the quantity of individuals varied greatly by s ite and location along
the sampling points, site 3 being the one with the highest values in comparison to the rest.

Graph 1: Richness of taxa in sampled sites.

Riqueza de taza: Richness of taxa
Sitios de muestreo: Sampling poi nts
Sitio: Site
Arriba: Upstream
Abajo: Downstream

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Graph 2: Richness (A) and abundance (B) of aquatic macroinvertebrate taxa collected at sites along Route 1856.

Número de individuos: Number of individuals
Sitios de muestreo: Sampling points
Sitio: Site
Arriba: Upstream

Abajo: Downstream

Based on the values of richness and abundance of taxa obtained for the control sites (upstream
from the Route) and the influence sites (downstream from the Route) it can be seen that in half

of the cases it is possible to affirm that bio -indicators did not present an evident response that
would indicate that there has been an impact on the macro -invertebrate communities, since the
values obtained are very variable.

A greater taxonomic abundance and richness was expected in control sites (upstream from the
Route), which did not turn out to be the case. In sites 5, 6, 7, 8 and 9, located within the segment

identified as impacted (Infiernito River to mouth of the San Carlos River), a punc tual impact was
observed in the community of aquatic macro -invertebrates, where the richness and abundance
decreased at the points located downstream from the Route (see Chart 18).

The previous result could be attributed to two factors: 1) the degradation in the quality of the

habitat, as a consequence of some activities that were partof the construction of the Route, such
as the movement of earth and cutting down of river margin vegetation, 2) the process of
sedimentation that occurs in the rivers, due to unstable slopes and landfills that are eroded by

rainfall.

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Chart18: BMWP-CR’ index values and water quality at sampled sites along Route 1856, 2013.

BMWP-CR'Index Value Water Quality
Site
Upstream Downstream Upstream Downstream

1 76 48 Moderate Low

2 44 62 Low Moderate

3 72 55 Regular Low
4 27 50 Very Low Low

5 84 63 Moderate Moderate

6 45 34 Low Very Low

7 66 75 Moderate Moderate

8 48 55 Low Low

9 37 20 Low Very Low

10 33 44 Very Low Low

Once altered, an aquatic environment is subject to periods of re-colonization that may vary
between a few days to severa l weeks or months, depending on the nature and the reaches of

the alteration (Minshall, 1984). The response of bio-indicators to the effects of the construction of
Route 1856 on aquatic ecosystems might not have been the expected one, or even resulted
imperceptible in some of the sampled sites, possibly because aquatic communities have already

recovered.

The field sampling was conducted approximately a year and half after most of the construction
works of the Route were developed (road plotting and installation of temporary passing
structures); it is probable that during such period of time the communities were able to reach

stability. It is also important to tak e into account that these bodies of water are found in low lying
areas where they receive large quantities of sediments all year round, originating in upper parts
of the watershed, so that it is expected that aquatic fauna becomes adapted to high levels of

sediments in the water (Roldan and Ramirez 2008).
Therefore, the quantity of sediment contributed by works of the Route is not considered to be

sufficient to cause a significant impact on the bio -indicators studied in the sampled locations.

5.1.2.3.3 Quality of Water

The results of water quality values, according to the BMWP -CR Index, are presented in Chart
19. The values range between 20 and 84, which corresponds to a moderate to bad quality level.

Of the 20 sites sampled, 7 presented a moderate quality, 9 were of a bad quality and the
remainder had very bad quality of water. At sites 1, 3, 5, 6 and 9, the quality went down in the
downstream sites (with influence of the Route) with a moderate to bad classification and from

bad to very bad in comparison to control s ites found upstream (with Route influence). It should
be noted that most of these sites are found within the impacted segment of the Route.

At sites number 7 and 8, the quality of water did not change, staying within the same category
while at the remainin g sites (sites 2, 4, and 10), the quality increased by one category at a point

located downstream from the Route with respect to its corresponding control site (upstrefrom
the Route) (See Map 21, 22 and 23).

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At sites located in the section classified s impacted (Infiernito River -mouth of the San Carlos

River), the quality of water was influenced by the works conducted in the Route, as were the
richness and abundan ce of the communities. In Chart 19 and Maps 21, 22 and 23, can be
observed that this sites , the value and category of the quality of water goes down, according to

the BMWP-CR, suggesting that it might be a reflection of the deterioration of the quality of the
habitat (e.g., decrease of availability, heterogeneity and stability of the substratum ) and the
decrease in the richness of taxa, in response to activities and processes conducted during and

after the construction of the Route, such as the movement of earth, tree cutting, erosion and
sedimentation.

In those instances where the point locate d downstream improved by one category or remained
the same, this could be representing the resilience of the community, the time period since the

works were conducted, the re -colonization capacity and the aquatic fauna adaptation skills to
bodies of water that should naturally present high levels of sediment content due to their location
in the lower part of the watershed.

Chart19: Water quality classification according to BMWP-CR Index.

BMWP-CR’
Water Quality Level Color
Value Quality

>120 Excellent Waters of excellent quality Blue

101-120 Good Good quality, not contaminated or altered. Blue

61-100 Moderate Moderate quality, eutrophic, moderate contamination Green

36-60 Low Bad quality, contaminated Yellow

16-35 Low Bad quality, very contaminated Orange

<15 Very Low Very bad quality, extremely contaminated Red

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Graph3: Water quality values according to BMWP-CR’ Index of the sampled sites along the Route 1856 “Juan Rafael
Mora Porras”, July - August, 2013.

Arriba" Abajo"

140"
Excelente

120" Buena

100"
Regular

80"

Val60"BMWP+CR'&
Mala

40"

Muy Mala

20"

Pésima
0"
Sitio"1"Sitio"2"Sitio"3"Sitio"4Sitio"5"Sitio"6"Sitio"7"Sitio"8"Sitio"9" Sitio"10"

Sitios&de&Muestreo&

Valor BMWP-CR: BMWP-CR Value

Sitios de Muestreo: Sampling Sites
Arriba: upstream

Abajo: downstream.
Excelente: Excellent
Buena: Good

Regular: Moderate
Mala, Muy Mala: Low
Pésima: Very Low

The BMWP -CR index works on the bas is of the presence of famili es or groups of macro -

invertebrates which are given points (one to nine) according to their sensitivity to alterations in
their e nvironment, so that organisms with greater sensitivity obtain higher points while those

more tolera nt receive lower points. Some of the families found in this study are considered
sensitive and therefore they obtain high points. Among them can be mentioned: Blaberidae

(Dictyoptera), Calamoceratidae, Glossosomatidae, Leptoceridae (Trichoptera),
Lepthophlebiidae, Heptageniidae (Ephemeroptera) Perlidae (Plecoptera), Gomphidae,

Megapodagrionidae, Platystictidae, Protoneuridae, Corduliidae and Polythoridae (Odonate),
Psephenidae and Ptilodactylidae (Coleoptera).

The presence of groups sensitive to alterations of the aquatic habitat is a good signal, since

these indicators usually disappear in cases of strong alteration of the aquatic habitat, especially
if the effect is persistent through time, because it does not allow sensitive taxa to re -colonize the

bodies of water. The finding of sensitive families in practically all sampled sites, and in points
above and below the road, may be interpreted as a positive signal of recovery and of lesser

impact of the road works on the environmental conditions a the points under study. Only the
sites number 9 (below) and 10 (above) did not present sensitive macro -invertebrates.

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Comparing the results of the present study with those obtained by Salvatierra et al. (2012), in the

study “Establishing the Environmental Base Line of the San Juan River- Nicaragua- 2013” where
during the two seasons of 2012 (rainy and dry), 38 aquatic macro -invertebrates were collected in
20 sampling stations located along the San Juan River and tributaries (9 of them in the stretch
between Border Ma rk 2 and Delta Costa Rica), it can be affirmed that the richness of families

(58) and genera (73) collected in the present study is superior.

The difference in sampling method could be one of the factors that influence the results.
According to Roldan and Ramirez (2008), the diversity of macro -invertebrates is greater along
the margins of bodies of water and decreases with depth. In the study by Salvatierra et al.(2013)
two sampling methods were used to collect aquatic organisms (dredging and artificial su bstrata),

both of them collecting organisms from the river bottom.
These two methods are frequently used in rivers of large size, great depths and very big volume,

such as the San Juan River, and in lentic habitats such as lakes and lagoons. The rivers
sampled in this study are tributaries of the San Juan, so that their characteristics are very
different and consequently the results obtained and the methods used were also very different
(our direct sampling was done with D nets in the margins and at depths no greater than one

meter).

In the same study, Salvatierra et al. (2013) applied a water quality index (IBF adapted to El
Salvador) and obtained four categories of water quality; very poor, poor, moderately poor and
moderate. It should be pointed out that none of the 9 stations that was within the section of the
study obtained a moderate quality of water. The IBF -SV works differently from the BMWP -CR,

where the first one takes into account the abundance and number of families present and the
second one only uses the number of families.

Also to be pointed out is the fact that the sampling of bio -indicators was done in tributaries of the
San Juan River, so that impacts detected due to the Route works on the aquatic environment,
such as modification of substra tum and sedimentation, are of a local level. The present study
had the limiting condition that it was not allowed to take samples in the San Juan River, so that

impacts detected were in rivers in Costa Rican territory.

These bodies of water were the ones which received a direct influence from the road works, and
the results obtained do not overlap to the San Juan River, since the San Juan is of a superior
order, with a much greater volume than the rivers that were sampled. The stretch of the San
Juan River which runs parallel to this road, is found in the lower part of the watershed, where the

quantities of sediment are normally high (Roldan and Ramirez, 2008), which leads to the
consideration that impacts from the Route on organisms that inhabit the San Ju an could have
been minimal and very diffuse, considering the high volume of that river.

Furthermore, evaluating the impacts that could have been produced by the construction of the
Route on the aquatic biota of the San Juan River would have been extremely difficult especially
because there are other factors that determine environmental conditions and diversity of species

in the river. Within these, the following can be mentioned: the rainfall (which varies from rainy to
dry season), the volume, depth, land use in the upper, medium and lower levels of the sub -
watersheds that empty into the San Juan, both in Costa Rica and in Nicaragua, and which are
exposed to anthropogenic activities.

Finally, another factor that must be taken into account is the adaptatio n capacity of aquatic

organisms in the natural conditions of the river, because due to having their habitat in t he lower
level of the watershed, they have a degree of adaptation to those conditions in particular.

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The season and time were limiting conditio ns on the study, since the study lasted only 4 months,

taking place during the rainy season of the Caribbean Coast. It was not possible to do sampling
during the short dry spells common in this part of the country. The time available for the study

limited the number of sites to be sampled, since it was necessary to select some bodies of water
to conduct bio -indicator analyses but it was not possible to sample all bodies of water located
along the Route, and thus the results are limited to the sample and do not to the total number of

such bodies. The sampling effort was greatest in the critical stretch of the Route, based on
recognition of the Project area, which concluded that this stretch would be the most indicated to
measure impacts.

5.1.2.4 Endemic Species with Reduced or Threatened Populations

The presence of endangered or highly threatened species in the study area is a condition that
justifies protecting the riparian ecosystems. These species have been affected mainly by the
reduction of habitat as a conseque nce of deforestation and the fragmentation of forests.

In the list of species obtained through bibliographic review, 59 species of aquatic fauna were

found to be included in some special conservation category according to the official lists of the
CITES convention of the IUCN and the Law on Conservation of Wild Life, which adds additional
value to the appropriate management of natural resources in the region. Chart 20 presents a list

of the aquatic species in the region, aimed at promoting their conservatio n.

Chart20: Species of aquatic fauna recorded for the project area included , included in some conservation category

Conservation Status
.Family Species a b,c
CITES IUCN SINAC

FISHES

Carcharhinidae Carcharhinus leucas NT

Characidae Hyphessobrycon tortuguerae LC
Cichlidae Parachromis friedrichsthalii LC

Megalopidae Megalops atlanticus VU A2bd

Pristidae Pristis pectinata CR A2cd

Pristis perotteti CR A2abcd

MAMMALS

Mustelidae Lontra longicaudis Appendix I DD PRA

Trichechidae Trichechus manatus Appendix I VU C1 PE

Tapiridae Tapirus bairdii EN A2abcd+3bce PE

Didelphidae Chironectes minimus LC

ANFIBIOS

Leptodactylidae Leptodactylus melanonotus LC

Leptodactylus labialis LC

Ranidae Rana taylori LC

Rana vaillanti LC

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Conservation Status
Family Species
CITES a IUCN b,c SINAC

REPTILES

Iguanidae Iguana iguana Appendix II

Chelydridae Chelydra serpentina LC

Geoemydidae Rhinoclemmys funerea MR / NT

Crocodylidae Caiman crocodilus Appendix I MR / NT

Crocodylus acutus Appendix I VU A2cd PE

BIRDS

Alcedinidae Chloroceryle aenea LC

Chloroceryle amazona LC

Alcedinidae Chloroceryle inda LC PRA

Anatidae Anas acuta LC

Anas clypeata LC

Anas crecca LC

Anas cyanoptera LC

Anas discors LC

Aythya affinis LC

Aythya callaris LC

Cairina moschata LC PARA

Dendrocygna autumnalis LC

Dendrocygna viduata LC PE

Oxyura dominica Appendix II PRA

Anhingidae Anhinga anhinga LC

Ardeidae Agamia agami VU A3c PRA

Ardea herodias LC

Botaurus pinnatus LC PRA

Casmerodius albus LC

Egretta caerulea LC

Egretta thula LC

Egretta tricolor LC

Tigrisoma fasciatum LC

Tigrisoma lineatum LC

Tigrisoma mexicanum LC

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Conservation Status
Family Species a b,c
CITES IUCN SINAC

Ciconiidae Jabiru mycteria Appendix I LC PE

Mycteria americana Appendix I LC

Heliornithidae Heliornis fulica LC PE

Podicipedidae Podilymbus podiceps LC

Tachybaptus dominicus LC

Scolopacidae Limnodromus scolopaceus LC

Tringa solitaria LC

Rallidae Amaurolimnas concolor LC

Threskiornithidae Eudocimus albus LC

Mesembrinibis cayennensis LC PARA

Plegadis chihi LC

Plegadis falcinellus LC

CRUSTACEA

Palaemonidae Macrobrachium carcinus LC

Macrobrachium acanthurus LC

Macrobrachium olfersi LC

Extinct (EX), Extinct in the Wild (EW), in Critically Endangered (CR), Endangered (EN), Vulnerable (VU), Near

Threatened(NT), Least Concern (LC), Data Deficient (DD), Not evaluated (NE), Minor Risk (MR), Limited or
Threatened Populations (PRA), In Danger of Extinction (PE).

Source: CITES, 2013; IUCN, 2013; MINAE, 2005.

Notes:
a
Appendix I inclu des threatened speciesThe commerce of individuals of these species is permitted under
exceptional circumstances

Appendix II inclu des species that are no necessarily under threat but whose commercecontrolled toavoid
uses that are incompatible with their survival.

Appendix III contains the species that are protected at least in one country, which has requested help from other
members of the CITES to control their commerce .
b
Vulnerable

A. Reduction of population size based on any of the following points:

1. The population has experienced an observed, estimated, inferred or suspected re≥ 50% in the last
10 years or in three generations, depending on which is the longest periowhich it is possible to show
that the causes of the decrease are clearly reversible and understood and that they have ceased, based on and
in compliance with at least one of the options (a) to (e) .

2. The population has experienced an observed, estiminferred or suspected reduction of ≥ 30% during the
last 10 years or three generations, depending on which is the longest period, where this reduction or its causes

may have ceases or may not be understood, or may not be reversible base don and in compliance with one of
the options (a) to (e).

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3. A reduction of the population ≥ 30% that is projected or suspected of being reached within the next 10 years or
three generations, depending on which is the longest period (for a maximum of 100 years) based onat least one
of the options (b) to (e).

(a) Direct observation

(b) An indexof abundance appropriate for the taxon

(c) A decrease in the occupation area, a reduction in extens ion of presence and or the quality of the habitat.
(d) Levels of real or potential exploitation.

(e) The effect of introduced taxa, hybridization, pathogens, contaminants, competitors or parasites.

C. Size of estimated population of less than 10,000 mature individuals.

1. An estimated continuous decrease of, at least, 10% in a period of ten years, or three geneons, whichever is
the longest period (up to a maximum of 100 years in the future).
c
Endangered

A. Reduction in the size of the population based on any of the following:

2. The population has exper ienced an observed, estimated, inferred or suspected reduction ≥ 50% in the last 10
years or three generations, depending on which is the longest period, where such reduction or its causes may
not have stopped or may not be understood, or not be reversible, based on the compliance with one of the
options (a) to (e).

3. A reduction of the population ≥ 50% that is projected or suspected of being reached within the next 10 years or
three generations, depending on which is the longest period (for a maximum of 100 years) based oncompliance
with at least one of the options (b) to (e).

(a) Direct observation

(b) An indexof abundance appropriate for the taxon

(d) Levels of real or potential exploitation .
(e)The effect of introduced tax a, hybridization, pathogens, pollutants , competitors or parasites.

5.1.2.5 Fragility of the Inland Aquatic Environment .

5.1.2.5.1 Ecosystem Fragility

Fragile ecosystems are understood to be those that are sensitive to human alterations or
extreme natural events and that do not recover easily. Among fragile ecosystems that can be

found in the study area are the forested areas and the bodies of water such as lagoons, rivers
and creeks.

The presence of a diverse and abundant fauna of aquatic m acro-invertebrates is important for

the river, due to the fact that they provide basic functions to the ecosystem. On the one hand,
they are important to the recycling of organic materials and nutrient cycles of the river since

many of them feed off the le afy material that falls in the river, while others are filters of fine
organic material in suspension thus providing a basic function in the self -recovery of the river
and improvement of the quality of the water. On the other hand, macro -invertebrates are an

important part of the food chains, both for aquatic species such as fish, and for terrestrial
species (birds, bats, amphibians, some reptiles, spiders and other insects.)

The activity and the transit of machinery on river beds destroy the micro -habitats and cause the

release of bentonic organisms which are then dragged downstream. Also the cutting of river
edge vegetation can have a negative effect on the aquatic fauna, due to the decrease of leafs

and submerged roots that implies a lesser quantity of food and less diversity of micro -habitats.

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Moreover, construction works can potentially provoke contamination due to hydrocarbons and

oils, and solid waste among other, which decreases considerably the quality of water at the site
and downstream.

All of the se effects can become more pronounced in conditions when the water leve l is low,
especially during the dry season. When the volume of water is lower, the dilution of sediments is
less, and the negative impact is greater.

Some impacts occasioned by the construction of highways on the creeks have been identified by
other authors, as follows: an increase in the non- organic sediments due to the erosion of river

margins which have been deforested, an increase in erosion of land surfaces due to contouring
and lev elling of the land and the alteration of the natural course of the stream due to re -
alignment necessary when placing gutters and building bridges (King and Ball, 1965; Duck 1985;
Johnson 2002, 2006; Urban and Rhoades 2003; Wohl 2000, 2006, in Hedrick, 2008 )

Construction projects are often implemented in a short period, so that recovery of a body of

water from the deposition of sediments and the levels of solid matter in suspension may return to
conditions similar to those present before the construction (Barton 1977 in Hedrick 2008) which
is contrary to the case of agricultural production, which is considered a permanent use of land
and which constantly provides sediments to the bodies of water. Cline et al, (1982 in Hedrick,

2008), evaluated the response of a creek to the construction of a road over a three year period
in a rocky mountain elevation.

The solids and sediments suspended increased in the impacted study sites. Nevertheless the
values in impacted sites approximated those of reference sites within two years after the end of
construction. The density of bentonic macro-invertebrates in the impacted sites were less than
those in reference sites during and immediately after the construction.

After one year of construction, the values were comparable to those of reference sites. The taxa

most intolerant to the effects of the road construction were the orders Ephemeroptera,
Plecoptera and Trichoptera; nevertheless, it is necessary to point out that this study was
performed in conditions different to those of Route 1856 in another latitude and altitude,
therefore the results of this study cannot be applied to those in the area of the Route project.

5.1.2.5.2 Buffer Areas
It is very important that mitigation actions take into account the conservation of the vegetation on

the edges of bodies of water, which according to Forestry Law No. 7575 must keep a protection
zone on the margins of rivers, creeks and streams, of 15 meters if the terrain is flat and 50
horizontal meters if the land is hilly.

In addition, there must b e a protection zone with a radius of 100 horizontal meters for permanent
water springs, and a protection zone of 50 meters for lakes and dams, natural or artificial, the

latter being limited to state property, and in areas of water recharge and aquifers of springs, in
which case the limits are determined by competent organs established by Law.

It is important that the construction project take into account the reforestation of river margin
areas which have been deforested, using native species from the reg ion, in addition to the river
margins along the Route which had been impacted before the construction by human activities.

5.1.2.5.3 Adaptation to Sedimentation

The transportation of sediments and sedimentation are natural processes in the lotic aquatic
environments that play an important role in the structuring of river habitats (Connolly and

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Pearson 2007). The aquatic systems of the lower topography generally have greater levels of
sedimentation due to their downstream location and anthropogenic perturbation. Neve rtheless,
the accelerated degradation, contamination and the high level of sedimentation in aquatic bodies
are the main problems that lead to the loss of aquatic diversity at a global level (Hedrick 2008).

The increase in sediment load may affect aquatic e cosystems in a variety of ways depending on

the form, size and density of the particles. Frequently the increase in transportation and
deposition of sediments are a consequence of anthropogenic activities such as agriculture, civil
engineering projects and extractive industries (silvi -culture and mining) (Connolly and Pearson
2007).

The effects of sediments on bentonic macro-invertebrates and fish in streams are very diverse.

Some species of macro -invertebrates and fish have learned through time to adapt to certain
conditions of high sedimentation. The aquatic fauna of low areas is very tolerant to
sedimentation even when exposure is more than 15 days (Connolly and Pearson 2007).

However, the excessive sedimentation in creeks may alter the composition and ab undance of
aquatic biota (Rabeni and Samie, 1995; Jones et al, 1999 in Hedrick, 2008) decreasing the
reproductive effect and the survival of fish. For instance, most bentonic macro-invertebrates

inhabit the bottom of rivers and are sensitive to changes in the environment. Many fish feed off
bentonic invertebrates and when there are alterations in the medium due to the deposition of
sediments, the abundance of bentonic organisms diminishes and, as a consequence, the food

available to the fish decreases, (Lem ly 1982; Scrivener and Brownlee 1989; O´Conner and
Andrew 1998; Sweka and Hartman, 2001 in Hedrick 2008; Waters, 1995 in Hedrick 2008).

Values reported in the literature consulted about the effect of the sedimentation on aquatic fauna
refers to studies con ducted in other countries ( (Bruton, 1985; Alabaster & Lloyd, 1980; Bruton,
1985; Wood & Armitage 1997, Packer et al. 2005, Melton 2009; Mol & Ouboter, 2003; Rabeni et
al., 2005;Connolly & Pearson, 2007; Hedrick, 2008; Wagenhoff et al., 2012; Wohl & Carlin e,

1996, in Hedrick, 2008; Ryan, 1991; Kaller & Hartman, 2004; Downes et al., 2006; Springer et
al., 2010). However, in the present study, it has not been possible to generate the necessary
information to determine the threshold of the sedimentary load and its possible effects on the

aquatic fauna of the study area.
In order to evaluate with greater certainty if the works on Route 1856 created a level of

sedimentation that could have an effect on the aquatic fauna of the San Juan River and its
tributaries in the area of this study, it is first necessary to determine and validate the thresholds
of sedimentation that could affect the species found in these rivers, since there is no information

for aquatic organisms in the area of the study.

5.1.2.5.4 Morbidity and Mortality Thresholds

The values reported in the literature reviewed are based on data obtained in studies conducted
in other countries for small rivers of first and second order; rivers that are characterized as being
very shallow with a strong current. The San Juan River is relatively deep and of great volume,
and therefore could be classified as a 5 thor 6 thorder river. Therefore the values established in

studies performed in other countries cannot be used to affirm that the quantities of sediment that
enter the San Juan River could have an impact on it.

In order to be able to evaluate with greater certainty if the works on Route 1856 had an effect on
the aquatic fauna of the San Juan River and its tributaries, first it is necessary to determine and
validate thresholds for morbidity and mortality of the species that are found in these rivers, as

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well as the levels of tolerance to sedimentation since there is no information for aquatic

organisms in the study area.

In order to establish such values, it would be necessary to conduct periodic analysis over a long
term period to evaluate tolerance capacity of fish and macro -invertebrates to different quantities

of sediment, and be able to determine the point at which aquatic organisms start to die or
experience a significant reduction in abundance and diversity.

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6 ENVIRONMENTAL DIAGNOSTIC

6.1 Comprehensive environmental susceptibility map vs.Project components.

This section exhibits 17 maps on a 1:10,000 scale (in geographic order from Border Marker 2 to
the site of Del ta Costa Rica) that present an environmental Diagnostic of the influence area of

Route 1856. The maps summarize graphically the environmental conditions along the
designated path of the Route and emphasize the ecological components identified in previous

chapters, using data on the types of land use, combined with different kinds of slopes observed
in the area of the Project, imposed on the path of the Route.

Following are the symbols of the factors analyzed in the maps:

Zonas urb anizadas: Urban zones; Cultivos: Agricultural lands ; Pastos: Pastures ; Pastos mezclados con arboles:
Pasture with trees; Bosque Primario de Ladera: Primary Foon sloping terrain; Bosque secundario de ladera:
Secondary Foresto on sloping terrain ; Charrales: Scrubland; Bosque degenerado: Degenerated Forest; Plantaciones
de arboles: Tree plantations; Bosque Secundario de Planicie: SecForest in plain terrain ; Bosque Primario de
Planicie: Primary Forest in plain terrain ; Zonas temporalmente inundadas: seasonal flooded areas ; Yolillales: Yolillo
patches; Humedales lacustrinos: lacustrine wetlands; areas intervenidas: intervened areas.

