Volume 5 - Annexes 17-18

INTERNATIONAL COURT OF JUSTICE
DISPUTE OVER THE STATUS AND USE OF THE
WATERS OF THE SILALA
(CHILE v. BOLIVIA)
COUNTER-MEMORIAL OF THE
PLURINATIONAL STATE OF BOLIVIA
ANNEXES 17 - 18
VOLUME 5
3 SEPTEMBER 2018

ANNEX N° TITLE PAGE N°
Technical Documents (Continued from Annex 17 and Annex 18)
VOLUME 5
ANNEXES 17 - 18
Danish Hydraulic Institute (DHI), Study of the Flows in
the Silala Wetlands and Springs System, 2018
Annex G: Integrated Surface Water / Groundwater
Modelling
(Original in English)
Annex H: Natural Flow Scenarios
(Original in English)
Annex I: Questionnaire put by the Plurinational
State of Bolivia to DHI
(Original in English)
Ramsar Convention Secretariat, Report Ramsar
Advisory Mission Nº 84, Ramsar Site Los Lipez, Bolivia,
2018
(Original in Spanish, English translation)
Annex 17
Annex 18
57
79
87
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LIST OF ANNEXES TO THE COUNTER-MEMORIAL OF THE
PLURINATIONAL STATE OF BOLIVIA

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Annex 17
Danish Hydraulic Institute (DHI), Study of the Flows in the
Silala Wetlands and Springs System, 2018
Annex G: Integrated Surface Water / Groundwater Modelling
(Original in English)
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3
Contract CDP-I No 01/2018, Study of the
Flows in the Silala Wetlands and Springs
System
Product No. 2 - 2018 Final Report
Annex G: Integrated Surface Water - Groundwater Modelling
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Plurinational State of Bolivia, Ministry of Foreign Affairs, Diremar
July 16, 2018
OHi • Agern Alie 5 • • DK-2970 H0rsholm • Denmark
Telephone: +45 4516 9200 • Telefax: +45 4516 9292 • [email protected] • www.dhigroup.com
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CONTENTS
Glossary .... ................... ................... ........ ..... ...... ........ ................... ......... .... ... ........ ..... .. 4
1 lntroduction ............................................................................................... 7
2 Objectives .................................................................................................. 7
3 Integrated model ... .... ............ ... ...... ........ .. ........... .. ........... .... ...... ... ............ 7
4 Conceptual model ..................................................................................... 7
4.1 Numerical model approach ........ ............. ............. ...... ..... ............. .... ......... ............... . 9
5 Numerical model code ............................................................................ 10
6 Model area and resolution ...................................................................... 11
7 Hydrological model components ........................................................... 13
7.1 Groundwater ... .... ........... ............. ......... .. .. ......... ........ .. ...... .......... ......... ....... .......... ... 13
7 .1.1 Hydrogeological model .. ....... .. .... ........... .. ........... ............. ... .......... ............. .............. 13
7 .1.2 Boundary conditions ...... ............. ........... .. ............. ........... .......... ... ............. ...... ..... ... 14
7 .1 .3 Parametrization ...... ....... .......... .. ...... ....... ................. ....... ........... .. ...... ...................... 16
7.2 Unsaturated zone .......... ...... ..... ........ ... ... .. ... ..... ...... .. ... ... .... ........ .... ..... ..... .. ............. 17
7.2.1 Summary of soil survey ............. ............. ............ ............. ............. ............. .............. 18
7.2.2 Parametrization .. ......... ............... ......... .. ............. .......................... ............. ........... ... 21
7.2.3 Evapotranspiration ......... ........ ..... ...... ... .. ... .......... ...... .. ...... .......... ......... ..... .. .......... ... 23
7.3 Overland and channel flow .... ... ...... .. ...... .. ... ..... ........ ...... .... ........ ...... .. ...... .. ............. 24
7.3.1 Artificial channel alignment... ...... .......... ... ............. ...... ..... ... ........ ...... .......... ............. 24
7.3.2 Canal cross sections .... .............. ........... ........... .... ..... .... .......... .. ... ..... .... ... ............... 27
7.3.3 Structural changes ......... ........ ... ........ ... .... ......... ........ .. .... .. .......... ......... ..... .. .......... ... 37
7.3.4 Overland flow component .. .... ..... ...... ...... ..... ..... ...... .. ...... .... ........ ...... ... ..... .. ............. 40
7.4 Model calibration ........... .... .... ..... .... ..... ... .. ............ ...... .... .. ............ ............ .. .......... ... 40
7.5 Model calibration parameters ... ... .......... ........... .. .. .... ..... ............... ..... ...... ............... .40
8 Results ..................................................................................................... 44
8.1 Surface water flows ...... .... .......... ...... ... .. ... .......... ...... ... ....... ........ ......... ..... .. ............ .44
8.2 Groundwater table ........ ... .. ....... ...... ..... ... .. ............ ...... .... .. ............ ............ .. .......... ... 45
8.3 Water balance .... ........... .......... ...... .. ...... .. ... ..... ...... .. ...... .. .......... .... .... ...... ... ........... .45
8.4 Results by zones. . . .... .. ... ..... ........ .. ... .... ........ ...... .. ...... .. ........... .46
8.4.1 Zone 1 : Northern wetland ..... . ... ......... .... ......... ........ ... ... .... ........ ......... ..... .. ............ .46
8.4.2 Zone 2 : Southern wetland .... ..... ............ ............ ............. ............. ............. ............. .47
8.4.3 Zone 3 : Mid-section of Southern Canal. ..... ..... .......... .... .... ........ ...... .. ...... .. ............ .47
8.4.4 Zone 4 : Ravine section of Southern Canal .. ... ....... ....... ............ ....... ..................... .48
8.4.5 Zone 5 : Confluence to border .... ............. ......... ........ ...... .... ........ ...... ... ..... .. ............ .48
9 Summary and conclusions ..................................................................... 49
10 References ........................................... ........ ........... .... ................... .. .. ...... 51
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FIGURES
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
Figure 19
Figure 20
Figure 21
Figure 22
Figure 23
Figure 24
Figure 25
Figure 26
Figure 27
Figure 28
Figure 29
Figure 30
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Model components and structure of the MIKE SHE - MIKE11 integrated model code . ..... ... ..... 10
Silala Near Field model area . ..... .. ... .... ... .... ... ... ... ... .. ... ... .. ... .. .. ..... ... ... .. ... ... .. ..... ... ... .. ... .. ... ... .. ..... 12
Groundwater level maps used in definition of groundwater component boundary
conditions .... ... ... .......... ... .... ...... ... .................... .......... ... ............. ....... ...... ... .. ............... ....... ... ... ... .. 15
Illustration of groundwater boundary condition ... ...... ... .. .. ..... .... .... ... ... .. ... .. ... .... ... ... ... ....... ... ... ... .. 16
Soil sampling sites in Northern and Southern wetland .. ... .... .... .. .. ... .. ... ... .. ... ... .. ... .. ... ... .. ... .. ... ..... 19
Soil thickness and ground water table profile, Northern wetland (in m below ground
surface) ................................. ................ ............. .......................................................................... 19
Peat soil profile at northern wetland ......... ... ............. ... .......... ... ....... ... .. .................. .......... ... ... ... .. 20
Soil profile distribution map (codes 1-6 referring to the above description), northern
wetland ........ ... ... .......... ... ............. .... ... .......... ... ....................... ... ... .. .. ...... ... ................. ... ......... ... .. 21
Soil retention curves (peat dry matter content ranging from 60 % (1) to 0 % (7)), Londra
P., 2010 ....... ... ... .......... ... .... ...... ... .... ... .......... ... .... ...... ... .... ...... ... ... .. .. ...... ... .. .. ... .. ..... ... ... ......... ... .. 22
Grasses and cushion wetland vegetation at Silala southern wetland. Close up of distichia
(photo from Fonken 2014) .... ... ... .. .. ... .......... ... .......... ... .......... ....... ... ... ... ... .. ............ ... ... .......... ... .. 23
Layout of the artificial channel alignment in the hydraulic model shown on top of the
orthophoto of the area ... .. .. ... ... ... .. .. ... .. ...... ..... .. .. ... ... ... ... .. .. ... .. ..... ... ... .. ... ... .. ... .. ... ... .. ... ... .. ..... ... .. 25
Artificial channel alignment in the upstream end of the Southern Catchment. The red lines
represent the hydraulic model , the blue pol ygon is the shape file from DIREMAR showing
were the canals/conveyers are located. .. ....... .. ..... ..... ....... ............ .......... .. ................ .... 26
Map of the canal layout including width and depth of selected canals (DIREMAR and
SENAMHI). .... ... .. ..... .. .... .. .. ...... .. ..... ... .......... ... .... .... .. ... .... ... .... .. .... ... ... .. ... ... .. ... .. ... ... .. ... ... . .. ... .. 27
A close-up of the information of width and depth for canals in the Main Canal System from
upstream end to approximately 300 meters downstream (Southern wetland) . ...... ..................... 28
A close-up of the information of width and depth for canals in the Main Canal System from
chainage 300 meters to chainage 600 meters (Southern wetland) ... ... ... ... ... .. .. ... .. ... ... .. ... .. ... ... .. 28
A close-up of the information of width and depth for canals in the Main Canal System
(southern ) from chainage 600 meters to chainage 900 meters .. .. ... ... ... ............................. ... ..... 28
A close-up of the information of width and depth for canals in the Main Canal System
(southern ) from chainage 900 meters to chainage 1200 meters .. .... .. .. ... .. ... ... ... .... ... ......... ... ..... 29
A close-up of the information of width and depth for canals in the Main Canal System
(southern ) from chainage 1200 meters to chainage 1500 meters ... ............. .......... .................... 29
A close-up of the information of width and depth for canals in the Main Canal System
(southern ) from chainage 1500 meters to chainage 2000 meters .. ... ... ... .. ... .... .... .. ... ......... .. ...... 29
A close-up of the information of width and depth for canals in the Main Canal System
(southern ) from chainage 2450 meters to chainage 2650 meters (no measurements from
chainage 2000 to chainage 2450) .. .......... ... ... .......... ... .... ... ... ... .... ... ... .. ... .. ....... ...... ... .......... ... ... .. 30
A close-up of the information of width and depth for canals in the Main Canal from
chainage 2800 meters to chainage 3100 meters (no measurements from chainage 2450
to chainage 2800.) ... ... ... .............................. ... ....................... ....... ... ... ... ... ............................. ..... 31
A close-up of the information of width and depth for canals in the Main Canal from
chainage 3100 meters to chainage 3300 meters . .... ... .. ... .... ... .... .. .. ... .. ... .. ... ... .. ... .. ... ... ... .... .. ...... 32
A close-up of the information of width and depth for canals in the Main Canal System from
approximately chain age 3300 meters to the border. .... ....... ...... ....... ....... ..................... . ......... 33
A close-up of the information of width and depth for canals in the Northern Canal. ........... ... ..... 34
A close-up of the information of width and depth for canals in the Northern Canal. ........... ... ..... 35
Example of how to define the extent of each canal by using alignment lines (in red). Blue
lines represent canals and the green one the cross sections in the canals ........ .......... ...... ... ..... 36
Variation in bottom level for the Main Canal and the North Canal from the confluence and
upstream ... ... ....... ... .... ...... .. ... .. ... ...... ... .. .. .... ... ... ... ... .. ... .. ... ... .... .... .. .. ..... ... ... .. ... .. ... ... .. ... ... .. ... .. .. ... 36
Canal cross sections organised in the MIKE11 cross section database ................ ... .......... ... ..... 37
Example of obstructions to the flow. These obstructions should be dealt with individually
in the hydraulic model as additional energy losses .. ... .. ... .... .... .. .. ... ... .. ... .. ... .... ... ... ... .......... ... ..... 38
Simulated longitudinal profile of canal flow .. ... .. .. ... ... ... .. .. ..... .... .... ... ... .. ... .. ... .... .... ............ ... ... ... .. 39
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Figure 31
Figure 32
Figure 33
Figure 34
Figure 35
Figure 36
Figure 37
Figure 38
Figure 39
Figure 40
TABLES
Table 1
Table 2
Table 3
Table 4
Table 5
Table 6
Table 7
Table 8
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Simulated water depth and flow in the Southern Wetland .... ... .... ... .... ... ................. ... .... ... ... .. .. .... 39
Photo showing example of Silala canal spills (1-D) and diversion to adjacent overland
area (2-D) . .... .. .. ... ... ... .... .. ... .. ... .... ... .... ... ... .. ... .... .. ... ... ... .. .. ... .... ... ... .. ... ... .. ... .. .. .. ... .. ... .. .. ... .. .. ... ... ... 40
Example of zonation, horizontal hydraulic conductivity of Upper Silala lgnimbrite (5e·6 -
5e·5 mi s)......... ... ....... ....................... . ................... ... ........................................ ... ...... .41
Mapping of flows and net inflows based on simultaneous mean canal flow measurements
(in I/s), Annex C .. ... ... .... ... .... ... ............. ... .... ... .... ... .... ... ... ... ... ... ... .. ... ... .. .. ... .. .. ... .. .. ... ... ....... ... .... .... 43
Groundwater table elevation contours based on measurements and model results,
respectively . ... ... .... ... .... ... ... .. ... .... ...... .... ... .. ... .... .. ... .. ... ... ... ... ... ... ... .. ... .. .. ... .. .. ... ... .. ... .. .. .... ... .... .... 45
Simulated groundwater flow to the canal and drainage network in Northern wetland ................ .46
Simulated overland water depth (0 - 15 cm) and flow vectors in Southern wetland . .... ... ... ....... .47
Simulated groundwater level and flow vectors in Zone 3 .. ... ... .... ... .... ... ................. ... .... ... ... .. .. ... .47
Groundwater discharge to the canal along the Zone 4 ravine section .. .. ..... ... .. ... .. ... .... ... .... ... ... .48
Cross section at the border showing groundwater layers and simulated groundwater table .. ... .49
Overview of Silala Near field zones and key processes affecting surface flows . .. .... .... ... ... .... ..... 8
Hydrogeological units in the hydrogeological model and the numerical groundwater
model. ............ ... ....... ... .. ...................... ... .... ... .... ... ................. ... .... ... ... .... ... ................. ....... ... ... ..... 14
Initial ranges of hydrogeological parameters considered for the integrated model. ..... ....... ........ 17
Overview of unsaturated zone property ranges ... .. .. ... .......... .. ... .. ... .... ... ....... ... .. ... .... ... ... .. ... .. .. .... 22
Estimated ET parameters (LAI ) .. ... .... ... ... .. ... .. .. .. ... ... ... .. .. ... .. .. ... .. ........ ... .... ... .... ... .............. ... .. .... 24
Summary of key calibrated model parameters . .. ... .. ... ... ... ...... ... .. ... .... ... ... ... ... ... ... .............. ... .. .... 42
Comparison of measured and simulated flows.... ................. ... ........... ... ... . ..... ... ....... .44
Water balance summary for the current conditions (with canals) ............ ... ... ........ ... ... ..... ... ....... .46
DOCUMENTATION OF THE STUDY
Main Report Containing the summary and conclusions
Technical Annexes:
Annex A.
Annex B.
Annex C.
Annex D.
Annex E.
Annex F.
Annex G.
Annex H.
Annex I.
The Silala catchment
Climate analysis
Surface waters
Soil Analyses
Water balances
Hydrogeology
Integrated surface water - groundwater modelling (this annex)
Natural flow scenarios
Questionnaire put by the Plurinational State of Bolivia to DHI
The expert in WATER ENVIRONMENTS 3
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Glossary
Term
Aquifer
Austral summer
Basin
Catchment
Confined aquifer
Depression, terrain
depression or sink
Desert climate
Digital elevation
model (DEM)
Discharge
El Nino
Meaning/Definition
Geological formation capable of storing, transmitting and yielding
exploitable quantities of water.
Summer period in the Southern Hemisphere.
Area having a common outlet for its surface runoff.
The whole of the land and water surface contributing to the discharge at
particular stream cross section. This means that any cross section of a
stream will have a unique catchment of its own. (Wilson, 1978).
Confined aquifers are aquifers that are overlain by a confining layer,
often made up of clay or other geological formations with low
permeability.
A depression (or sink) is a low point in the terrain surrounded by higher
ground in all directions. If the soil is impervious, the depression collects
rain water from a local catchment. Surface water or groundwater inflows
will accumulate in the depression until:
- the water level reaches the nearest terrain threshold and runs off or
- the evaporation from the depression is equal to its combined surface
water groundwater inflows. However, a depression may also drain subsuperficially
to lower lying areas through pervious soils, geological
faults or groundwater aquifers.