Plano: plain; Pendiente bajo: small slope; Pendiente moderado a alto: moderate to steep slope.

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6.2 Identification of impacts and environmental risks

This chapter , in accordance with the guide established through Resolution No. 2572-09
SETENA, identifies and descri bes the impacts, starting with two basic criteria. The first one
refers exclusively to the reality analyzed and the conditions existing along the study area, which
corresponds to the 108,2 km of Route 1856 from Border Marker 2 to Delta Costa Rica, a topic

that was discussed in Chapter 5, specifically in the section related to the description of the
biological environment.

The second criterion has to do with the evaluation of the impacts itself, and for which purpose
the Matrix on the Importance of the Env ironmental Impact (MIIA) was applied, as officially
approved by the SETENA for this technical aspect of the study. The identification as well as the

evaluation of environmental impacts was conducted focusing only on those effects that are
thought to require environmental control measures or actions.

6.2.1 Activities susceptible of causinge nvironmental impacts

As indicated in Chapter 3, the different activities performed for the construction of the Route, are
related to the appearance of some environmental impacts. The main activities that were
identified in the Project were:

1. Clearing of land and brush in some sites located along the Route.

2. Earth movements, formation of slopes and landfills

3. Implementation of erosion control measures

4. Installation of drainage system s and temporal bridges
5. Installation of landfills, road base layers and rolling surface.

It should be pointed out that activities 1 and 2 were performed in specific sites of the Project and

not as a continuous actions along the Route, and this is due to the fact that most of the terrain
where the Route is located is flat or plain topography.

6.2.2 Impacted or potentially impacted environmental factor s

According to what has been discussed previously, there are environmental factors that could be
affected to a minor or major degree by the development of the road works. These factors are:

1. Surface waters

2. Soils
3. Natural threats (erosion, landslides)

4. Flora and Fauna (terrestrial and aquatic)

5. Landscape

6.2.3 Identificationof environmental impacts

Taking into account the environ mental characteristics present along the route of the road, and
the activities that are capable of generating an impact on the environment, as well as those

factors that could potentially be impacted, a Leopold Matrix was formulated with some

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modifications accounting for conditions and characteristics of the road project. The matrix offers
quantitative identification of the potential impacts related to the works (see Chart 21).

In this matri x environmental factors that are suscepti ble to impact are identifi ed (vertical

column),as well as the components or activities of the Project that can generate impacts
(horizontal row).

When the activity is significant, it is identified with aA, indicating the need to evaluate and
establish specific measures. Furthermo re three categories apply: Low ( X), Moderate ( XX) and

High (XXX). When the activity is identified with a B, this indicates that its analysis is not relevant.
It is necessary to indicate that only moderate and high impacts were analyzed in detail.

In the c ase of the factor “flora and fauna”, these are separated for better understanding and
evaluation into terrestrial and aquatic flora and fauna. It is important to note that some of these

factors have similar characteristics, and for that reason they have be en grouped in order to
present a logical and sequential order.

Chart21: Modified matriz for impact identification related to Route 1856.

Factor Components

Installation
Clearing and Implementation of Installation of
deforestation in some Soil movements, of erosion drainage landfills, sub-
sites along the right ofcutting of slopes control systems base and
and creation of
way landfills measures and rolling road
temporal surfaces
bridges

Terrestrial A A A
flora – B B
fauna (XX) (X) (X)

Aquatic
A A B A A
flora- (XX) (XX) (XX) (XX)
fauna

BiLandscapeResource A A B B B
(XX) (XX)

6.2.4 Description of identified Environmental impacts

The following is an analysis of the environmental impacts identified or which could be gene rated
by the Project. These are described according to the environmental factor affected.

6.2.4.1 Terrestrial flora and fauna

a. Logging in the right of way and adjacent areas

According to the evaluation of the plant cover along the length of the Project, it was estimated
that, for purposes of clearing the land on the designated route of the road, 14,9 hectares of

secondary for est were cut down along with 68, 3 hectares of altered primary forest, which
corresponds to 4,2% and 19,5% respectively of the area affected by the road design.

In complement, some 2,3 hectares were altered that were not forests but natural wetland
systems. It was determined in the field that the opening of the route was executed mostly in

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open areas without forest (74%). In cases where forests w ere cut down, it was due to the fact

that there were no open areas where the path of the route could be directed.

b. Partial sedimentation of wetland margins near Route 1856
During the field work, it was observed that in the majority of wetland places along t he Route, no

areas are observable that are affected by sedimentation, since most of them are located on
plains or flat terrain, where no significant earth movements occurred, except where filling was
done on the road surface.

However, it was determined that at two wetland sites that are located next to hilly terrain, some
sedimentation accumulation was observed, leading to a slight obstruction of sites close to the

path of the natural drainage system of these wetlands. Even though no loss of tree or palm
vegetation was observed it is possible that this loss is affecting ecosystems close to the road,
with some natural substitution or alteration taking place of the original vegetation.

In complement, the lacustrine wetland Remolinito Grande has been affected by the filling of the
road segment, even though there had been alteration oc curring years ago, prior to the Route
construction, substituting the aquatic vegetation with pasture and building a drainage system to

allow for the wetland to be used for cattle g razing. These punctual impacts are located in the
section between mouth of San Carlos and the mouth of the Sarapiqui rivers.

c. Elimination of trees and bushes on river margins due to flooding

It was determined that in the section between Border Marker 2 and the Infiernito River there are
some sites with small streams that showed at the time of visit (during the rainy season) an
accumulation of water, forming small pools of water on the plant vegetation along the side of the
stream. This was due to the fact th at gutters or drainage tubes collapsed, causing the flooding of

ecosystems in the area estimated at 100 to 200 meters per site. This flooding led to the loss of
vegetation.

d. Landslides and slope erosion that affects the forest margin along the route

In the sites of several land cuts where the road passes, and where there is forest vegetation on
the margins of the cut, erosion layers of the ground of such cuts was observed, which generally
causes the small trees (also two large trees were observed) to be upro oted due to the
displacement of soil in their radicular system, causing them to fall on the road.

In similar form, but with lesser alteration, it was found that at several sites with steep slopes,
landslides have occurred off the slopes on the sides of the road, carrying with them the edges of

the slopes, including some small and large trees that fell and obstructed the road. Field
observations led to the determination that this is accentuated by the surface runoff which takes
place above the slopes.

This phenomena occur generally at the sites with steeper slopes, which are also often covered
by forest, causing damage to the vegetation on slopes that run down past the Route. This impact

is punctually located mostly between the sector close to the Infiernillo River and the sector
known as Chorreras. This alteration has been occurring after the aperture of the Route and will
probably continue to happen, as generally happens in these types of topographic settings and
with soils that are susceptible to erosion.

e. Alteration of the wetland ecosystem (due to drainage and landfills)

This alteration corresponds with the alterations caused on wetlands by drainage and
construction of artificial land fills in small areas along the path of the Route. This impact is very

specific, located in defined points along the Route.

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In the case of Yolillo palm pa tches, these present a loss of 0, 7 hectares of the ecosystem due to

drainage, burning or the constru ction of artificial landfills. The “Yolillal” is difficult to recover
through reforestation and the only alternative is natural regeneration. In terms of landscape, the
impact is minimal when the extension of the influence area of the Route is taken into account.

f. Impact on structural connectivity

This corresponds to the loss of structural connectivity as a result of the cutting down of forest
cover in forests along some sections of the Project.

The identification of connectivity routes and the important connectivity areas along the
landscape of the study area, it becomes clear th at such are not related to the route traced for the

road, despite the fact that the Route is located in the area of greatest forest cover in the study
area. Given the reduced extension of natural ecosystems impacted (83, 2 hectares), it is possible
to say that the Route has not generated a significant impact on the structural connectivity of the
landscape under study.

6.2.4.2 Aquatic flora y fauna

g. Potential alteration of the aquatic habitat

Possible alterations of the aquatic habitat are due to the drainage system a nd the laying of
cement structures where gutters and drains are located. It could affect some of the aquatic

organisms, since it produces homogenization of the substratum at a local level in sites where the
Route cuts across the bodies of water, affecting the re-colonization of the aquatic ecosystem by
macro-invertebrates because these organisms prefer heterogeneous substrata (Williams and
Felmate 1992).

h. Potential alteration of the micro -habitats and substrata of the aquatic macro -
invertebrates due to filli ng of interstices with sediments

Sedimentary material in the water and the decrease in the contribution of vegetal matter to the

aquatic means, along with decrease in shade, cause the filling in of cavities and modify the
substratum where aquatic macro -invertebrates normally live.

i. Potential alteration of taxonomic abundance and richness
Similarly to the previous impact, taxonomic richness could be diminished by sediments in the

water, a decrease in vegetal matter in the aquatic environment, and the loss of shade.

j. Potential alteration of the quality of water due to turbidity
The contribution of sediments on the stream of water could affect the water quality due to the

turbidity, or cloudiness, in some rivers, due to the construction works of the Route.

6.2.4.3 Landscape

k. Landscape Alteration due to the Route

The exposed surfaces of slopes and road cuts at some specific sites along the tracing of the
Route, contrasts with the forest, pastures and dominant farming field landscapes. These visible

points are located mainly along Border Marker 2 and the vicinity of the mouth of the San Carlos
River.

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6.3 Assessment of Environmental impacts and corective measures

6.3.1 Methodology

The assessment of environmental impacts that follows is based on the previous analysis and in

correspondence with the methodology applied.

Starting with the characteristics established in the preceding chapters and sections, referring to
the Project, as well as environmental conditions and the integrated analysis of such variables,
each one of the participat ing professionals offered his/her technical criteria as related to an
expected impacts, taking as criteria the guidelines offered by the Conceptual Guide for the

Formulation of Environmental Impact Studies that the Secretaría Técnica Nacional Ambiental
(SETENA) has recommended since 1998 and the modifications to this document found in
Executive Decree No. 32967 of May 4, 2006: Technical Instruments Guide for Environmental
Impact (EIA Manual) Part IV, Annex 2: Instructions for the Assessment of Environmenta l

Impacts).
In this sense, conceptual definitions are reconsidered which will facilitate the final understa nding

of the Matrix of Importance of Environmental Impacts (MIIA), which summarizes the analysis of
the expected impact of the project on the environ ment.

i. Impacted Environmental Factor: this denomination includes factors or elements of the
environment (ecological component) that may be affected by the development of the
project or by any of its actions. The elements that have been selected for environm ental

evaluation are those that are considered to be potentially related to Project activities.
ii. Action that Causes an Impact: definition at a detailed level is offered of the act, activity

or component of the Project that exerts an impact on one or sever al of the environmental
factors defined in the previous point. The impacting act may be related to the
construction or operative phase of the Project.

iii. Impact: Indicates the effect expected in each of the impact possibilities identified by the
members of th e study team. If the expected impact is the contamination of water, the

cause of impact is identified, along with the source of contamination and the phase of the
Project where the potential impact may occur.

iv. Impact Assessment: correspond to the quantitati ve grade given to the environmental
impact, the evaluation is based on the criteria offered by the Leopold Matrix (modified)
and which have been discussed for some time in Costa Rica, where they have been
adapted to the Matrix of Importance of Environmenta l Impacts (MIIA) by SETENA and

made official by Executive Decree No. 32966 –MINAE (Technical Instruments Guide for
the Process of Environmental Impact Assessment (EIA Manual) -Part IV).

Criteria to be evaluated correspond to those in Chart 22.

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Chart22: Evaluation criteria for the MIIA.

Evaluation
Element Description Value Range

Beneficial(+)
The sign referring to effect and thus to impact, refers to the
Sign beneficial (+) or negative (-) c haracter of the different Negative(-)
Undetermined
actions that affect the different factors under consideration
(*)

Degree of in cid ence of the action on the factor, in the Low: 1
Intensity (IN) specific context. The scale ranges from 1 to 12, where 12
is the maximum destruction of the factor (AP totaland 1 is Medium: 2
Degree of
Incidence the minimal impact value. High: 3
This evaluation is a function of the percentage of the Very high: 4
Project area (PA and/or influence areas where applicable)
Total: 12
that is being directly affected.

This is the theoretical influence area of impact in relation to
the environment of the activity (percentage of the area, with
respect to the context in which the effect is present). In

Costa Rica it will be used a s reference for quantification of
the Direct Influence Area ( DIA).
If the action produces a localized effect, the impact will be

considered to have a punctual effect (1). If, on the other Punctual: 1
hand, the effect does not permit a precise localization Partial: 2
Extensión (EX) within the context of the a ctivity, having instead a
Extended: 3
Influence Area generalized influence in all of it, the impact will be
considered to be total (8), taking intermediate areas, Total: 4
according to their degree, to be partial (2) and extended (4) Critical: (+4)

In case the impact occurs in a critical location (spill ne ar
and upstream from a water source, landscape degradation
in an area of high visitation or near an urban center, etc.)

will receive a grade of 4 units above that which would
correspond as a function of the percentage of the
extension of its presence.

The moment of impact is the period during which the
impact occurs from the initiation of the action (t ) and the
o
beginning of the impact (t j on the factor/environmental
aspect being consired.

Momentum When the time period elapsed is null, the moment will be Long term: 1
immediate, and if it is inferior to a year, it will be considered Medium term: 2
(MO) short term, assigning both a value of (4). If it is a time
period that ranges from 1 to 5 years, it will be considered Immediate: 4
Critical: (+4)
medium range, and if the impact takes longer than 5 years
to manifest itself, it will be considered long term, with an
assigned value of (1). If a circumstance appears that
makes the impact moment critical it would receive a value

of (4) units above those spec ified.

Persistence This refers to the time of permanence of the effect from its Passing: 1
(PE) inital appearance and the point at which the impacted Temporal: 2
factor World return to the ini tial conditions prior to th e
Permanent: 4
impact, base on natural processes or the introduction of

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Evaluation
Element Description Value Range

corrective measures.

If the permanence of an impact has place during a time
period of less than a year, the impact is considered to have
a passing effect, with a value of (1). If it lasts between 1
and 5 years, it is considered temporal (2); if the impact has

a duration over 5 years, it is considered to be permanent,
receiving a value of (4).

This value refers to the possibility of reconstruct ing the
impacted factor as a consequence of the actions taken,
that is, the possibility of returning to ini tial conditions

present before the impact through natural means once the
impacting action ceases to impact the environment. Passing: 1
Reversibility If it is short term, that is to say less than 1 year, it is Temporal: 2
(RV)
assigned a value of (1), and if medium term, a 1 to 5 years Permanent: 4
period, it is assigned a value of (2), and if the impact is

irreversible or lasts more than 5 years, it is assigned a
value of (4). Intervals that comprehend the se periods are
identical to those assigned in the previous parameter.

This refers to the possibility of total or partial reconstruction
of the impacted factor as a consequence of the activity in Immediate
Recovery: 1
question, that is to say, the possibility of returning to ini tial
conditions present prior to the impact, through human Medium Term
intervention (introduction of corrective measures). Recovery: 2
Recovery
(MC) If the impact permits total recovery, and if recovery is Partial
immediate, it receives a value of (1), or a value of (2) if Recovery and
recovery is at medium range; and if recovery is partial and Mitigation
the impact can be mitigated, the value assigned is (4). Possible: 4

When the impact is not capable of recovery (impossible to Recovery
repair either by natural or human action) the value Impossible: 8
assigned is (8).

This attribute considers the reinforcement of two or more

simple effects. The total component of the manifestatio n of
simple effects, provoked by actions that act simultaneously,
is superior to what could be expected from manifestation of
actions that act independently and not simu ltaneously (the No synergy: 1
Sinergy Moderate
(SI) lethal dos e of a product A, is the DLA and the dos e of Synergy: 2
product B is D LB. Applied simultaneously, the dose of both
products DLAB is greater than DLA and DLB). Very Synergic:
4
When an action that impacts on a factor is not synergic
with other actions that act on the same factor, the value
assigned is (1), and if synergy is moderate, the value is (2).

It there is high synergy, the value is (4).
This characteristic is based on the idea of the prog ressive

Accumulation and cumulative effect of the impact, when the action that Simple: 1
generates it is persistent or continuous.
(AC) Cumulative: 4
When an action does not produce cumulative effects
(simple accumulation), the effect is assigned a value of (1).

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Evaluation Description Value Range
Element
If the effect is cumulative, the value assigned is (4).

This feature refers to the cause-effect relationship in terms

of direction, that is to say the manner in which the effect
manifests itself on a factor as a consequence of an action.
The effect may be direct or primary, in which case the

impact is a direct consequence of the act ion, with a value Indirect
Effect assigned of (4). (secondary): 1
(EF) In case an indirect or secondary effect is present, that is to
Direct: 4
say, the effect is a result of a primary effect and no direct
effect exists associated to that action, the impact value
assigned is (1). Its manifestation is not a direct
consequence of the action, but it is the result of a primary
effect, acting as a secondary order.

This refers to the regular manifestation of the effect,

whether cyclic or recurrent (periodi c effect), sporadic in
time (irregular effect), or constant over time (continuous). Irregular,
Continuous effects are assigned a value of (4), while sporadic
Periodicity and dis-
periodic effects receive a value of (2) and those of irregular
(PR) manifestation, which must be evaluated in terms of continuous: 1
probability of occurrence, as well as discontinuous over Periodic: 2
time, receive a value of (1).
Continuous: 4
An example of continuous effects is the occupation of a
space due to construction of a building.

Source: Manual de Instrumentos Técnicos para el Proceso de Evaluación de Impacto Ambiental (Manual de EIA) -
Parte IV-SETENA).

According to what is established in Decree No. 32967, the importance of the impact or effect of
an action over an environmental factor is represented by a number that is obtained through the

proposed model, as a function of the value assigned to the previously discussed symbols :

I = ± [IN + 2 EX + MO + PE + PV + SI + AC + EF + PR + MC]

The importance of the impact is assigned values betw een 13 and 100 according to the expected
impact on each element or factor, and presentes intermediate values (betwee 40 and 60), when
some of the following circumstances apply:

¥ Total Intensity, and minimal impact on the remaining symbols

¥ High or very high intensity, and high or very high effect in the remaining symbols

¥ High intensity, no recovery effect and very high impact on some of the remaining
symbols.

¥ Medium or low intensity, no recovery, and very high impact in at least two of the
remaining symbols.

Therefore, the importance of the impacts is provided by the following values :

¥ Importance of impacts inferior to 25, makes them irrelevant.

¥ Importance between 25 and 50, means moderate impacts.

¥ Importance between 50 and 75 means severe impacts.

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¥ Importance greater to 75 is a critical level of impact.

In those squares that correspond to the more important impacts, or when occuring in critical
moments or places and are not subject to recovery, which will lead to the higher scores in the
chart related to impor tance, the Alert of Red Flags are superimposed, in order to call attention to
the effect and search for other alternatives in the activity´s productive process, work or project,

to eliminate the cause or have it permutted to another activity with less harm ful effects.

6.3.2 Impact Assessment

Starting with the negative impacts associated with the project, the criteria and parameters of
evaluation are applied in each case. The prevously identified impacts will be the object of this
evaluation. These are :

1. Deforestation along the right of way and contiguous areas.

2. Partial sedimentation of the edges of wetlands neighboring Route 1856.

3. Loss of trees and bushes located on the margins of streams due to flooding

4. Landslides and erosion of slopes that affect the forested m argins of the road
5. Impact on the ecosystem of the wetlands (drainage of landfill)

6. Impact on the structural connectivity

7. Potential impact on aquatic habitat

8. Potential impact of micro -habitats and aquatic macro -invertebrate substrata due to filling
of interstices with sediment

9. Possible decrease in taxonomic abundance and richness

10. Possible impact on the quality of waters due to turbidity caused by sediment.

11. Landscape impact due to the construction works.

Chart 23 corresponds to the Matrix of Importance of Env ironmental Impact s (MIIA) defined with
the application of criteria established by the Manual of Technical Instruments for the
Environmental Impact Evaluation Process (EIA Manual) - Part IV (SETENA, 2004) taking into

account the importance of each according to their characteristics, environmental aspects and
effects that are generated.

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te te
ate

Assessment Moder Irrelevant Irrelevant IrrelevanIrtrelt lIrrelevanModera IrrelevaModera Irrelevant

I
-4 -5 -8 -4 -4 -8 -4 -9 -0 -4 -5 -75

Ecological Component
–
4 4 2 4 4 4 2 2 2 2 2
MC

PR 4 2 2 2 1 1 2 1 1 1 1

Environmental Diagnosis Assessment (EDA)

EF 4 1 1 1 4 1 4 1 1 4 4

AC 1 4 1 4 1 1 1 4 4 4 4

SI 1 1 1 2 1 1 1 1 1 1 1

140
RV 4 2 2 2 2 2 2 2 2 2 2 )SETENA, 2004).

Impact Characteristics
PE 4 2 2 2 2 2 2 2 2 2 2 -arte IV

4 4 2 2 4 1 2 2 2 2 4
MO

1 1 1 1 1 1 1 1 1 2 1
EX

IN 2 1 1 1 1 1 2 4 1 4 1

2013
- - - - - - - - - - - -
+/

.
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Impact
-abitats and aquatic macro

Matrix of Importance of Environmental Impacts (MIIA) for the Route 1856 project in Costa Rica territory

Environmental impacts r
impact due to the construction worksnicos para el Proceso de Evaluación de Impacto Ambiental (Manual de EIA)

-INAE (

DeforePaRrtioauldio56suneotnosfdheieIsspachIoneIldnocstnyntsalhrPahosonftlctaoteeeiibftingoofmnttiutlindofncttaeendrcnttoesrbidity

Factor Total
! Decreto Ejecutivo Nº 32966

Environmental
TeFreustial Flora and AqFuatuicnaFlora and Landscape
Matrix of Importance of Environmental Impacts (MIIA) for the Route 1856 project in Costa Rica territory
Modified from
23: No. 1 2 3 1:
e
Chart Not
!

640 Annex 10

Environmental Diagnostic Assessment (EDA)
Route 1856 Project – Ecological Component

Taking into account the results of the evaluations of Chart 23, it is determined that only 8

irrelevant impacts have been identified and 3 impacts of moderate type. Furthermore, these
present very unique characteristics, among them:

1. None of the impacts is recurrent along Route 1856; the se are located in very specific
sites of the Project.

2. All impacts present a low to medium degree of intensity on the environment.

3. All impacts present a uniform evaluation between grades 20 to 34, which indicates a
degree of homogeneity in the low incidence of impacts along Route 1856.

On the other hand, it is considered necessary to evaluate the conditions that were previously
identified, from the perspective of potential impacts on Nicaraguan territory, where a similar
analysis was done, of each of the pot ential activities that might generate an impact, in order to

verify if the same could have manifestations on the San Juan River.

It is worth stating that it was not possible to carry out the previous suggestion since the
Government of Nicaragua did not al low the scientists that conducted this study to enter
Nicaraguan territory along the San Juan River in order to conduct sampling in the mouths of the
different bodies of water that were analyzed. Chart 24 shows the results of the analysis of such

evaluations.
Although it was not possible to prepare such a matrix based on field data taken at Nicaraguan

territory, it is not considered there could be any significant impact on the San Juan river.

6.4 Risk analysis and contingency plans

6.4.1 Sources of environmental ri sk

According to the activities that were developed as part of the road construction, some sources of
environmental r isk were identified and mitigation measures implemented in or der to avoid

disturbance of terrestrial and aquatic environments:
1. Risk of cutting down trees that are threatened with extinction.

2. Risk of erosion and instability on slopes due to inappropriate drain design and lack of

protection of the slopes.
3. Risk of alteration of natural drainage.

4. Risk of obstruction of waterways due to potential c ollapse and fall of trees, metal
structures and construction aggregates that could create artificial obstruction of such.

5. Risk of sedimentation due to the Project construction works.

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641Annex 10

- - - - - waterways.

Assessment
analyzed

I 0 0 0 0 0 0

–cological Component
at the river mouths of
MC - - - - -
river

- - - - -
PR San Juan
Environmental Diagnosis Assessment (EDA)

- - - - -
EF

- - - - -
territory AC

SI - - - - -

Nicaragua 142
RV - - - - - )SETENA, 2004).

Impact Characteristics Parte IV
PE - - - - - -

- - - - -
MO

- - - - -
EX
Government for the Costa Rican scientific team to collect samples in the

IN - - - - -

Nicaragua 2013
-
+/ - - - - -

CENTRO CIENTÍFICO TROPICAL

territory

Nicaragua esidual

!
-abitats and aquatic macro
Impacto

Matrix of Importance of Environmental Impacts (MIIA) for the Route 1856 project in

EnviManual de Instrumentos Técnicos para el Proceso de Evaluación de Impacto Ambiental (Manual de EIA)

-INAE (

Ipact onPotential imPpoascstilfecsirreadieyinsttxonnetet cuaabliutyndoafnwcaetearntoestusrbidity

to conduct the impact analysis and assessment on the Nicaraguan territory due to prohibition by the
Total
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Factor ambiental
AqFuaaticnaFlora and Landscape

:atrix of Importance of Environmental Impacts (MIIA) for the Route 1856 project in
1 2 1:odi:t was not possible
No. 2e

Chart 24 ! NoteNot

642 Annex 10

Environmental Diagnostic Assessment (EDA)
Route 1856 Project – Ecological Component

6.4.2 Environmental risk evaluation

Chart 25 presents the evaluation for each of the risk sources identified, as well as the mitigation

measures that should be incorporated in the Environmenta l Adequacy Plan. These will be
classified as Low, Moderate and High, according to the value obtained.

Chart25: Environmental risk evaluation for the Route1856 project.

Risk Source Evaluation Contingency Measure

¥ Inventory of trees along

Cutting down threa tened the right of way of Route
tree species Low 1856
¥ Monitoring the designated

route of Route 1856.

¥ Design of slopes that
adjust to the topography
and design of the road.

¥ Preventiveinitiatives
Erosion and Instability of through the construction of
Slopes Low civil works.

¥ Monitoring of the path
designated for the
construction of Route

1856.