Desert climate (in the Koppen climate classification BWh and BWk,
sometimes also BWn), also known as an arid climate, is a climate in
which precipitation is too low to sustain any vegetation at all , or at most
a very scanty shrub and does not meet the criteria to be classified as a
polar climate.
Data files holding terrain levels often organised in a quadratic grid with
a certain cell size (e.g. 30m by 30 m). They are very convenient tools
for and often used as standard tools in Geographic Information
Systems (GIS) for delineation of topographical catchment and for many
other purposes.
Volume of water flowing per unit time, for example through a river
cross-section or from a spring or a well.
El Nino is the warm phase of the El Nino Southern Oscillation
(commonly called ENSO) and is associated with a band of warm ocean
water that develops in the central and east-central equatorial Pacific
(between approximately the International Date Line and 120°W),
including off the Pacific coast of South America. El Nino Southern
Oscillation refers to the cycle of warm and cold temperatures, as
measured by sea surface temperature (SST) of the tropical central and
eastern Pacific Ocean. El Nino is accompanied by high air pressure in
the western Pacific and low air pressure in the eastern Pacific. The cool
phase of ENSO is called "La Nina" with SST in the eastern Pacific
below average and air pressures high in the eastern and low in western
Pacific. The ENSO cycle, both El Nino and La Nina, causes global
changes of both temperatures and rainfall.
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Evapotranspiration
Food and Agriculture
Organization of the
United Nations (FAO)
Geographic
Information System
(GIS)
Groundwater
Hydrogeological
Conceptual Model
(HCM)
Hydrogeological
Framework Model
(HGFM)
Hydrological
catchment
Infiltration
Penman-Monteith
Recharge
Reference
evapotranspiration
(Eto)
Combination of evaporation from free water and soil surfaces and
transpiration of water from plant surfaces to the atmosphere.
Specialized agency of the United Nations that leads international efforts
to defeat hunger. FAO is also a source of knowledge and information,
and helps developing countries in transition modernize and improve
agriculture, forestry and fisheries practices, ensuring good nutrition and
food security for all.
A geographic information system (GIS) is a system designed to
capture, store, manipulate, analyse, manage, and present spatial or
geographic data.
Subsurface water occupying the saturated zone (i.e. where the pore
spaces (or open fractures) of a porous medium are full of water).
The conceptual understanding of the individual components in a
hydrologic system (i.e. groundwater, surface water, and recharge) and
the processes involved between each component.
A three-dimensional geologic model that defines the spatial extent of
stratigraphic and structural features . The development of the HGFM
incorporates topographic, geologic, geophysical , and hydrogeologic
datasets.
The hydrological catchment is the total area contributing to the
discharge at a certain point. The hydrological catchment includes all the
surface water from rainfall runoff, snowmelt, and nearby streams that
run downslope towards a shared outlet, as well as the groundwater
underneath the earth's surface. Since groundwater may cross the
topographical divides a hydrological catchment to a point may be larger
than the corresponding topographical catchment as indicated in the
Princi le sketch below.
// topographical
waler divide
surfoc
I rain
catchment
A
runof I catchment
B
Hydrological catchment B
The movement of water from the surface of the land into the
subsurface.
Method for estimating reference evapotranspiration (EtO) from
meteorological data . It is a method with strong likelihood of correctly
predicting ETo in a wide range of locations and climates and has
provision for application in data-short situations.
Contribution of water to an aquifer by infiltration.
The evapotranspiration per area unit under local climate conditions from
a hypothetical grass reference crop with an assumed crop height of
0.12 m, a fixed surface resistance of 70 s m-1 and an albedo of 0.23.
The reference surface closely resembles an extensive surface of green ,
well-watered grass of uniform height, actively growing and completely
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Remote sensing
Satellite
Sensitivity analysis
Spatial variation
Spring
Topographical
catchment
Weather station
Wetland
shading the ground. A good approximation to the maximum
evapotranspiration that under a certain climate can evaporate from an
area unit covered by an ever-wet short green vegetation (e.g. a
wetland)
Acquisition of information about an object or phenomenon without
making physical contact with the object and thus in contrast to on-site
observation. In current usage, the term "remote sensing" generally
refers to the use of satellite- or aircraft-based sensor technologies to
detect and classify objects on Earth, including on the surface and in the
atmosphere and oceans, based on propagated signals (e.g.
electromagnetic radiation).
Artificial body placed in orbit round the earth or another planet in order
to collect information or for communication.
Sensitivity analysis is the study of how the uncertainty in the output of a
mathematical model or system (numerical or otherwise) can be
apportioned to different sources of uncertainty in its inputs.
When a quantity that is measured at different spatial locations exhibits
values that differ across the locations.
A spring is a place where groundwater emerges naturally from the rock
or soil. The forcing of the spring to the surface can be the result of a
confined aquifer in which the recharge area of the spring water table
rests at a higher elevation than that of the outlet. Spring water forced to
the surface by elevated sources are artesian wells. Non-artesian
springs may simply flow from a higher elevation through the earth to a
lower elevation and exit in the form of a spring, using the ground like a
drainage pipe. Still other springs are the result of pressure from an
underground source in the earth, in the form of volcanic activity. The
result can be water at elevated temperature such as a hot spring.
A catchment delineated strictly by topographical divides of the terrain.
The topographical catchment includes all the surface water from rainfall
runoff, snowmelt, and nearby streams that run downslope towards a
shared outlet. This is the correct catchment if all discharge is surface
flow (i.e. no groundwater). The topographical catchment is often a good
approximation to the catchment, particularly for larger catchments.
A facility, either on land or sea, with instruments and equipment for
measuring atmospheric conditions to provide information for weather
forecasts and to study the weather and climate.
A wetland is a land area that is saturated with water, either permanently
or seasonally, such that it takes on the characteristics of a distinct
ecosystem. The primary factor that distinguishes wetlands from other
land forms or water bodies is the characteristic vegetation of aquatic
plants, adapted to the unique hydric soil. Wetlands play a number of
roles in the environment, principally water purification, flood control,
carbon sink and shoreline stability.
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1 Introduction
This annex to the final report of the study of the flows in the Silala Wetlands and Springs System
documents the set up and calibration of an integrated surface water - groundwater model of the
Silala Near Field Area. The model is used in scenario analysis (Annex H).
Numerical models are widely used for simulation of hydrological systems and for prediction of
impacts of water management scenarios. An integrated surface water - groundwater model is
developed for the Silala Near Field area, partly to describe the current flow system and partly as
a management tool to assess the effects of specific changes.
2 Objectives
An integrated hydrological modelling tool of the Silala Near Field area is developed and used in
scenario analysis. The main objective of the scenario analysis is to assess the differences
between the current conditions (with canals), and a scenario where the canals are removed.
The integrated model is composed by interconnected hydrological components describing the
surface and subsurface flow system . (Garraud , et al. , 2003).
3 Integrated model
An integrated model refers to a numerical model tool built for simulating flows and water levels
in an interlinked surface - subsurface hydrological system. Due to the diverse and spatially
variable features of the Silala Near Field area, distributed flow properties must be considered
when analysing the combined subsurface and surface water system. For this purpose, an
integrated numerical modelling system have been developed. Apart from providing simulations
of current flows, the model will be used in scenario analysis to assess the effect of a given
change .
For the Silala Springs System, the impact of the manmade canals and drainage networks is
assessed by comparing a baseline model with canals corresponding to current conditions and a
model scenario where the canal and drainage system is removed. Flow results from the
scenario model run , when compared to a model run of the current situation , will provide an
estimate of the impacts of the manmade canal and drainage network on both surface flow and
groundwater flow.
An integrated hydrological model includes dynamic flow exchange between hydrological
domains. In the one-dimensional (1-D) surface water model (MIKE11 ), the drainage and canal
network has been set up to exchange water with both the groundwater (3-D) and the
surrounding wetland areas (2-D MIKE SHE OL) as a function of water level differences. This
coupling allows description of canal spills, two-dimensional (2-D) flow across the wetlands and
wetland flows into the canals. The subsurface coupling between the drainage and canal network
and the groundwater aquifer simulates canal seepage losses driven by local water level
gradients and losses via riparian zone evapotranspiration.
4 Conceptual model
A conceptual model of the combined surface water and groundwater system forms the basis for
subsequent analysis of hydrology, water balances and flows. It presents the governing
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processes affecting the surface flows and groundwater flows in the Silala Near Field area under
the current conditions. It also serves the purpose of outlining how the canalisation has changed
the hydrological/hydrogeological system and thus impacted flows. The basis for the conceptual
model is partly field visits and partly surface water and groundwater data collected during the
field suNey campaign in 2017 or earlier.
A conceptual model for the Silala surface water system is reported in Annex C. The surface
water system is described and analysed in a 5-zone subdivision:
• Zone 1 : Northern wetland
• Zone 2 : Southern wetland
• Zone 3 : Southern canal, mid-section
• Zone 4 : Southern canal, ravine section
• Zone 5 : Confluence to border
The main surface water hydrological processes are summarized in Table 1.
Table 1 Overview of Silala Near field zones and key processes affecting surface flows.
Silala Near Field Process Specifics
sub-area
Zone 1 : Northern 1. Distributed spring inflows Attenuation by wetland storage
Canal, Northern
2. Wetland interception and storage Capillary rise of peat soils
wetland
and
3. Evapotranspiration in wetlands and Canal spilling at canal blockages
riparian zone
Transpiration from wetland
Zone 2 : Main
Canal, Southern
4. Canal and drain system seepage vegetation
wetland
gains/losses to soil and groundwater
Canal seepage
5. Diffuse inflows by groundwater
6. Canal-wetland spills and redistribution
(1-D / 2-D)
7. Inundated areas and free water
surface evaporation
Zone 3 : Main 1. Distributed spring inflows Flow in wide flow section in non-
Canal, middle
2. Evapotranspiration in riparian zone
canalised reaches
section
3. Canal seepage gains/losses to
Riparian zone water uptake and
riparian fringe and groundwater
evapotranspiration
4. Canal-wetland spills and redistribution
(1 -D / 2-D)
5. Inundated areas and free water
surface evaporation
Zone 4 : Main 1. Distributed spring inflows Restricted canal flow
Canal, narrow valley
2. Evapotranspiration in riparian zone Narrow riparian fringe interaction with
section
3. Canal seepage gains/losses to
canal
and
riparian fringe and groundwater Groundwater discharge in narrow
Zone 5: Near valley section
border section
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A conceptual subsurface hydrogeological model is presented in Annex F. Surface geological
maps, resistivity profiles, borehole lithology and borehole tests were merged into a 3-D
conceptual hydrogeological model of all major hydrogeological subsurface units.
Although groundwater flow in fractures and faults plays a role in the Silala area, the structural
hydrogeological interpretation suggests that an equivalent porous media approach can be
adopted. Consequently, the groundwater flow component of the integrated hydrological model
solves the differential equations of matrix flow in a porous media.
Due to data constraints, the spatial scale and process description the integrated hydrological
model cannot represent the physical hydrological system in detail. Instead, the numerical model
is based on the conceptual model which despite simplification is assumed valid to represent the
overall, key processes of the Silala Near Field area. The numerical model results thus rely
implicitly on the validity of the conceptual model to properly account for key flow processes.
4.1 Numerical model approach
A numerical model of the current conditions including the canal and drainage network is
developed. It is calibrated to provide a reasonable description of the measured canal flows
(Annex C) at the 7 continuous flow gauging sites (C1-C7).
Flow measurements show a large base flow contribution by groundwater discharged to springs,
wetlands and canals. Temporal fluctuations in measured flow records has been attributed to
measurement inaccuracy and replacement of equipment rather than through a correlation
between local rainfall events and short-term canal flow changes. The local runoff contribution is
thus minor and of a short-term nature. For the purposes of the study the mean flow conditions
are considered essential rather than short term fluctuations.
According to the water balance calculations for the Silala Far Field presented in Annex E, the
mean recharge based on long meteorological time series is estimated to 176 I/s. The analysis
considers a 231 km2 upstream catchment and the specific recharge can be calculated to 0.76
l/s/km2 . Assuming a similar recharge within the Silala Near Field area covering 2.56 km2 the
corresponding local recharge from precipitation is less than 2 I/s. The local recharge by
precipitation in the Silala Near Field Area is thus insignificant compared to the inflows across the
model boundaries that sustain the cross-border canal outflows of approximately 150 I/s plus
groundwater outflow. Consequently, local precipitation and runoff has not been included in the
integrated Silala Near Field model.
Temporal changes in canal flow may otherwise occur through temporal variations in
groundwater recharge and groundwater levels within the near field area or the larger upstream
catchment. Groundwater level data collected by pressure transducers are only available for a
short period . Most time series show limited or no variation in time (Annex F). The measurements
suggest no significant temporal groundwater table changes.
Therefore, it is assumed that the Silala Near Field areas is close to steady-state and a stationary
model approach has been adopted. A stationary model implies that no temporal variation in
model inputs nor boundaries are included. The flow and water levels of both surface water and
groundwater simulated by the model will reach an equilibrium of constant flow variables, inflows
and outflows.
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5 Numerical model code
10
The interactions between groundwater fed springs, the wetlands and the canal and drainage
network require a suitable model approach. It also requires a model tool which is capable of
addressing all relevant processes and interactions within the coupled groundwater-surface water
system, as outlined in the conceptual models (Annex C on surface water, and Annex F on
hydrogeology).
Only a few model codes have been developed to deal with interconnected subsurface and
surface flows and only a few have been tested and widely applied in practical projects and water
management within integrated surface water - groundwater systems. For the Silala project
MIKE SHE is used. The MIKE SHE modelling system comprises of hydrological modelling
components which can be added and interlinked depending on the nature of the specific
hydrological system and the particular analysis required.
MIKE SHE - MIKE11 is an integrated and dynamically coupled hydrological modelling system . It
is a well proven modelling tool which has been applied on a wide range of integrated projects
related to wetlands, groundwater, surface water, climate change etc. Figure 1 shows the
structure, components and governing equations of MIKE SHE.
• Semi-distributed
◊6 Uns-aturated Zon-e Flow
• 1 D Finite Difference:
• Richards Equation
• Gravity Flow
• 2-Layer Water Ba lance
• Net Recharge (e.g. DAISY)
Channel Flow (MIKE 1
1D St Venant Equatto
Kinematic wave appro
iffusive wave appro
ully dynamic
her-order fully dyn
outing:
·ng
m
Cunge
6 ----------------~~ Groundwater Flow
• 3D Finite Difference - Darcy Flow
• Lumped, Conceptual - Linear Reservoir
Figure 1 Model components and structure of the MIKE SHE - MIKE11 integrated model code.
A stand-alone groundwater model requires recharge as an input and interaction with surface
water is described through boundary input data. This is problematic regarding Silala where the
groundwater - surface water exchange is a dominating factor and essential in quantifying
scenario impacts. The integrated model applied here has been chosen because exchange is a
15
function of state variables and not fixed through boundary inputs. The coupling between model
components makes the calculation of flow exchange between groundwater and surface water
(through springs, diffuse sources and canal seepage) dependent on catchment specific
physically properties (topography, canal geometry etc.) and actual stat variables (simulated
water levels and gradients).
6 Model area and resolution
A horizontal and vertical extent of the model area must be defined. Given the purpose of the
model, data availability and the key surface water features the horizontal extent of the integrated
model has been chosen to incorporate the Silala Near field area. All Silala spring, wetland and
canal features are represented within the model area.
The effects of removing the Silala Canals are most clearly expressed in surface water along the
relatively narrow wetland and canal corridor but secondary effects of generally higher surface
water levels will potentially influence the groundwater tables in a larger area. Effects on
groundwater levels may not be spatially restricted to the canal and wetland corridor but may in
principle propagate through the surficial aquifer towards the boundaries of the model. As a
general rule, the effects of removing the canal on groundwater boundary conditions should be
minimized by extending the model area sufficiently far away from the canal. Therefore, the
model area is extended to cover a total of 2,56 km2 (See Figure 2).
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GWcontours
o Springs
SilalaNearFieldZones
c:] Modelarea
Figure 2 Silala Near Field model area.
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The model area is subdivided into a finite difference grid of computational nodes. Water levels is
calculated in each grid node and flow between nodes. Finite difference grid resolutions of 5 m
and 10 m, respectively, were tested. The coarser resolution (10 m) provides a reasonably high
resolution and is more efficient in terms of model run times. The higher resolution (5 m) takes
much longer to run model simulations but is better suited for capturing details including any
abrupt changes or heterogeneities e.g. in the wetlands and along the canal where simulation of
water table gradients is important. Given the time constraints and the considerable time required
to run calibration and scenario runs a 10 m grid was chosen. In the 10 m grid model, a total of
25632 grid elements are included in the overland flow solution and 76896 elements in the 3
layer groundwater model.