¥ Design of road adjusted to
the drainage and rainfall
characteristics.

Alteration of natural Low ¥ Preventive actions thr ough
drainage systems the construction of
appropriate civil works.

¥ Monitoring of the route
designated for the road.

¥ Monitoring of the state of
Obstruction of waterways Low structures along designed
path of the Route 1856.

¥ Control of sedime ntation

processes in different
Alluvial Sedimentation Medium bodies of water.

¥ Monitoring along the path
of Route 1856.

As presented in the previous chart and taking into account that the majority of risks identified

along Route 1856 have been assessed as being low, it is generally de termined that the risks
studied are of an irrelevant character. In the case of alluvial sedimentation, several factors exist
that alter the results of the evaluation due to the fact that there is a sedimentation behaviour in

the rivers that is due to the f act that analyses were conducted during the rainy season. It is also
necessary to point out that in the majority of the upper part of the watersheds analysed there are
agricultural activities taking place that in some way affect the results obtained.

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Nevertheless, that does not mean that the proposed measures should not be implemented, on

the contrary. It is the responsibility of the CONAVI (National Transportation Commission) and
institutions involved in the Project, to guarantee the mitigation of all the effects produced by the
work, even though of a low and punctual character.

In the case of risk due to erosion and instability of slopes, and even though this is present only at
specific points along the route, the degree of slope is a determinant aspect of the stability

condition. That is the reason why they should been improved and mitigated for each specific
case, taking into account first the degree of slope and, second, the composition of the geological
materials in situ.

As a function of this assessmen t, the subject of risk has been objectively considered and for this
reason it will be necessary at the same time to establish concrete actions as part of the
Environmental Adequacy Plan (PAA).

6.5 Environmental control measures

Continuing with the guidelines established in Resolution No. 2572 -2009-SETENA, environmental

control measures refer to “all measures tending to prevent, attenuate or compensate the
negative impacts of the activity, following such order of priority. Moreover, it includes the
management an d control of environmental risks. Such measures arise as a result of the
evaluation of negative environmental impacts, as well as the risks evaluated in the EDA, and

they are a basic component of the Environmental Adequacy Plan (PAA).

In the environmental evaluations of the previous chapters, a total of 11 punctual environmental
impacts were identified, 8 of the type considered “irrelevant” and 3 of the moderate type, that
were produced during the construction of Route 1856, and which, if not properly manag ed, could
appear once again in the short run. An additional 5 sources of environmental risk were identified

that require the establishment of mitigation measures.

6.5.1 Environmental control measures for the identified impacts

The following measures estimate pre ventive actions, in case the impact does occur, as

mitigation or compensatory measures. All environmental measures will be cited in the
Environmental Adequacy Plan (PAA).

The identified environmental impacts that the Project generated or that could be gene rated, will
be analyzed later. These are described according to the environmental factor impacted.

6.5.1.1 Control measures for terrestrial flora and fauna

a. Partial deforestation along the right of way and adjacent areas

Source of impact/risk

Due the clearing of land and vegetation along the Project route, it was necessary to eliminate
some trees along sections of the designated path of the route, specifically at sites where no
previous roads existed.

The quantity of trees cut down was determined by the needs of eac h section of the route and the
existing plant cover. This is so because along most of the designated route at least 74% of the

way was in areas of open lands without plant cover. For that reason, in most sections where the
Route was built, it was not neces sary to eliminate forest cover. Nevertheless, it is necessary to

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establish environmental measures to avoid deforestation along the Route path, in the medium

and short range.

Environmental measures implemented

During the final months, a reforestation initia tive has been developed with the planting of
thousands of trees along both sides of the right of way of Route 1856, as mitigation measures
proposed by the Ministry of the Environment, Energy and Telecommunications (MINAET). This
plan has had an important p rocess of growth and maintenance of the trees, involving local

communities in the planting and protection activities.

Environmental measures to be implemented

1. To strengthen reforestation plans in existence with the planting of trees in areas where it
is not necessary to cover road cuts, reforesting with scarce native species, threatened or
endemic, avoiding exotic plants or species that are not present locally. It is
recommended to mix species, simulating the forest diversity and that species include an

approximate proportion of 50% of those common in the area, which are now decimated,
such as the manú, cocobolo and jícaro. The other 50% should include species that are
planted commonly in reforestation plans in the area. Priority areas should be sites with
undulating slopes or strongly undulated and in the border strand along the San Juan

River, and other rivers or creeks in the area of Route 1856.
2. To allow the natural regeneration of secondary vegetation where it appears aggressively,

not cutting it down to plant trees, or making use of arboreal species as shade to favour
species that are intolerant to the sun or which grow better in the shade in their early
growth stages, such as the manú, pinillo or the almendro de montaña, for example. At
sites with very s lanted slopes it is advisable to allow secondary growth vegetation to re -

establish itself, if possible. Given the fact that the total loss of natural forest cover was
quantified at 83 hectares, it is suggested that an area similar to that deforested be
allowed to recover its natural secondary vegetation, in a section lying next to the road,
giving priority to hilly areas adjoining the San Juan River, as a way to compensate the

native ecosystem, since commonly reforestation programs do not propitiate ecosyst ems
such as those required to maintain native biodiversity. With the purpose of verifying the
existence of tree species that are threatened within the right of way of the Route, it would
be advisable to establish a forest inventory of forest species found along the Route.

3. To establish a protection and maintenance plan for trees identified.

4. To conduct periodic monitoring along the route design to avoid squatter incursions in the
neighboring areas.

5. To promote the identification of different sections and ecos ystems along the route as a
tourism incentive.

b. Parcial sedimentation of wetland margins neighboring to Route 1856

Source of impact/risk

Soil movements, slope building and land fills generated slope instabilities on hillsides in some
places where the degree of sloping is very high, as well as superficial runoff increase ,

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sedimentation along some nearby wetland margins; and the landscape disturbance along some
sections of the Route 1856.

This impact corresponds with punctual alterations along the Route, where , in some adjacent
sites, small quantities of sediment accumulate.

Environmental measures to be implemented

1. To conduct a cleanup of the accumulated sedimentary material to permit the free flow of
water in natural drainage systems. When the road cuts into a wetland lagoon, such as is

the case with the Remolinito Grande lagoon, it will be necessary to avoid cutting off free
circulation of water, allowing drains and other means to permit the water that usually
flows into the lagoon to flow freely on both sides of the Route.

2. To improve drainage structures and land fills to avoid impacts on both.

3. Continue with civic works for the protection of slope surfaces through the placing of geo -
textiles and improvement of the angle of slopes and drainages.

c. Loss of trees and bushes along river margins due to flooding

Source of impact/risk

The placement of some drainage systems and temporary bridges could be associated to the

alteration of specific points in aquatic ecosystems and the modification of natural drainage
systems in the area. This impact is very punctual, since it was observed in few sites (at least 4
between Border Marker 2 and Infiernito River).

An accumulation of water is generated which forms a kind of dam on the river margin forest
vegetation, causing the l oss of some specimens. This is due to the fact that drains and drainage

tubes became obstructed, leading to the flooding of these small ecosystems.

Environmental measures to be implemented

1. To promote a good drainage of waters in the sites mentioned, throu gh placement of an
adequate drainage system, or lowering the levels of drains to avoid the accumulation of
waters and alteration of the road itself. Once excess water is drained, it is suggested that
the area simply be allowed to recover naturally through the secondary regeneration of

native vegetation.

d. Occurrence of landslides and slope erosion affecting the forest borders of the road

Source of impact/risk

Due to the cuts on the terrain of the route where there is forest vegetation along the border,
erosion in layers is caused, which in turn causes small trees to fall due to the loss of root
strength.

Environmental measures implemented

In recent months the roadside slopes along the route have been protected along with the
drainage systems at the same sit es, to avoid landslides.

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Environmental measures to be implemented

1. Continue with civil works for the protection of the surface of slopes along the road making
use of geo-textiles and by improving the slant of slopes and drains.

2. To evaluate the technical p ossibility of modifying the route designated for Route 1856 at
the point called Infiernillo to include the use of local roads built on less sloping terrain,

tracing the road some km. to the south, where there are open areas and settlements w ith
more favorable topographic conditions.

e. Impact on wetland ecosystem (due to drainages and landfills )

Source of impact/risk

Due to the placement of drains, landfills and sub -surface layers and the rolling surface of the

road. It corresponds with the alteration of the e cosystem at some points of the designated path
due to sedimentation and drainage in some wetlands along the Route.

Environmental measures to be implemented

1. To improve drainage structures and landfills with the purpose of avoiding impacts.

2. To allow recovery of the natural ecosystem.

3. To establish a monitoring plan along the designate path of Route 1856 with the aim of
verifying wetland recovery and prevent the cutting of Yolillo and other tree species
associated with wetlands due to activities of the local po pulation.

f. Impact on structural connectivity

Source of impact/risk

Due to the land and vegetation clearing at some sites along the route path, it was necessary to
eliminate some trees, in sections where roads were not previously present.

This loss of plant cover in some specific points of the Route, could generate an alteration of the
structural connectivity due to the cutting down of trees.

Environmental measures implemented

In recent months a reforestation plan with thousands of trees has been put into e ffect as a
mitigation measure proposed by the Ministry of the Environment( MINAE). This plan is providing

good results in terms of growth and maintenance of the trees, and it has involved community
participation in planting and protection activities .

Environmental measures to be implemented

1. To continue to implement reforestation activities with native species.

2. To promote natural regeneration and ecological restoration to improve connectivity
among populations, species and communities.

3. To establish a monitor ing plan along Route 1856 with the aim of verifying the recovery of
connectivity.

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6.5.1.2 Aquatic flora and fauna

g. Potential impact on aquatic habitat

Source of impact/risk

The construction of drains and building cement structures in some streams where bridges are
located along the Route. This impact was identified in very few sites.

Environmental measures to be implemented

1. To consolidate the civil engineering works along the Route at impacted sites.

2. To avoid applying cement along the bottom of streams below drains and bridges.

3. To conduct a monitoring plan of aquatic habitat conditions in the streams below drainage
systems and bridges.

h. Possible impact of the micro-habitats and substrata of aquatic macro -invertebrates
due to filling of interstitial gaps with sediment

Source of impact/risk

Land movements, slopes formation and landfills originated instability in slopes at some sites
where the degree of slant is strong, where there has been an increase in the surface runoff and
sedimentation has increased along some bodie s of water close to some sections of the Route.

The previous conditions originate a filling of sediment in rock cavities that modifies the temporal

substratum where aquatic macro -invertebrates normally live.

Environmental measures implemented

In recent mon ths a reforestation plan with thousands of trees has been put into effect as a
mitigation measure proposed by the MINAET. This plan is providing good results in terms of
growth and maintenance of the trees, and it has involved community participation in pl anting and
protection activities.

Environmental measures to be implemented

1. To consolidate civil works to improve slopes and drainage systems as soon as possible,

especially on unstable slopes to avoid sedimentation of aquatic media.
2. To continue with reforestation activities using native species of the region.

3. To promote natural regeneration and ecological restoration along the margins of rivers

and streams.
4. To establish a monitoring plan along the path of Route 1856 in order to verify the state of

the substrata of streams.

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i. Potential Impact onTaxonomic Abundance and Richness

Source of impact/risk

Generated by sedimentation in the waters, the decrease in the vegetal material that flows into
aquatic media and the decrease of shade which causes an impact o n the abundance of species
in the bodies of water.

Environmental measures implemented

In recent months a reforestation plan with thousands of trees has been put into effect as a
mitigation measure proposed by the MINAET. This plan is providing good result s in terms of

growth and maintenance of the trees, and it has involved community participation in planting and
protection activities.

Environmental measures to be implemented

1. To consolidate civil works to improve slopes and drainage systems as soon as pos sible,
especially on unstable slopes to avoid sedimentation of aquatic media.

2. To continue with reforestation activities using native species of the region.

3. To promote natural regeneration and ecological restoration along the margins of rivers
and streams.

4. To establish a monitoring plan along the path of Route 1856 in order to verify the status
of biodiversity.

j. Potential Impact on the Quality of Water due to Turbidity

Sources of impact/risk

Land movements, the building of slopes and landfills generate an increase in superficial runoff
and sedimentation in some bodies of water close to sections of the Route.

Environmental measures i mplemented

In recent months a reforestation plan with thousands of trees has been put into effect as a
mitigation measure prop osed by the MINAET. This plan is providing good results in terms of
growth and maintenance of the trees, and it has involved community participation in planting and

protection activities.

Environmental measures to be i mplemented

1. To consolidate civil works to improve slopes and drainage systems as soon as possible,
especially on unstable slopes to avoid sedimentation of aquatic media.

2. To continue with reforestation activities using native species of the region.

3. To promote natural regeneration and ecologica l restoration along the margins of rivers
and streams.

4. To establish a monitoring plan along the path of Route 1856 in order to verify the status
of substrata in the rivers and streams.

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6.5.1.3 Paisaje

k. Impacton landscape in some sections of the Route due to const ruction activities

Sources of impact/risk

Due to land clearing and vegetation removal along sections of the route, it was necessary to
eliminate some trees specifically in areas where no previous roads existed.

Despite the fact that the route runs mostly ( 74%) on pre- existing roads and areas with minimal
slopes, at some specific points it is possible to observe exposed surfaces on slopes and road
cuts on the terrain, mainly between Border Marker 2 and the mouth of the San Carlos River.

Environmental measures implemented

In recent months a reforestation plan with thousands of trees has been put into effect as a

mitigation measure proposed by the MINAET. This plan is providing good results in terms of
growth and maintenance of the trees, and it has involved co mmunity participation in planting and
protection activities.

Environmental measures to be implemented

1. To reforest in front of all road cuts that are visible from the right margin of the San Juan
River using various species per site, planting parallel rows in front of the cuts, starting
from the river margin, or the area alongside the slope and going up, with species that are

short in height and have a wide canopy, such as sotacaballo and balsamo (planted
sparsely to maintain a wide treetop), followed by me dium height trees such as guabillo or
balsa and other species of high profile, such as cebo, botarrama and roble coral, in such
way that the density of the trees provide the necessary foliage cover from a few meters

above ground to an approximate height of 30 meters.

2. To promote the growth of grasses on the surface of slopes. It was observed along the
Route that the species of native and adapted gramineae known as sainillo ( Axonopus sp)
and rotana ( Ischaemun indicum ), are covering a good portion of the road cuts of limited
height in the area in an efficient manner, avoiding rainfall from falling directly on slope

surface.
3. To promote the identification of landscapes and ecosystems in different sections of the

Route as an incentive to tourism.

6.6 Environmental Management Plan – Environmental Adequacy Plan (PAA)

According to the EDA guide (SETENA Resolution No. 2572 -2009) environmental action
programs that follow are the most important final products since their function is to adapt the
implementation and managem ent conditions, in this case Route 1856, to an environmental focus
perspective. This chapter is called the Environmental Management Plan which includes the

Environmental Adequacy Plan, formulated on the basis of a diagnostic study, description and
analysis of the Project’s own characteristics and its natural environment.

The PAA summarizes in concrete fashion all aspects developed in previous chapters in their
thematic components, and for this reason it is presented as a summary chart, so that it can be
seen in simplified manner. In this sense the PAA presented in this EDA seeks to strengthen the

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environmental advances made presently in the design and construction of Route 1856.

Furthermore, in such Resolution it is stated that the PAA suggests actions and control
procedures necessary to guarantee the appropriate application of environmental measures
required for the construction of the Project, in such a way that an adequate protection of the
quality of the environment is obtained, in accordance with the le gislation, requirements and

norms which hold during the operation of the Project.

It is necessary to point out that Chart 26 presents a summary of the PAA. However the column
that makes reference to the Cost of the Measure has been omitted. This is due to the fact that
some of the environmental measures were implemented some months ago. Another factor that

is an obstacle or difficulty is the fact that the quantification of costs is waiting for the final design
of the Route and some bridges are still in proc ess of being contracted by the Government of
Costa Rica; a process that does not facilitate the definition of costs.

Finally, the organization responsible for the execution of environmental measures is the National
Transportation Council (CONAVI) with the collaboration of the MINAET and other government

organizations assigned to the construction and supervision of the Route.

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651Annex 10

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CENTRO CIENTÍFICO TROPICAL
Environmental Diagnosis

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CENTRO CIENTÍFICO TROPICAL

Environmental Diagnosis

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CENTRO CIENTÍFICO TROPICAL

Environmental Diagnosis

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CENTRO CIENTÍFICO TROPICAL

Environmental Diagnosis

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655Annex 10

Environmental Diagnostic Assessment (EDA)
Route 1856 Project – Ecological Component

7 Conclusions y recommendations

7.1 Conclusions

1. The Route 1 856 project consisted in the construction of a ballast road that starts in the
site of San Jerónimo de Los Chiles and runs all the way to the site of Delta 7 (better
known as Delta Costa Rica). Route 1856 is 159, 7 km. long. A 63 % of the road designed

(101.5m) is made up of roads and access paths that have existed for over 30 years. The
remaining 35,9% (57, 4 km.) of the Route corresponds to roads that are new and were
established in order to join existing roads. Nevertheless, the present study contemplates
only the design route that runs parallel to the San Juan River with a length of 108, 2 km of

the total length of the Route.
2. For purposes of building the Route, and as is common in this type of project, it was

necessary to carry out several important seconda ry works. Among them were the
clearing of terrain, the building up of slopes, placing gutters and drains, as well as laying
the base of the road and rolling surface.

3. The environmental aspects related to the construction activities were:

a. Clearing the land and vegetation in some sections of the route design: this activity
is associated with the elimination of plant cover along sections of the route where
no roads existed previously.

b. Land movements, slope formation and landfills: could generate unstable slop es in
some points where the slope is very steep. The increase in surface water runoff

and contribution of sediments to some nearby bodies of water and the alteration
of landscape along the Route.

c. Installation of drainage systems and temporal bridges: this factor could be
associated to the alteration of aquatic ecosystems at specific points and the
modification of natural drainage systems in the area.

d. Placement of landfills, base layers and rolling surface on the road: this activity is
related to a potentia l contribution to the sedimentation of some bodies of water
close to the Route.

7.1.1 Terrestrial Biology

1. In the study area, two life zones were found: very humid pre -montane basal transition

forest and very humid tropical forest. The very humid tropical forest is the most
representative life zone in the northern part of Costa Rica and adds up to 61% of the
territory in the lowlands of Sarapiquí and San Carlos. It is the life zone that provides the
main connecting habitat between the South Atlantic watershed of Nicaragua and the
Volcanic Central Range of Costa Rica.

2. Within the Project area various ecosystems, or ecological associations, were identified,

among them: forest associations (altered primary and secondary forests), wetlands
systems, riparian systems an d Yolillo palm associations.

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3. During the last decades and due to the pressure of the agricultural frontier, many of the

primary forests ecosystems in the border area have been altered and/or destructed to
later convert into natural forests. Even so, these f orests present a high floristic diversity.

4. Regarding the wetlands systems, there is in the area a large number of rivers, streams,
channels and lagoons where the vegetation is typical of lacustrine and palustrine
wetlands.

5. The area of the Project was deter mined to be 10. 475 hectares based on interpretation of
aerial photos taken before and after the construction of the Route, but the road pr oject

only partially affected 4.921, 3 hectares, which represents 47% of the total.

6. This evaluation of the plant vegeta tion along the route, led to a quantification as follows:
for purposes of clearing of the terrain where the road route was laid, some 14,9 hectares
of secondary forests were cut down and 68, 3 hectares of primary forests were altered,
which represents 4,2% and 19,5% of the altered area of the Route design.

7. As complement, 2, 3 hectares were altered that are not forests but natural systems of the
wetland type. In the field it was possible to see that the road opening was done mostly in

open areas(74%) that wer e not forested. In cases where forests were cut down, it was in
areas where no open lands were available to establish the route.

7.1.2 Aquatic Biology

1. To assess the effect of the construction on the 1856 Route on the aquatic ecosystems
that run across the road and empty into the San Juan River, ten lotic bodies of water
were selected (creeks, channels, rivers), the structure of the communities was

characterized and the quality of water evaluated using the BMWP index (MINAE -S,
2007) focusing on the macro -invertebrates aquatic groups as indicator species.

2. In each of the bodies of water two sampling points were located, one upstream (without
direct influence) where the road crosses the body of water sampled and the other
downstream (direct influence), for a total of 20 sampling locations.

3. In general , the aquatic community of most sites sampled had a very low diversity and
richness in taxa. This result is possibly due to three reasons: current volume, turbidity -

sedimentation and type of substrata.
4. With the values of abundance and richness of the taxa obtained for the upstream sites

(upstream from the Route), and the sites with influence (downstream from the Route), in
half of the cases it is possible to state that bio- indicators did not present evident
information that indicated impact on the community of macro -invertebrates, since values
were too variable.

5. The lattercould be caused by 2 factors: 1) degradation of the quality of the habitat as a
consequence of some of the activities that were carried out in the constr uction of the

Route, such as the movement of earth and cutting down of river vegetation, and, 2)
sedimentation processes in the rivers due to unstable slopes and land fills that erode due
to rainfall.

6. An aquatic environment once altered is subject to re -colonization periods that can vary
from a few days to weeks or months, depending on the nature and reach of the

alteration. The response of bio -indicators to the effects of the construction of Route 1856
on aquatic ecosystems was imperceptible in some sampli ng sites, possibly because the
aquatic communities have already recovered.

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7. Field sampling occurred approximately one year -and-half after the road construction

works, and it is probable that during this period the communities were able to stabilize. It
is also important to take into account that these bodies of water are in low -lying areas
and that they receive large quantities of sediment all year round from the upper
watershed, so that aquatic fauna should be adapted to receive high levels of sediments

in the water.

8. The quantity of sediment that the Route contributes is not sufficient to cause a significant
impact on the bio-indicators studied in the sample sites.

9. The presence of groups sensitive to the alterations of the aquatic habitat is a good signal,
since these indicators often disappear when there are strong alterations in the aquatic
habitat, especially if the effect is persistent over time, since it does not permit the
sensitive taxa to re- colonize the bodies of water. The finding of sensitive fam ilies in

practically all sampled sites, up and downstream from the Route, can be interpreted as a
positive sign of recovery and of a minor impact of the construction on the environmental
conditions at the points of study. Only two sites did not show the pr esence of macro -
invertebrates considered sensitive.

10. It should also be taken into account that the sampling for bio -indicators was done on

rivers that flow into the San Juan River, so that the impacts that were detected due to the
construction works of the Route on the aquatic environment, such as the modification of
substrata and sedimentation, are local level events.

11. These bodies of water received a direct influence from the construction works, therefore
these results do not overlap to the San Juan River, since the latter is of a superior order,
with a greater volume of water than present at the sampled sites. The section of the San

Juan that runs parallel to this road is found in the lower part of the watershed where the
quantity of sediments is naturally high, and thus it is thought that the impacts of the
Route construction on the organisms that live in the San Juan River could have been
minimal and very diffuse, taking into account the water volume of the river, as a receptor

body.

12. In order to be able t o evaluate with greater certainty if the construction works of the
Route created a level of sedimentation that could generate an effect on the aquatic fauna
of the San Juan River, and the tributary streams of the study area, it is first necessary to
determine and validate the thresholds of sedimentation that could affect the species

found in these rivers, due to the fact that there exists no information for the aquatic
organisms in the study area.

13. It would also be necessary to determine and validate the thr esholds of mortality and
morbidity for the species found in those rivers, as well as the levels of tolerance to
sedimentation, to better evaluate if the construction of Route 1856 has an effect on the
aquatic fauna of the San Juan River. T his due to the f act that there is no information on

the aquatic organisms of the study area. To establish these values it would be necessary
to conduct periodic analyses over a long term that evaluate the tolerance of species and
macro-invertebrates to different qualities of sediments, and thus be able to determine at
what point the aquatic organisms began to die or experience a significant reduction in

abundance and diversity.

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7.1.3 Tourism

the right nor on the left margin of the San Juan River. The only site where there are
services and facilities is Delta Cabins, and these are mostly for national visitors. Towards
the two extreme areas of the river, infrastructure and facilities improve, concentrating in
the towns of San Carlos and San Juan del Norte.

2. It is important to note th at tourism axes have concentrated in the endpoints of the river. In

the case of Nicaragua, it offers services in San Carlos and neighbouring areas, and in
Greytown, San Juan and its proximities. The remainder of the river, mainly the margin
under study, has no services other than fluvial transportation from site to site. Tourism
services in the study area are extremely limited accounting for 3,54% of the tourism

nationwide (PNDTS 2011- 2020). The San Juan River department is among the poorest
in the country, and is therefore one of the regions of the country with least tourism
services.

3. The city of San Carlos is the tourism distribution centre for the San Juan River (El
Castillo, Sábalo, Solentiname Islands), but it does not offer visitors the necessary
physical infrastructure to meet their needs. Visitation to this area does not reach beyond

an estimated 10,000 visitors per year, a very small number to be able to consider
developing a competitive and consolidated tourism.

4. Some of the lodges that have appropriate facilities of a middle level, well integrated to the
natural surroundings, are developing tourism products focused on international visitors
with an emphasis on eco -tourism: wildlife observation, tours within the reservations,

specialized nature paths, fishing, etc. However, some of these have been unable to
consolidate a visitation level that would allow them to reach their point of equilibrium, so
that their services are seasonal and not year -round.

5. Tourism services concentrate mainly on nature obser vation, nature walks, boat tours and
fishing. These activities concentrate in Sábalo, El Castillo and the Indio -Maíz Refuge and
neighboring areas.

6. Even though sportfishing activities are widely provided in the region of San Carlos and

neighboring areas suc h as El Castillo and Sábalo, no commercial or fishing activities
were identified along the river for the study area. Fishing activities from Border Mark 2 to
Delta Costa Rica is sporadic, subsistence fishing.

7. The tourism potential of the region is sufficie nt to justify attracting international visitors.
However, infrastructural conditions, the state of access routes, the existing services and
products offered, the quality of the existing offer, a weak image for the region, information

and commercialization mechanisms of an incipient nature, are not sufficiently satisfactory
to attract more visitors.

8. The previously mentioned factors, in addition to a climate of instability and insecurity in
the region, generated by images of continuous border disputes between Costa Rica and
Nicaragua, do not favor the kind of private investment that could strengthen tourism in
the region.

9. All the same, Nicaragua (PNDTIS 2011- 2020) points strongly to the San Juan River

department as one of its priority destinations to strengthen and raise nature tourism in

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the country. To date, there are no significant changes in the flow of visitors. In some

instances, the contrary is what is taking place, with important decreases in tourism
visitation being reported, (see Chart 1).

10. The growth in visitation to San Carlos could increase further, though slightly, due to the
new road that connects Managua with San Carlos, which has reduced travel to 4.5
hours. However, this new access seems to be attracting mainly local tourism and

backpackers.
11. The use of fluvial transportation means that tourists travel mainly on public transportation

services which have pre- established itineraries with very accessible costs (see Annex 1).
On the other hand, private transportation services are costly and practicall y non-existent.

12. The profile of tourists who visit the region and specially those who visit across the San
Juan River is mostly that of backpackers who are willing to pay minimally for very basic
services.

13. To date, navigation on the river, requires extra in vestment due to the additional taxes that
Costa Rican boats must pay when reporting to Nicaraguan authorities in San Carlos, in

addition to the less than friendly requirements placed on tourists; conditions that add to
the sense of insecurity and distrust in trying to conduct organized tourism.

14. The effect of the construction of Route 1856 has no direct impact on tourism in recent
years.

7.1.4 Ecological Connectivity

1. The analysis of the landscape structure in the region makes evident some of the gaps
present in t he goals of biodiversity conservation and in ecosystems on the Atlantic
Watershed of Costa Rica. On the other hand, there is also evidence of a dynamic and

heterogeneous environment that can impact processes of ecological adaptation,
succession, maintenanc e of the diversity of species, community stability, competition,
interaction between predators and prey, parasitism, epidemics and other stochastic
events.

2. Identification of connectivity routes and the important connectivity areas in the landscape

of the study area, show that these are not related to the design of the route of the road,
despite the fact that this access road to the border is located in the area of most forest
cover in the study area. Likewise, it can be affirmed that the Route, due to the l imited
extension of the natural systems affected, has not originated a significant impact on the

structural connectivity of the landscape of the study.
7.1.5 Identified Impacts

1. On the basis of the evaluation of the activities conducted by the Project, a s eries of
impacts were identified, which are presented next:

a. Cutting down of the forests in the right of way of the road and neighbouring areas

b. Partial sedimentation of wetland borders near the Route

c. Loss of trees and bushes located on the margin of bodie s of water, caused by
flooding

d. Landslides and erosion of slopes affecting the forested side of the Route.

e. Alteration of the wetlands ecosystems (drainage and landfill)

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f. Alteration of the structural connectivity

g. Possible alteration of aquatic habitat

h. Possible alteration of micro- habitats and aquatic macro- invertebrate substrata due
to filling of interstitial areas with sediment.

i. Possible decrease in taxonomic abundance and richness

j. Potential impact on the quality of water due to t urbidity

k. Landscape alteration due to the construction

2. Taking into account the results of the evaluation of the Matrix of Important Environmental
Impacts, only 8 irrelevant impacts were identified, and 3 moderate impacts. These show
very particular characteristics, among them:

a. None of the impacts is recurrent along the Route; these have been identified in
very specific points along the Project.

b. All impacts show a degree of low or medium intensity on the environment.

c. All impacts have a uniform value, between the values of 20 to 34, which indicates
homogeneity in the low incidence of the impacts along the Route.

7.2 Recommendations

A series of recommendations follow that have been previously considered in the present study,

in this instance presented as a summary that advises the implementation of a number of
activities as part of the measures of prevention, mitigation and improvement of environmental
conditions in the area of the path of Route 1856.

1. To strengthen reforestation plans in existence with the planting of trees in areas where it
is not necessary to cover road cuts, reforesting with scarce native species, threatened or

endemic, avoiding exotic plants or species which are not present locally. It is advisable to
mix species, simulating the forest diversity and that species include an approximate
proportion of 50% of those common in the area which are now decimated, such as the
manú, cocobolo and jícaro species. The other 50% should include species that are

planted commonly in reforestation plans in the area. Sites with undulating slop es or
strongly undulated and in the border strand along the San Juan River, and other rivers or
creeks in the area of Route 1856, should be priority areas.

2. To allow the natural regeneration of secondary vegetation where it appears aggressively,
not cutting it down to plant trees, or making use of arboreal species as shade to favour
species that are intolerant to the sun or which grow better in the shade in their early

growth stages, such as the manú, pinillo or the almendro de montaña, for example. At
sites with very slanted slopes it is advisable to allow secondary growth vegetation to re -
establish itself, if possible. Given the fact that the total loss of natural fo rest cover was
quantified at 83 hectares, it is suggested that an area similar to that defor ested be

allowed to recover its natural secondary vegetation, in a section next to the road, giving
priority to hilly areas adjoining the San Juan River, as a way to compensate the native
ecosystem, since commonly reforestation programs do not propitiate e cosystems such
as those required to maintain native biodiversity. With the purpose of verifying the

existence of tree species that are threatened within the right of way of the Route, it would
be advisable to establish a forest inventory of forest species found along the Route.

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3. Establishment of an integrated land use plan in the region.

4. Establishment of a plan for protecting and maintaining trees identified as in danger of

extinction or banned.
5. To promote the identification of different landscape sections a nd ecosystems along the

route as an incentive for tourism.

6. To establish a protection and maintenance plan for trees identified to be in danger of
extinction, or banned.

7. To clean up all accumulated sediments to allow the free path of water through natural
drainage systems.

8. In circumstances when the road runs close to a wetland, as is the case of Remolinito
Grande Lagoon, obstruction of the free flow of waters should be avoided, allowing free
circulation through gutters and other means, so that the water that normally enters the

wetland can flow freely on both sides of the road.
9. Improve the drainage structures and landfills to avoid alterations to wetlands.

10. Continue with civil works for the protection of slope surfaces through the application of
geo-textiles and the improvement of slope angles and drainage systems.

11. To favor a good drainage of waters in the sites mentioned, through placement of an

adequate drainage system, or lowering the levels of drains to avoid the accumulation of
waters and alteration of the road itself. Once excess water is drained, it is suggested that
the area simply be allowed to recover naturally through the secondary regeneration of
autochthonous vegetation.

12. Evaluate the technical possibility of modifying the Route design at the point o f Infiernillo
to follow local roads built previously, deviating for some km. to the South, where there

are settlements and open areas with topographic conditions that are more favourable to
this type of project.

13. To establish a monitoring plan along the Rou te to verify the recovery of wetlands and
prevent the cutting of trees by locals, as well as avoid squatter incursions in areas
neighbouring the Route.

14. Continue to reforest using native species of the region.

15. To promote natural regeneration and ecologica l restoration to improve the connectivity
between species, communities and populations.

16. To establish a monitoring plan along the Route to verify the recovery of connectivity.

17. Avoid using cement in river and stream beds under drainage gutters and bridges .

18. To conduct a monitoring plan of aquatic habitat conditions in the streams below drainage
systems and bridges and to monitor the status of substrata of the monitored streams and
take necessary measures.

19. Consolidate civil works to stabilize slopes as so on as possible, especially those
considered unstable, to avoid sedimentation of aquatic environments.

20. To continue to implement reforestation activities with native species

21. To promote the natural regeneration and ecological restoration of river margins.

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22. To establish a monitoring plan along Route 1856 with the aim of verifying the status of
the substrata of streams that were monitored in this study.

23. Consolidate plant cover in the region as a means to prevent and recover the region from
the historically unso und practices in the use of land prior to the intervention of Route
1856, particularly in spaces associated with the San Juan River margin, assuring that in

the future, the population respects the conditions on the river margin.

24. Even though reforestation efforts implemented by CODEFORSA respect the use of
species that are proper to the region, it is recommended that species of rapid growth be
considered, in order to reduce visual impacts in the short run. In this process of

reforestation it is also advisa ble to make use of species that may cover vertical spaces
such that they may serve as visual barriers starting as low as 60 cm. onward.

25. It is basic to the process that the recovery of landscape be an integral part with
participation of neighbouring commu nities, for which purpose it is recommended that
initiatives include environmental education programs, civic education, entrepreneurship,

self-development and others. The purpose is not only reforestation, but also that in this
region of the country more t han any other, a clear comittment is reached with a vision of
a country that fights for sustainability and therefore for an integral and visionary action.

26. To generate development opportunities for local communities through the creation of
policies that sup port local tourism. Eventually this could become a motor to generate

tourism towards Nicaragua, as has been the intent in the past.
27. Improve safety and security conditions for inhabitants and for visitors in the region.

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Managua, Nicaragua: MARENA , Proyecto Manejo Sostenible del Municipio El Castillo, Río San
Juan / DANIDA, afiche.

Melton, B. 2009. In -stream gravel mining impacts and environmental degradation feedback
associated with gravel mining on the Rio Tigre of the O sa Peninsula, Costa Rica, and the
proposed ADI Jimenez Gravel Mining Concession. Austin, Texas: Melton Engineering Services.

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propuesto Parque Nacional Maquenque. San José, Costa Rica: Centro Científico Tropical.
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the Instream Habitat an d Fish Community of a Small Neotropical Rainforest Stream.
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gravel extraction on anadromous fishes and their habitats, with recommendations for avoidance,
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recomendaciones para la conservación de la lapa verde (Ara amb igua) en Costa Rica. San
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deposited sediment. Aquatic Sciences 67: 395- 402.

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Oxford University Press.

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continents, between two seas. London: The University of Chicago Press.

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de agua en el área de la explotación minera Crucitas, San Carlos, Costa Rica. San José, Costa
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México. San José, Costa Rica: Unión Mundial para la Naturaleza.

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manejo adaptativo de zonas de amortiguamiento en parques nacionales del Cerrado, Brasil.
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una estrategia exitosa de conse rvación. The Nature Conservancy, Centro Científico Tropical,
CATIE.

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Vreugdenhill, D., J. Meerman, A. Meyrat, L.D. Gómez& D. J. Graham. 2002. Map of the
ecosystems of Central America: final report. Washington, DC: World Bank.

Wagenhoff, A., C. Townsend & C. Mattgaei. 2012. Macroinvertebrate responses along broad
stressor gradients of deposited fine sediments and dissolved nutrients: a stream mesocosm
experiment. Journal of Applied Ecology 49: 892 –902.

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of Central America (ArcView regional map files at 1:250,000). Washington, DC: World Bank,

Comisión Centroamericana de Ambiente y Desarrollo (CCAD), World Institute for Conservation
and Environment (WICE), Centro Agronómico Tropical de Investigación y Enseñanza (CATIE).

Zamora, N., Q. Jiménez & L. Poveda. 2000. Árboles de Costa Rica. Vol. II. Santo Domingo de
Heredia, Costa Rica: Instituto Nacional de Biodiversidad, Centro Científico Tropical,
Conservación Internacional.

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9 ANNEXES

9.1 BioSketches of consultants participating in the realization of the EDA -
Ecological Component

9.1.1 Geography and Land Use Plannin g Expert

Name Oscar Arturo Lücke Sánchez

Profession Forest Engineer
Date of Birth 15/05/1950
Nationality Costa Rican
Residency San José, Costa Rica

Telephone/Fax 2280-0270
Email [email protected]

Education

1982 Master of Forestry, Duke, N orth Carolina, USA
1978 Forest Engineer (Bachelor’s), Costa Rican Institute of Technology. Cartago, Costa
Rica

Professional Experience

Professor of land use planning in the University of Costa Rica’s School of Geography. He has
worked as a consultant fo r several Central American bodies since 1989, including: Central
American Integration System (SICA); Regional Committee on Hydraulic Resources (CRRH);
PNUD; BID; State of the Nation Project (CR); Central American Commission for Environment

and Development ; “Program for the Sustainable Development of the Central American Humid
Tropics” (UICN)/ European Economic Community (CEE)/French Research and Technological
Change Group (GRET). He also held the position of Regional Project Director of the “Strategic
Actions to Strengthen the Policies for the Integrated Management of Central American
Watersheds and Coastal Areas”, which was funded by the OAS and executed by the SICA’s

Regional Committee on Hydraulic Resources. Former Regional Technical Assistant Director o f
the International Union for the Conservation of Nature (UICN -ARPA), Central America Regional
Office, years 1992-93. From 1990 to 1991 he was a Fulbright Guest Lecturer in Clark University,
Worcester, Massachusetts. He was also in charge of the “Managemen t of Tropical and

Subtropical Forest Ecosystems from Southern Mexico to Panama with CATIE/PNUMA” project
in charge the Watershed Management Unit of the Costa Rican Water and Sanitation Institute.

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9.1.2 Sustainable Tourism Expert

Name Ana L. Baez
Profession Biologist, Museologist

Date of Birth 04/03/1958
Nationality Costa Rican
Residence La Guácima, Alajuela, Costa Rica
Telephone 8837-3240

Email [email protected]

Education
1980 Bachelor in Biology, University of Costa Rica . San Jose, Costa Rica.

1984 Licentiate Degree in Zoology, University of Costa Rica. San Jose, Costa Rica
1990 Master’s Degree in Museology, Leicester University, United Kingdom

Professional Experience

President of the company Turismo & Conservación Consultores S.A. , Ana Baez works as an
international consultant in areas such as the development, management, and strengthening of
tourism; and sustainability, conservation, quality of life, museology, and management initiatives.

Her areas of expertise include planning, dev eloping, and assessing regional strategies, policies,
plans, and products relating to private initiatives and protected areas; designing and managing
sustainable development initiatives; designing tourism and visitor programs for protected areas;

and applying guidelines and tourist certification standards for the management and operation of
sustainable services. Her international clients include BID -FOMIN, AID, PNUD, PNUMA, USAID,
GEF, TNC, WWF, FUNBIO, SEBRAE, AED, CREST, TIES, CBD, GSTC, UNWTO, Rainforest
Alliance, and Tourism Institutes from Guatemala, Honduras, Nicaragua, Brazil, Bolivia, and the

Dominican Republic, among others. In Costa Rica she works with the National System of
Conservation Areas (SINAC) and the Costa Rican National Tourism Institute. Her past
experiences include: Assistant Director of the Costa Rican National Museum, Dean of ULACIT’s
School of Tourism, and National Coordinator of the Regional Project Paseo Pantera (“Path of

the Panther”) Ecotourism Program. She has worked as researche r and contributor in projects
such as Heritage Tourism in Central America (UNEP- Rainforest Alliance); monitoring systems
for the public use of the National System of Conservation Areas in Cuba (PNUD -CNAP); training
program for business owners that design s ustainable tourism products (COTELCO -

ANTIOQUIA); sustainable tourism development alternatives for community forest concessions
within the Maya Biosphere Reserve, Petén, Guatemala (TIES); Mainstreaming Biodiversity
Conservation into Tourism through the Deve lopment and Dissemination of Best Practices
(UNEP-GEF); Sustainable Tourism Cluster as a Development Alternative for Latin -America and

the Caribbean (BID -FOMIN); Nationwide Sustainable Tourism Strategy for Protected
Conservation Areas (SINAC -ICT-BID); designing of sustainable tourism products (UCI); among
others.

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9.1.3 Biology and Management of Natural Resources Expert

Name Guisselle Monge Arias
Profession Biologist

Date of Birth 02/12/1970
Nationality Costa Rican
Residence Santa Ana, San José, Costa Rica
Telephone 8931-0947

Email [email protected]

Education
1996 Bachelor in Tropical Biology

2002 Licentiate Degree in Tropical Biology with an emphasis on Management of Natural
Resources, National Univer sity. Heredia, Costa Rica
2010 Doctorate in Management of Natural Resources and Sustainable Development with an
emphasis on Management of Natural Resources, Costa Rican Institute of Technology.

Cartago, Costa Rica.

Professional Experience

Dr. Guisselle M onge currently works in the Centro Científico Tropical (Tropical Science Center)
in Costa Rica, as Co- director of the Green Macaw Research and Conservation Program; Co -
coordinator of the Local Council of the San Juan -La Selva Biological Corridor; Founding Member

of the Mesoamerican Parrot Conservation Network; and Vice -president of the Mesoamerican
Society for Conservation Biology, Costa Rican Chapter. Guisselle Monge has ample working
knowledge in sustainability and a wide experience in designing projects, fundraising, and
implementing conservation biology programs, biological corridors, leading inter -institutional

alliances at national, binational, and regional levels, and in the creation of protected areas. She
has worked as a researcher and collaborator in several projects, among which the following can
be highlighted: ecology of the green macaw ( Ara ambiguus); assessment of the conservation
and population viability of the green macaw ( Ara ambiguus) in the El Castillo -San Juan -La

Selva, Costa Rica -Nicaragua Binational Biological Corridor; biological monitoring of Ara
ambiguus nests in the northern area of Costa Rica; Management of the San Juan -La Selva
Biological Corridor; biological justification for the proposed establishment of Maquenque National
Park; involvement of nine strategic rural communities in the management, adoption, and

reconstruction of the San Juan -La Selva Biological Corridor; Fact sheet for the El Castillo-San
Juan-La Selva, Costa Rica -Nicaragua Binational Biological Corridor; Maquenque M ixed National
Wildlife Refuge Management (MMNWR) Plan; Environmental assessment of the Maquenque
MNWR; Sustainable and development principles application model for the monitoring of

biological corridors; Landscape dynamics for the Northern Caribbean region of Costa Rica:
implications for the conservation of the moist rainforest ( bosque tropical muy húmedo) ;
establishment of a cross- border conservation and development area in the lower San Juan
watershed.

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9.1.4 Land Use Expert

Name Rafael A. Bolaños Montero
Profession Forest Engineer

Date of Birth 17/09/1956
Nationality Costa Rican
Residency Venecia, San Carlos, Costa Rica
Telephone 2472-1821

Email [email protected]

Education
1978 Bachelor in Forest Engineering. Costa Rican Institute of Tech nology. Cartago, Costa

Rica
1975 Agriculture and Livestock Expert. San Carlos Institute of Agriculture and Livestock.
Alajuela.

Professional Experience
Former Director of Monteverde Cloud Forest Reserve; and former Coordinator and
Administrative Assistant of the Network of Small Reserves (CCT). As a consultant he has
worked in land use studies for private properties (INTA, MAG); ecology, forest coverage and

land use studies for EIA of the following projects: Hydroelectric Project Don Carlos (Upala),
Hydroelectric Project Chimurria (Upala), HYDROELECTRIC PROJECT Angostura (ICE);
Northern Area of Costa Rica (DESFIL -USAID); HYDROELECTRIC PROJECT Toro (ICE);

HYDROELECTRIC PROJECT Sandillal; HYDROELECTRIC PROJECT Arenal;
HYDROELECTRIC PROJECT Boruca; Kuna Yala R eserve (Panama). Life Zones Expert in
Costa Rican Life Zone Maps and Pichis Palcazu Valley Life Zones (Peru); Hawaii Islands,
Papua New Guinea, San Juan River (Nicaragua); Bay Islands (Honduras); EIA Coordinator in

lithic material concessions, Platanar riv er (San Carlos); creation of dry season maps of Costa
Rica, 1:200.000 scale (CCT); Methodology and field survey consultant for the Ecosystem Map of
Ecuador (in progress) (CCT -ESPEA); Coordinated the study to compensate the alterations
caused to the Tambor (Cóbano) wetland; Environmental regent and Form D1 for the paving of a

private road in Paquera (Puntarenas); biodiversity valuation under the PSA (Payment of
Environmental Services in Spanish) program’s economic valuation of Costa Rica (FONAFIFO -
CCT); Mah ogany diagnosis in Mesoamerica (CCT -PROARCA/CAPAS-IRG-USAID); Costa
Rican forest coverage map (CCT -CIEDES-FONAFIFO); EIA HYDROELECTRIC PROJECT

Pirrís land use expert (CCT -ICE).

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9.1.5 Aquatic Biology Expert

Name Bernald Pacheco
Profession Biologist

Date of Birth 21/11/1978
Nationality Costa Rican
Residence San Pedro, San José, Costa Rica
Telephone 8992-2693

Email [email protected]

Education
1980 Bachelor in Biology, University of Costa Rica. San José, Costa Rica

1984 Licentiate Degree in Biology, University of Costa Rica, San José, Costa
Rica
Present Master’s Degree in Project Management, University for International
Cooperation. San José, Costa Rica

Professional Experience

Expert in aquatic entomology and bio -monitoring; he h as specialized training in the following
disciplines relating to aquatic ecosystems: Aquatic Entomology, Bio -monitoring of aquatic
environments, Environmental Issues and Possible Solutions, Ecology of Aquatic Environments,
Environmental Impact Assessment, Aquaculture, Aquatic Ecosystems: threats, risks, and

conservation; Hydrothermal Vents, Geographic Information Systems, Ichthyology, and
Herpetology. He currently works as Manager of AquaBioLab S.A.’s Bio- monitoring Laboratory, a
company with which he has c onducted various studies concerning aquatic fauna and limnology
with regards to Environmental Impact Studies, Environmental Management Plans, bio -

monitoring of hydroelectric projects, industrial and agricultural pollution, and mining, among
others. He also works as an associate researcher for the Zoology Museum of the University of
Costa Rica’s School of Biology. He has taught aquatic bio -monitoring workshops for UCR’s
Integral Environmental Management Program; in addition, he has participated as guest lect urer

on courses such as Tropical Biology and Tropical Field Ecology (USAP -OET, Kent State
University) for the aquatic bio -monitoring sections. He has contributed as researcher and
assistant in various projects, among which the following can be highlighted: Integral
Management Project for Jabonal River’s Watershed (PROGAI -UCR); “Effects of irrigation canals

on stream ecosystems in a tropical dry forest region of Costa Rica ” (Suzzane Moellendorf
Doctoral Dissertation- University of Florida); Hymenopteran parasitoids associated with rice
crops in Costa Rica ” (UCR -Dr. Paul Hanson). Furthermore, he has presided over aquatic
entomology conferences (University of Costa Rica, XIIIth Congress of Mesoamerican Society:

Biology and Conservation -Belize, IIIrd Colombian C ongress of Zoology -Colombia); and has
published several papers on aquatic entomology.

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9.1.6 Geographic Information Systems Expert

Name Andreas Mende
Profession Geologist

Date of Birth 14/12/1966
Nationality German
Residence San José, Costa Rica
Telephone/Fax 2292-8785

Email [email protected]

Education
1995 Geology Degree, University of Bonn and University of Cologne, Germany

1999 Doctorate in National Sciences, Stuttgart University, Federal Republic of Germany

Professional Experience
Ever since 2005 he has worked as a consultant for Geo-Resiliencia S.A. in the fields of

Geographic Information Systems (GIS), environmental geology, natural disaster prevention,
hydrogeology, and geotechnics. He has additionally participated as a researche r and scientific
contributor in several projects, including: "Land Suitability Mapping" (UCR/German Research
Foundation – DFG); TICOSECT (German Research Foundation – DFG/ University of Stuttgart,

Germany); Archeological Field Survey (Archeological Service /University of Cologne, Germany).
Other projects of his include: Digital Atlas for the United Nations’ “Integrating Watershed and
Coastal Areas Management in Caribbean Small Island Developing States” program; “Natural

Disaster Risk Analysis for Costa Rican Communities” for the National Commission for Risk
Prevention and Emergency Management (CNE); Territory Ordering in the Maritime and
Terrestrial Zone of the provinces of Guanacaste and Puntarenas (EPYPSA S.A.); Environmental
Characterization for the Develo pment of Marinas and Piers in the Costa Rican Pacific Coast;

Environmental Zoning and Territorial Base Study -PRUGAM (INDECA-Astorga); Zoning Proposal
based on the Environmental Fragility Indices for the Municipality of Escazu’s Zoning Plan (Geo -
Resiliencia S.A.); Geological -Environmental Analysis of Jabonal river’s subwatershed (progai -
ucr); Land Suitability and Environmental Fragility Assessment of Orosi and the creation of

Guidelines for Land Use (CNE); Geological- Geomorphological Study for Drake Bay’s Zo ning
Plan (Geo-Resiliencia S.A.).

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9.1.7 Connectivity Expert

Name Olivier Chassot Labastrou
Profession Gestión de Recursos Naturales

Date of Birth 17/09/1972
Nationality Suizo-Costarricense
Residency Santa Ana, San José, Costa Rica
Telephone 8822-0226

Email [email protected]

Education
1997 Bachelor´s in Arts, History, Old History, Language and French Literature, Université de

Lausanne. Switzerland
2005 Masters in Project Management, University for International Cooperation. San Jos é,
Costa Rica
2010 Doctorate in Natural Sciences for Sustainable Development, Costa Rican Institute of

Technology. Cartago, Costa Rica

Professional Experience

Executive Director at the Tropical Science Center (Costa Rica), Co- Director of the Great Green
Macaw Research and Conservation Project, Co -Coordinator of the Executive Committee of the

San Juan -La Selva Biological Corridor, Chairman of the Foundation for Participatory
Environmental Management, Coordinator of the Mesoamerican Parrot Conservation Net work,
Chairman of the Mesoamerican Society for Conservation Biology, Deputy Vice -Chair for
Connectivity Conservation at the Mountains Biome of the World Commission on Protected Areas

(WCPA-IUCN), Vice-Chair for Mesoamerica at the Transboundary Specialist G roup of the World
Commission on Protected Areas (WCPA -IUCN), Coordinator of the International Connectivity
Conservation Network (WCPA -IUCN), Director of Communications for the Austral and
Neotropical America Section of the Society for Conservation Biology (SCB), and is also an active

member of the World Commission on Ecosystem Management (CEM -IUCN). He has been the
Director of Science at the Tropical Science Center, Dean of Environment and Sustainable
Development and Director of the Latin American School fo r Protected Areas (ELAP) at the
University for International Cooperation (UCI) in Costa Rica, from 2009 to 2010. Dr. Chassot has

an extensive knowledge in sustainability topics, and experience in designing, fundraising and
implementing conservation biology programs, biological corridors, leadership of inter -institutional
alliances at the national, bi -national and regional level, as well as in the creation of protected
areas. Author of 102 publications and 123 presentations at international conferences and

workshops (Costa Rica, Nicaragua, El Salvador, France, Germany, Ecuador, Peru, Belize,
Puerto Rico, Brazil, Honduras, Panama, Spain, Mexico, Guatemala, the United States,
Colombia, Korea, Cuba, Switzerland, New Zealand, Australia, Chile and Monaco). Coordinator
of 70 national and regional events (Costa Rica, Nicaragua, El Salvador, Honduras, Guatemala,

Cuba, Mexico, Brazil, Panama, South Korea and Belize).