7 Hydrological model components
7.1 Groundwater
The 3-D groundwater model component is built to simulate groundwater levels, gradients, flow
rates and flow direction in the subsurface of the Silala Near Field area. The groundwater
discharge to the wetlands and springs and the flow exchange with the canal is of particular
importance. A significant proportion of the water entering the Silala Near Field area through the
subsurface as groundwater emerges as surface flow in the springs, wetlands and canal inside
the Silala Near Field area. The surface water system is fed almost entirely by groundwater with
a minor local runoff contribution as observed in approximately constant measured canal
discharge.
7.1.1 Hydrogeological model
The 3-D hydrogeological model developed from geological maps, geophysical transects and
borehole data (Annex F) is implemented in the numerical groundwater model. The
hydrogeological units and their spatial extents defined in the hydrogeological model are
represented in the numerical groundwater model. The hydrogeological units are described by
the upper and lower interfaces of layers and lenses. Layers by definition cover the entire area
while lenses have a restricted horizontal extent, only partly covering the model area.
The numerical groundwater model applies 3 layers. The top layer has varying thickness and
hydrogeological properties as it incorporates all surficial lens deposits (HGU 1 - HGU 4). The
second layer includes the upper Silala ignimbrite (HGU 5) and the third layer represents the
deep ignimbrite layer (HGU 6). In the parametrization a distinction is made between the upper 0-
200 m b.g.s. sequence as opposed to the lower 200-400 m b.g .s of HGU 6 to introduce at
decreasing conductivity with depth. The fault zone (HGU 7) defined from the surface to a depth
of 400 m cuts across the layers and introduces an approximately 50 m wide, high permeable
flow corridor along the canals. The fault zone extends from upstream the southern and northern
wetlands, joins at the confluence and continues across the border. Due to its relatively high
permeability it is a key groundwater flow feature with respect to both groundwater discharge to
the canals and the total groundwater flow.
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Table 2 Hydrogeological units in the hydrogeological model and the numerical groundwater model.
Hydrogeologic Integrated model setup
Basic Lithology
Unit
HGU1 Colluvial deposits Included as HGU1 lense
HGU2 Glacial deposits, sandy loams Included as HGU2 lense
HGU3 Weathered lava flows Included as HGU3 lense
HGU4 Felsic volcanic sequences Included as HGU4 lense
HGU5
lgnimbrite deposits, low degree of Included as HGU5 layer
welding
HGU6
lgnimbrite deposits with a high degree of Included as HGU6 layer
welding
HGU7 Near canal fault zone Included as HGU7 lense
HGU8 Volcanic neck of Silala Chico Outside model area
7 .1.2 Boundary conditions
14
In order to compute the groundwater flow and water level conditions at the outer model
boundaries, boundary conditions must be assigned. As discussed in Annex E, the Silala Near
Field area receives groundwater inflows from a larger catchment along parts of the model
boundaries. An open flow prescribed fixed head boundary condition has been used along
sections of the boundary where a head gradient allows inflow to the Silala Near Filed model
area. The fixed head boundary implies that flow into the model area may change if the
groundwater tables changes, e.g. due to changes in the surface water system. Increasing
groundwater table inside the model propagating to the boundary will decrease flow gradients
and inflow. Where the model boundary runs perpendicular to the head contour lines there is no
water table gradient to drive inflows and the sections are subsequently assumed closed (no
flow). At the downstream model boundary, at the border, a groundwater table gradient boundary
condition is applied. ARCADIS 2017 calculated groundwater table gradients of approximately
0.05 between boreholes at the border and upstream of Quebrada Negra. The gradient boundary
condition implies that groundwater flow across the boundary is adjusted to maintain the
specified water table gradient.
Water level data available for the Silala Near Field area include piezometric levels from
boreholes, spring water level and water levels recorded as part of the soil survey. The water
level information has been processed to derive a piezometric contour map (Annex F). The
highest density of observed water levels is found relatively close to the canals and wetlands, i.e.
the central parts of the model area. The contour lines have been extrapolated away from the
observation points which means that the uncertainty on the contours is higher at the model
boundaries than the internal areas along the wetlands and canals. The contour data have been
used as direct input for describing both an initial groundwater head map for the integrated model
simulation and the boundary groundwater head values at the model boundaries of all
groundwater layers (Figure 3). The groundwater table elevations range from 4420 m at the
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model boundary upstream of the southern wetland (east) to approximately 4290 m close to the
downstream model boundary at the Bolivian-Chilean border (west). The groundwater contours
indicate significant groundwater head gradients and inflows upstream of both the southern and
northern wetland,
The observed water level data predominantly represent the near surface aquifer conditions and
no data is available for the deep layer sequence of the groundwater system. The piezometric
contour map has been used to define boundary conditions for all groundwater layers, which
implies that any upward pressure gradients from deeper confined layers are not represented in
the model boundary conditions. Horizontal flow gradients, e.g. at the southern wetland, thus
drives inflows from the model boundary to the upstream springs and canals.
Pressure transducers installed in a number of boreholes were used for water level monitoring.
Groundwater table elevations were collected for a relatively short period. The water tables were
relatively stable with an average temporal variation of less than 0.5 m in all boreholes except
two (Annex F). The groundwater head values assigned as boundary conditions in the integrated
model have thus been considered constant in time. The inflow to the model area is a function of
the assigned boundary head values, the hydraulic conductivity and thickness of the geological
layers and the groundwater heads inside the model domain. With a fixed head upstream
boundary and the downstream gradient controlled outflow boundary condition the stationary
integrated model will gradually approach a steady-state equilibrium balancing upstream
groundwater inflows versus downstream surface and subsurface outflows.
[meter]
7566800
7566600
7566400
7566200
7566000
7565800
7565600
7565400
7565200
7565000
600000
Figure 3
Initial potential head in the saturated zone
. . . ---- - - - --- - - - - --- - - -- -- - - - -- - - - - - - -- - - - _,.. __ - - ' .... .. - - -- - - - - -....~ - - - - - - -- -- - - - . .
600500 601000 601500 602000 602500 603000 603500
(meter)
(meter)
- Above4'30
- •◄20-•◄JO □ ••10-'420 E3 ◄◄ 00-4410
◄ 390- .uoo
◄ 380 - -4390
◄ 370- ◄ 380
◄ 360 - ◄ 370
- •350-4360
- ◄3-40- ◄350
- ◄330-43-40
■ ◄320-4330
◄ 310-•320
- 4300 -4310
- •290- ◄300
- Below-4290 D Undefined Vakle
Groundwater level maps used in definition of groundwater component boundary conditions.
Figure 4 below shows an illustration of groundwater tables, cross sectional flow and discharge
from an upstream head boundary towards a downstream surface water body.
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Constant head v
Ground surface
Figure 4 Illustration of groundwater boundary condition
7 .1.3 Parametrization
16
Key parameters controlling groundwater flow and groundwater levels include vertical and
horizontal hydraulic conductivities and storage coefficients. In Annex F hydrogeological
parameters for the hydrogeological units are discussed based on published general ranges and
Silala field data. The field data include borehole testing i.e. slug-testing, packer testing (Lugeon
and Lefranc) and pumping tests to assess hydrogeological properties of the surrounding aquifer.
Combining these data sources provides fairly wide parameter ranges (Table 3 ). However,
during model calibration a narrower parameter range, mainly defined by the site-specific pump
test data were used subdividing the model area by zones (see section 7.4 ).
Not all of the parameters are equally important and the model results are more sensitive to
parameters of the main aquifer layers than local lenses. The key parameters are associated with
the upper Silala ignimbrite covering the entire model area, the lower Silala ignimbrite and the
high permeable fault zone (HGU 7). In comparison, HGU-1 and HGU-3 surface deposit lenses
cover limited areas, are mostly dry and of low permeability.
21
Table 3 Initial ranges of hydrogeological parameters considered for the integrated model.
HGU Kh Kv Sy Ss Comment
(m/s) Kv:Kh- (-)
(-)
ratio
Colluvial/Alluvial 1e-6-1e4 1 - 10 0.03-0.22 Se-5 - 1 e-4 Moderate extent,
(HGU-1) dry
Glacial, Sandy 1 e·8 - 1 e-5 1 - 10 0.03-0.19 9e-4 - 1.3e-3 Limited extent
Loam (HGU-2) and flow, GWSW
exchange
Weathered Lava 1e-14 -1e-8 1 - 10 0.01-0.19 1 .6e-6 - 2e-4 Moderate extent,
(HGU-3) mostly dry,
largely
impermeable
Felsic Volcanic 1e·13_ 1e-6 1 - 10 0.001-0.02 3e-6 - Se-5 Moderate extent,
(HGU-4) dry (confining)
Upper Silala 1e-7-1e-5 1 - 10 0.001 - 0.10 3e-6 - Se-5 Upper aquifer,
lgnimbrite
(1e-5- Se·4)
local/regional
(HGU-S) flow unit. SWGW
exchange
Lower Silala 2e·'' - 2e-1 1 - 10 0.001 -0.20 3e-6 - Se-5 Lower aquifer,
lgnimbrite (HGU-
(1e-5- Se·4)
local/regional
6) flow unit.
Fault zone 6e-5 - 4e4 1 - 10 0.01 - 0.20 1e-5-1e-6 Key flow feature,
(HGU-7) local, SW-GW
exchange
7.2 Unsaturated zone
The 1-D unsaturated zone forms an interface between the surface and the saturated conditions
at the groundwater table below. Key processes included through the unsaturated zone
component are infiltration or exfiltration in the vertical soil column and evapotranspiration losses
occurring in the upper part of the soil profile (the root zone). In proximity of the springs, wetlands
and canals where the groundwater table has been observed to be close to the surface the
unsaturated soil thickness is shallow, typically within 0-1 m, but it increases towards higher
elevations with relatively deep groundwater tables reaching up to hundreds of meters. The
unsaturated zone normally controls the rate of infiltration of rainfall and potentially recharge of
the underlying groundwater aquifer. In the Silala Near Field area local rainfall, infiltration and
recharge is very low compared to the inflow of groundwater (Annexes A and E). However, at the
wetlands with shallow groundwater tables the unsaturated zone may interact with the
groundwater table and enhance upward directed flow by capillary forces to sustain the
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evapotranspiration of wetland vegetation. This is, in particular, the case in organic rich soils such
as peat with a high storage capacity and high capillary potential.
The most distinct contrast between soils in the Silala Near Field area is between, on one hand,
the wetland and riparian corridor soil profiles and, on the other hand the drier, higher altitude
areas covering the remaining part of the model area. In the wetlands with generally shallow
groundwater tables, sandy sediments and organic rich peat soils overlay the fractured rock
(ignimbrite). In the higher altitudes the ignimbrite rock outcrops or is covered by a relatively thin
coarse sediment layer.
7 .2.1 Summary of soil survey
18
A field soil survey was conducted by DIREMAR, 2017, with the purpose of mapping soil profiles,
estimating soil thicknesses and estimating soil hydraulic properties. A number of hand-dug pits
and auger holes were carried out in the wetlands to characterize profiles (see Figure 5).
NORTH WETLAND
Auger - Trial pits - Infiltrations
DATA DATA SCALE: 12000
Eng. M.Sc. Edwin Torrez Soria PROJECTION: UTh1 o 35 70 140
CONSULTA:NT-SOILS SPECULIST DATUM: WGS 1984 f!!F-1!!5•~-~~~~~ l\·lctcrs
'CJ-l~,),.CTERIZ.A.TION OF TiiE SILALA WETLANDS AREA ZONE: 19th HEMISPHERE SOlrrH
ANTI ITS VICil\'ITIES
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SOUTH WETLAND
Auger - Trial pits - Infiltrations
Figure 5 Soil sampling sites in Northern and Southern wetland .
Barrena Barrena
Punta 10 Punta 9
0,4
:f .
0,3
. J--
PROFUNDIDAD Y NIVEL FREATICO BOFEDAL NORTE
PUNTOS DE MUESTREO
Barrena Barre no Barre no Barre no Barrena Barrena Barrena
Punta 8 Punta 7 Punta 6 Punta 5 Punta 4 Punta 3 Punta 2
o,2 . o;... . ~i~ - . ~ .
..-'[ • -
0,15 - I ....._ 0,4 0,4 ~ - · I -
- • Nivel Freatico --Profundidad (m)
Barrena
Punta 1
0
0,4 0,2
---'[ 0,4
0,6 ~
0,8 Cl .. Cl
ci
z
1,2 ::,
1,4 ~
1,6
1,8
2
Figure 6 Soil thickness and ground water table profile, Northern wetland (in m below ground surface).
The soil profiles have been described by depth , i.e. from the ground surface to the underlying
base rock (Figure 6). The soil profile depths range from 0.55 - 1 .40 m in the northern wetland
and 0.40 - 1.20 m in the southern wetland. The profiles are described by an organic material
horizon followed by a predominantly mineral, sandy loam or gravel material. Organic material
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horizons of 0-40 cm were found. However, observations during the field trip showed peat soil
depths of up to 60-70 cm at the edges of undisturbed patches of the northern wetland (Figure 7).
Figure 7 Peat soil profile at northern wetland.
Six characteristic soil profiles have been introduced in the Silala near field area to describe the
vertical and horizontal hydraulic properties:
1. Rock, lgnimbrite : 0 - 100 m
2. Shallow soil on rock, Sandy loam : 0 - 0.15 m, lgnimbrite : 0.15 m - 100 m
3. Deep soil on rock, Sandy loam : 0 - 0.5 m, lgnimbrite : 0.15 m - 100 m
4. Shallow organic on sandy loam, Peat : 0-0.2 m, sandy loam : 0.2-1 .0 m, ignimbrite : 1-100 m
5. Medium organic on sandy loam, Peat: 0-0.4 m, sandy loam: 0.4-1.0 m, ignimbrite : 1-100 m
6. Deep organic on sandy loam, Peat: 0-0.6 m, sandy loam: 0.6-1 .2 m, ignimbrite: 1-100 m
The six profiles have been distributed across the Silala Near Field area. In the wetlands the
distribution of shallow versus deep organic soils has been carried according to the soil survey,
field visits and satellite images. Deep organic soils are only found in a limited number of
undisturbed areas of the northern wetland. The shallow to medium organic soil are distributed
within the remaining wetland areas and riparian corridor (Figure 8).
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Spatial Distribution: Data Type:
Distributed Grid codes (.dfs2)
Grid Distribution File:
IC:\ Data\tvj\ 11820137 _Silala\Model\Maps\UZclaSSES_5m_U bicacion.dfs2 1[ •.•
[meter]
7566400
7566350
7566300
7566250
7566200
7566150
600600 600700 600800
Create ...
EdL
600900 601000
Figure 8 Soil profile distribution map (codes 1-6 referring to the above description), northern wetland .
7.2.2 Parametrization
The unsaturated zone component of the integrated hydrological model requires that a number of
characteristic vertical soil profiles are defined and distributed across the model area. The
profiles are described by depth intervals of specific soil types with associated hydraulic
parameters in terms of soil water retention (relation between soil water content and pressure)
and hydraulic conductivity curve (relation between hydraulic conductivity and pressure).
Hydraulic conductivity curves and retention curves have not been estimated as part of the Silala
soil survey and laboratory tests. Londra P., 2010, tested a range of mixes between peat and
mineral fractions to calculate van Genuchten parameters for both retention and hydraulic
conductivity (Figure 9). The shape of the curve with water contents above 50 % at saturation
and a significant drop to field capacity (pF=2) are characteristic for organic rich soils and have
been adopted in the peat soil retention curves applied in wetlands.
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100
-+- I
-&-2
......... 3
- 4
75 -tr-5 ,-._
'7 --e-6 5 -0--7
E u
i 50
c
B
"0 u
.~,
~
25
0 +----~----~----~---~---~
0
Figure 9
2 3 4 s
pF
Soil retention curves (peat dry matter content ranging from 60 % (1) to O % (7)), Londra P.,
2010.
Schwarze! et. al. 2006 tested decomposed peat core samples from German fen bogs to
determine hydraulic properties and van Genuchten parameters in the laboratory. The van
Genuchten analytical model was fitted to measured retention data points and saturated
hydraulic conductivity value measured using a constant head method. All of the peat core
hydraulic conductivity curves showed a similar shape but with different saturated hydraulic
conductivity values (Ks). The curve shape parameters were used in parametrisation of Silala
peat soil (Table 4). Both the organic rich wetland soil and finer grained sand deposits have a
capillary potential. In the wetlands an upward flow can occur either by vertical groundwater flow
(as observed by groundwater piezometric levels above ground level in standpipes and
observation wells) or by soil capillary forces generating a capillary fringe with upward
unsaturated flow. The upward flow maintains a high water content close to the ground surface in
low lying areas with a continuous water supply for evapotranspiration.