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9.2 Impact assessment of the implementation of the Route 1856 project on the

development of tourism activities in the San Juan River

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Environmental Diagnosis Assessment

Route 1856 Project – Ecological Component

Impact Assessment of the Implementation of the Route
1856 Project on the Development of Tourism Activities in

the San Juan River

By :

Ana L. Báez.

(Planning and Visitor Management in Natural and Cultural Areas Specialist

- Sustainable Tourism Management)

San José, Costa Rica.
November, 2013.

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TABLE OF CONTENTS

1 ! INTRODUCTION ................................................................................................................!.6

1.1 ! Background.............................................................................................................!......6
1.2 ! Objectives ............................................................................................................!.........6

1.2.1 ! Especific Objectives ............................................................................................!...6

1.3 ! Methodology ...........................................................................................................!......6

2 ! GENERAL DESCRIPTION OF THE STUDY AREA .............................................................8 !
2.1 ! Socio-Economic Summary ............................................................................................8 !

2.2 ! Tourism Circulation ...................................................................................................!....9

2.3 ! Tourist Profile........................................................................................................!......10
2.4 ! Services and activities ...............................................................................................!.10

2.5 ! Tourism routes ........................................................................................................!....12

2.5.1 ! Specialized observation of nature .........................................................................13 !

2.5.2 ! Biosphere Reserves scientific tourism ..................................................................13 !
2.5.3 ! Adventure tourism ...............................................................................................!.13

2.5.4 ! Cultural tourism ................................................................................................!....13

3 ! LANDSCAPE CHANGE AND ASSESSMENT ...................................................................14 !

3.1 ! Conservation efforts ..................................................................................................!..15
3.1.1 ! The Biological Border Corridor is a declared Wildlife Refuge. ..............................15 !

3.2 ! Landscape approach ...................................................................................................1!

4 ! RESULTS .....................................................................................................................!.....17

4.1 ! On the diagnosis ......................................................................................................!...17
4.2 ! On the route constructed .............................................................................................1!

5 ! RECOMMENDATIONS ......................................................................................................20 !

6 ! BIBLIOGRAPHY.................................................................................................................!1

7 ! APPENDIX ....................................................................................................................!....22
7.1 ! Summary of companies and institutions consulted by phone call of personal
communication......................................................................................................................22

7.2 ! Itineraries for public transportation services in the department of Rio San Juan .........22 !

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i. Chart Index

Chart 1: Tourist arrivals to Nicaragua according to travel means and entry point (Serie 2008 -
2012). ..................................................................................................................................9

Chart 2: Destination Classification according to PNDTS 2011 -2020. ......................................!1

i. Map Index

Map 1: Tourism routes in the South of Nicaragua. ...................................................................13!

ii. Photograph Index

Photograph 1: Reforested areas along the Route. ...................................................................17!

iii. Glossary

Abiotic: designation for that which is not biotic, that is not a part of or a product of living
organisms.

Tourism attraction : Any point or element of the natural or cultural patrimony of a site that is

capable of motivating a visit by a tourist
Biodiversity: the variety of genetic material found in the flora and fauna of a locality.

Biotic: that which is characteristic of living organisms or that maintains a link to them

Local communities: communities that are adjacent to, or near, wildlife area s

Contamination: the addition of any natural or artificial matter to the air, water or ground in
quantities such as to turn the resource inadequate for a specific use

Destination: geographic zone or area located in a distant place which is visited by a tou rist,
with limits that are physical, of political context, and of perception from the perspective of the

marketplace. From a business perspective, organizational as well as strategic, the perimeter
of a destination is constituted by the relationships that are built among the group of productive
units that participate in the tourism activity.

Geographic Space: concept used by science to define spaces organized by society.

Excursion: a series of integrated services under a fixed itinerary which includes a num ber of
places to visit (cities, sites).

Fam tours/ familiarization visits : (in English: “fam” tours), courtesy visits offered to
journalists, tour operators and travel agencies so that they can experience first hand a visit to
a destination so as to gain a better understanding of the product and a closer relationship,

leading to improved future commercialization.
Tourism Industry : or Travel Industry, set of businesses dedicated to offering services related

to travel which includes transport personnel, hotel staff and travel agencies of different types
(wholesalers, retailers, tour operators, local operators).

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Infrastructure: a set of elements or services that are considered necessary for an
organization to function properly or for an activity to evolve effec tively.

Tour Operator : An enterprise that creates and sells trips with all services included, or offers
tourism services to be sold through other agencies in addition to selling directly to the public.

Tourism Package: a set of two or more tourism services that can be bought by and individual

or group (regardless of number) and which normally includes lodging and a combination of
other elements such as transportation, meals, local visits, etc.

Tourism Product : a set of material and immaterial services offer ed in the market with the aim
of satisfying tourists´ desires and expectations.

Tourism: activities performed by individuals during their trips and visits to places that are not
their habitual living place, for a continuous period of no more than a year an d longer than one
day, for purposes of recreation, business or other motives (OMT).

Sustainable Tourism : the type of tourism that is fully aware of the present and future

economic, social and environmental repercussions of the fulfilment of their needs, th e needs
of industry, of the surrounding and host communities (OMT)

Tourist: visitor (internal, receptor o sender) who classifies as tourist (or visitor who stays
overnight) if the trip includes an overnight stay.

Tourism Route : travel extension designed fo r the tourist to visit designated areas of tourism
interest, or specific tourism attraction sites.

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1 INTRODUCTION

1.1 Background

As part of an environmental analysis initiative related to the construction of the road known as
Route 1856 (the Route, in this study), the services of the Tropical Science Center (TSC) were

commissioned based on the organization´s well known prestige, exp erience and technical
knowledge on environmental assessment topics, to condu ct and Environmental Diagnostic
Assessment (EDA) with emphasis on the Ecological Component. Closely related to this
component, an assessment of impacts of the construction and oper ation of the road on the

development of tourism activities in the San Juan River was included along with the EDA. The
tourism study was directed by consultant Ana L. Báez.

Regarding the subject of tourism, the following precepts are to be determined:

1. If there is a technical basis to determine that the construction of Route 1856 adversely
affects tourism on the San Juan River.

2. Goal: to investigate whether Route 1856 generates important visual and aesthetic
impacts to tourism on the San Juan River.

1.2 Objectives

To justify the existence of potential impacts that might affect landscape value and the future
development of ecotourism in the neighbouring areas due to the construction of Route 1856

on the right margin of the San Juan River (Costa Rica territory) base d on technical criteria.

1.2.1 Especific Objectives

1. To describe the current and potential tourism development in the San Juan River.
2. To research potential aesthetic and visual impacts of Route 1856 on the potential for

tourism development in the region of the Sa n Juan River.

1.3 Methodology

The work conducted was based on three basic information collection methods:

¥ Bibliographic analysis.

¥ Interviews with key informants, commercial organizations and institutions.

¥ Fieldwork in the project area.
The specialist in charge of this project visited the study area on July 27, travelling from Tiricias

to Delta Costa Rica, as a tourist on board a private small boat in order to gain a tourist
perspective of the landscape, and to observe affected sites and initiatives that are underway
in reforestation and protection of slopes along the Route.

Furthermore, on August 18 , 2013 an observation flight was performed over the road
construction area, flying in both directions and obtaining an excellent perspective of the route

traced for the road.

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The specific information on tourism activity, systematized offer and history of the development
of services, and growth or decrease in visitation, is very limited and based on very different

sources of information which are not consistent among them.

It was not possible to conduct a survey in the area, therefore direct telephone interviews were
conducted with some of the main actors on both sides of the river; information that is
presented in Annex 1.

Additionally, the stud y was complemented in a very productive way with periodic review

processes and discussions with specialists in the team in charge of the EDA, and this offered
a global view of the problems under study.

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2 GENERAL DESCRIPTION OF THE STUDY AREA

2.1 Socio-Economic Summary

Conditions in the region of the study are generously described in the document “National Plan
for the Development of Sustainable Tourism (PNDTS), San Juan River Destination,
Development Strategy 2011 -2020” INTUR -BID-AECID, which provides the follow ing

information. The San Juan River belongs to a political -geographical division known as
Department of Rio San Juan, reported as the third poorest of such divisions in the country:
55% of the population in this department lives in conditions of extreme po verty. The

department has 190,353 residents (2010). The capital of the department is the town of San
Carlos, with a population of 42,358 inhabitants in 2010 (estimate d by INIDE).

The percentage of houses with electrical services is 30.1%, which decreases t o 12.4% in rural
areas. Thrash disposal in 75% of homes is done by burning the thrash or placing it in empty

lots, and only 1.4 of homes have potable water services.
The service of telephone communications, by cable or cellular, offers very low coverage. T he

cell phone company Claro offers their services in the town of San Carlos, while in other
municipalities of the department the only communication option is by satellite, or, in some
places by using cellular nets based in Costa Rica. San Juan in Nicaragua has cell phone and

internet services.

Terrestrial transportation from Managua makes use of the new Managua -San Carlos highway,
with an approximate length of 300 km lasting 4.5 hours. A proposed bridge over the San Juan
River would without a doubt improve access to this destination, especially for tourism flows

from Costa Rica.

The PNDTS considers this new highway as a means “that would allow proposing with a
relatively short time (3 to 5 years) not only an increase in tourism to the San Juan river but
also the development of tourism circuits of a bi -national type around Lake Cocibolca (Lake
Nicaragua) or down the San Juan river all the way to San Juan del Norte and be able to

connect with the Costa Rican coast”. According to Costa Rican businessmen, that w ould only
diminish travel by boat and it would provide benefits only when relations between the two
countries are normalized and the region becomes safer.

Regarding fluvial transportation, the company Empresa Portuaria Nacional provides a service

that runs between Granada and San Carlos, lasting 14 to 16 hours, using boats that are low
on the scale of tourist expectations. From that point it is possible to take medium and large
boats that travel on the San Juan River.

Collective transportation vessels are v isibly deteriorated and do not offer comfortable

conditions for a travel route that is longer than 2 hours to El Castillo and 13 hours to San Juan
de Nicaragua. Nevertheless, there are private boats that offer better conditions, but at very
high cost, estimated at up to $1,000 US dollars.

Concerning aerial transportation, the airline La Costeña covers the distance Managua to San
Carlos. In early 2011 the company Nicawings offers hydroplane transportation from Managua

and Granada to San Juan de Nicaragua. De tails of all these services are included in Annex 2.

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2.2 Tourism Circulation

Despite the fact that tourism development in Nicaragua has reported a sustained increase of
1
9% during the last decade , such growth does not reflect on tourism activities in the study
area. Its main impact is still slow in San Carlos, El Castillo and San Juan de Nicaragua (see

Chart 1).

The more recent visitation and point of entry information for control points in the study area
indicate that entry at San Carlos totalled 13,464 touris ts, an increase of 18% over the previous
year. This is contrary to information from other sites such as San Juan del Sur, Sarapiquí (in

Costa Rica), San Juan del Norte, and Papaturro, which show consecutive decreases between
2008 and 2011, with an increase of 5% in 2012, as summarized in the following chart
(statistical bulletin: Boletín Estadístico de Turismo, 2012. Instituto de Turismo de Nicaragua).

It is worth noting that entrance through the different fluvial entry points in Nicaragua has

suffered significant decreases during these years, starting with 25,502 in 2008 down to 16,574
in 2012.
2
Chart 1: Tourist arrivals to Nicaragua according to travel means and entry point (Serie 2008-2012) .

Aquatic entry point and post 2008 2009 2010 2011 2012

Potosí 917 862 814 855 693

Corinto 6,632 8,832 2,094 776 513

Puerto Sandino 83 22 1 83 17
Puerto Cabezas 18 8 0 140 0

Bluefields 373 251 190 136 254

San Carlos 8,952 8,942 8,608 11,213 13,464

Other posts 1/ 8,527 6,974 2,731 1,564 1,633

Total tourists 857,901 931,904 1011,251 1060,031 1179,581

1/ Relates to tourists arriving to Nicaragua via San Juan del Sur, Sarapiquí, el Castillo, San Juan del Norte y

Papaturro. Source: INTUR with data from Dirección General de Migración y Extranjería.

Studies conducted for the PDTS Strategy of the San Juan river, 2011 -2020 report a tourism

flow in the San Juan estimated at an average of 10,000 international tourists, about which the
study concludes that “this is a v ery limited number that does not help the emergence and

consolidation of a minimally viable tourism sector in the whole complex (which does not
impede the existence of individual initiatives and businesses that are perfectly viable, as is in
fact happening), and makes tourism a secondary activity, incapable of leading the economy of

the department and acting as a motor in the social and economic development of the region”.

The image of San Juan River outside of the region is still undefined and very weak, d espite
the fact that it is a tourism destination that focuses mainly international tourists.

1
Boletín Estadístico, 2012 http://www.intur.gob.ni/index.php?option=com_content&view=article&id=27…

2IDEM

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2.3 Tourist Profile

Available studies that offer data on tourism in the region of the study are very few and non -

systematic. The main and most recent source is the in formation prepared for the
PNDTS/PDTS Strategy for the San Juan River, 2011.2020, based mainly on reports of the
Araucaria Project XXI (AECID) which focuses attention on El Castillo and other neighbou ring
zones.

It is important to note that data correspond to year 2010, prior to the period of conflict that

developed after the construction of Route 1856. Following is the typolog3 cited for tourists who
visit El Castillo and other areas neighbouring San Juan, Nicaragua

a) International tourist (61.4%): Spain, Germany, France and United Kingdom are
31% and the United States 14%. Entry: 20% of tourists arrive through Costa Rica.
Nicaraguans average between 7 and 12%.

b) Many tourists combine their visit to San Juan with other national destinations,

mainly Granada, Leon, Managua and Masaya.
c) Arrival is strongly seasonal, with an absolute maximum occurring in the month of

august.

d) Short stays are prevalent (the number of overnight stays is between 1,7 and 1,9
nights).

e) Age: 65% of tourists are aged 26 to 45 years.

f) The average daily expenses are around $ 53 US dollars.

g) Tourists generally travel with a group of friends and in second place in family
groups (they prepare their own travel plans).

h) The main source of information are the tour guides (40,4%), followed by
recommendations of friends and family (34,8%).

i) INTUR assumes that in 2010 a total of 12,100 tourists visited San Juan River
(3,032 visited El Castillo), but due to the lack of consistent data this study offers an
estimate of 10,000 persons who visited San Juan in cluding national visitors.

j) During the first semester of 2010, 1,2% of tourists who visited Nicaragua reported

having visited the San Juan River, 0,7% visited San Carlos and 0,3% visited El
Castillo.

2.4 Services and activities

The variety and richness of touri sm opportunities in the San Juan river region are based on
the exuberant biodiversity present, the existence of large protected areas such as the

Guatuso Refuge and Indio -Maiz Reserve, as well as the great extension of water that
nourishes these resources.

Remoteness of the region and access that is mainly through fluvial means both cause this
region to achieve a modest level in tourism development. To date this destination is assigned

the following characteristics according to PNDTS 2011 -2020, which also v iews this region as
the highest development priority:

3Plan de Desarrollo Turístico Sostenible de Nicaragua. Destino río San Juan. Estrategia de desarrollo. 2011 -2020
BID-INTUR-AECID. !

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Chart 2: Destination Classification according to PNDTS 2011-2020.

4
Destination Main attractions Main products Priority

1. Natureobservation
1. Natue r
2. Adventure tourism
SanJuanRiver 2. Adventure 1
3. Cultural tourismo
3. History
4. Transit

The 50% of the services in the region are concentrated in the town of San Carlos and tourism
activity is only 3,54% of that for the whole country. San Carlos acts as a distribution center for

interest areas such as the Solentiname Islands, Lake Cocibolca, El Castillo and San Juan
Norte. Communication among these locations is through fluvial means, which restricts travel
mainly to established itineraries for public transportation services.

Infrastructure at this destination is very basic and limited, therefo re important public and

private investment is required in order to mature and progress as a tourism destination with a
nature avocation. A total of 40 visitor boarding places are reported with 321 rooms and 616
beds available.

Only a few of these boarding places offer conditions for the type of product that is intended to
be offered. In fact, hotels that are reported in the web site www.riosanjuancanatur.org are the

hotels Montecri sto, Mancarron, Sábalo, Sábal o Lodge, Gran Lago, Victoria and E squina del
Lago.

Following are the tourism products that are offered in the web pages of the main
establishments in the area:

1. Travel by boat/nature observations: this is one of the more common programs
which includes short boat or kayak rides, as well as longer stretches that include the

almost 300 km. to San Juan del Norte. In the proximity are found important channels
and water surfaces that offer extraordinary visiting experiences.

2. Walks: in neighbouring areas or in plan ned routes with guides from the Indio Maiz
Reserve or the Guatuso Refuge.

3. Sports Fishing: Royal Tarpon (Sábalo), Róbalo, Guapote. Gaspar and Machaca.
Fishing is done by trolling and casting, normally with Rapala flies. Fishing areas are:

Mouth of the Sábal o River, Poco Sol, Santa Cruz, El Castillo, Medio Queso, Santa Fe
and El Pitazo rivers and lagoons. If the fishing is poor in the area clients can ask for a
fishing tour in the Solentiname Islands where they can cast for Guapote and

Laguneros fish.

4. Rest: the landscape offers excellent views and the tranquillity of the site permits
contemplation and enjoyment of nature.

4
Taken from Plan de Desarrollo Turístico Sostenible de Nicaragua. Destino Río San Juan. Estrategia de
desarrollo. 2011-2020 BID-INTUR-AECID.

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5. Culture: the offer includes crafts, cultural activities and the daily life patterns and
practices of the multi-cultural groups present in th e region.

2.5 Tourism routes

The development of tourism in Nicaragua points to a consolidation process of tourism routes

as a strategy of differentiation and strengthening of destinations. In the case of San Juan
River there are tourism proposals dating back b efore 2006 that include bi -national initiatives
that joined efforts between Costa Rica and Nicaragua.

The governments of Costa Rica and Nicaragua worked jointly on the initiatives for the Water
Route (Southeastern Nicaragua -Northeastern Costa Rica) based o n natural attractions in

rivers and channels, adding the interesting cultural and historical traditions of local
populations. Likewise, the Nautical Route was a bi -national initiative based on nautical tourism
in the Caribbean region that offered the best option to bring together tourism from Nicaragua,

Costa Rica and Panamá.
Sports fishing activities, mainly of sail fish and related, along with sailing and cruisers

visitation, would permit diversification of natural products, sun and beach, adding value t o
natural products and allowing attraction of new markets based on the developing tourism port
cities along the Caribbean coasts of Central America 5. Neither of the previously mentioned

initiatives has been able to move forward primarily due to the politic al instability in the San
Juan River which has effectively dampened all joint developments.

Nevertheless, according to PNDTS 2011 -2020, Nicaragua salvages the idea and various
priority routes are identified for the region such as the consolidation of the San Juan River
route also known as the Water Route (Transit Route) and the evaluation of the future Gold

Route which stretches from San Juan del Norte to Greytown, on the Atlantic coast, all the way
to San Juan del Sur on the Pacific side.

Growth projections for such destination are based mainly on the implementation of such
routes as were identif ied as projects for the development of the region but which, up to the
present, have not been implemented in their totality. This destinations are mentioned in

PNDTS 2011 -2020 as “these destinations with medium priority, with the appropriate
improvement in infrastructure, services and conditions of the local populations, and the
valuing of their resources, can become in the medium term big attractions for the holiday

travel international markets, being as they already are, in large measure, tourism destinat ions
for national and regional tourists.”

5
Comisión Regional de Iniciativa Mesoamericana de Turismo. Perfil de Proyecto. Ruta del Caribe
Centroamericano!
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Map 1: Tourism routes in the South of Nicaragua .

Taken from: PNDTS (2011-2020).

The PNDTS proposes 4 main market segments to concentrate activities and potent ial offers
for this destination:

2.5.1 Specialized observation of nature

The Water Route , which runs down the San Juan River and has natural and landscape

resources, allows visitation of the Indio -Maiz Biosphere Reserve and Los Guatusos Refuge for
observation of flora and fauna, birds and manatees. The Lake Cocibolca coast and Islands
provide a unique combination of landscapes and volcanoes, archipelagos and islands.

2.5.2 Biosphere Reserves scientific tourism

Bosawás is the largest and best preserved tropical forest in Central America and it includes
natural reservations such as Cerro Banacruz, Cerro Kilambé, Macizo Peñas Blancas and the

Cerro Saslaya National Park. The San Juan River destination includes the In dio-Maíz
Biological Reserve, the Los Guatusos Wildlife Refuge, the San Juan River Wildlife Refuge and
the nature reserves of Cerro Silva and Punta Gorda.

2.5.3 Adventure tourism

The Water Route facilitates access to the Indio Maiz Reserve, the Solentiname Archipelago,

and the Guatusos Refuge , allowing for adventure and recreational tourism.

2.5.4 Cultural tourism

Cultural tourism in the San Juan region can be based on the Water Route destination, the
Lake Cocibolca communities and Granada, all of which constitute the historical scenario of
colonial development in Nicaragua and the pirate incursions which gave rise to fortresses, etc.

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The Gold Route stretches beyond the San Juan river across the Rivas isthmus and to San
Juan del Sur provides an historical account of the gold rush to California using the San Juan
River as a transit route, and the arrival of the filibuster troops in Nicaragua.

3 LANDSCAPE CHANGE AND ASSESSMENT

The landscape is defined as an area that can be observed from a site and that involves an
observer and an observed object whose ou tstanding features are the visual and spatial

qualities.

In general, landscape is understood to be a terrestrial surface area resulting from the

interaction of the different factors present in it and which have a visual reflection in space. The
geographic space is defined by the forms, natural or anthropic that compose it. All landscapes
are formed by elements that are articulated among them. These elements are essentially of

three types: abiotic (non -living), biotic 6resulting from the activities of living organisms) and
anthropic (resulting from human activity) .

There are multiple methods for the assessment and valuation of landscape, according to
interest, function and discipline from which the analysis is done. In our case we consider the
landscape of the study area as a representative sample of the conditions existing before and

after Route 1856 came into existence, on the margin of San Juan river in the stretch that
covers from Landmark 2 to Delta Costa Rica, with the main purpose of this analysis bei ng the
possible alterations that such landscape might have suffered due to the intervention and the
creation of the terrestrial access route.

The territorial unit of study in its original conditions was constituted by extensive areas of
7
tropical forest mix ed with wetland systems in addition to a large number of tributaries of San
Juan River including two important rivers, the San Carlos River and the Sarapiquí River, which
contribute significantly to the dynamics of the study area.

The study area was alre ady an anthropic landscape with agricultural and cattle -raising
activities present for more than a century and with some stretches of roads that represent a

large percentage of the landscape before the intervention of Route 1856.
Route 1856 takes advantage of the many roads existing in the region to interconnect with the

main road and facilitate communication among some of the towns and hamlets along the
route designed. An example is that of the 108.2 km. that make up the route under study, 46.2
% (52 km.) already existed before the road construction.

The presence of communities and small hamlets along the road in the study area is evidence

of a clear and marked human presence associated to agricultural and cattle -raising activities
that dates over one centu ry. The different modifications in the use of land due to human
presence constitute a landscape of a mosaic type, integrated by pastures, agricultural
production, live fences, forest patches, which in many cases blend with important extensions

of tropical forests. The set of these resources and activities results in a mixed, dynamic
landscape which is proper in rural areas of Costa Rica.

6
7!Source: Wikipedia
For technical details, see “Terrestrial Ecological Environment” in EDA - Ecological Compon!nt Report.
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3.1 Conservation efforts

3.1.1 The Biological Border Corridor is a declared Wildlife Refuge.

The Route 1856 is part of the Nicaragua-Costa Rica Biological Border Corridor National
Wildlife Refuge. Arrieta (2013) summarizes the conservation status of the area of this study,

thus:
It is important to point out that despite its condition as Wildlife Refuge, the Border Corridor has

been characterized by the presence of inhabitants and settlements in its area who are afflicted
by poverty, a condition that led the government to declare it: “Declaration of Public Interest by
the Inter -institutional Commission of the National Wildlife R efuge Biological Border Corridor

and All Other Northern Territories” all in accordance with Decree No. 35849- MINAET.
On the other hand, the Maquenque Mixed Wildlife Refuge was created by Executive Degree

No. 32405 -MINAE of 23 May 2005, with an extension o f 51,855 hectares and which
incorporates under this new management category the following: Forest Reserve Cerro El
Jardin, (Executive Decree 22990- MIRENEM), Forest Reserva La Cureña (23074 -MIRENEM)
the Wetland Lagoon Tamborcito (22965 -MIRENEM) and the Lagu na Maquenque Palu strine

Wetland (22964-MIRENEM).