Table 4 Overview of unsaturated zone property ranges
Soil Hydraulic Water content, Water content, Inverse air Pore size
conductivity saturation residual entry suction distrib.
Ks(m/s) 8sat(-) 0,(-) a(cm·1 ) n (-)
Peat soil 5e-7 - 5e-4 0.55 - 0.75 0.10-0.25 0.2-0.4 1.10-1.50
Sandy loam 1e·6 - 1e-4 0.25-0.45 0.01 -0.10 0.01-0.1 1.00-1.45
lgnimbrite rock 1e-7 -1e-4 0.01-0.10 0.01-0.05 0.05-0.1 1.10-2.50
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7 .2.3 Evapotranspiration
Evapotranspiration (ET) losses occur partly by evaporation from the surface and the top soil and
partly by transpiration by vegetation. Evapotranspiration varies temporally and spatially as a
function of not only climate, soil and vegetation parameters but also water availability. The Silala
area is characterised by relatively high potential rates of evapotranspiration due to the climate
conditions but the actual rate of evapotranspiration is typically much lower. Actual rates of
evapotranspiration approach zero in drier upland areas while in the lower lying wetland areas
water is available to maintain rates of actual evapotranspiration close to the potential rate. The
lack of vegetation outside the confined wetland areas is a clear sign of the contrast in water
availability and thus transpiration potential.
In the distributed, integrated model, actual rates of ET are calculated as the sum of evaporation
from free water surfaces, soil evaporation and transpiration by the vegetation. An assigned
potential rate of ET constitutes an upper limit for the actual ET losses in each time step of the
model simulation. A detailed description of the method and equations solved in the
evapotranspiration component of MIKE SHE is given in DHI, 2017.
Two types of vegetation are dominant in Silala. Grass species either at the outer edges of
wetlands and the riparian corridor or intrusive in drained and dry areas of wetlands. In
undisturbed and permanent wet parts of the wetlands altiplano bofedal species of Distichia is
dominating and forms hard, undulating cushions which in time adds to the peat accumulation
(e.g. Distichia Muscoides). Outside the wetlands there is no or locally very scattered irregular
grass.
Transpiration by the vegetation is a function of the density of vegetation expressed by the leaf
area index (LAI) and the root depth and root mass distribution. An empirical function adjusts the
actual rate of ET to LAI. Leaf area index (LAI) is a key parameter controlling the rate of actual
evapotranspiration. Vegetation data have not been collected as part of the field survey. Due to
the lack of site-specific vegetation property data vegetation parameters have been approximated
by general and similar grassland and wetland vegetation type characteristics.
Figure 10 Grasses and cushion wetland vegetation at Silala southern wetland. Close up of distichia
(photo from Fonken 2014)
The average rate of potential ET (Annex B) ranges between 1268 mm/year-1940 mm/year
from climate stations at Sol de Manana, Laguna Colorado and Silala. At the Silala station, the
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long-term average is 1472 mm/year. A mean potential rate of 4 mm/day corresponding to 1460
mm/year has been used in the integrated model.
Table 5 Estimated ET parameters (LAI).
Vegetation LAI
Grass 3.0
Wetland species 3.0
7.3 Overland and channel flow
The surface water components of the integrated hydrological model includes a 1-D canal
network flow component (MIKE11) linked with a 2-D overland flow component. The 1-D model
simulates flows and water levels within the canal and the 2-D overland model simulates water
levels and flows on the ground, i.e. inundation in wetlands and areas adjacent to the canal. The
1-D canal flow model and the 2-D overland model are connected. Exchange of flow is described
as a function of the water level gradient between the canal and adjacent flooded areas.
The surface water model has been built and tested prior to the integration with sub-surface
components (Annex A). This preliminary surface water model has been tested to determine if
the conceptual model, the input data and reasonable parameter ranges will provide model
simulations results in accordance with measurements.
The main purpose of the Silala Springs study is to assess Silala canal flows and the effect of
canalisation. The flow at the border is a function of climate, hydrogeology, hydrology and
hydraulics connected in a series of upstream to downstream processes. From the net recharge
and inflows feeding the spring and canal system storage, losses and gains play a key role with
respect to the Silala water balance and thus, the quantity of water available for downstream
canal flow.
The extent of the surface water systems in Silala is restricted to the spring areas, wetlands, the
drainage and canal network and the adjacent, narrow riparian corridor. The surface water model
includes a hydraulic canal component. The surface water model includes 46 canals and covers
approximately 6600 meters of canal and wetland.
The data used to set up the 1-D canal model includes the canal alignment, topographical data,
locations of structural changes to the undisturbed canals and boundary conditions as collected
through field surveys and inspections during 2017.
7.3.1 Artificial channel alignment
The digitisation of the artificial channel alignment is primarily based on a shape file provided by
DIREMAR and SENAMHI. This shape files represents known canals and drainage features. In
addition to this, branches are included by inspection of the orthophoto from the 2016 drone
survey. Where the photo indicates an open canal connected to the main canal system a branch
is included. An overview of the area is shown in Figure 11 . A more detailed view of the upstream
end of the Southern Wetland can be found in Figure 12. This picture illustrates how the artificial
channel alignment, represented by red lines , were constructed. Altogether, the model includes
46 individual branches with a combined length of approximately 6600 meters to describe the
canal and drainage network.
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Figure 11 Layout of the artificial channel alignment in the hydraulic model shown on top of the orthophoto of the area.
The expert in WATER ENVIRONMENTS 25
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E iv'
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~ 0 -"c'. "(/)
:::, <ii
(1) C
-.c ""' -~ Q)
-c.c
(1) (1)
E <ii
§, ,: = 0)
Ol C
~ ~
C .C "'(/) .c Cl:'.
~<(
~2
~w
t::9::
<(0
N
(0
N
31
7.3.2 Canal cross sections
Each of the canals in the model must have cross sections attached to it. The cross sections
define the storage in the canal, basically by describing the flow area, i.e. the width as a function
of level. The slope and the conveyance of the canal are also defined by the cross sections.
DIRE MAR and SENAMHI provided a pdf file, based on data obtained by the IGM (206), showing
width and depth for the canals in which cross sections has been surveyed. An overview of this
file is shown in Figure 12. Close-ups of the different parts of the Main Canal System are shown
are shown in Figure 13 - Figure 23. Close-ups for the North Canal System are shown in Figure
24 and Figure 25. For canals with no cross-section information an assumed cross section width
is used.
Figure 13
MANANTIALES DEL SILALA
~ Manantial dentro del bofedal
- Canal enterrado
- Canal cublerto con pledra plana
i2?IJ7Aj Tuba de fierro
c::::::::J Construccl6n
ESC 1, 3000
Map of the canal layout including width and depth of selected canals (DIREMAR and
SENAMHI).
The expert in WATER ENVIRONMENTS 27
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Figure 14
Figure 15
Figure 16
28
A close-up of the information of width and depth for canals in the Main Canal System from
upstream end to approximately 300 meters downstream (Southern wetland).
[g]
A close-up of the information of width and depth for canals in the Main Canal System from
chainage 300 meters to chainage 600 meters (Southern wetland).
A close-up of the information of width and depth for canals in the Main Canal System
(southern) from chainage 600 meters to chainage 900 meters.
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Figure 17
Figure 18
Figure 19
A close-up of the information of width and depth for canals in the Main Canal System
(southern) from chainage 900 meters to chainage 1200 meters.
A close-up of the information of width and depth for canals in the Main Canal System
(southern) from chainage 1200 meters to chainage 1500 meters.
A close-up of the information of width and depth for canals in the Main Canal System
(southern) from chainage 1500 meters to chainage 2000 meters.
The expert in WATER ENVIRONMENTS 29
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Figure 20
30
0
0
VJ + ('\J
A close-up of the information of width and depth for canals in the Main Canal System
(southern) from chainage 2450 meters to chainage 2650 meters (no measurements from
chainage 2000 to chainage 2450).
35
Figure 21
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A close-up of the information of width and depth for canals in the Main Canal from
chainage 2800 meters to chainage 3100 meters (no measurements from chainage 2450 to
chainage 2800.)
The expert in WATER ENVIRONMENTS 31
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Figure 22 A close-up of the information of width and depth for canals in the Main Canal from
chainage 3100 meters to chainage 3300 meters.
37
Figure 23 A close-up of the information of width and depth for canals in the Main Canal System from
approximately chainage 3300 meters to the border.
The expert in WATER ENVIRONMENTS 33
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Figure 24 A close-up of the information of width and depth for canals in the Northern Canal.
34
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Figure 25 A close-up of the information of width and depth for canals in the Northern Canal.
Canal cross sections were processed in the following steps:
1. If there are no cross sections at the upstream or downstream end of the branches, the nearest cross
section is copied to any of the ends with missing cross sections.
2. Since the cross sections (which at this point is still only width and depth and no elevation) can be
located quite a distance apart they are interpolated to ensure that we have cross sections, i.e. depth
and width, with a maximum distance no more than 20 meters.
3. Cross sections are extended to the left and to the right perpendicular to the flow direction of the canal
by use of elevations from the digital surface model (DSM). In Figure 26, an example is shown where
the main canal is surrounded by a loop on each side. The red alignment lines define the extent of
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the cross sections for each canal and thus the extent of the 1-dimensional description. Note that at
locations where loops are present the neighbouring canals will have alignment lines in common. This
process of defining alignment lines was repeated for all canals included in the model.
4. After extending the simple cross sections and combining them with the digital surface model (DSM)
it is now ensured that the canal part (i.e. the depth-width cross sections) matches the bed level found
by combining it with the DSM. Notice that since the interpolation was performed before merging the
depth-width cross sections with the DSM, the information in the DSM is used directly in the final cross
sections. Thus variation in the bottom level reflects the variation in the terrain, (see Figure 27).
Figure 26
4410
Example of how to define the extent of each canal by using alignment lines (in red). Blue lines
represent canals and the green one the cross sections in the canals.
Bottom profile in Main Canal and North Canal from the confluence and up
North Canal Main Canal
4390
4370
4350
4330
4310
0 500 1000 1500 2000 2500 3000 3500
Figure 27 Variation in bottom level for the Main Canal and the North Canal from the confluence and upstream.
4000
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The cross sections created for the canal and drainage network combining SENAMHI canal
dimension surveys and the digital surface model (DSM) refers to specific canals (by name)
and specific locations (canal chainage). The cross sections are organised in a database
containing all the geometric information of the canal network (Figure 28).
,~_,_ --- ~ '' Rv< .,.,,,.,..
0-- '--Cl J/'NtllJ ...:-.. --~
- l'
e-•11-
□-
r-.-.-T--lfd\-1-...,._ " - • - ,1 ., Rial,...,_ ,= - ·
,mm
1nom
•mm -m 111,0.00 -m ""m
""m
nwm
llia.00
MH
=,,,.m_
n•m '"'m
""m
1'1000
1• J000
:~ao
HXICO
,~ m ••m -""~m 0 ,,...,_ __
0 ......... --.... _....,
Wlllf~ • EXJSnJG - 2270 0000
Figure 28 Canal cross sections organised in the MIKE11 cross section database.
7.3.3 Structural changes
I
At several locations rocks across the flow path expands the flow area and introduce local head
losses. These rocks introduce an increased resistance to the flow that cannot be described by
the traditional flow equation used in a hydrodynamic model. To include the effect in the model,
energy losses are introduced in the model at selected locations. The locations are identified by
inspection of the orthophoto made during the drone flight and by field inspection. An example of
is shown in Figure 29.
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... ,.. . ~ ..
., ~' : ' f ~ ,;
~ ,; • '. ~ ,
, .
. ~.., .: ~
..
. . ~. '
: : ·-,,' :.,. : .. : .
::. , .. d . , "
Figure 29 Example of obstructions to the flow. These obstructions should be dealt with individually in
the hydraulic model as additional energy losses.
The surface water model has been tested separately prior to embedding it into the integrated
model. When run as a stand-alone surface water model boundary conditions in terms of lateral
inflows must be specified. A constant flow distributed according to spring flow measurements
and calculation of diffuse inflows (Annex C) was used to define inflow boundaries. The
preliminary canal flow model included subsurface canal seepage, wetland interaction (1 D / 2-
D) and canal blockage single head losses. The model has been run for a 1-year period with
constant inflows adding up to 160 1/s.
Figure 30 shows the distributed flow simulated by the surface water model through the
drainage and canal network increasing from upstream to the downstream. Figure 31 shows an
example of results produced by the surface water model, zooming in on the Southern
Wetland. The locations of spring discharge to the canal network are shown by red dots. The
spring water enters the canal and stays within the canal section until it reaches a downstream
blocked section.
Locally where the canal water level rises above the canal cross section it starts flowing into the
adjacent wetland. The colour code indicates the depth of water on the surface ranging from 0
- 15 cm. Water spills out of the canal flows into the low-lying wetland area and continues
further downstream where it re-enters the canal network. Comparing the extent of flooding of
the model simulation results (above) with the satellite image (below) shows the wet (darker)
wetland patches on the photo align well with the inundated areas appearing in the model
result. The preliminary results demonstrate that the coupled canal and wetland model is able
to reproduce the larger scale flooding patterns in the Southern Wetland.
43
Q(l/s)
■ 160
■ 140
■ 120
■ 100
■ 80
■ 60 191
Figure 30 Simulated longitudinal profile of canal flow
, ......
,...,.,
'fSf,Sf&O ~ L .t. )
""'"
, ......
..,,.. .,,,.. .,,.., ..,,..
Figure 31 Simulated water depth and flow in the Southern Wetland
The expert in WATER ENVIRONMENTS 39
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7.3.4 Overland flow component
The overland flow component of the integrated hydrological model simulates 2-D flow across
the ground surface. The flow is calculated as a function of water table slope, topographical
slope and the surface resistance to flow.
In the Silala Near field area overland flow occur in the wetlands and in the riparian corridor
along the canals. Either by canals spilling onto adjacent low-lying areas or by upwelling
groundwater seepage. Due to e.g. changes in canal cross section geometry, bed slope or
blockages the canal spills onto wetlands. The flow in the wetlands outside the canals is
handled by the 2-D overland flow component. Ponding or flowing overland water is subject to
evapotranspiration losses and potentially infiltration.
Figure 32 Photo showing example of Silala canal spills (1-D) and diversion to adjacent overland
area (2-D).
A key parameter controlling the rate of overland flow is the surface roughness. The surfaces
are generally highly irregular, with microscale variations and with larger obstacles to flow. In
the wetlands the vegetated surfaces retain water creating several micro thresholds and pools.
Overland flow is dispersed on distichia surfaces even at moderate slopes. The site
characteristics suggest high roughness corresponding to low values of the Mannings M
roughness coefficient. In densely vegetated wetlands Manning's resistance numbers of 1-5
have been reported. In the overland component of the integrated model values in the range of
2-5 m113/s have been used.
7.4 Model calibration
Before the integrated model can be used to evaluate the current Silala hydrological system
and in scenario analysis calibration must be carried out. Calibration entails adjustment of
model parameters to obtain agreement between key model simulation results and field
measurements.
7.5 Model calibration parameters
Groundwater discharge to surface water bodies including wetlands, the springs, the canal and
through diffuse seepage faces are key hydrological processes in the Silala near field area.
Due to upstream groundwater table elevation, the hydrogeological properties and the
significant drop in topography across the area in general, and along the ravine in particular,
45
groundwater flows towards the Silala Near Field area and feeds wetlands and springs. This
dominant groundwater flow implies that subsurface properties and parameters are of relatively
high importance in the integrated model. According to the hydrogeological model the high
permeabilities and significant layer thicknesses of the upper Silala ignimbrite and the fault
zone implies that hydraulic conductivities of these hydrogeological units are important
calibration parameters. The parameters control not only the head gradients and inflows across
the model boundaries, but also groundwater heads generally in the area and the subsurface
flow across the border at the downstream model boundary.
In the distributed, integrated model different parameters can be assigned for each of the
25600 computational nodes in each of the 3 groundwater layers included . This is, however,
not supported by available field data and not feasible in terms of the number of independent
parameters to calibrate. Instead a zonation approach has been adopted. The subdivision in
zones each having uniform parameters reflect partly the zone subdivision presented in Annex
C, the general near field characteristics and areas surrounding boreholes with pump tests
(Figure 33). Zonation of parameters has been used for hydraulic conductivity in the upper
Silala ignimbrite and the fault zone. No data exist for distributing parameters in the deep
groundwater layers and uniform values have subsequently been used.
The leakage coefficient describes the degree of hydraulic contact between the canal and the
groundwater. A low hydraulic contact would typically represent a low permeable lining, e.g.
due to a thick fine-grained sediment deposit in the canal. This is not the case along the Silala
canal and a moderate to high hydraulic conductivity has been specified. The leakage
coefficient has been assigned and calibrated for different canal network segments.
Figure 33
Honz.Ol'UlconcluctM 1nthesat11aledzone
, __,_
00,00,0,0.0- 00----·•--· ·oo-:ioo-a-oo·oo-o» 000008·0-• •-tt-0~ 0-tl-O_ .. , __,_. ,
G00000.-000000&
, __,_ ... __ ,_
--.OO-OOOvOI-.O·-OCIO-OO"
Example of zonation, horizontal hydraulic conductivity of Upper Silala lgnimbrite (5e·6 - 5e·
5 m/s).
Calibrated key model parameters are listed in Table 6. The final set of calibrated parameters
reflects a calibration process focusing on the hydrogeological model (Annex F) with respect to
keeping the parameter ranges within the initial ranges (Table 3), assigning conductivities
decreasing with depth, keeping higher conductivities in the fault zone relative to the
surrounding ignimbrite layers and applying a high vertical to horizontal conductivity ratio to
reflect vertical fault and fractures. Canal discharge by groundwater to surface water is a key
process which requires a positive gradient between the aquifer and the canal. The
groundwater parameters were initially adjusted to obtain sufficiently high groundwater tables
along the canals and total discharges in accordance with the measured mean canal flows.
Secondly the canal-aquifer leakage coefficients were revisited and adjusted reach by reach.
Both the deep ignimbrite layer (HGU 6) and the fault zone (HGU 7) with an assumed depth of
400 m were subdivided in an upper sequence (upper 200 m) and a lower sequence (200 -
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400 m). Hydraulic parameters were assigned to each sequence and later merged into the
effective parameters of the numerical model layer. The upper sequence values are typically a
factor 1 0 -100 times larger than the deep sequence values in order to account for the
decrease in conductivity with depth.
Table 6 Summary of key calibrated model parameters.
Model component Calibrated key parameter ranges
Groundwater (3-D) Kh(m/s) Kv/Kh Sy Ss
HGU-1 : 1e-5 1 0.1 1e4
HGU-2 : 1e-6 1 0.15 1e4
HGU-3 : 5e-7 1 0.1 1e·5
HGU-4 : 1e-9 1 0.02 1e-5
HGU-5 : 2e·6 - 5e·5 1-10 0.05 1e·5
HGU-6 : 5e-7 1 0.1 1e-5
HGU-7 : 2e·6 - 1e-3 1-10 0.1 1e-5
Overland (2-D) Mannings no. (m"3/s)
Overland roughness : 2-5
Unsaturated zone (1-D) Ks(m/s) : 8s (-) 8, (-) a n
Peat soil 1e-• 0.70 0.15 0.4 1.37
Sandy loam 4e-5 0.40 0.04 0.05 1.25
lgnimbrite rock 5e-5 0.05 0.01 0.07 1.45
Canal (1-D) Mannings no. (m"3/s)
Canal roughness : 10
Leakage coefficient (s-1): 5e-6 - 5e-5
47
167 I/s, 108%
........___/ 162I/s,105%
~ oliv ian-Ch ilean border
157I/s,102%
59I/s
Legend
Q Continuous Flow Stations
e Simultaneous Flow Stallons
--WbalZones
o COORDENADAS_OJOS_AGUAS
tJ Canal Inflow
eJ
Figure 34 Mapping of flows and net inflows based on simultaneous mean canal flow measurements (in 1/s), Annex C.
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38I/s t9
~
37 I/s v
25 % 24 % 18 %
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8 Results
44
Approximately 45 model simulations for calibration were run. In the process of calibration, the
key model parameters were adjusted for each model run. When making parameter changes the
effects propagate through the flow model. This occurs relatively quickly in the surface water
system but the groundwater system has longer time scales and it takes longer to reach a steady
state solution for the combined surface - groundwater system. Generally, depending on the
initial conditions, it requires simulation periods of 6 months - 2 years to reach a steady state
solution for the Near Field model.
For each model run, the results are evaluated in the following order of priority:
1) Measured canal flows (C1-C7)
2) Water balance
3) Observed groundwater levels
8.1 Surface water flows
The simulated canal flows are compared to the measured mean synchronous (C1-C7) flow
measurements (Figure 34,Table 7). The inflow and thus the simulated canal flow at the southern
wetland is slightly underestimated between C1-C3 but at C4 the simulated flow equals the
measured indicating that inflows for the full C1-C4 reach are well simulated. At the confluence
the model slightly underestimates the flows at C5, C6 and C?. The differences of 3-6 % are,
however, small compared to measurement uncertainty. From the confluence and the siltation
chamber at C-7 the flow remains unchanged indicating that the net inflow and outflow from the
canal to the groundwater balances out, while the field observations indicate a very small flow
increase on this stretch.
Table 7 Comparison of measured and simulated flows.
Gauging location Measured Simulated Difference
canal flow canal flow
(%)
(1/s) (1/s)
C-1 28 25 10.7
C-2 37 32 13.5
C-3 38 31 18.4
C-4 59 59 0.0
C-5 97 91 6.2
C-6 57 55 3.5
C-7 (C5+C6) 154 150 2.6
At border 157 150 4.5
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8.2 Groundwater table
"'
Figure 35
-...
Groundwater table elevation contours based on measurements and model results,
respectively.
'-'30 . 4440
U20-U30
«10-'420
«00-UIO
,390 . uoo
4380-4390
4370-43&0
•360-4370
4350 - 060
43'0-43SO
43,30 - 43'0
4320-4330
4310 -4320
4300-4310
•290 - 4300
Bebw•290
Un6efrledV1kle
The ground water table contour map derived from water level observations in borehole, springs
and dug soil profile pits is used for the definition of initial conditions and boundary conditions in
the groundwater component of the integrated hydrological model. In Figure 35, the contour map
based on observations is shown in red versus the model simulation results in colours and lined
by black contours. The model results are plotted for model layer number 2 corresponding to the
Upper Silala lgnimbrite aquifer. At the area upstream of the southern wetland the model
overestimates the groundwater head by 1-2 m. However, the difference levels out across the
southern wetland and from the southern wetland outflow around C3 to the downstream similar
groundwater head contour levels are found . The shape of the contour lines from the numerical
model deviates slightly from the contour lines interpolated and extrapolated from observations
reflecting the type of boundary condition specified and the canal drainage effect.
8.3 Water balance
The results of the integrated model can be processed to produce a water balance for the model
area. The water balance includes all surface and subsurface inflows, outflows and storage
changes for the simulation period. It also calculates error terms in case the numerical model
produces water balance errors. The main water balance results are presented in Table 8, partly
by flow equivalents (I/s) and partly by volume (mm) across the model area.
Approximately 253 I/s enter the model as groundwater boundary inflow. At the downstream
model boundary 150 I/s flows across the border in the canal while 106 I/s is discharged through
the subsurface groundwater layers. Two of the main processes of discharging groundwater to
the surface water system is groundwater seepage to the canal network as baseflow and by
overland flow generated by upwelling groundwater in low lying areas and wetlands. The
'Storage Change' and 'Error' terms are relatively small indicating that a steady flow situation has
been reached without any significant numerical errors. Evapotranspiration losses within the
model area amount to 10 I/s. Since water is only available for evapotranspiration in relatively
restricted wetland and riparian corridor areas the total ET loss is limited.
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Table 8 Water balance summary for the current conditions (with canals).
Volume Flow
Water balance
equivalent equivalent
component
(mm/y) (1/s)
Inflow 3116 253
Net canal baseflow
(groundwater discharge 1113 90
to canal)
Net overland flow to 134 11
canal
Storage change 49 4
Evapotranspi ration 125 10
Error 25 2
Outflow (canals) 1846 150
Outflow (overland) 0 0
Outflow (groundwater) 1310 106
8.4 Results by zones
The Silala Near Field area was divided in to 5 characteristic zones (Annex C). In the following
selected model outputs are presented for the respective zones.
8.4.1 Zone 1: Northern wetland
The Northern wetland has been formed along the fault line and topographical depression limited
by steep terrain and rock faces to the north and south. At the base of the rocks a large number
of springs are formed and drained to the sloping main canal crossing the center of the wetland .
The groundwater discharge to the canal and drainage network is high as illustrated in Figure 36 .
..
Figure 36 Simulated groundwater flow to the canal and drainage network in Northern wetland.
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8.4.2 Zone 2: Southern wetland
The southern wetland is relatively flat compared to the rest of the Silala Near Field area. A
cluster of springs is situated along the fault zone and receives groundwater discharge from the
upstream catchment. The flow from the springs is intercepted by the dense canal network but
due to local water level differences and blockages water is diverted and spread across the
adjacent wetlands generating a shallow overland flow. Figure 37 shows model simulated water
depths and flow vectors at the Southern wetland . The model simulated overland flow is
generated by canal spills and upwelling groundwater. The flow and shallow inundation pattern
follows the observed wetland extent. The inundation generally stays within the light blue polygon
indicating the maximum extent of the wetland with the exception of a shallow flooded area
extending to the southeast towards a dried out former wetland patch. The general overland flow
downstream of the wetland is closely aligned with the canal and the narrow riparian corridor . ..
Figure 37 Simulated overland water depth (0-15 cm) and flow vectors in Southern wetland.
8.4.3 Zone 3: Mid-section of Southern Canal
01)• 0 ,~
on.on
011- 012
OOf-010
Oot-0.ot
001.oae
OOS-007
OOS-0.N
003-0().1
O.Ol-O.OJ
000-001
-o.~-0.00 -..... ~ __ ,,,_
The mid-section of the Southern Canal covers the reach from the Southern wetland at C3 to the
entrance to the ravine at C4. The canal slope is moderate and the canal rock alignment has
been removed in most of the reach, reestablishing flow across a wider cross section and riparian
corridor. A number of canal loops branching off and rejoining the main canal are found in this
reach. Figure 38 shows the simulated groundwater table (colours) ranging from approximately
4405 m upstream to 4370 m downstream. The flow vectors show the dominant groundwater
flows in the fault zone along the canal. In this reach a significant groundwater volume is
discharged to the canal with a simulated total inflow of 28 1/s.
'"-'
Figure 38 Simulated groundwater level and flow vectors in Zone 3.
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8.4.4 Zone 4: Ravine section of Southern Canal
The Southern Canal enters the upper part of the ravine at C4. From C4 to CS, at the confluence,
the ravine becomes increasingly deep with relatively high canal bed slopes. The canal, at the
ravine floor, is confined to the narrow ravine profile with steep slopes. Figure 39 shows
simulated groundwater discharge to the canal at each 10 m grid cell (green coloured) with flow
rates of 0 - 1 I/s. The results show the distinct drainage effect of the canal and fault zone in the
ravine as positive inflow of groundwater to the canal along the entire reach. The total simulated
inflow between C4 and CS is 32 I/s .
...
Figure 39 Groundwater discharge to the canal along the Zone 4 ravine section
8.4.5 Zone 5: Confluence to border
"'
, .... J:t.1•
U-U
l.•-U
U-H
u-:u
11.,,
.... ,i
D• -01
U-O• -o,.o,
◄ •-.o •
-tl--01
_,, .. ,i
-lt--1, _,, --·
The Northern Canal at C6 and the southern Canal at CS merge into the main canal (C7). From
the confluence to the border the canal shape and bed slope is fairly uniform. According to the
hydrogeological model (Annex F) Zone 5 is, as opposed to the remaining part of the near field
area, characterized by no groundwater inflow to the canal or potentially a net loss from surface
water to groundwater. The simulated canal flow entering Zone 5 at the confluence and leaving
Zone 5 at the border is both 150 I/s corresponding to no net inflow. Within Zone 5 areas with
both positive and negative water level gradients between the canal and the upper groundwater
layer can be found indicating local canal losses and gains. However, the sum of losses and
gains balances over the reach to produce zero net total inflow. Figure 40 shows a subsurface
cross section at the downstream model boundary including layers and simulated ground water
table. The groundwater table sits at the canal level with a slight vertical gradient from the upper
to the lower ignimbrite layers.
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.,. .
.,,,
'"' '"'
43 10
.,.. .,..
.,,,
., .. "''
4270 ....... : ...... , .............•.... "''
"" ""
•250 ·······!······ ""
•2•0
'"'
mo
,210
4200 •..•••. : ...... "''
JOO '" ...
Figure 40 Cross section at the border showing groundwater layers and simulated groundwater table
9 Summary and conclusions
An integrated surface water - groundwater model has been developed to serve as a tool in
scenario analysis, e.g. in order to assess the effects of removing the canals (Annex H). Before
applying the model in scenario analysis, the conceptual model was implemented in the
numerical model and subsequently the model was tested and calibrated it against field
measurements. Partly to demonstrate that the model qualitatively describes the Silala Near Field
hydrology in accordance with conceptual understanding and partly to demonstrate that the
model results produced quantitatively matches the measured values.
The overall results of the integrated model agree with the conceptual model and field
observations in terms of:
• Significant groundwater inflows to the Silala Near Field area through the high permeable
fault zone and upper Silala ignimbrite
• Overall groundwater flow towards the low-lying wetlands, the canals and the deep cut
ravine sections.
• Groundwater feeds the surface water by discharges to the springs, canal and drainage
network
• Upstream gaining canal reaches versus the downstream neutral or losing reach from
the confluence to the border.
• Outflow of the Silala Near Field area as combined canal and groundwater flow at the
border
The calibration against field data show
• The model simulates groundwater discharge to the canal system in terms of measured
mean canal flow (C1-C7) reasonably well, i.e. 0 - 18 % deviation.
• The largest relative difference is found at upstream southern canal (C1 -C3). From C4 to
the downstream confluence and border area including the northern branch (C6). The
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model performs well with differences to the observations which are within the canal flow
measurements uncertainty.
• The calibrated model water balance shows groundwater flow across the downstream
model boundary in the order of 106 I/s compared to surface water flow of 150 I/s. There
are no groundwater flow measurements in the cross section to verify the model
simulated groundwater flow.
• Evapotranspiration mainly occurs in the wetlands and along the canal riparian corridor.
Due to the restricted total area the total ET losses correspond to only 10 I/s under
current conditions.
The numerical model is developed from the conceptual understanding and the field data
collected. The calibrated model is able to simulate the canal flows (C1-C7) reaching
approximately 150 I/s at the border. The model results suggest a considerable groundwater flow
component but it cannot be compared to any measurements and is more uncertain than surface
water flows. However, the model results confirm a coupled groundwater - surface water system
within the Silala Near Field area extending across the border.
The calibrated model is considered suitable for use in scenario analysis (see Annex H).
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1 O References
ARCADIS Final Report "Characterization of the Drainage Patterns and River Network of the
Silala River and Preliminary Assessment of Vegetation Dynamics Using Remote Sensing",
Memorial of Chile, Volume 4, Annex II, [Book]. - 2017.
Benavides J. Vitt D. "Response curves and the environmental limits for peat-forming species in
the northern Andes", Plant Ecology 2015 (9) [Book]. - 2014.
DHI MIKE SHE documentation, Volume 2 : Technical Reference [Book]. - 2017.
DIREMAR Final Report "Characterization of the soils of the Silala bofedales and surrounding
areas" [Book] . - 2017.
Garraud R., Vuille M. and Clement A. The climate of the Altiplano: observed current conditions
and mechanisms of past changes [Journal] // Palaeography, Palaeoclimatology, Palaeecology. -
2003. - Vol. 194. - pp. 5-22.
M.S.M Fonken "An Introduction to the Bofedales of the Peruvian High Andes", Mires and Peat,
Volume 15 (2014/15), Article 0 [Book]. - 2014.
Munoz J.F. [et al.] Hydrology of the Silala River Basin, International Court of Justice over the
status and use of the waters of Silala [Report]. - [s.l.] : Memorial of the Republic of Chile,
Volume 5, Annex VII , 2017.
Schwarze! K. Simunek J., Stoffregen H., Wessolek G., van Genuchten M "Estimation of
Unsaturated Hydraulic Conductivity oif Peat Soils, Laboratory versus Field data", Vadose Zone
Journal vol 5. [Book). - 2006.
Squeo F. Warner B., Aravena R., Espinoza D. "Bofedales: high altitude peatlands of the
central Andes", Revista Chilena de Historia Natural, 79: 245-255 [Book]. - 2006.