The Executive Office justified the decision to create such Refuge with the following:
“Given its scientific interest, this is an area considered of importance for conservation

since it presents special characteristics for the conservation of important species of
flora and fauna, among them: the green parrot (Ara ambigua), the Jaguar (Panthera
onca), the Almendro tree (Dypterix panamensis), the Manatee (Trichechus manatus),

the Gaspar fish (Atractosteus tropic us) and the Pinillo tree (Podocarpus
guatemalensis). The geographic location of this area is of great importance since this
protected wildlife area would be located within the Bi -national El Castillo -San Juan-La
Selva Biological Corridor, which is a continuation of the Mesoamerican Biological

Corridor between Nicaragua and Costa Rica and which constitutes the last significant
block of natural forest cover that maintains biological connectivity between the two
countries, so that this area would connect key h abitats and wildlife corridors, preventing
the isolation of species and native ecosystems.” 8

The TSC considers this as “the central conservation unit of the San Juan -La Selva Biological

Corridor” since it is located south of the Indio- Maiz Biological Reser ve and lies on the western
limit of the National Wildlife Refuge Barra del Colorado. It is particularly relevant because of
humid tropical forest extensions and for being the ecosystem of the green parrot (Ara
ambigua).

With respect to the construction of a pathway or road in this protected area, the Executive

Decree No. 32405 -MINAE indicates that “even though it is not usual to build new pathways
within a conservation area such as a wildlife refuge, it is not prohibited, since such
construction may be nece ssary to better achieve the assigned conservation goals; to better
fend off eventual hunters and collectors of biod iversity samples, among other.”

It is appropriate to note that from the perspective of the San Juan River margin on the
Nicaraguan side, ther e are important conservation efforts taking place and presently there

exist the Lo s Guatusos Refuge, the Indio -Maíz Biological Reserve, which is part of the
Mesoamerican Biological Corridor.

8
Executive Decree No. 32495, articl! 7.
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According to Martínez -Sanchez (2001) a strip of land of 10 km wi de was cut off the Indio -Maiz
Reserve, on the Nicaraguan margin along the length of the San Juan River, to allow tourism
development and other recreation activities along the river and the coastal area. For this

purpose, t his area of the Indio -Míiz Reserve was re- classified to the category of Wildlife
Refuge, a conservation category with in Nicaragua is more permissive than that of Reserve.

The previous change was done in order to permit the establishment of hotel complexes along
the San Juan River and on t he Caribbean coast. Nevertheless, the dominant landscape
continues to be the forest in different states and no infrastructural development, facilities or
other tourism developments are evident except for very isolated houses and the vigilance and

migratory posts.

3.2 Landscape approach

On the topic of the alterations created on the landscape by Route 1856 that might affect
tourism development in Nicaragua as presented, the study contemplated landscape sets from
the perspective obtained from the San Juan River, currently a place of very sporadic transit by

visitors or tourists, as well as from an aerial perspective. This leads to some considerations:

a. The anthropic landscape of the territorial unit under study contains the elements that
correspond to a rural Costa Rican landscape, altered by a series of elements such as
pastures, agriculture, housing areas and animal husbandry areas, live fences,
interconnected forest patches and, in some cases, a creek or river that provides a

boundary.

b. The rural landscape changes as important patches of forest appear which in most
cases are part of the public -private units under protection and that, under different
management categories, assure the presence of forests in the region.

c. In the study area, alteration of terrain due to the establishment of a part of the Route is
recent and made evident by the formation of very particular geological zones of

reddish clay soils common in local sub strate which contrast with the series of multiple
shades of green that dominate the landscape.

d. There are points of reference and visibility in the Route related to areas where the road
had to be built on terrains having the most inclined slopes and where it is possibl e to
see landslides due to the cuts made on the hills.

e. Most slopes were discontinu ously observed in the section between Marker 2 and the
mouth of the San Carlos river. This is not very significant in terms of the general areas

where there is alteration of the site. The remaining stretches that show some form of
alteration are of little visibility from the river where eventually tourists would be
travelling.

f. The bridge system does not exist and the installed services are temporary, some of
them being collapsed, so that jointly they do not contribute to consolidate a landscape,

and to some extent they limit the fluid travel along the Route, a situation that until it is
improved will stop all other forms of development that might lead to changes in the
region´s typical landscape.

g. A number of efforts are being conducted to recover plant veg etation along the Route
through a reforestation program coordinated by CODEFORSA 9, which reports the

9
CODEFORSA. Consultoría para el Desarrollo e Implementación de un Plan de Gestión Ambiental en el Camino
Fronterizo Juan Rafael Mora Porras. SINAC-CDE-004-2012. Enero, !013
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planting of 27,000 trees in affected areas between Tiricias, Las Chorreras and the

mouth of the San Carlos River, with an estimated 98% of trees located be tween the
road and the margin of the San Juan River. Short term plans include planting and
additional 25,000 trees before the construction of the Route 1856.

Photograph 1: Reforested areas along the Route.

4 RESULTS

4.1 On the diagnosis

1. The study area specifically does not offer conditions for tourism development, nor has
it ever been an area of tourism development. To date, the stretch between Border
Landmark 2 and Delta Costa Rica does not have any kind of tourism facility nei ther on
the right nor on the left margin of the San Juan River. The only site where there are
services and facilities is Delta Cabins, and these are mostly for national visitors.

Towards the two extreme areas of the river, infrastructure and facilities imp rove,
concentrating in the towns of San Carlos and San Juan del Norte.

2. It is important to note that tourism axes have concentrated in the endpoints of the river.
In the case of Nicaragua, it offers services in San Carlos and neighbouring areas, and
in Grey town, San Juan and its proximities. The remainder of the river, mainly the
margin under study, has no services other than fluvial transportation from site to site.

3. In any case, tourism services in the study area are extremely limited accounting for

3,54% of the tourism nationwide (PNDTS 2011 -2020). The San Juan River department
is among the poorest in the country, and is therefore one of the regions of the country
with least tourism services.

4. The city of San Carlos is the tourism distribution centre for the San Juan River (El
Castillo, Sábalo, Solentiname Islands), but it does not offer visitors the necessary
physical infrastructure to meet their needs. Visitation to this area does not reach

beyond an estimated 10,000 visitors per year, a very small number t o be able to
consider developing a competitive and consolidated tourism.

5. Some of the lodgings that have appropriate facilities of a middle level, well integrated
to the natural surroundings, are developing tourism products focused on international
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visitors with an emphasis on eco -tourism: wildlife observation, tours within the
reservations, specialized nature paths, fishing, etc. However, some of these have been
unable to consolidate a visitation level that would allow them to reach their point of

equilibrium, so that their services are seasonal and not year- round.
6. Tourism services concentrate mainly on nature observation, nature walks, boat tours

and fishing. These activities concentrate in Sábal o, El Castillo and the Indio -Maíz
Refuge and neighboring areas .

7. Even though sports fishing activities are widely provided in the region of San Carlos
and neighboring areas such as El Castillo and Sábalo, no commercial or fishing
activities were identified along the river for the study area. Fishing activities from

Border Mark 2 to Delta Costa Rica is sporadic, subsistence fishing.

8. The tourism potential of the region is sufficient to justify attracting international visitors.
However, infrastructural conditions, the state of access routes, the existing services
and products offered, the quality of the existing offer, a weak image for the region,
information and commercialization mechanisms of an incipient nature, are not

sufficiently satisfactory to attract more visitors.
9. The previously mentioned factors, in addition to a climate of instability and insecurity in

the region, generated by images of continuous border disputes between Costa Rica
and Nicaragua, do not favor the kind of private investment that could strengthen
tourism in the region.

10. All the same, Nicaragua (PN DTIS 2011- 2020) points strongly to the San Juan River
department as one of its priority destinations to strengthen and raise nature tourism in

the country. To date, there are no significant changes in the flow of visitors. In some
instances, the contrary i s what is taking place, with important decreases in tourism
visitation being reported, (see Chart 1).

11. The growth in visitation to San Carlos could increase further, though slightly, due to the
new road that connects Managua with San Carlos, which has reduc ed travel to 4.5

hours. However, this new access seems to be attracting mainly local tourism and
backpackers.

12. The use of fluvial transportation means that tourists travel mainly on public
transportation services which have pre -established itineraries with very accessible
costs (see Annex 1). On the other hand, private transportation services are costly and

practically non-existent.
13. The profile of tourists who visit the region and specially those who visit across the San

Juan River is mostly that of backpackers who are willing to pay minimally for very basic
services.

14. To date, navigation on the river, requires extra investment due to the additional taxes
that Costa Rican boats must pay when reporting to Nicaraguan authorities in San
Carlos, in addition to the less than friendly requirements placed on tourists; conditions

that add to the sense of insecurity and distrust in trying to conduct organized tourism.

15. The effect of the construction of Route 1856 has no direct impact on tourism in recent
years.

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4.2 On the route constructed

1. Landscape alterations resulting from the construction of Route 1856 create the
possibility of natural or artificial regeneration of altered areas, natural or assisted
regeneration, or the development of short and medium term reforestatio n projects with
native species from the region.

2. The process of visual recovery of the landscape in the most affected area (between

Tiricias and the mouth of the San Carlos River) has already been subjected to
intervention with reforestation projects with t he participation of local neighbors, offering
an optimistic possibility of recuperation, or at least a first barrier or curtain of natural
vegetation.

3. The flow of visitors or the potential tourism development that may lead to an increase

in visitors through this means continues to be very modest; a condition that to some
extent ensures that there will be no landscape alteration in the short and medium term.

4. In any case, as a result of the current reforestation processes a significant
improvement could be expected in terms of the landscape that can be observed from
the San Juan River.

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5 RECOMMENDATIONS

1. It is of fundamental importance for the good image of the country, which represents a
green country with a conservationist vocation, to implement the necessar y initiatives to
recover the plant cover of the affected zones, mainly exposed hillsides and slopes.

2. Efforts intent on the consolidation of plant cover should reinforce and recover some of
the historical bad practices prior to the alterations produced by t he Route, especially in

all San Juan River margin areas, ensuring that the river margin is respected in the
future.

3. Even though it is true that reforestation efforts being conducted by CODEFORSA
make use of species from the region, it is recommended that fast growing species be
used in order to lower the visual impacts in the short term. In the reforestation process

it is also advisable to use species that can cover vertical spaces to serve as integral
visual barriers starting at a height of 60 cm.

4. It is o f basic importance that landscape recovery efforts be an integral process that
includes the participation of local communities, for which purpose it is advisable to
consider environmental education, community organization, entrepreneurship, local
initiative and other. The purpose is not only reforestation but also that this region

become an example of commitment and vision of a country that is seeking to be
sustainable through integral, visionary work.

5. Given new access roads, distance and time improvements, access to energy
resources and other services, this region has many possibilities of seeing new tourism
initiatives in rural communities or in protected public and private areain the midterm.

This possibility could create development opportunities for l ocal communities. It could
eventually become a means to generate more tourism from Costa Rica to Nicaragua,
as has been intended in the past.

6. According to the World Tourism Organization and related organizations, safety is the
first condition required by t ourists in order to visit an area. Therefore, as long as safety
and security remain uncertain in the area of the Route, opportunities for visitation by

international tourists who are not backpackers will remain limited.

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6 BIBLIOGRAPHY

AECID, Araucaria XXI . 2006. Programa de la cooperación española para la sostenibilidad
ambiental en América Latina. Managua, Nicaragua: AECID.

Arrieta, L. 2013. Informe so bre franja fronteriza. San José, Costa Rica: Cancillería de la
República.

Boletín Estadístico de Turismo . 2012. Instituto de Turismo de Nicaragua.
http://www.intur.gob.ni/index.php?option=com_content&view=article&id=27…

Cámara Nacional de Turismo de Nic aragua, sección Río San Juan.
www.riosanjuancanatur.org

CODEFORSA. 2013. Consultoría para el Desarrollo e Implementación de un Plan de Gestión
Ambiental en el Camino Fronterizo Juan Rafael Mora Porras. Informe de actividades para la
Cancillería de la República de Costa Rica . San José, Costa Rica: SINAC.

Comisión Regional de la Iniciativa Mesoamericana de Turismo. (s.f.) . Perfil de Proyecto. Ruta
del Caribe Centroamericano.

Instituto de Turismo de Nicaragua. (s.f.). Plan Nacional de Desarrollo Turístico Sostenible de
Nicaragua 2011-2020. Managua, Nicaragua: BID-INTUR-AECID.

Instituto de Turismo de Nicaragua. (s.f.). Plan de Desarrollo Turístico Sostenible de
Nicaragua. Destino Río San Juan. Estrategia de desa rrollo 2011-2020. Managua, Nicaragua:

BID-INTUR-AECID.

Instituto de Turismo de Nicaragua. (s.f.). Plan Nacional de Desarrollo Turístico Sostenible de
Nicaragua 2011-2020. Plan de Marketing. Managua, Nicaragua: BID-INTUR-AECID

Martínez-Sánchez, J. C. 2001. Biodiversidad zoológica en Nicaragua . Proyecto Estrategia
Nacional de Biodiversidad y su Plan de Acción PNUD -NIC/99/G31-MARENA. Managua,
Nicaragua: MARENA.

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7 APPENDIX

7.1 Summary of companies and institutions consulted by phone call of
personal communication.

COMPANY/INSTITUTION CONSULTED LOCATION

COMPANIES

Hotel Montecristo Lodge Sábalo, Río San Juan, Nic.

Agua Trails La Fortuna, Costa Rica

Aventuras Arenal La Fortuna, Costa Rica

María José Paniagua Consultora, Nicaragua

INSTITUTIONS

Instituto Costarricense de Turismo Costa Rica

Instituto Nicaragüense de Turismo Nicaragua

7.2 Itineraries for public transportation services in the department of Rio

San Juan

Nicaragua.

AIR TRANSPORTATION SERVICE

La Costeña aircrafts depart from Managua airport at 1:30 p.m., daily, arrive to San Carlos 2:15
pm, 45 min after takeoff.

Aircrafts depart San Carlos 2:25pm., 15 min after disembarking passangers. Arrival to
Managua 3:05 pm.

Returning flight should be confirmed a t the San Carlos terminal .

Round trip ticket price is $116.00

La Costeña phone number in San Carlos is (505) 2583- 0367

Address: ENACAL 60 varas al Norte, Sector 2. San Carlos

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BY BOAT CROSSING THE GREAT LAKE OF NI CARAGUA. (Lago Cocibolca)

The trip is 14 hours long and starst at the port city of Granada, from where ferry departs to
Ometepe island, San Miguelito port and Morrito, arrives at San Juan river origination in San
Carlos.

Ferry departs twice a week from Granada, Monday and Thursday at 2:00 PM, crosses the
lake of Nicaragua or Cocibolca. Stops at Altagracia in Ometepe island, Morrito and San
Miguelito. Passes by Solentiname islands before arriving to San Carlos in the early morning,

between 5 and 7am.

Ticket Price is C$ 90.00 córdobas, econo mic class in load cabin, and C$ 180.00 Córdobas en
upper part, which is refered to as “First Class” . AC, tables and TV are available here.

They also offer a prívate cabin with two beds, fan, prívate bath, TV and DVD for C$1,000.00

one way. For more information call ENAP 2552-2966.

The boat trip is uncomfortable, for which carrying a hammock to rest is recommended. It is

chilly at night in the middle of the lake, and it might raA windbreaker and/or warm jacket is
also recommended. Food and refres hments for sale aboard. Consuming alcoholic drinks or
drugs is not allowed on board.

GROUND TRANSPORTATION

Buses depart from M ercado de Mayoreo in Managua 4 times a day , ticket price is C$160.00,

the trip takes 9 hours to San Carlos.

FROM COSTA RICA.

From San José or La Fortuna to Los Chiles, in public buses departing from terminal, or prívate
vehicles.

From Los Chiles, Costa Rica to San Carlos, San Juan river in public boats departing twice a
day at 1:00 y 3:00 PM, a 500 colones fee should be paid to Alcaldía and boat ticket price to
San Carlos is $10.00.

It is possible to rent a private boat to pick up passengers in Los Chiles at a negotiable time, 1
to 10 passengers is $320.00 the trip.

San Carlos to Los Chiles, Monday through Saturday 10:30 pm, 1:30 pm and 4:00 pm
C$200.00 or $9.50, Sunday 1:00 pm and 3:00 pm.

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San Juan River – Boat Transportation

PUBLIC BOAT SCHEDULE

Monday through Saturday

Departure Port Time Destination Price
San Carlos 8:00Am Sábalos, MonteCristo, El Castillo 48.00 Cor

12:00 PmSábalos, MonteCristo, El Castillo 48.00 Cor

1:00 Pm Sábalos, MonteCristo, El Castillo 48.00 Cor

2:00 Pm Sábalos, MonteCristo, El Castillo 48.00 Cor

3:00 Pm Sábalos, MonteCristo, El Castillo 48.00 Cor

El Castillo 8:00Am MonteCristo, Sábalos, San Carlos 48.00 Cor
12:00 PmMonteCristo, Sábalos, San Carlos 48.00 Cor

1:00 Pm MonteCristo, Sábalos, San Carlos 48.00 Cor

2:00 Pm MonteCristo, Sábalos, San Carlos 48.00 Cor

3:00 Pm MonteCristo, Sábalos, San Carlos 48.00 Cor

Sunday

San Carlos 1:00Am Sábalos, MonteCristo, El Castillo 48.00 Cor

El Castillo 5:00 Am MonteCristo, Sábalos, El Castillo 48.00 Cor

2:00 Am MonteCristo, Sábalos, El Castillo 48.00 Cor

5:00 Am San Carlos 180.00 Cor
San Juan del Norte

Monday

Papaturro 6:00 Am San Carlos (4 hours) 45.00 Cor

Tuesday

San Carlos 6:00 Am San Juan Del Norte (8 hours ) 180.00 Cor
San Carlos 7:00 Am Papaturro (4 hours) 45.00 Cor

Thursday

San Juan del Norte5:00 Am San Carlos (8 Hours) 180.00 Cor

Papaturro 6:00 Am San Carlos (4 Hours) 45.00 Cor

Friday

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San Carlos 6:00 Am San Juan Del Norte (8 hours ) 180.00 Cor

San Carlos 7:00 Am Papaturro (4 Hours) 45.00 Cor

PRIVATE BOATS (EXPRESS TRIPS)

Prices per boat, max. 9 passengers per boat

San Carlos Monte Cristo 100.00 US. one way

170.00 US round trip

San Carlos - El Castillo 140.00 US. one way

170.00 US round trip

25.00 US. waiting day
San Carlos - Solentiname 150.00 US. round trip to an island

50.00 US. tour in the islands

25.00 US. per waiting day

San Carlos - San Juan del Norte950.00 US. round trip

100.00 US. waiting day

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9.3 Analysis of the structural connectivity in the landscape of Route 1856

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!
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!
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Olivier!Chassot!L.,!PhD!
!
Centro!Científico!Tropical!

November,!2013!
!
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!
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EXECUTIVE(SUMMARY(
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The!connectivity!analysis!of!ecosystem!fragments!in!the!North!Caribbean!of!Costa!Rica!indicates!
the!existence!of!gaps!in!relation!to!the!conservation!goals.!We!analysed!the!degree!of!structural!
connectivity!between!2454!nodes!of!natural!ecosystem!units!with!areas!over!5!ha.!The!integral)
index)of)connectivity!(IIC)!of!the!landscape!is!0.03,!and!the!probability)of)connectivity)index)(PC))

is!0.14!for!a!dispersal!probability!of!88%!with!a!500!m!threshold.!Both!indices!indicate!a!low!
percentage!of!connectivity!in!the!landscape!of!the!area!of!study.!The!most!important!nodes!are!
located!in!the!border!area!with!Nicaragua!and!in!the!coastal!area!of!the!Caribbean.!We!highlight!
the!fundamental!importance!of!the!Maquenque!National!Wildlife!Refuge!in!relation!to!the!other!
protected!wildlife!areas!of!the!study!area,!as!it!provides!essential!connectivity!nodes!South!as!

well!as!Northeast!and!East.!We!found!that!the!establishment!of!Route!1856!in!the!area!of!study!
has!a!minimal!effect!on!the!connectivity!of!the!landscape.!!!
(

INTRODUCTION(
!
The!heterogeneous!landscape!of!the!North!Caribbean!of!Costa!Rica!includes!several!fragmented!
ecosystems! where! conservation! and! sustainable! development! strategies! have! been!
implemented,!along!with!significant!financial!investments!by!government!institutions,!national!

nonUgovernmental!organizations!and!international!cooperation!institutions.!The!humid!tropical!
rainforest! of! the! North! Caribbean! has! undergone! a! strong! fragmentation! process,! and! the!

706 Annex 10

ecological! connectivity! of! the! North! Caribbean! of! Costa! Rica! has! been! significantly! reduced!
(Chassot!et)al.!2002,!Chassot!et)al.!2003,!Sesnie!et)al.!2003,!Ramos!&!Finegan!2007,!Morse!et)al.!
2009,!Chassot!2010).!With!the!establishment!of!Route!1856!in!the!border!area!of!Costa!Rica!

with! Nicaragua,! it! is! important! to! analyse! the! potential! impact! on! the! conservation! of!
connectivity!by!identifying!priority!sites!and!critical!connectivity!linkages.!!
!
!

CONCEPTUAL(FRAMEWORK(
(
Connectivity(

Connectivity!is!a!vital!element!of!landscape!structure!(Taylor!et)al.!1993).!One!of!the!strategies!
to! mitigate! the! effects! of! fragmentation! of! ecosystems! is! maintaining! or! reUestablishing!
landscape!linkages!(Noss!1991).!Connectivity!is!described!as!“how!the!spatial!arrangement!and!

quality!of!elements!in!the!landscape!affect!the!movement!of!organisms!among!habitat!patches”!
(Bennett!2004).!Crome!(1997)!warns!of!the!minimalist!approach!that!consists!of!establishing!
that!very!small!or!relatively!isolated!fragments!lack!importance;!he!indicates!that!the!baseline!
consists!of!understanding!that!the!number!of!natural!fragments!in!existence!at!a!specific!time!is!

the!minimum!to!be!preserved.!A!large!number!of!organisms!have!daily!or!temporary!movement!
patterns!that!often!take!them!from!one!fragment!of!an!ecosystem!to!another.!In!terms!of!
management,! connectivity! is! manifested! in! biological! corridors! (Worboys! 2010);! however,!
corridors!can!represent!both!an!opportunity!for!movement!as!well!as!a!barrier!for!organisms,!

depending!on!the!type!of!coverage!of!the!corridor!and!of!the!specific!organism!(Hilty!et)al.!2006,! 2
Anderson! &! Jenkins! 2006).! Consequently,! both! the! linkages! of! natural! ecosystems! and! the!
surrounding!matrix!play!an!important!role!in!the!efficiency!of!ecological!connectivity!(Schelhas!

&! Greenberg! 1996,! Crome! 1997,! Bierregaard! &! Stoufer! 1997,! Bennett! et) al.! 2006).! In! the!
landscape,!the!value!of!connectivity!will!depend!to!a!large!extent!on!the!behaviour!of!each!
organism!in!relation!to!the!use!of!corridors!(Soulé!1991,!Bélisle!2005,!Sanderson!et)al.!2006,!
Fagan!&!Calabrese!2006).!Conservation!strategies!based!on!corridors!consist!of!optimizing!the!

width!and!variety!of!a!natural!habitat!in!landscape!linkages!so!that!the!entire!spectrum!of!native!
species!has!the!opportunity!to!move!among!natural!areas!within!the!landscape!(Noss!1991).!
Connectivity!is!also!expressed!in!connectivity!networks,!which!exist!or!are!reUestablished!among!

fragments! of! ecosystems! that! were! separated! by! anthropogenic! factors! (Forman! &! Godron!
1981,!Bruinderink!et)al.!2003),!allowing!the!free!movement!of!organisms!from!one!fragment!to!
another! (Dobson! et) al.! 1999).! The! underlying! idea! of! ecological! networks! is! to! identify! the!
biological!diversity!and!natural!resources!of!the!landscape,!guided!by!conservation!planning!

principles!combined!with!information!regarding!the!need!to!fill!conservation!gaps!to!preserve!
natural!communities!(Hoctor!et)al.!2000).!Connectivity!theory!within!landscape!ecology!and!
conservation!biology!indicates!that!it!is!probable!that!connectivity!linkages!have!the!capacity!to!
mitigate,!to!a!certain!extent,!the!collateral!effects!of!climate!change!on!the!need!for!movement!

of!certain!organisms,!in!response!to!the!increase!in!annual!temperatures!(Noss!1991,!Hay!1991,!
Dobson! et)al.!1999,!Thomas! et)al.!2006).! Connectivity!provides!two!fundamental!functions:!
Firstly,!it!allows!the!regular!movement!of!organisms,!ensuring!that!the!various!subdivisions!of!a!

population!can!maintain!a!genetic!equilibrium!(Soulé!1991,!Britten!&!Baker!2002,!Frankham!
2006).!Secondly,!connectivity!facilitates!the!dispersal!between!the!home!range!of!the!species!

707Annex 10

and!their!migration!areas!(Harrison!1992,!Dobson!et)al.!1999,!Chassot!et)al.!2005).!There!are!

various!scales!of!connectivity,!namely:!fragment,!local,!landscape!and!regional!or!continental!
(Taylor!et)al.!2006).!The!structural!connectivity!of!the!landscape!is!determined!by!the!spatial!
distribution!of!the!types!of!habitats,!which!depends!on!the!continuity!of!habitats,!the!distance!

between!the!elements!of!the!landscape!and!the!size!of!the!gaps!between!fragments!(Theobald!
2006).!Behavioural!connectivity!is!related!to!the!behavioural!response!of!the!species!to!the!
structure!of!the!landscape!(Bennett!2004).!The!scale!and!design!of!the!connectivity!elements!
depends!on!the!management!goals!and!must!be!adapted!to!the!focus!species!for!which!the!

corridor’s!maintenance!or!reUestablishment!is!sought!(Soulé!1991,!De!Campos!&!Finegan!2002,!
Bennett!et)al.!2006).!Particularly,!the!definition!of!a!dispersal!threshold!according!to!the!needs!
of! the! organisms! has! significant! implications,! and! it! does! not! always! correspond! to! other!
ecological! thresholds! (With! 2002).! These! also! depend! on! the! potential! ecological! changes!

brought!about!by!the!uncertain!impacts!of!climate!change!(Pearson!2006,!Chester!&!Hilty!2010).!
There!is!a!controversy!that!feeds!the!debate!on!the!adequacy!of!corridors!since!the!appearance!
of!the!concept,!with!the!popularity!of!the!theory!of!island!biogeography!(McArthur!&!Wilson!