Wilson E.M. Engineering Hydrology [Book). - Stanford: TheMacmillan Press LTD., 1978.
Zambrano-Bifiarini M. [et al.) Temporal and spatial evaluation of satellite-based rainfall
estimates across the complex topographical and climatic gradients of Chile. , Hydrol. Earth Syst. ,
Sci ., 21 , 1295-1320 [Journal) // Hydrologial Earth Systems. - 2017. - pp. 1295-1320.
The expert in WATER ENVIRONMENTS 51
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Annex 17
Danish Hydraulic Institute (DHI), Study of the Flows in the Silala
Wetlands and Springs System, 2018
Annex H: Natural Flow Scenarios
(Original in English)
58
59
Contract CDP-I No 01/2018, Study of
the Flows in the Silala Wetlands and
Springs System
Product No. 2 - 2018 Final Report
Annex H: Natural Flow Scenarios
Plurinational State of Bolivia, Ministry of Foreign Affairs, Diremar
July 16, 2018
OHi • Agern Alie 5 • • DK-2970 H0rsholm • Denmark
Telephone: +45 4516 9200 • Telefax: +45 4516 9292 • [email protected] • www.dhigroup.com
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CONTENTS
Glossary ...................................................................................................................................... 3
Introduction ................................................................................................................. 6
2 Scenarios ..................................................................................................................... 6
2.1 Scenario Results ........ ......... .............. ... .......... .... ... . .. 6
2.2 Scenario Details. .... ............. .......... .... ... . .. 7
2.2.1 Baseline Model ......... ........ . .. 7
2.2.2 No Canal Scenario... ......... ............ . .. 7
2.2.3 Restored wetland scenario....... ......... ........ . ...... 10
3 Confluence to border local model ............................................................................ 12
3.1 Hydrogeology of the confluence to border zone .................. ................................... 12
3.2 Model setup and parameters .14
3.3 Modelled infiltration capacity .... ..... ...... .. ........ ... ....... ..... .. ....... . 15
4 Summary and conclusion ......................................................................................... 16
5 References ................................................................................................................. 17
FIGURES
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
TABLES
Table 1
Table 2
Groundwater flow to surface water and effects of removing canals (USGS, 1998). . .... 8
Change in overland water depth between the 'Baseline' and the 'No Canal' scenario. . .... . .... 9
Change in Silala lgnimbrite groundwater table between the 'Baseline' and the 'No Canal'
scenario ... 9
Illustration of a confined/unconfined aquifer system and artesian flowing well/spring. . .. 11
Change in overland water depth between the 'Baseline' and the 'Restored Wetland'
scenario... . ...... ...... ..... .... . ............................................................................. 11
Change in Silala lgnimbrite groundwater table between the 'Baseline' and the 'Restored
Wetland' scenario. .. ....................... .12
Geological profile C along the canal from the confluence to the border based on borehole
logs (top) and profile showing spot flows and groundwater levels {bottom) ......... 14
Model grid and boundary conditions .................................................. ......... 15
Summary of key scenario results.... ........ ........... .. .. ..... ............ .. . ........ 7
Parameter intervals used for overland flow, canal flow, the unsaturated and saturated
zones. (Note: some parameters were not modified for the sensitivity analysis)..... . ....... 16
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DOCUMENTATION OF THE STUDY
Main Report Containing the summary and conclusions
Technical Annexes:
Annex A.
Annex B.
Annex C.
Annex D.
Annex E.
Annex F.
Annex G.
Annex H.
Annex I.
2
The Silala catchment
Climate analysis
Surface waters
Soil Analyses
Water balances
Hydrogeology
Integrated surface water - groundwater modelling
Natural flow scenarios (this annex)
Questionnaire put by the Plurinational State of Bolivia to OHi
63
Glossary
Term
Aquifer
Austral summer
Basin
Catchment
Confined aquifer
Depression, terrain
depression or sink
Desert climate
Digital elevation model
(OEM)
Discharge
El Nino
Meaning/Definition
Geological formation capable of storing, transmitting and yielding
exploitable quantities of water.
Summer period in the Southern Hemisphere.
Area having a common outlet for its surface runoff.
The whole of the land and water surface contributing to the discharge at
particular stream cross section. This means that any cross section of a
stream will have a unique catchment of its own. (Wilson , 1978).
Confined aquifers are aquifers that are overlain by a confining layer,
often made up of clay or other geological formations with low
permeability.
A depression (or sink) is a low point in the terrain surrounded by higher
ground in all directions. If the soil is impervious, the depression collects
rain water from a local catchment. Surface water or groundwater inflows
will accumulate in the depression until:
- the water level reaches the nearest terrain threshold and runs off or
- the evaporation from the depression is equal to its combined surface
water groundwater inflows. However, a depression may also drain subsuperficially
to lower lying areas through pervious soils, geological
faults or groundwater aquifers.
Desert climate (in the Koppen climate classification BWh and BWk,
sometimes also BWn), also known as an arid climate, is a climate in
which precipitation is too low to sustain any vegetation at all, or at most
a very scanty shrub and does not meet the criteria to be classified as a
polar climate.
Data files holding terrain levels often organised in a quadratic grid with
a certain cell size (e.g. 30m by 30 m). They are very convenient tools
for and often used as standard tools in Geographic Information
Systems (GIS) for delineation of topographical catchment and for many
other purposes.
Volume of water flowing per unit time, for example through a river
cross-section or from a spring or a well.
El Nino is the warm phase of the El Nino Southern Oscillation
(commonly called ENSO) and is associated with a band of warm ocean
water that develops in the central and east-central equatorial Pacific
(between approximately the International Date Line and 120°W),
including off the Pacific coast of South America. El Nino Southern
Oscillation refers to the cycle of warm and cold temperatures, as
measured by sea surface temperature (SST) of the tropical central and
eastern Pacific Ocean. El Nino is accompanied by high air pressure in
the western Pacific and low air pressure in the eastern Pacific. The cool
phase of ENSO is called "La Nina" with SST in the eastern Pacific
below average and air pressures high in the eastern and low in western
Pacific. The ENSO cycle, both El Nino and La Nina, causes global
changes of both temperatures and rainfall.
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Evapotranspiration
Food and Agriculture
Organization of the
United Nations (FAO)
Geographic
Information System
(GIS)
Groundwater
Hydrogeological
Conceptual Model
(HCM)
Hydrogeological
Framework Model
(HGFM)
Hydrological
catchment
Infiltration
Penman-Monteith
Recharge
Reference
evapotranspiration
(Eto)
Combination of evaporation from free water and soil surfaces and
transpiration of water from plant surfaces to the atmosphere.
Specialized agency of the United Nations that leads international efforts
to defeat hunger. FAO is also a source of knowledge and information,
and helps developing countries in transition modernize and improve
agriculture, forestry and fisheries practices, ensuring good nutrition and
food security for all.
A geographic information system (GIS) is a system designed to
capture, store, manipulate, analyse, manage, and present spatial or
geographic data.
Subsurface water occupying the saturated zone (i.e. where the pore
spaces (or open fractures) of a porous medium are full of water).
The conceptual understanding of the individual components in a
hydrologic system (i.e. groundwater, surface water, and recharge) and
the processes involved between each component.
A three-dimensional geologic model that defines the spatial extent of
stratigraphic and structural features. The development of the HGFM
incorporates topographic, geologic, geophysical, and hydrogeologic
datasets.
The hydrological catchment is the total area contributing to the
discharge at a certain point. The hydrological catchment includes all the
surface water from rainfall runoff, snowmelt, and nearby streams that
run downslope towards a shared outlet, as well as the groundwater
underneath the earth's surface. Since groundwater may cross the
topographical divides a hydrological catchment to a point may be larger
than the corresponding topographical catchment as indicated in the
Princi le sketch below.
//
catchmenl
A
surfo
runo
lopogrophicol
water div ide I ra in I catchmenl
B
Hydrological catchment B
The movement of water from the surface of the land into the
subsurface.
Method for estimating reference evapotranspiration (EID) from
meteorological data. It is a method with strong likelihood of correctly
predicting ETo in a wide range of locations and climates and has
provision for application in data-short situations.
Contribution of water to an aquifer by infiltration.
The evapotranspiration per area unit under local climate conditions from
a hypothetical grass reference crop with an assumed crop height of
0.12 m, a fixed surface resistance of 70 s m·1 and an albedo of 0.23.
The reference surface closely resembles an extensive surface of green,
65
Remote sensing
Satellite
Sensitivity analysis
Spatial variation
Spring
Topographical
catchment
Weather station
Wetland
well-watered grass of uniform height, actively growing and completely
shading the ground. A good approximation to the maximum
evapotranspiration that under a certain climate can evaporate from an
area unit covered by an ever-wet short green vegetation (e.g. a
wetland}
Acquisition of information about an object or phenomenon without
making physical contact with the object and thus in contrast to on-site
observation. In current usage, the term "remote sensing" generally
refers to the use of satellite- or aircraft-based sensor technologies to
detect and classify objects on Earth, including on the surface and in the
atmosphere and oceans, based on propagated signals (e.g.
electromagnetic radiation).
Artificial body placed in orbit round the earth or another planet in order
to collect information or for communication.
Sensitivity analysis is the study of how the uncertainty in the output of a
mathematical model or system (numerical or otherwise) can be
apportioned to different sources of uncertainty in its inputs.
When a quantity that is measured at different spatial locations exhibits
values that differ across the locations.
A spring is a place where groundwater emerges naturally from the rock
or soil. The forcing of the spring to the surface can be the result of a
confined aquifer in which the recharge area of the spring water table
rests at a higher elevation than that of the outlet. Spring water forced to
the surface by elevated sources are artesian wells. Non-artesian
springs may simply flow from a higher elevation through the earth to a
lower elevation and exit in the form of a spring , using the ground like a
drainage pipe. Still other springs are the result of pressure from an
underground source in the earth, in the form of volcanic activity. The
result can be water at elevated temperature such as a hot spring.
A catchment delineated strictly by topographical divides of the terrain.
The topographical catchment includes all the surface water from rainfall
runoff, snowmelt, and nearby streams that run downslope towards a
shared outlet. This is the correct catchment if all discharge is surface
flow (i.e. no groundwater). The topographical catchment is often a good
approximation to the catchment, particularly for larger catchments.
A facility, either on land or sea, with instruments and equipment for
measuring atmospheric conditions to provide information for weather
forecasts and to study the weather and climate.
A wetland is a land area that is saturated with water, either permanently
or seasonally, such that it takes on the characteristics of a distinct
ecosystem. The primary factor that distinguishes wetlands from other
land forms or water bodies is the characteristic vegetation of aquatic
plants, adapted to the unique hydric soil. Wetlands play a number of
roles in the environment, principally water purification, flood control ,
carbon sink and shoreline stability.
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1 Introduction
An integrated model has been developed for the current Silala Near Field conditions and
calibrated against recent measurements (Annex G). The purpose of the model tool is to carry
out scenario analysis to investigate the effects of changes to the current hydrological system. In
particular to quantify the effects of interventions to restore the Silala Springs system to a more
natural state.
2 Scenarios
The specific purpose of the project and the integrated model is to assess the effects of the canal
and drainage network. The following baseline and scenario models have been run:
1) Baseline model. Represents the current (2018) Silala Near Field area with the existing
canal and drainage network. The surface water canal model includes both reaches which
are more or less unchanged compared to the original canal construction but also those
reaches where the canal has been removed or blocked.
2) No canal scenario. The entire canal and drainage network in the baseline model is
removed. Surface water flow is no longer restricted to well-defined narrow canal cross
sections and the direction of flow is largely controlled by the surface topographical slope.
3) Wetland restoration scenario. The removal of the existing canal and drainage network will
lead to the gradual restoration of the degraded wetlands and riparian corridors. The scenario
considers how the fully restored wetland might be expected to function by considering longterm
peat accumulation in wetlands.
2.1 Scenario Results
The overall scenario results can be summarized by model water balance outputs (Table 1 ). In
the Baseline scenario, 253 I/s enters the model area as boundary inflow. A significant part of the
groundwater inflows is discharged to surface water. At the downstream boundary, the integrated
model simulates a total outflow of 256 I/s comprising both groundwater (106 I/s) and canal flow
(150 I/s). The storage change and error terms are relatively small compared to the inflows,
indicating that steady state conditions with insignificant numerical errors have been reached.
Evapotranspiration accounts for losses in the order of 10 I/s or less than 10% of canal flows.
In the 'No Canal' scenario, the surface water levels are generally higher than the canal water
levels and because of the coupling to the groundwater , the groundwater table rises as well.
Higher groundwater tables inside the model area reduce the groundwater gradients as well as
the inflows at the groundwater boundary. Without the canals, there no exchange between the
groundwater and a well-defined canal. Instead groundwater discharge by aquifer-overland
seepage becomes the dominant exchange term. As a result, the total inflow to the springs
reduces to 221 I/s and the total outflow is 209 I/s. The ratio between groundwater and surface
water and groundwater outflows also changes. Without the canals the integrated model
simulates a groundwater outflow of 115 I/s which is greater than the simulated surface water
outflow of 94 I/s. With higher resistance to flow on the surface groundwater flow accounts for a
larger proportion of the total flow. The evapotranspiration increases by 20 % compared to the
baseline but in the larger water budget the actual evapotranspiration is less important.
In the 'Wetland Restoration' scenario, the boundary inflow adds up to 216 I/s. The outflow from
the model area is 207 I/s, 107 I/s as groundwater and 90 I/s as overland flow. Compared to the
baseline the evapotranspiration increases by 30%.
67
Table 1 Summary of key scenario results
Baseline Scenario No canal scenario Restored wetlands
Water balance
Volume Flow Volume Flow Volume Flow
component
equivalent equivalent equivalent equivalent equivalent equivalent
(mmly) (Vs) (mmly) (Vs) (mmly) (I/s)
Inflow 3116 253 2722 221 2655 216
Storage change 49 4 12 1 64 5
Evapotranspiration 125 10 150 12 164 13
Error 25 2 0 0 -2 0
Outflow (canals) 1846 150 0 0 0 0
Outflow ( overland) 0 0 1159 94 1112 90
Outflow (groundwater) 1310 106 1418 115 1441 117
2.2 Scenario Details
The integrated surface water - groundwater model has been set up and run as a steady-state
model as explained in the model approach (Annex G). The scenario model setups were run for a
period of 1-2 years to establish a steady state solution and minimise effects of the initial
conditions on the final scenario results.
2.2.1 Baseline Model
The baseline model includes coupled flow components for groundwater (3-D), unsaturated zone
(1-D), evapotranspiration, overland flow (2-D) and canal flow (1-D). This is normally referred to
as a fully coupled integrated model.
2.2.2 No Canal Scenario
The 'No canal' scenario model is identical to the baseline model except that the 1-D canal flow
model has been removed from the setup. The 'No canal' model thus include coupled flow
components for groundwater (3-D), unsaturated zone (1-D), evapotranspiration and overland
flow (2-D).
Figure 1 (USGS, 1998) shows the seepage of groundwater to surface water at the base of a
slope, groundwater flow to a combined canal and riparian zone cross section and groundwater
flow to surface water in a cross section without canals. Due the topographical features and the
hydrogeological properties of the Silala Near Field area, groundwater discharge zones in terms
of springs and seepage faces are formed. The canal forms a flow conduit which drains the
surrounding area. The resistance to flow in the canal is lower than the adjacent vegetated
riparian zone which means that the canal increases the conveyance capacity and lowers the
water table. In a coupled groundwater-surface water system , a lower surface water level
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increases the gradient between the aquifer and the surface water leading to a higher flow
exchange rate and draining the groundwater and potentially lowering groundwater tables. With
the canals removed, the surface flow cross sectional area increases and the roughness to
surface flow increases causing a higher resistance and corresponding higher surface water
levels. Higher resistance and lower flow velocities can potentially increase sedimentation and
build-up of organic matter, especially in low slope reaches. Higher resistance and water level in
surface water will affect the groundwater discharge and ground water tables.
I GW seepage to SW
Areas fa vorable for
wetland fo rmation
SEEPAGE FACE
BREAK IN SLOPE~ ~-- .---
Wetland
Stream
Direction of ground-water flow
I GW flow to overland Wetland
Direction of ground-water flow
Land surface
Land sur1ace
-----
Figure 1 Groundwater flow to surface water and effects of removing canals (USGS, 1998).
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Figure 2
Figure 3
Change in overland water depth between the 'Baseline' and the 'No Canal' scenario.
0 COORDENADAS_OJOS_AGUAS
c::J ModolAro~
0 Cont,nuo11:1Flow St.olion1
3 D ORENA.IE
• S.lo~BorderCro u _1
Change in Silala lgnimbrite groundwater table between the 'Baseline' and the 'No Canal'
scenario.
Figure 2 and Figure 3 show the change in overland water depths and water table of the upper
groundwater layer when removing the canal. Overland water depth increase along the canals
and wetlands. Due to the higher water levels on the surface the groundwater table also
increase. General increase in groundwater tables is seen in the area but the largest change is
found in the ravine, at the northern wetland and from the confluence to the border.
The integrated hydrological model applies a 10 m grid resolution which is sufficient to capture
the flow changes of the Silala Near Field area in general. As expected the model results showed
an increase in overland water levels when removing the canals. However, in narrow sections of
the southern canal ravine ponding overland water locally reach more than 2 m. The formation of
these overland storage areas is due to topographical thresholds holding back pools of water and
they may be a result of the grid resolution not properly representing the ravine floor levels. To
investigate the scale and grid resolution effect on the overall scenario results, the topography
was locally corrected to obtain a continuous downhill surface slope. Running this revised 'No
Canal' test model showed that overland water levels decreased and the surface water flow at
the border increased to 103 I/s compared to 94 I/s in the model run without topography
corrections. The groundwater outflow reduced from 115 I/s to 113 I/s. It has not been possible to
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further assess the effect of grid resolution by running higher grid resolution models within the
available project time frame.
2.2.3 Restored wetland scenario
The 'Restored wetland' scenario model is identical to the 'No canal' scenario model but the
surface topography and unsaturated soil profile description has been modified. The 'Restored
wetland' scenario model includes coupled flow components for groundwater (3-D), unsaturated
zone (1-D), evapotranspiration and overland flow (2-D).
Currently, both the southern and the northern wetlands are severely degraded due the canal
and drainage network lowering the water tables, subdivision by canals intercepting flow and
excavations exposing peat deposits to oxygen and decomposition. Wetland restoration
initiatives removing the man-made constructions will provide basis for a long term recovery and
re-establishment of the wetland.
Field inspection and the wetland soil survey has shown clear contrasts in soil profiles between
degraded and relatively undisturbed wetland patches especially in the northern wetland. Up to
60 cm thickness of peat soils were found in the few undisturbed areas versus 0 - 40 cm in the
remaining part of the wetland with partial or heavy disturbance and degradation. The rate of peat
accumulation is low in altiplano bofedales, likely in the range of 0.1 - 1 cm/year, requiring
several years for recovery. In this restored wetland scenario, the maximum depth of peat across
the wetlands accumulated over a long time span is assumed to reach the 60 cm found in
undisturbed areas. In wetland areas with peat thicknesses less than 60 cm the peat thickness is
adjusted up to 60 cm. A thicker peat layer has two main hydrological effect. It partly raises the
wetland ground level and topography and it partly increase a organic top soil with specific
capillary rise and water storage properties. A thicker peat layer implies a higher resistance to
groundwater emerging in the wetland. Figure 4 illustrates groundwater flow through a
confined/unconfined aquifer system and the artesian flow generated in a low-lying area. The
flow rate at a well or a spring is a function of head gradient and the combined resistance
represented by the layer thicknesses and hydraulic properties. Thicker layers imply higher
resistance and lower spring flow. Thicker peat layers introduce larger water storage and higher
water contents and potentially a higher upward directed flow from capillary forces.
The 'Restored wetland' scenario model has been modified by adjusting the topography to reflect
a peat layer thickness increase up to 60 cm. The unsaturated zone soil profiles have been
adjusted accordingly assuming 60 cm of peat in all wetland soil profiles.
71
Recharge
Wat!:cl~ab le Artesian Ground
well surface
Modified after Harian and othe~, 1989
Figure 4 Illustration of a confined/unconfined aquifer system and artesian flowing well/spring.
Figure 5 and Figure 6 show the change in overland water depths and water table of the upper
groundwater layer when removing the canal and restoring the wetlands. Overland water depth
and the groundwater table increase, mainly along the canals and wetlands.
Figure 5 Change in overland water depth between the 'Baseline' and the 'Restored Wetland'
scenario.
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Figure 6
0 COCRDEtlA.DAS_OJOS_,AGUJI
D ModlllAru
0 ContinuousFIDwSta'ians
3 O oRENAJE
• Silal11Bo<d.C1ou_1
Change in Silala lgnimbrite groundwater table between the 'Baseline' and the 'Restored
Wetland' scenario.
3 Confluence to border local model
12
In order to analyse more closely the surface water and groundwater flow from the confluence to
the border and to assess the infiltration capacity without the canal , a local model was extracted
from the Silala Near Field model and further refined. This refined local scale model is used in
sensitivity analysis to explore the ranges of infiltration, groundwater flow and surface water
along this reach without canals. The local confluence to border is using the integrated MIKE
SHE surface water-groundwater modelling system and the model is developed from the larger
Silala Near Field setup (Annex G).
As information on the hydrogeology including soil properties and surface water - groundwater
interactions are very limited in the ravine area, different plausible scenarios have been
investigated to provide an assessment of the likely infiltration capacity along this reach. It should
be noted that no studies of soil properties or canal bed properties are available for this part of
the system. Furthermore, there is very limited information on groundwater water levels or flows
which could be used as a basis for model calibration. A steady-state model approach was
adopted which is run with different input parameter sets to provide an assessment of the surface
water and groundwater impacts without the presence of the canal.
3.1 Hydrogeology of the confluence to border zone
According to the hydrogeological model developed for the Silala springs area (Annex F),
groundwater flows in a fault zone beneath the canal in a north-east south-westerly direction with
limited surface water-groundwater flow exchanges along this part of the canal. Geological logs
from four boreholes along this reach indicate a thin layer of eluvium underlain by highly
fragmented lava deposits or andesit to a depth of approximately 1-10 m below the canal. This is
in turn underlain by lgnimbrite which has been identified to a depth of 110 m below ground in
borehole DS-35.
Simultaneous flow measurements taken along the in the canal in Figure 7 indicate a small gain
along the upper part of the canal section and a minor loss towards the end of the ravine with a
total average gain of approximately 4 I/sec along the full reach. This is supported by observed
73
groundwater levels along the canal presented in the same figure. At the upstream end of the
canal, water levels are close to the canal bed in the upper part of the lava deposits as indicated
by water levels at DS-37 and a spring SP-64. This suggests that this part of the canal is a
gaining reach and relatively well connected to the shallow aquifer. Further downstream,
groundwater levels are located below the canal at varying depths from 17 m below ground in the
ignimbrite at DS-35 to 0.8-1 .6 m below ground at DS-31 and DS-32 in the shallower lava
deposits. Groundwater levels in DS-35 and DS-31iDS-32 indicate that the upper deposits at DS-
31 and DS-32 are not well-connected to the underlying ignimbrite aquifer but form a perched
aquifer. This agrees with observations made by (Arcadis, 2017) further downstream in Chile who
found the presence of intermittently saturated conditions below the canal at four locations in
fluvial and alluvial deposits below the canal. Groundwater levels in the deeper ignimbrite aquifer
were found at depths between 8-9 m below ground. Overall, the groundwater levels along the
lower part of the canal indicate a losing reach with limited connectivity between the canal and
the underlying shallow and deeper aquifers.
In terms of infiltration, limited information is currently available on soil properties in the upper
deposits (eluvium and lava deposits) in this area. (Arcadis, 2017) estimated permeabilities from
infiltration tests further downstream in Chile to between 0.02-2.05 mid (2 .3 x 10-07- 2.4 x 10-05
mis) for alluvial and fluvial deposits, 0.03 - 1.61 mid (3.5 x 10-07 - 1.9 x 10-05 mis) for fractured
and weathered lavas and 0.37 - 0.48 mid (4.3 x 10-06 - 5.6 x 10-06 mis) for the lgnimbrite aquifer.
A pumping test conducted in Chile close to the border indicates higher hydraulic conductivities
of the lgnimbrite of 8-17 mid (9.3 x 1 o-05 - 2.0 x 1 o-0• mis). No information is available on the
properties of the lining of the canal or connectivity between the canal and shallow deposits of
eluvium or lava fragments.
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4380
__________ G_e_o_lo~g~ic_a_l ~pro_fi_le_o_f_c_a_nal _________ _
4360
4340
05-37
~ 4320 ~
-E,; 4300 [ 05·35 ~~~'.:_1:: _____ .--------- 0 5-3205-31 .i 4280 ~ _,..,.
w
4260
4240
3540 3440 3340 3240
canal chainage (m)
3140 3040 2940
E1uvlum - Sandandgrave l - Andesh(lan fragments) - tgnimbrtte Sand - Topoeraphy - DS•32 - DS·31 - 0S·35 - 0S-37
Profile - Canal
----------------------------~ 180
4390 ·······--····------------·····················-··
4370
~ 4350
~
.§. 4330
C
0 'i 4310
w
4270
5-19 160
........... 5·20 ............................................................................ Cfi.t 5 140
·············-·······················-·························································· 120
SP 64 ~
·············-·······················-·························································· 100~
05·35·1 (lgnimbrite)
~
80 "§
i5
60
40
4250 -'-----~----~----~--------~-----+ 0
Figure 7
3540 3440 3340 3240
canal chainage (m)
3140 3040 2940
--Surface elevation • Groundwater level - •-· Groundwater level (shallow} ~ Discharge
Geological profile C along the canal from the confluence to the border based on borehole
logs (top) and profile showing spot flows and groundwater levels (bottom).
3.2 Model setup and parameters
14
The local model of the confluence to border section was based on the larger model with upper
boundary conditions of groundwater head and aquifer properties taken from this model. It should
be noted that the smaller modelling study was undertaken while the larger model was being
calibrated which means that there may be some differences in groundwater inflow around the
upstream boundary between the two models.
The local model area (Figure 8) uses a grid size of 10m_ The model comprises geological units
of sand and gravel, lavas and lgnimbrites with a high permeable fault zone of lgnimbrite along
the canal overlain by eluvium and lava deposits. Upstream boundary inflows have been kept
constant by fixing head and hydraulic properties at the boundary. Downstream, a gradient
boundary condition of 0.05 was used in both the upper lava deposits and the lgnimbrite. This
was estimated based on shallow groundwater levels in the upper deposits in DS-37 and DS-
31 /DS-32 and has been assumed to apply both in the shallow aquifer and deeper lgnimbrite.
75
The model uses a horizontal hydraulic conductivity of 10-4 m/s for the upper lava deposits and a
3 x 10·5 m/s for the upper lgnimbrite to a depth of approximately 60-65 m. Below this a horizontal
conductivity of 1.1 x 10·5 m/s was used. The vertical conductivity was set to the same value in
the upper two layers but a factor 10 lower in the lower lgnimbrite. These values are generally at
the higher end of those derived by (Arcadis, 2017) (see above). In the unsaturated zone, the
saturated conductivity was set to match with those used for the saturated zone with a hydraulic
conductivity of eluvium of 3.5 x 10·5 m/s and 10-4 m/s for fragmented lava deposits.
Canal inflow at the upstream end was set to 160 I/s and the canal leakage coefficient was
specified as 5 x 10·5 m/s corresponding to moderately permeable material/lining. Canal
roughness and roughness of the surface in the ravine was assumed to be 5 m113/s and 2 m113/s
respectively corresponding to fairly dense wetland vegetation .
I
('
- ~
I - ~
\
._ v~
I I I\.
.._
~ I .....
j -
~ I/ r-...
... I IL)
7 -- "I ~ ~ - ~ - ~
~ - - ~ .I
l.. :_.r
-. .,~ ....
Figure 8 Model grid and boundary conditions.
3.3 Modelled infiltration capacity
To assess the infiltration capacity of the ravine, two models were run to steady-state: a model
including the channel and a revised model without the canal from the confluence at the
upstream boundary. The outflow across the border was then compared with and without the
channel to determine the effect of removing the canal on cross-border surface water flows.
According to the model removing the canal from the ravine results in a loss of 12 I/s equivalent
to 8% of the canal flow. Running the model using a finer discretisation of 5 m resulted in only a
slightly increased reduction of 14 I/s indicating that the coarse model resolution of 10 m is
adequate for the analysis.
A sensitivity analysis of some of the input parameters were subsequently undertaken to assess
the effect of, for example, the saturated hydraulic conductivities and roughness coefficients on
surface water outflows. Model parameters for the analysis were primarily selected to determine
the highest plausible leakage/infiltration along the ravine while still providing an adequate
representation of groundwater depths in the lava and ignimbrite aquifer. The parameter intervals
tested in the analysis are summarised in Table 2.
The expert in WATER ENVIRONMENTS 15
76
D~
The highest infiltration rate achieved was 39 lis equivalent to 25% of total canal flow. This was a
result of using a high horizontal hydraulic conductivity of 10·3 mis in the lava deposits and 104
mis in the upper ignimbrite and high vertical conductivities of 104 mis in the lava and 5 x 104
mis in the ignimbrite. These values are generally higher than the values determined by Arcadis,
2017. Using even higher conductivities is not considered realistic and produces large drops in
groundwater heads in the upper lgnimbrite aquifer far below observed levels.
Table 2 Parameter intervals used for overland flow, canal flow, the unsaturated and saturated zones.
(Note: some parameters were not modified for the sensitivity analysis).
Component Parameter Min Max
Overland/canal Mannings M (m1 /3/s) 2 15
Unsaturated zone Eluvium Ks (mi s) 2.74E-05 1.00E-04
Lava Ks (mi s) 1.00E-04 1.00E-04
Saturated zone Eluvium+Lava Kh (mis) 1.00E-04 1.00E-03
Eluvium+Lava Kv (mis) 1.00E-04 1.00E-04
Upper lgnimbrite Kh (mi s) 3.00E-05 1.00E-03
Upper lgnimbrite Kv (mis) 5.00E-05 5.00E-04
Lower lgnimbrite Kh (mi s) 1.20E-05 1.20E-05
Lower lgnimbrite Kv (mis) 1.60E-06 1.60E-06
This local confluence to border model analysis shows that it is unlikely that removing the canal
from the confluence to the Chilean border will remove all cross-border surface water flow into
Chile. With the highest infiltration capacity achieved using very high conductivities, a maximum
of 25% of current canal flow will be lost to the subsurface. This is associated with a high degree
of uncertainty and most likely an overestimation of infiltration. A more realistic estimate is 12-15
lis (8-10%) using lower hydraulic conductivities more in agreement with values reported by
(Arcadis, 2017) and values used in the final version of the full Silala Near Field model.
4 Summary and conclusion
16
According to the integrated model scenario results, removing the canals and restoring wetlands
will affect both groundwater and surface water and both inflows and outflows of the Silala Near
Field area.
• The simulated surface water flow at the downstream model boundary (located at the
Bolivian-Chilean border) is reduced by 31-40 % compared to current conditions.
• The simulated groundwater flow at the downstream model boundary (located at the
Bolivian-Chilean border) increases by 7-11 % compared to current conditions.
• The total model boundary inflow at the upstream model boundary decreases by 10-15
%.
• The evapotranspiration increases by 20-30 % by removing the canals and restoring
wetlands. corresponding to increases of only 2 lis and 3 lis respectively
77
A local model sensitivity study shows that without the canals a maximum of 25 % will
infiltrate to the subsurface between the confluence and the border but 8-12 % is the
most realistic range. Losses are included in the Silala Near Field model scenarios.
All the scenario results evaluated here and the local model analysis suggest that both
surface water flow and groundwater flow should be expected at the border.
The flow impact percentages describe the model results ranges but not explicitly the uncertainty
on model results. Despite the strength of integrated models in combining a range of site specific
data, such numerical model results are inherently uncertain. Model predictive uncertainty
depends on a number of factors and uncertainty sources, e.g. limitations in input data, model
structure, and parametrisation and measurement errors. A strictly quantitative uncertainty
analysis is not feasible and has not been attempted but model uncertainty should not be ignored
in the interpretation of results.
5 References
Arcadis Detailed Hydrogeological Study of the Silala River. International Court of Justice
Dispute over the status and use of the waters of Silala (Chile vs.Bolivia) [Report]. - [s.l.] :
Memorial of the Republic of Chile, Volume IV, Annex 2, 2017.
Wilson E.M. Engineering Hydrology [Book]. - Stanford: TheMacmillan Press LTD. , 1978.