1967)! and! the! hypothesis! that! corridors! are! a! solution! to! increasing! isolation! in! protected!
wildlife!areas!in!the!landscape!matrix!(Beier!&!Noss!1998).!Some!authors!(Simberloff!&!Cox!
1987,!Simberloff!et)al.!1992,!Hobbs!1992)!warn!of!the!cost!of!investment!in!corridors,!and!the!
potential! danger! of! involuntary! dissemination! of! certain! organisms! that! lack! natural!

connectivity,!given!that!an!artificial!corridor!can!provide!connectivity!between!fragments!that!
were!historically!separated!by!other!types!of!ecosystems,!especially!with!regard!to!invasions!of!
exotic!species!in!natural!ecosystems!(Janzen!1986,!Crooks!&!Suarez!2006)!or!diseases!that!can!
lead!species!to!extinction!(Hess!1994,!McCallum!&!Dobson!2006).!In!some!cases!this!attitude!is! 3

due! to! the! false! premise! that! preUagricultural! landscapes! were! habitats! comprised! of!
homogeneous!blocks!(Dobson!et)al.!1999).!!
!

Fragmentation(
The!deforestation!phenomenon!causes!a!loss!of!nutrients!in!the!ecosystem!(Bormann!et)al.!
1968)!and!it!is!accompanied!by!fragmentation!processes,!or!reduction!in!size!and!increase!in!the!
isolation!of!forest!fragments!(Schelhas!&!Greenberg!1996,!Sánchez!et)al.!2001),!such!as!forest!

remnants,!forests!subjected!to!forestry!management,!natural!forests,!sacred!forests!and!gallery!
forests!or!riparian!forests.!This!phenomenon!causes!fragmentation!processes,!or!reduction!in!
the!size!and!increase!in!the!isolation!of!forest!fragments!(Lindenmayer!&!Fischer!2006),!as!well!

as! an! increase! in! the! negative! effect! of! natural! or! anthropogenic! barriers! (Clevenger! &!
Wierzchowski! 2006,! Crooks! &! Sanjayan! 2006).! The! fragmentation! of! ecosystems! causes!
different!impacts!on!the!biota!(Saunders!et)al.!1991,!Laurance!et)al.!2002).!The!most!drastic!
effect!of!forest!fragmentation!is!the!decrease!in!the!population!of!wildlife!organisms!and!the!

extinction!of!wildlife!organisms!in!the!fragment,!local!and!landscape!scales!(Levin!&!Paine!1974,!
Jordan! 1986,! Franklin! &! Forman! 1987,! Collado! &! Dellafiore! 2002,! Kattan! 2002,! Gallego! &!
Finegan! 2004,! Laurance! et) al.! 2002,! Laurance! &! Vasconcelos! 2004,! Santos! &! Telleria! 2006,!
Haddad! &! Tewksbury! 2006).! Fragmented! landscapes! are! subject! to! the! constant! actions! of!

humans,! which! complicates! the! expansion! of! protected! wildlife! networks! (Lindenmayer! &!
Fischer!2006).!These!fragments!can!contain!a!number!of!organisms!absent!from!the!protected!
wildlife! areas! (Schelhas! &! Greenberg! 1996).! Even! a! matrix! composed! of! different! types! of!

708 Annex 10

dynamic!agroUlandscapes!maintains!important!ecological!functions!(Gascon!et)al.!2004,!Bennett!

et)al.!2006).!It!is!important!to!consider!the!landscape!as!a!whole!instead!of!as!a!collection!of!
separate!biotic!entities!(Saunders!et)al.!1991).!
!

In!the!tropical!regions!where!forest!cover!loss!processes!have!been!severe,!fragments!may!play!
an!important!role!as!seed!banks,!sources!of!seed!dispersal!(Guariguata!et)al.!2000),!buffering!
zones!for!intact!forest!patches,!providing!resources!for!a!large!number!of!organisms!that!use!
biological! corridors! and! acting! as! a! refuge! for! local! or! longUdistance! migrating! organisms!

(Greenberg!1996,!Bennett!2004).!!
!
Fragmentation!forces!several!organisms!that!were!previously!present!in!continuous!connected!
habitats! to! act! as! metapopulations! or! remnants! of! natural! ecosystems! (Lefkovitch! &! Fahrig!

1985,!Opdam!et)al.!1985,!Gilpin!&!Hanski!1991,!McCullough!1996,!Moilanen!&!Hanski!2006)!and!
to! move! between! fragments! of! natural! ecosystems! (Dale! et) al.! 1994).! On! the! other! hand,!
fragmentation! exposes! forest! organisms! to! the! edge! effect! (Lovejoy! et) al.! 1986),! causing!

increases!in!the!level!of!sunlight,!invasion!of!organisms!from!open!areas,!(Laurance!et)al.!1985),!
drying!processes!due!to!the!penetrating!effect!of!wind!(Laurance!1997)!and!changes!in!the!
characteristics! of! the! vegetation! structure! (Lovejoy! et) al.! 1997,! Lezcano! et) al.! 2002,!
Lindenmayer!&!Fischer!2006).!However,!an!investigation!of!the!area!of!the!study!shows!that!the!

edges!of!the!remnants!of!humid!tropical!rainforest!have!recovered!after!two!decades!of!being!
exposed!to!the!surrounding!matrix!(Forero!&!Finegan!2002,!Schedlbauer!et)al.!2007,!Finegan!&!
Bouroncle).!A!fragment!can!be!too!small!to!provide!sufficient!food!sources!to!organisms!with!
broad!home!ranges,!or!it!can!only!support!small!populations!which!are!subject!to!high!risks!of! 4

extinction!due!to!various!factors,!including!stochastic!variations!in!population!size!(Andersen!et)
al.! 1997).! The! organisms’! response! to! fragmentation! processes! depends! on! the! degree! of!
ecological!specialization,!body!size!and!movement!patterns!(Kellman!et)al.!1996,!Guindon!1996,!

Tewksbury!et)al.!2006).!A!large!number!of!the!ecological!processes!whereby!organisms!are!
affected!by!the!edge!effect,!whether!natural!or!provoked,!have!not!been!understood!yet!(Harris!
1988);!however,!some!studies!point!to!a!decline!in!richness!and!abundance!of!fauna!(Willis!
1974,!Ernst!et)al.!2006,!Lees!&!Peres!2006)!and!longUterm!effects!on!the!pollination!processes!of!

vegetation! species! that! lack! the! capacity! to! move! among! isolated! fragments! (Murcia! 1996,!
Manning!et)al.!2006,!Hanson!et)al.!2007,!Hanson!et)al.!2008),!especially!in!places!with!high!
biodiversity!indexes!and!where!plants!and!trees!are!subject!to!a!greater!occurrence!of!decline!or!

extinction!due!to!a!lack!of!specialized!pollinators!(Vamosi!et)al.!2006).!Cramer!et)al.!(2007)!have!
demonstrated!how!tree!species!whose!seeds!are!dispersed!by!medium!and!large!animals!have!a!
greater!difficulty!of!dispersal!of!their!genes!in!fragmented!landscapes.!Fragmentation!processes!
and! their! ecological! implications! are! extremely! complex! (Crome! 1997)! and! require! greater!

applied!research!efforts!(Bierregaard!et)al.!1997).!
!

709Annex 10

(

(
METHODOLOGICAL(FRAMEWORK(
!

Methodology((
The!general!methodology!follows!Chassot!(2010)!and!encompasses!the!following!steps:!

1. Define!the!study!area!!

2. Compile!the!information!available!
3. Incorporate!the!information!compiled!in!the!Geographic!Information!System!

4. Classify!the!vegetation!and!land!use!cover,!with!input!from!the!Landsat!(2005)!satellite!
images!

5. Analysis!of!structural!connectivity!

!
Connectivity(indices(
We!calculated!the!integral)index)of)connectivity)(IIC)!and!the!probability)of)connectivity)index)

(PC)!using!the!program!Conefor!Sensinode!2.2!(Saura!&!Pascual!2007b).!This!program!allows!
quantifying!the!importance!of!habitat!fragments!to!maintain!landscape!connectivity!by!means!
of! graph! structures! and! habitat! availability! indices.! The! program’s! inputs! and! outputs! are!
expressed!by!means!of!ASCII!files,!which!can!be!manipulated!in!ArcView!(ESRI!2004,!ESRI!s.f.).!
5
The!IIC!is!descriptive;!it!represents!the!degree!of!connectivity!of!the!landscape.!On!the!other!
hand,!the!PC!is!based!on!the!concept!of!habitat!availability!and!probability!of!generic!dispersal!
between!fragments.!The!PC)expresses!an!estimate!of!the!strength,!frequency!and!feasibility!of!
dispersal!between!two!or!more!fragments,!and!it!indicates!the!probability!that!two!organisms!

located! in! any! habitat! fragment! in! the! landscape! can! disperse.! These! indices! also! allow!
identifying!the!fragments!or!nodes!that!are!of!greater!structural!importance!for!connectivity!
and!that!react!to!changes!in!the!landscape!structure,!which!is!a!useful!tool!in!terms!of!habitat!

conservation! planning! (Opdam! 2002,! Pascual! &! Saura! 2006,! Saura! &! Pascual! 2007a).! We!
calculated!the!euclidean!distance!(Urban!&!Keitt!2001)!between!the!edges!of!all!fragments!
equal!to!or!greater!than!5!hectares!(N=2454),!applying!an!arbitrary!dispersal!threshold!of!500!
metres!(Villard!et)al.!1999).!

!
Structural(connectivity(network(
Habitat! networks! offer! a! solution! for! fragmentation! (Opdam! 2002).! First,! we! identified! the!
nodes!or!linkages!of!greater!structural!importance!within!the!area!of!study!according!to!the!

results!of!the!IIC!and!PC!indices!(with!the!program!Conefor!Sensinode!2.2),!which!correspond!to!
basic! landscape! measurements! such! as! fragment! size,! distance! to! closest! fragment! (Kramer!
1997,!Corra!do!Carmo!et)al.!2001).!The!nodes!were!classified!on!a!priority!scale!of!very!high,!
high,!medium,!low!or!very!low.!We!adapted!the!methodology!of!Hoctor!et)al.!(2000),!applied!in!

the!different!structural!connectivity!analyses!of!the!biological!corridors!in!Costa!Rica!(Ramos!
2004,!Murrieta!et)al.!2007,!Ramos!&!Finegan!2007,!Baltodano!&!Zamora!2009).!The!planning!
units!of!the!analysis!are!the!ecosystem!units,!including!natural!forest!cover,!secondary!forest!

710 Annex 10

and! bodies! of! water.! On! the! other! hand,! we! establish! the! connectivity! routes! through! an!
analysis!of!the!connection!with!the!least!cost!path,!where!cost!is!a!function!of!the!friction!

determined!through!the!Cost)Distance!and!Cost)Path!functions!on!a!raster!in!the!extension!
Spatial)Analyst!of!ArcGIS!9.x!(Walker!&!Craighead!1997,!Hoctor!et)al.!2000,!Rouget!et)al.!2004,!
Kautz!et)al.!2006).!The!least!cost!path!is!calculated!based!on!a!friction!map,!which!indicates!

which!elements!of!the!landscape!represent!greater!resistance!to!the!movement!of!organisms!
(grade!of!friction:!forest!=!1,!secondary!forest!=!2,!body!of!water!=!3,!agricultural!=!4,!uncovered!
soil!=!5,!banana!=!6,!pineapple!=!7).!We!took!the!five!connectivity!nodes!of!greatest!structural!
importance!on!the!east,!west,!north!and!south!sides!of!the!landscape!to!generate!the!different!

connectivity!routes,!select!the!main!routes!and!identify!priority!areas!of!connectivity.!!
!
RESULTS(

(
Connectivity(indices(
We!integrated!2454!nodes!of!natural!ecosystem!units!with!a!size!equal!to!or!greater!than!5!

hectares!based!on!the!classification!of!Landsat!TM!2005!satellite!images!(source:!University!of!
Alberta,!Canada)!performed!by!Chassot!(2010).!These!nodes!generated!3827!connections.!The!
integral)index)of)connectivity!(IIC)!of!the!landscape!is!0.03,!and!the!probability)of)connectivity)
index)(PC))is!0.14!for!a!dispersal!probability!of!88%!with!a!500!m!threshold.!Both!indices!indicate!

a!low!percentage!of!connectivity!in!the!landscape!of!the!area!of!study!(Moilanen!&!Hanski!
2001).!In!our!case,!the!PC!indicates!that!there!is!a!14%!probability!that!two!animals!located!in!
any!fragment!of!the!habitat!within!the!landscape,!with!the!capacity!of!moving!over!distances!
equal!to!or!less!than!500!meters,!can!meet.!On!the!other!hand,!the!calculation!of!the!Delta) 6

value!(dI)!of!each!fragment!–!derived!from!the!connectivity!analysis!–!allows!prioritizing!the!
most!important!fragments!in!terms!of!global!connectivity!(Rae!et)al.!2007).!These!are!the!most!
relevant! elements! of! the! landscape! to! maintain! connectivity,! meaning! the! elements! whose!

absence!has!an!impact!on!the!connectivity!between!large!fragments!of!natural!cover!and!on!the!
global!quality!of!the!group!of!habitat!fragments;!therefore,!they!offer!a!spatial!representation!
for!the!prioritization!of!management!actions!geared!toward!improving!the!quality!of!the!habitat!
in!the!landscape!(Figure!1).!

! !

711Annex 10

!
Figure(1:(Prioritization(of(the(nodes(to(maintain(structural(connectivity(of(the(landscape((dIIC!
–(higher(values(indicate(higher(priority),((Chassot(2010)(

!
The!importance!of!a!specific!node!reflects,!in!general,!the!intrinsic!characteristics!of!the!habitat!

(in!our!case,!the!area)!and!the!topological!position!within!the!landscape!network!(for!example,!a!
node!fulfilling!a!linkage!function).!The!notes!with!the!highest!Delta)values!(dIIC)!are!those!of!
greater!importance!for!the!connectivity!between!fragments!and!within!fragments!(Pascual!&! 7
Saura!2006).!In!addition,!the!largest!nodes!could!maintain!the!internal!sources!of!recolonization!

(Fahrig!&!Merriam!1994)!and!sustain!large!populations!(Pickett!&!Thompson!1978).!!
!
The!most!important!connectivity!nodes!of!the!landscape!correspond!to!areas!of!greater!forest!
cover,!located!on!the!eastern!portion!of!RNVS!Maquenque,!as!well!as!the!western!portion!of!

said!refuge!and!the!coastal!area!of!PN!Tortuguero!and!RNVS!Barra!del!Colorado.!In!general,!the!
connectivity! nodes! of! greater! importance! (medium,! high! and! very! high)! are! adequately!
represented!in!the!protected!areas!system!(50.2%),!except!for!certain!sectors!on!the!northwest!

of! RNVS! Maquenque! in! the! area! TiriciasUCrucitas! (Pocosol! and! Infiernito! districts),! to! the!
southwest! of! RNVS! Maquenque! in! the! area! of! San! MarcosUAlmendrosUCastelmare! (Cutris!
district),!to!the!south!of!RNVS!Maquenque!between!the!communities!of!Sahino!and!Quebrada!
Grande! (Tres! Amigos! district),! another! sector! further! south! of! RNVS! Maquenque,! along! the!

south!bank!of!Río!Toro,!in!a!sector!between!the!communities!Pangola!and!Sardinal!(Río!Cuarto!
district),! and! south! of! PN! Tortuguero.! The! RNVS! Border! Corridor,! on! which! Route! 1856! is!
located,!plays!a!major!role!in!maintaining!structural!connectivity.!We!observe!that!the!most!

important!nodes!are!located!on!the!border!area!with!Nicaragua,!and!in!the!entire!Caribbean!
coastal!area.!Due!to!their!latitudinal!orientation,!these!offer!the!capacity!of!intercepting!the!
northUsouth!fauna!immigration!corridors!and!maintaining!the!recolonization!processes!of!the!
fragments!of!natural!ecosystems!(Gutzwiller!&!Anderson!1992,!Freemark!et)al.!2002).!We!note!

the!lower!relative!importance!of!ZP!La!Selva!and!PN!Braulio!Carillo!(due!to!their!peripheral!
location!in!the!area!of!study!at!higher!levels),!and!of!the!western!sector!of!RNVS!Barra!del!

712 Annex 10

Colorado!in!maintaining!the!structural!connectivity!of!the!ecosystem!units!of!the!plains!of!the!
North! Caribbean.! Finally,! we! highlight! the! fundamental! importance! of! RNVS! Maquenque! in!
relation!to!the!other!protected!wildlife!areas,!as!it!provides!essential!connectivity!nodes!to!the!

south!as!well!as!to!the!northeast!and!east.!!
!
Structural(connectivity(network(

Our!analysis!of!the!different!connectivity!routes!originating!from!the!geographic!points!of!the!
five!priority!nodes!to!maintain!the!structural!connectivity!of!the!landscape!indicates!that!the!
majority!of!the!connectivity!proposals!are!located!on!the!protected!wildlife!areas!adjacent!to!

San!Juan!River!and!on!the!Caribbean!coast!(Figure!2,!Chassot!2010).!
!!

!
!

Figure(2:(Priority(routes(of(landscape(connectivity((Chassot(2010)!
!
RNVSM!Maquenque!provides!connectivity!routes!to!the!northwest,!to!the!east!and!to!the!south.!

In!this!regard,!Maquenque’s!location!is!strategic!in!the!context!of!the!landscape.!We!identified!
18! priority! areas! for! structural! connectivity! based! on! the! nodes! or! connections! of! greater!
structural!importance!within!the!area!of!study,!none!of!which!are!related!to!the!layout!of!Route!

1856.!!!
!
Table(1:(Characterization(of(the(priority(areas(of(connectivity(

Coordinates(
No( Name( Canton( Lambert(North( Connectivity(node(

1! Río!TicoUMoravia! San!Carlos! 497500/305500! Jardín!U!Coopevega!
2! RecreoUSan!Carlos! San!Carlos! 515800/302800! Maquenque!–!Río!San!Carlos!
3! Santa!Rita! San!Carlos! 515100/296!300! Maquenque!–!Río!San!Carlos!

4! Boca!Tapada! San!Carlos! 509300/293200! Maquenque!–!Río!San!Carlos!

713Annex 10

5! Mollejón! Sarapiquí! 524800/285300! Maquenque!–!Braulio!Carrillo!
6! Sardinal! Sarapiquí! 527000/276900! Maquenque!–!Braulio!Carrillo!
7! Chilamate! Sarapiquí! 529800/267600! Maquenque!–!Braulio!Carrillo!

8! Golfito! Sarapiquí! 531900/290300! Maquenque!–!Braulio!Carrillo!
9! Arbolitos! Sarapiquí! 535500/292200! Maquenque!–!Barra!Colorado!
10! Unión!del!Toro! Sarapiquí! 536400/293700! Maquenque!–!Barra!Colorado!

11! Trinidad!1! Sarapiquí! 539100/297600! Maquenque!–!Barra!Colorado!
12! Trinidad!2! Sarapiquí! 541900/296800! Maquenque!–!Barra!Colorado!
13! Ruta!Este!Superior! Sarapiquí! 562200/298800! Maquenque!–!Barra!Colorado!
14! Ruta!Este!Mediana!1! Sarapiquí! 543600/293400! Maquenque!–!Barra!Colorado!

15! Ruta!Este!Mediana!2! Sarapiquí! 547400/293000! Maquenque!–!Barra!Colorado!
16! Ruta!Este!Inferior!1! Sarapiquí! 539400/289500! Maquenque!–!Barra!Colorado!
17! Ruta!Este!Inferior!2! Sarapiquí! 547400/283900! Maquenque!–!Barra!Colorado!

18! Ruta!Este!Inferior!3! Sarapiquí! 549700/281500! Maquenque!–!Barra!Colorado!
!
Of!the!18!priority!connectivity!areas,!10!have!the!potential!of!maintaining!and!strengthening!the!

connectivity! routes! between! RNVSM! Maquenque! and! RNVS! Barra! del! Colorado! in! areas! of!
agricultural! use! with! low! demographic! density! and! marshlands! that! are! not! suitable! for!
production!activities.!Between!RNVSM!Maquenque!and!Parque!Nacional!Braulio!Carrillo!there!

are!4!critical!areas!located!on!the!northUsouth!axis,!in!areas!of!agricultural!use!and!subject!to!the!
progress!of!intensive!single!crops!(mainly!pineapple)!on!the!banks!of!the!rivers!Toro,!Sardinal!

and!Sarapiquí!which!cross!the!axis!toward!the!northeast.!There!are!3!priority!areas!located!on!
the!course!of!San!Carlos!River,!between!the!two!conservation!blocks!of!RNVSM!Maquenque.! 9
Finally,!there!is!a!priority!area!that!allows!extending!connectivity!between!the!western!block!of!

Maquenque!and!Coopevega!area!to!the!west.!!
!
The! identification! of! the! connectivity! routes! and! the! priority! areas! of! connectivity! in! the!

landscape!of!the!area!of!study!agrees!with!6!of!the!7!critical!areas!identified!by!Ramos!(2004)!in!
the! territory! of! the! Biological! Corridor! of! San! JuanULa! Selva.! Of! the! 18! priority! areas! of!
connectivity,!13!are!located!along!the!course!of!important!bodies!of!water!such!as!the!rivers!San!

Carlos,!Toro!Amarillo,!Sarapiquí!and!Sardinal,!which!indicates!a!high!potential!to!implement!
projects!for!ecological!restoration!and!protection!of!riverside!vegetation.!The!area!between!

national!wildlife!refuge!Maquenque!and!Barra!del!Colorado!is!a!place!of!strategic!importance!to!
maintain!and!reUestablish!the!structural!connectivity!of!the!landscape.!!
!

!
!

CONCLUSION(
!
In!the!North!Caribbean!of!Costa!Rica!the!increase!in!fragmentation!(Chassot!2010)!is!consistent!

with! the! study! by! Schelhas! and! Sánchez! (2006)! in! the! vicinity! of! the! intermediate! lower!
watershed! of! Sarapiquí! River,! including! part! of! Braulio! Carrillo! National! Park! and! La! Selva!
Biological! Reserve.! Similar! to! Morse! et) al.! (2009),! we! attributed! the! decrease! in! the!

714 Annex 10

reforestation!rate!from!1998!to!2005!in!comparison!to!the!previous!period!(1987U1998)!to!the!
enactment!of!Forestry!Law!7575!(Chassot!2010),!which!explicitly!prohibits!land!use!change.!
!

The!identification!of!the!connectivity!routes!and!priority!areas!of!connectivity!in!the!landscape!
of!the!area!of!study!demonstrate!that!they!are!not!related!to!the!layout!of!Route!1856,!even!
though!this!border!road!is!located!in!the!area!of!greatest!forest!cover!of!the!area!of!study.!
Similarly,!it!can!be!stated!that!Route!1856,!due!to!the!reduced!extension!of!the!affected!natural!

ecosystem!(83!ha),!has!not!generated!a!significant!impact!on!the!structural!connectivity!of!the!
landscape!subject!to!this!study.!!
!
The! analysis! of! the! landscape! structure! in! the! North! Caribbean! of! Costa! Rica! indicates! the!

existence!of!gaps!in!the!biodiversity!conservation!goals!and!their!ecosystems!in!the!Atlantic!
watershed! of! the! country.! On! the! other! hand,! it! evokes! a! dynamic! and! heterogeneous!
landscape! that! can! have! an! impact! on! processes! of! ecological! succession,! adaptation,!
maintenance!of!diversity!of!species,!stability!of!communities,!competition,!interaction!between!

predators!and!prey,!parasitism,!epidemics!and!other!stochastic!events!(Legendre!&!Fortín!1989).!
Conversely,!the!increase!in!heterogeneity!detected!in!the!landscape!over!time!(Chassot!2010)!
allows!suggesting!that!some!species!could!benefit!from!this!(Dauber!et)al.!2003).!Therefore,!we!
recommend!integrating!ecological,!social!and!economic!variables!in!a!connectivity!analysis!to!
establish! a! functional! conservation! landscape! that! is! feasible! from! a! biocentric! and!

anthropocentric! perspective.! This! landscape! will! seek! to! prevent! local! extinction! of! the!
organisms! that! live! the! evergreen! tropical! broadleaf! rainforest! of! the! Costa! Rican! Atlantic,!
considering!that!these!plain!topographic!areas!could!be!subject!to!greater!changes!in!use!than! 10
slope!areas!(Kemper!et)al.!2000).!

!
Thanks!to!the!focus!on!landscape!ecology,!the!design!of!a!functional!conservation!landscape!for!
protected!wildlife!areas!and!their!buffering!zones!will!allow!identifying!priority!areas!of!natural!
habitats! and! promote! ecological! connectivity,! taking! into! account! the! continuity! of! the!

ecosystems!characteristic!of!the!North!Caribbean!of!Costa!Rica!and!the!socioUeconomic!factors!
that!affect!the!land!use!decision!by!the!local!communities,!reflected!in!the!structural!definition!
of!a!zoning!proposal!based!on!priority!linkages.!!!
!

!
!
(

(
(

(
(
(

715Annex 10

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15
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721Annex 10

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722 Annex 10

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723Annex 10

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724 Annex 10

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!
!

725Annex 10

Environmental Diagnostic Assessment (EDA)
Route 1856 Project – Ecological Component

9.4 Threatened species potentially found in the Border Biological Corridor Mixed

Wildlife Refuge and Maquenque Mixed Wildlife Refuge.

Main sources : UICN 1999, Elizondo 1997, McDade (ed.) 1994, Janzen (ed.) 1983, MARENA

2001.

MAMMALS:

Species Common Name Status Cause Altitude

1 Metachirus nudicaudatus zorricí Less common PH 0 - 1200

2 Myrmecophaga tridactyla oso caballo endangered PH/CI 0 - 800

3 Cyclopes didactylus serafín de platanar threatened PH 0 - 1500

4 Choloepus hoffmanni perezoso de dos dedos reduced PH/CI 0 - 3300

5 Bradypus variegatus perezoso tres dedos threatened PH/CI 0 - 2400

6 Cabassous centralis armadillo zopilote threatened PH 0 - 1800

7 Cyttarops alecto murciélago rare 0 - 100

8 Micronycteris daviesi murciélago very rare 0 - 300

9 Vampyrum spectrum murciélago threatened PH/CI 0 - 1500

10 Ectophylla alba murciélago blanco less common 0 - 700

11 Thyroptera discifera murciélago rare 0 - 300

12 Cebus capucinus mono carablanca reduced PH/CI 0 - 2000

13 Alouatta palliata mono congo endangered PH/CI 0 - 2500

14 Ateles geoffroyi mono colorado threatened PH/CI 0 - 2200

15 Sciurus deppei ardilla threatened PH 0 - 2800

16 Dasyprocta punctata guatusa threatened PH/CI 0 - 2400

17 Agouti paca tepezcuintle threatened PH/CI 0 - 2000

18 Bassariscus sumichrasti cacomistle, olingo threatened PH 0 - 2700

19 Bassaricyon gabbii martilla threatened PH 0 - 1700

20 Galictis vittata grisón threatened PH 0 - 1500

21 Lutra longicaudis nutría endangered PH/CI 0 - 3000

22 Puma concolor puma threatened PH/CI 0 - 3500

23 Panthera onca jaguar threatened PH/CI 0 - 2000

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Environmental Diagnostic Assessment (EDA)
Route 1856 Project – Ecological Component

Species Common Name Status Cause Altitude

24 Leopardus pardalis manigordo threatened PH/CI 0 - 3500

25 Leopardus wiedii tigrillo threatened PH/CI 0 - 3000

26 Herpailurus yaguarondi león breñero threatened PH/CI 0 - 2000

27 Trichechus manatus manatí endangered PH/MA/CI 0 - 50

28 Tapirus bairdii danta threatened PH/CI 0 - 3000

29 Tayassu tajacu saíno threatened PH/CI 0 - 3000

30 Tayassu pecari cariblanco endangered PH/CI 0 - 1900

31 Odocoileus virginianus venado cola blanca threatened PH/CI 0 - 2600

32 Mazama americana cabro de monte threatened PH/CI 0 - 2800

Source: Reid 1997.

BIRDS

Species Common Name Status Cause Altitude

1 Tinamus major gongolona threatened PH/CI 0 - 1700

2 Crypturellus boucardi gongolona threatened PH 0 - 700

3 Botaurus pinnatus puncus threatened PH 0 - 600

4 Ixobrychus exilis mirasol threatened PH 0 - 1400

5 Agamia agami garza pechicastaña threatened PH 0 - 300

6 Jabiru mycteria galán sin ventura endangered PH/CO 0 - 200

7 Mesembrinibis cayennensis coco negro threatened PH 0 - 200

8 Ajaia ajaja pato cuchara threatened PH/CO 0 - 300

9 Cairina moschata pato real threatened PH/CI 0 - 600

10 Oxyura dominica pato enmascarado threatened PH 0 - 1200

11 Sarcoramphus papa rey de zopilotes threatened PH 0 - 1200

12 Chondrohierax uncinatus gavilán threatened PH 0 - 1000
piquiganchudo

13 Rostrhamus sociabilis gavilán caracolero threatened PH 0 - 500

14 Geranospiza caerulescens gavilán ranero threatened PH 0 - 500

15 Accipiter superciliosus camaleón threatened PH 0 - 1200

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Environmental Diagnostic Assessment (EDA)
Route 1856 Project – Ecological Component

Species Common Name Status Cause Altitude

16 Leucopternis semiplumbea gavilán dorsiplomizo threatened PH 0 - 800

17 Buteogallus urubitinga gavilán silbero threatened PH 0 - 1200

18 Busarellus nigricollis gavilán pescador threatened PH 0 - 300

19 Morphnus guianensis águila crestada endangered PH 0 - 800

20 Harpia harpyja águila harpía endangered PH 0 - 2000

21 Spizastur melanoleucus aguilillo blanco y endangered PH 0 - 3000

negro

22 Spizaetus ornatus aguilucho penachudo threatened PH 0 - 1500

23 Spizaetus tyrannus aguilucho negro threatened PH 0 - 2000

24 Daptrius americanus cacao endangered PH 0 - 1200

25 Micrastur mirandollei halcón de monte threatened PH 0 - 800

26 Falco peregrinus halcón peregrino threatened CO 0 - 1200

27 Falco deiroleucus halcón pechirrufo endangered PH 0 - 1300

28 Crax rubra pavón threatened PH/CI 0 - 1200

29 Penelope purpurascens pava threatened PH/CI 0 - 1200

30 Odontophorus melanotis chirrascuá threatened PH/CI 0 - 1000

31 Rhynchortyx cinctus codorniz cariroja threatened PH 150 - 800

32 Heliornis fulica pato cantil endangered PH 0 - 200

33 Eurypyga helias sol y luna threatened PH 100 - 1200

34 Columba speciosa torcaza threatened PH 0 - 1200

35 Geotrygon violacea perdiz violácea threatened PH 0 - 800

36 Geotrygon veraguensis paloma bigotiblanco threatened PH 0 - 900

37 Ara ambiguus lapa verde endangered PH/CI 0 - 900

38 Ara macao lapa roja endangered PH/CI 0 - 800

39 Amazona autumnalis lora threatened PH/CI 0 - 800

40 Amazona farinosa lora threatened PH/CI 0 - 500

41 Neomorphus geoffroyi cuco hormiguero rare PH 0 - 900

42 Lophostrix cristata lechuza threatened PH 0 - 1500

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Environmental Diagnostic Assessment (EDA)
Route 1856 Project – Ecological Component

Species Common Name Status Cause Altitude

43 Trogon clathratus trogón threatened PH 90 - 1100

44 Chloroceryle inda martín pescador threatened PH 0 - 300

45 Jacamerops aurea jacamar grande threatened PH 0 - 500

46 Carpodectes nitidus cotinga nivosa threatened PH 0 - 750

47 Cephalopterus glabricollis pájaro sombrilla threatened PH 100 - 2000

48 Piprites griseiceps saltarín cabecigris threatened PH 100 - 750

49 Laniocera rufescens plañidera moteada threatened PH 0 - 700

50 Aphanotriccus capitalis mosquerito threatened PH 0 - 1000

51 Icterus mesomelas chorcha, chiltote threatened CI 0 - 1000

52 Lanio leucothorax tangara threatened PH 100 - 900

piquiganchuda

Source: Stiles et al. 1995, Stotz et al. 1996.

AMPHIBIANS

Species Common Name Status Cause Altitude

1 Dermophis parviceps solda con solda threatened 100 - 1500

2 Gymnopis multiplicata dos cabezas threatened 0 - 1400

3 Bolitoglossa colonnea salamandra threatened 50 - 1000

4 Oedipina alfaroi salamandra threatened E/PH 0 - 500

5 Oedipina carablanca salamandra threatened E/PH 0 - 300

6 Oedipina collaris salamandra threatened 0 - 500

7 Oedipina cyclocauda salamandra threatened 0 - 800

8 Bufo melanochloris sapo threatened E/PH 0 - 2000

9 Centrolene ilex rana de vidrio threatened PH 0 - 800

10 Centrolenella magna rana de vidrio threatened PH 50 - 800

11 Cochranella spinosa rana de vidrio threatened 0 - 600

12 Dendrobates auratus sapo venenoso threatened PH/CI 0 - 800

13 Dendrobates pumilio sapo venenoso threatened PH/CI 0 - 900

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Environmental Diagnostic Assessment (EDA)
Route 1856 Project – Ecological Component

Species Common Name Status Cause Altitude

14 Phyllobates lugubris sapo venenoso threatened PH 0 - 650

15 Agalychnis calcarifer rana de árbol threatened PH/CI 0 - 600

16 Agalychnis saltator rana de árbol threatened PH/CI 0 - 70

17 Anotheca spinosa rana coronada threatened PH 0 - 1200

18 Hyla microcephala rana de árbol threatened 0 - 1200

19 Phyllomedusa lemur rana de árbol threatened 60 - 1900

20 Eleutherodactylus altae sapo, rana threatened E/PH 100 - 1200

21 Eleutherodactylus biporcatus sapo, rana threatened PH 0 - 800

22 Eleutherodactylus gollmeri sapo, rana threatened 50 - 1500

23 Eleutherodactylus mimus sapo, rana threatened 15 - 900

24 Eleutherodactylus noblei sapo, rana threatened 0 - 1200

25 Eleutherodactylus rugulosus sapo, rana threatened 0 - 2370

Source: Leenders 2001.

REPTILES

Species Common Name Status Cause Altitude

1 Caiman cocrodilus caimán reduced PH/CI 0 - 200

2 Crocodylus acutus cocodrilo endangered PH/CI 0 - 200

3 Kinosternon angustipons tortuga candado threatened PH/CI

4 Chelydra serpentina Tortuga lagarto endangered PH 0 - 550

5 Thecadactylus rapicauda gecko threatened 0 - 200

6 Iguana iguana iguana verde threatened PH/CI 0 - 800

7 Norops carpenteri lagartija threatened 40 - 1500

8 Norops fungosus lagartija threatened 0 - 500

9 Norops lemurinus lagartija threatened 0 - 800

10 Norops pentaprion lagartija threatened 0 - 800

11 Norops sericeus lagartija threatened 0 - 1300

12 Dactyloa frenata lagartija threatened 0 - 850

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13 Dactyloa insignis lagartija threatened 0 - 1000

14 Polychrus gutturosus lagartija threatened 0 - 1800

15 Ptychoglossus plicatus lagartija threatened 0 - 700

16 Lepidophyma reticulatum perro zompopo threatened E/PH 0 - 1300

17 Celestus hylaeus lagartija threatened E/PH 0 - 700

18 Boa constrictor boa, béquer threatened CI 0 - 900

19 Corallus annulatus boa threatened CI 0 - 800

20 Epicrates cenchria boa threatened CI 0 - 500

21 Clelia clelia zopilota threatened CI 0 - 800

22 Geophis ruthveni culebra de tierra threatened E/PH 0 - 300

23 Sibon argus culebra threatened E/PH 0 - 900

24 Trimetopon pliolepis culebra threatened E/PH 40 - 1700

25 Trimetopon simile culebra threatened E/PH 100 - 800

26 Trimetopon viquezi culebra threatened E/PH 100 - 800

27 Ungaliophis panamensis culebra threatened PH 0 - 200

Source: Leenders 2001.

FISHES

Species Common Name Status Cause Altitude

1 Carcharhinus leucas tiburón toro limited CI/CO

2 Pristis perotteti pez sierra limited CI/CO 0 - 30

3 Pristis pectinatus pez sierra limited CI/CO 0 - 30

4 Centropomus undecimalis robalo limited CI

5 Atractosteus tropicus gaspar endangered CI/CO

6 Rivulus isthmensis olomina threatened PH/CO 0 - 1500

7 Brachyrhaphis olomina olomina less common PH/CO 10 - 900

8 Priapichtys annectens olomina endemic PH/CO 25 - 1270

9 Agonostomus monticola tepemechín threatened CI/PH/CO 0 - 650

10 Joturus pichardi bobo less common CI/PH/CO 0 - 600

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Source: Bussing 1998.

TREES

Species Common Name Status Cause Altitude

1 Aspidosperma spruceanum amargo, caretigre Limited

2 Tabebuia guayacan corteza, guayacán threatened PH 100 - 600

3 Ceiba pentandra ceiba threatened 50 - 300

4 Copaifera aromatica camíbar threatened PH 0 - 350

5 Cynometra retusa guapinol negro very limited 0 - 150

6 Prioria copaifera cativo threatened PH 0 - 150

7 Sclerolobium costarricense tostado endangered PH 50 - 700

8 Terminalia amazonia roble coral threatened 30 - 300

9 Terminalia oblonga surá, guayabón threatened 20 - 400

10 Dalbergia melanocardium bálsamo threatened 100 - 900

11 Dalbergia glomerata granadillo threatened 0 - 500

12 Dipteryx panamensis almendro threatened

13 Dussia macroprophyllata sangregao threatened PH 0 - 600

14 Hymenolobium mesoamericanum cola de pavo endangered PH 30 - 700

15 Platymiscium pinnatum cachimbo, cristobal endangered PH 0 - 600

16 Humiriastrum diguense chiricano alegre threatened PH 0 - 700

17 Vantanea barbourii chiricano triste threatened PH 0 - 800

18 Povedadaphne quadriporata ira rosa rare

19 Couroupita guianensis bala de cañon rare

20 Lecythis ampla olla de mono threatened PH 50 - 300

21 Ruptiliocarpon caracolito caracolito threatened 200 - 650

22 Carapa guianensis caobilla decreased 50 - 250

23 Cedrela fissilis cedro real endangered PH 50 - 500

24 Cedrela odorata cedro amargo threatened PH 0 - 1200

25 Trichilia pittieri rare

26 Minquartia guianensis manú threatened PH 0 - 500

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Species Common Name Status Cause Altitude

27 Podocarpus guatemalensis cipresillo, pinillo endangered PH 50 - 1500

28 Elaeoluma glabrescens carey threatened 50 - 300

29 Sideroxylon capiri danto amarillo threatened PH 0 - 900

30 Christiana africana piedra rare

31 Vochysia allenii botarrama rare E/PH

32 Qualea paraensis areno threatened PH 100 - 850

Source: Jiménez 1993, Jiménez 1997, Sánchez -Vindas et al . 1987, Quesada et al . 1997, Holdridge et al . 1997,
Zamora et al. 2000.

Status:

E: endemic

Cause:

PH: habitat loss

CI: intensive hunting or over fi shing

CO: pollution

Plant species predominat in wetlands of the Northern zone of Costa Rica

1
Common Name Scientific Common Name Scientific

Sota de Suampo Zygia confusa Yolillo Raphia taedigera.

Roble Coral* Terminalia Amazonia Gavilán Pentaclethra macroloba

Gavilán Pentaclethra macroloba Botarrama* Vochysia ferruginea

Fruta Dorada Virola sebifera Tabacón de Suampo Cespedesia macrophylla

Pejibayito Maranthes panamensis Baco Couma macrocarpa

Repollito Eschweilera costaricensis Cedro María Calophyllum brasiliense

Repollito Eschweilera panamensis Maquengue Amargo Socratea exorrhiza

Botarrama* Vochysia ferruginea Labios de puta Psychotria poeppigiana

Mouriri Mouriri gleasoniana Capiruto (Melastomataceae)

Maquengue
Amargo Socratea exorrhiza Fruta dorada Virola koschnyi
Laguna Canacas

1
* Species with some degree of vulnerability.

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Nace blanco Byrsonima crispa Palma Conga Welfia regia

Miconia Miconia punctata Tamarindo Dialum guianense

Vismia Vismia macrophylla Baco Brosimum utile.

Sapotillo Pouteria durlandii Cuero de sapo Licania affinis

Nancite blanco Byrsonima crispa Ferdinandusa Ferdinandusa panamensis

Casearia Casearia arborea Repollito Eschweilera costaricensis

Ferdinandusa Ferdinandusa panamensis Mouriri Mouriri gleasoniana

Botarrama* Vochysia ferruginea Maquengue Amargo Socratea exorrhiza

Laurel Muñeco Cordia bicolor Carey* Elaeoluma glabrescens

Gallinazo Jacaranda copaia Gavilán Pentaclethra macroloba

Sthryphnodendron
Vainillo Repollito
microstachyum Eschweilera panamensis

Guabo Inga alba Licania hoja dorada Licania belloi

Gavilán Pentaclethra macroloba Aceituno Simarouba amara

Sota de Suampo Zygia confusa Gallinazo Jacaranda copaia

Baco Brosimum utile. Manga Larga Laetia procera

Aceituno Simarouba amara Cucaracho Chiricano* Vantanea barbourii

Croton Croton smithianus Maquenque Swartzia maquenqueana

Colpachi Croton schiedeanus Botarrama* Vochysia ferruginea

Melina Gmelina arborea Miconia plata Miconia sp.

Manga Larga Laetia procera Miconia Miconia punctata

Cedrillo Tapirira guianensis Hirtella Hirtella media

Alibertia Alibertia atlantica Cedrillo Tapirira guianensis
Laguna Tambor

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9.5 Limited and threatened species to be used in local reforestation.

Tree species from the study area, considered limited according to several authors, suggested to

be considered in reforestation programs to protect riversides along Route 1856.

SPECIES COMMON NAME

Aspidosperma spruceanum amargo, caretigre

Balizia elegans ajillo

Carapa guianensis caobilla

Cedrela fissilis cedro real
Cedrela odorata cedro amargo

Ceiba pentandra ceiba

Copaifera aromatica camíbar

Couroupita guianensis bala de cañón

Cynometra retusa guapinol negro

Dalbergia melanocardium bálsamo

Dipteryx panamensis almendro

Dussia macroprophyllata sangregao

Elaeoluma glabrescens carey

Enterolobium schomburgkii guanacaste blanco

Gordonia fruticosa campano blanco

Guettarda turrialbana ??

Hymenolobium mesoamericanum cola de pavo

Ilex skutchii plomillo, campano

Lecointea amazonica costilla de danto

Lecythis ampla olla de mono

Licania affinis cuero de sapo

Manilkara zapota níspero chicle

Micropholis melinoniana zapotillo

Minquartia guianensis manú

Ormosia velutina nene

Podocarpus guatemalensis cipresillo, pinillo

Prioria copaifera cativo
Pseudolmedia spuria ojochillo

Qualea paraensis areno

Ruptiliocarpon caracolito caracolito

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Sclerolobium costarricense tostado

Sideroxylon capiri danto amarillo

Tabebuia guayacan corteza, guayacán

Talauma gloriensis magnolia

Terminalia amazonia roble coral

Terminalia oblonga surá, guayabón

Vantanea barbourii chiricano triste

Vatairea lundellii cocobolo, amargo

Vochysia allenii botarrama

Williamodendron glaucophy llum aguacatillo

Source: CCT, 2013.

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9.6 Tree species observed in the area of Las Crucitas, San Carlos.

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Source: Centro Científico Tropical. 1996. Inventario de Vegetación en el Proyecto Minero Cerro Crucitas. Placer

Dome de Costa Rica S.A. (Dendrólogos Sanchez Pablo y Poveda Luis).

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9.7 Taxa richness and abundance of individuals of aquatic macroinvertebrates

collected at study sites along Route 1856, Juan Rafael Mora Porras, July -

August, 2013. Upstream (Abj) and downstream (Arb) of the road. (*) less

common taxa or with limited distribution in the country.

Sitio 1 Sitio 2 Sitio 3 Sitio 4 Sitio 5 Sitio 6 Sitio 7 Sitio 8 Sitio 9 Sitio 10
Taxon
Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb

Coleoptera

Dytiscidae

Derovatellus 1

Vatellus 1

Gen. Indet. 1 1 1

Elmidae

Cylloepus 1

Heterelmis 2

Hexacylloepus 1

Macrelmis 1 1

Microcylloepus 1

Hydrophilidae

Gen. Indet. 2 2 1

Limnichidae

Limnichites* 8 1 3 8 1 1

Psephenidae

Dicranoselaphus * 1

Ptilodactylidae

Anchytarsus 1 1

Scirtidae

Gen. Indet. 1 2

Staphylinidae

Gen. Indet. 1

Lampyridae *

Gen. Indet. 1

Dryopidae

Elmoparnus 1 1

Diptera

Ceratopogonidae

Bezzia 1 1

Probezzia 1 1

Chironomidae

Chironomini 9 4 2 2 1 1

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Sitio 1 Sitio 2 Sitio 3 Sitio 4 Sitio 5 Sitio 6 Sitio 7 Sitio 8 Sitio 9 Sitio 10
Taxon
Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb

Orthocladiinae 1 2 1 1

Tanypodinae 2 2 1 10 1 2 2

Tanytarsini 2 1 4 1 1

Gen. Indet. 1 1 5 1

Tipulidae

Hexatoma 1

Gen. Indet. 1

Culicidae

Aedes 1

Anopheles 1

Culex 1

Gen. Indet. 1

Simuliidae

Simulium 13 1 32 1 1 1

Ephemeroptera

Baetidae

Americabaetis 2 49 10 13 2 2 1 3

Apobaetis 1 1 1 1 3 1 2 1 2 2

Callibaetis 1 1

Cloeodes 1 1 1 1 2

Fallceon 1 1

Caenidae

Caenis 2 4 6 2 2 13

Leptophlebiidae

Farrodes 5 1 11 6 15 17 2 3 1 1

Terpides * 7 1 22 2 1

Tikuna * 2

Ulmeritoides* 6 1 1 1 3 1 4 1

Heptageniidae

Maccaffertium* 3

Leptohyphidae

Cabecar * 4

Epiphrades 1 3 7 9 1 1

Leptohyphes 3 1 1

Tricorythodes 3 7 2 1 1 5 1 2 9 4 1

Vacupernius * 1

Hemiptera

Belostomatidae

Belostoma 1

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Sitio 1 Sitio 2 Sitio 3 Sitio 4 Sitio 5 Sitio 6 Sitio 7 Sitio 8 Sitio 9 Sitio 10
Taxon
Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb

Gen. Indet. 2

Gerridae

Brachymetra 1 1
albinervis

Potamobates 1

Potamobates 2 3 1
unidentatus

Rheumatobates 1 1
bergrothi*

Tachygerris 2

Telmatometra 1 1 1

Telmatometra 1
withei*

Gen. Indet. 1 1 1 3 3 1 1 7 7 6

Corixidae

Tenagobia 1 1 1

Hydrometridae

Hydrometra 1

Nepidae

Ranatra* 1

Notonectidae

Martarega* 3 1 2 6 25

Gen. Indet. 2 3 7 6 2 34 27 16

Veliidae

Microvelia 1 1 1

Rhagovelia 1 14 5 3 1 4 2 2 4 2 9 1

Stridulivelia* 3

Odonata

Calopterygidae

Hetaerina 5 2 1

Coenagrionidae

Acanthagrion 3 1 1

Argia 19 1 1 2

Megapodagrionidae

Heteragrion 1 1

Protoneuridae

Neoneura* 2 4 2 3 2 1 1 2

Gen. Indet. 1

Platystictidae

Palaemnema* 1 4

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Sitio 1 Sitio 2 Sitio 3 Sitio 4 Sitio 5 Sitio 6 Sitio 7 Sitio 8 Sitio 9 Sitio 10
Taxon
Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb

Polythoridae *

Gen. Indet. 1

Gomphidae

Agriogomphus * 1

Epigomphus 1 1 1

Erpetogomphus 1

Perigomphus* 2

Gen. Indet. 1

Libellulidae

Zenithoptera* 1

Gen. Indet. 1 2 2 1 3 1 2

Corduliidae

Neocordulia * 1

Fam. Indet.

Gen. Indet. 2 1 1

Sitio 1 Sitio 2 Sitio 3 Sitio 4 Sitio 5 Sitio 6 Sitio 7 Sitio 8 Sitio 9 Sitio 10
Taxon
Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb

Trichoptera

Glossosomatidae
1
Protoptila

Helicopsychidae
2
Helicopsyche

Hydropsychidae
1 5 2 8
Leptonema
1
Macronema*

Smicridea 7 1 1 1 2

Leptoceridae

Nectopsyche 4 3 1 1 1

1 2
Oecetis

Polycentropodidae
5
Cernotina *

Calamoceratidae
2
Phylloicus

Plecoptera

Perlidae
6 1 2 2 3
Anacroneuria

Megaloptera

Corydalidae

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Sitio 1 Sitio 2 Sitio 3 Sitio 4 Sitio 5 Sitio 6 Sitio 7 Sitio 8 Sitio 9 Sitio 10
Taxon
Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb

Corydalus 2 1

Lepidoptera

Pyralidae

1 1
Gen. Indet.

Dictyoptera

Blaberidae
1
Gen. Indet.

Trombidiformes

Fam. Indet.
6 3 2 2 5 1
Gen. Indet.

Haplotaxida

Haplotaxidae

Gen. Indet. 2 1 2 1 1

Naididae
1
Gen. Indet.

Rhynchobdellida

Glossiphoniidae
1
Haementeria
1
Fam. Indet.

Tricladida

Planariidae

Gen. Indet. 1 1 1

Architaenioglossa

Ampullariidae

1
Gen. Indet.

Basommatophora

Lymnaeidae
1 12 1
Gen. Indet.

Physidae
1
Gen. Indet.

Planorbidae

Gen. Indet. 2

Neotaenioglossa

Hydrobiidae

1
Gen. Indet.

Sorbeoconcha

Thiaridae
3
Gen. Indet.

Decapoda

Palaemonidae
1 2 2
Macrobrachium

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Sitio 1 Sitio 2 Sitio 3 Sitio 4 Sitio 5 Sitio 6 Sitio 7 Sitio 8 Sitio 9 Sitio 10
Taxon
Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb

Pseudothelphusida
e
1
Gen. Indet.

Sitio 1 Sitio 2 Sitio 3 Sitio 4 Sitio 5 Sitio 6 Sitio 7 Sitio 8 Sitio 9 Sitio 10
Taxon
Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb Abj Arb

Isopoda

Fam. Indet.
1
Gen. Indet.

Ostracoda

Fam. Indet.

Gen. Indet. 1

Total de 42 53 43 23 119 126 58 11 73 82 13 25 21 34 24 21 65 23 71 30
individuos
Riqueza de 12 22 20 13 19 26 17 6 17 25 8 12 14 16 15 13 10 11 11 9

Taxa

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Document file FR

152-20131219-WRI-01-01-FR.pdf

Document Long Title

Volume II - Annexes 1-10