The expert in WATER ENVIRONMENTS 17
78
79
Annex 17
Danish Hydraulic Institute (DHI), Study of the Flows in the
Silala Wetlands and Springs System, 2018
Annex I: Questionnaire put by the Plurinational State of Bolivia
to DHI
(Original in English)
80
81
Contract CDP-I No 01/2018, Study of
the Flows in the Silala Wetlands and
Springs System
Product No. 2 - 2018
Annex I - Questionnaire put by the Plurinational
State of Bolivia to DHI
Source: DIREMAR, 2017
Plurinational State of Bolivia, Ministry of Foreign Affairs, DIREMAR
July 16, 2018
Page 1 of 5
82
Page 2 of 5
83
Questionnaire put by the Plurinational State of Bolivia to DHI
1 Introduction
In relation with DH l's final report: "Study of the Flows in the Silala Wetlands and Springs System" the Client
(Bolivia's Strategic Office for the Maritime Claim, Silala and International Water Resources -
DIREMAR) has submitted seven clarifying questions to DHI. The questions and DH l's response to each of
them are listed below.
2 Questions and responses
1. DHI has found the waters of Silala to be a system of springs with a
"modified flow", how do you explain the concept of "modified flow"?
Response:
A system with modified flows is a system in which the flows have changed as a consequence
of human interventions, typically in contrast to a 'natural' flow system unaffected by man.
2 What is the impact that the modifications introduced in the Silala
Springs System had on the latter's surface flow?
Response:
The canalization and the excavations associated with it, have lowered the water levels and
reduced the water storage in the wetlands as compared to a natural system. This has
increased the hydraulic gradients, reduced hydraulic resistance through the springs and
increased their discharge. The lowered water levels in the wetlands has also reduced
evaporation relative to a natural wetland.
Hence, the canalization increases the drainage flows, lower the groundwater tables, reduces
the evapotranspiration and alter the groundwater/surface water interactions.
3 Can the current surface flow of the Silala from Bolivia to Chile be
regarded, from a hydrological perspective, as a natural water flow?
Response:
No, the canals have increased the surface water flow at the border as compared to a natural
situation.
While the discharge of groundwater through the springs and by seepage in wetlands has not
been introduced by man, the canals have increased surface water flow artificially.
The canal and drainage system have impacted flow, storage and water levels in Silala as
compared to a natural system, i.e. a system unaffected by man. Model analyses show a
decrease in surface flow without canals.
Page 3 of 5
84
4 What is the behavior of the groundwater of Silala?
Response:
Although groundwater level gradients and hydrogeological properties clearly indicate
groundwater flow from Bolivia to Chile, the total groundwater flow across the entire depth and
width of the border area is not known. However, available data and modeling support that the
groundwater flow across the border is at least of the same order of magnitude as surface
water discharge at the border.
5 In which of the hydrogeological units, inside Bolivian territory, has the
existence of aquifers in the Silala been identified? Do any of this
aquifers cross the border?
Response:
Silala surface water is predominantly comprised of groundwater discharge from the aquifers
through springs and diffuse inflows along the canals.
The groundwater system in Silala is complex and is comprised of a fractured ignimbrite
aquifer, with variable degrees of interconnectivity between different interbedded layers. We
have identified the ignimbrite layers (HGU5, HGU6) and the fault zone in the Silala ravine
(HGU7) as the dominant aquifers of the system. All these aquifers cross the border
6 Taking into account the dating of the waters of Silala, could it be
affirmed that part of the groundwaters are not renewable?
Response:
Analyses of groundwater samples from springs and shallow piezometers in the northern
wetland and southern wetland, respectively, demonstrate significant differences in water
chemistry indicative of two different sources of origin. Also the radiocarbon dating suggest that
groundwater discharge to the southern wetland is significantly older (potentially on the order
of thousands of years older) than that to the northern wetland , with an apparent age less
than a thousand years. The water in the northern wetland may be from a combination of
various sources, for example significantly younger water mixed with older water from the same
source as the southern wetland or simply a more localized source of recharging waters.
Since the groundwater residence times in the Silala aquifers maybe very long, high
groundwater ages do not in themselves imply that the water is non-renewable. Our analyses
indicate that a substantial part of the Silala discharge may be recharged in the upstream
groundwater catchment. This, however, does not preclude that a portion of the groundwater
discharging to the Silala wetlands is from non-renewable sources. It has not been not possible
to determine the magnitude of such portion.
Page 4 of 5
85
7 Will the removal of the canals installed in the bofedales and in the Silala
ravine in Bolivia contribute to the natural recovery of the wetland
ecosystem?
Response:
Restoration of the hydrological conditions is a prerequisite for achieving a wetland ecosystem
comparable to pre-canal conditions. Hence, a proper removal of the canals will contribute to a
natural recovery.
Restoration of wetlands by removing the drainage and canal system will have an immediate effect
on flows and hydrological processes. Reestablishing wetland vegetation and the formation of
peat by biological processes will affect the eco-hydrological conditions but over a much longer time
scale, probably decades.
Page 5 of 5
86
87
Annex 18
Ramsar Convention Secretariat, Report Ramsar Advisory
Mission Nº 84, Ramsar Site Los Lipez, Bolivia, 2018
(Original in Spanish, English translation)
88
CONVENTION ON WETIANDS
CONVENTIO ' SUR LES ZONES HUMIDES
CONVENCI6 ' SOBRE LOS l·IUMEDALES
(Ramsa r, lrnn, 1971)
Secretaria de la Convenci6n Ramsar
lnforme
Misi6n Ramsar de Asesoramiento No. 84
Sitio Ramsar Los Lipez, Bolivia
Agosto 3 de 2018
1
89
Ramsar Convention Secretariat
Report
Ramsar Advisory Mission Nº 84
Los Lipez Ramsar Site, Bolivia
3 August 2018
■ CONVENTION ON WE'llANDS
CONVENTION SUR LES ZONES IIUMIDES
CONVENCl6N S013HE I.OS IIUMEDALES
(Ramsar, lmn, 1971)
90
INDICE
Misi6n Ramsar de Asesoramiento Sitio Ramsar Los Lipez
lntroducci6n General .. .... ..... ... ... .. ... .. ...... . .... ... .... .. ... ... ... .. ........... ....... ......... ... .. .... .. .... ... Pagina 4
1.1 Los Humeda les de lmportancia Internacional y disposiciones de la Convenci6n ....................... 4
1.2 Los conceptos de cambio en las caracterfsticas eco16gicas, uso racional y
se rvicios ecosistemicos...... ... .. .... .. ... .. .... ... ..... . ... ... .... .. ... .... ... .. ... .... ... .... .... .... ..... ..... 5
1.3 Misiones Ramsar de Asesoramiento (MRA) ... ... ............ .. ............. ... ... ... ........................................... 5
1.4 Aplicacion de la Convencion Ramsar en Bolivia ..... ............. ............. ................................... ............. 6
2. Programa de trabajo de la Mision .. ................................................. ... ......... ....... .. ....... .... ....... .... 6
2.1 Objetivo de la Mision ... ....... .. ... ........................ ...................... .. .......... .................................................. 7
2.2 Programa de Actividades ... .. ... .... .... ..... ... ... ...... ... ...... ........ .. ... ..... ... .. .... ... .. .... ... ... ... ... ....... .. ... ..... .. .. .... . 7
3. Aspectos de Unea Base del Sitio Ramsar ....................................................................... ..... .. .. 7
3.1 Aspectos generales, criterios de designacion, otros aspectos ... .. ... ... ... ...................................... 7
3.2 Servicios eco-sistemicos ................................................................................................................... 10
3.3 Aspectos ffsicos ...................................... ............................................................................................ 11
3.3.1 Clima y geomorfologia ................................................................................................................... 11
3.3.2 Geologia ........................................................................................................................................... 17
3.3.3 Hid rologfa superficial ..................................................................................................................... 21
3.3.4 Hidrologia subterranea ................................................................................................................. 22
3.3.5 Suelos .............................................................................................................................................. 23
3.4 Uso del suelo ................................................................................................................................. 24
4 Est ado actual del sitio ................................................................................................................... 24
(factores de deterioro naturales/antropogenicos pasados presentes)
4.1 Componente ffsico .................................................................................................................... 26
4.1.1 Geomorfologia ... .......................... ... ................ ............ ..... .... ... ............... .. ...................................... 27
4.1.2 Hidrologia superficial .................. ... ... ....................... ............ ............ ........... ..... ... ............. ........... .. 27
4.1.3 Hidrologia subterranea ..................................................................................... .. .... .. ...... ... .... ...... 27
4.1.4. Suelos ................................................... ......................................................................................... 28
4.2 Componente ecosistemico ................................. ..... ................... .... .. .................. ......................... 28
4.2.1 Flora y vegetacion ............ ... ......... ......... .......... .............. ... ... ... ... ...... ...... ....... ..... ....... ..... .. ... ......... 28
4.2.2 Fauna ...... ..... .. .................. ..... ...... ... ... .. .... ............. ................................. .. ............ ... ....... .. ..... ..... ..... 29
5. Evaluacion del cambio en las caracteristicas ecologicas ... .... .. ... ............ .... ... ........ ...... ..... .... 29
5.1 Aspectos ffsicos ............... .. ..... .... .......... ............ ... ... ... ............ ............... ... ... ................. ................. 29
5.1.1 Hidrologia superficia l ...... .............................. .. .. .... .... ............... ........................... ........................ 29
5.1.2 Hidrologia subterranea ......................... ..... ................... ........ .. .. ............. ....... ..... ............. ... ........ .30
5.1.3 Suelos ........... ... ......... .. .... .. ... ... ......... .. ........ .... .... ..... ............... .. .... ...... ...... ............ ....... ........ .. ...... 36
2
91
INDEX
Ramsar Advisory Mission—Los Lipez Ramsar Site
1. General Introduction
1.1 Wetlands of International Importance and the provisions of the Convention
1.2 The concepts of change in ecological characteristics, rational use, and ecosystem
services
1.3 Ramsar Advisory Missions (RAM)
1.4 Application of the Ramsar Convention in Bolivia
2. The Mission’s Working Program
2.1 The Mission’s Objective.
2.2 Activity Program
3. Baseline Aspects of the Ramsar Site
3.1 General Aspects, designation criteria, and other aspects
3.2 Ecosystem services
3.3 Physical Aspects
3.3.1. Climate and geomorphology
3.3.2. Geology
3.3.3. Surface hydrology
3.3.4. Groundwater hydrology
3.3.5. Soils
3.4. Land use
4. Current state of the site (past and present natural/anthropogenic factors of
deterioration)
4.1 Physical component
4.1.1 Geomorphology
4.1.2 Surface hydrology
4.1.3 Groundwater hydrology
4.1.4 Soils
4.2 Ecosystem component
4.2.1 Flora and vegetation
4.2.2 Fauna
5. Assessment of changes in ecological characteristics
5.1. Physical aspects
5.1.1 Surface hydrology
5.1.2 Groundwater hydrology
5.1.3 Soils
92
5.1.4 Geomorfologfa ......... ............... ................................................................................................... 36
5.1.5 Salin idad ... ......... ... ...... ... ...... ..................... ................................. ...................................... ...... ..... 38
5.1.6 Calidad del agua ...................................................................................................................... .. 38
5.2 Aspectos ecologicos ..................................................................................................................... 38
5.2.1 Flora y vegetacion ..................................................................................................................... 39
5.2.2 Fauna .......................................................................................................................................... 39
6.
7.
Conclusiones ......... ... ..... . . ................................................................................... 39
Recomendaciones ..................... ............ .. . . ............................... ......... ......... .......... 40
8. Referencias bibliograficas .................................................................................................. .41
Anexo 1 ............................................................................................................................................... .43
3
93
5.1.4 Geomorphology
5.1.5 Salinity
5.1.6 Water quality
5.2. Environmental aspects
5.2.1. Flora and vegetation
5.2.2. Fauna
6. Conclusions
7. Recommendations
8. Bibliographic references
Annex 1
94
Misi6n Ramsar de Asesoramiento No. 84
Sitio Ramsar Los Lipez
1. lntroducci6n General
La Convenci6n sobre los Humedales de lmportancia Internacional o Convenci6n Ramsar es un
tratado intergubernamental que proporciona el marco para la acci6n nacional y la cooperaci6n
internacional para la conservaci6n y uso racional de los humedales y sus recursos. A marzo de 2017
hay 169 Paises Pa rte en la Convenci6n y 2,261 Humedales de lmportancia Internacional, con una
superficie total de 215, 277, 357 hectareas.
La Convenci6n basa su acci6n en tres pi la res, el uso racional de todos los recursos de humedales en
cada pais, la designaci6n de humedales de importancia internacional y su gesti6n, y la cooperaci6n
internacional.
1.1 Los Humedales de lmportancia Internacional y disposiciones de la Convenci6n
Las Partes Contratantes en la Convenci6n sobre los Humedales tienen el deber, con arreglo al parrafo
4 del articulo 2, de designar por lo menos un sitio para ser inscrito en la Lista de Humedales de
lmportancia Internacional al firmar la Convenci6n o depositar su instrumento de ratificaci6n ode
adhesion, de conformidad con las disposiciones del Articulo 9.
Segun el artfculo 1, parrafo 1 "son humedales las extensiones de marismas, pantanos y turberas, o
superficies cubiertas de aguas, sean estas de regimen natural o artificial, permanentes o temporales,
estancadas o corrientes, dulces, salobres o saladas, incluidas las extensiones de agua marina cuya
profundidad en marea baja no exceda de seis metros" y "podran comprender sus zonas riberefias o
costeras adyacentes, asi como las islas o extensiones de agua marina de una profundidad superior a
los seis metros en marea baja, cuando se encuentren dentro del humedal" (articulo 2, parrafo 1).
La Lista Ramsar de Humedales de lmportancia Internacional, de conformidad con el Articulo 2 del
texto del tratado, es la piedra angular de la Convenci6n de Ramsar y su principal objetivo es crear y
mantener una red internacional de humedales que revistan importancia para la conservaci6n de la
diversidad biol6gica mundial y para el sustento de la vida humana a traves del mantenimiento de los
componentes, procesos y beneficios/servicios de sus ecosistemas. lgualmente, tiene como fin
promover la cooperaci6n entre las Partes Contratantes, y los interesados directos locales en la
selecci6n, designaci6n y manejo de los sitios Ramsar.
La designaci6n de sitios para ser incluidos en la Lista de Humedales de lmportancia Internacional
"debera basarse en su importancia internacional en terminos ecoI6gicos, botanicos, zooI6gicos,
limnoI6gicos o hidrol6gicos" (parrafo 2 del articulo 2). Segun el articulo 3 parrafo 1 de la Convenci6n,
las Partes estan obligadas a "elaborar y aplicar su planificaci6n de forma que favorezca la
conservaci6n de los humedales incluidos en la Lista y, en la medida de lo posible, el uso racional de
los humedales de su territorio".
4
95
Ramsar Advisory Mission Nº 84
Los Lipez Ramsar Site
1. General Introduction
The Convention on Wetlands of International Importance, or Ramsar Convention
is an intergovernmental treaty that provides a framework for national actions and
international cooperation directed towards the preservation and rational use of wetlands
and their resources. As of March 2017, there are 169 countries that are parties to the
Convention and 2,261 wetlands of international importance registered, covering a total
area of 215,277,357 hectares.
The Convention bases its actions on three pillars, i.e. the rational use of wetland
resources in each country, the designation and management of wetlands of international
importance, and international cooperation.
1.1 Wetlands of International Importance and the provisions of the Convention
The Contracting Parties to the Convention on Wetlands have the duty, by virtue of article
2, paragraph 4, to designate at least one site to be registered in the List of Wetlands
of International Importance when signing the Convention, or when depositing their
instrument of ratification or adhesion, in conformity with the provisions of Article 9.
In accordance with Article 1, paragraph 1, “wetlands are areas of marsh, fen, peatland
or water, whether natural or artificial, permanent or temporary, with water that is
static or flowing, fresh, brackish or salt, including areas of marine water the depth of
which at low tide does not exceed six meters” and, under Article 2, paragraph 1, “may
incorporate riparian and coastal zones adjacent to the wetlands, and islands or bodies
of marine water deeper than six meters at low tide lying within the wetlands” (Article
2, paragraph 1).
The Ramsar List of Wetlands of International Importance, in accordance with Article 2
of the treaty text, is the cornerstone of the Ramsar Convention and its main objective
is to create and maintain an international network of wetlands that are relevant for the
preservation of global biological diversity and for the sustenance of human life by
ensuring that the components, processes, and benefits/services of their ecosystems are
preserved. It also aims at promoting cooperation between the Contracting Parties and
local stakeholders in the selection, designation, and management of Ramsar sites.
The designation of sites to be included in the List of Wetlands of International
Importance must be based on “their international significance in terms of ecology,
botany, zoology, limnology or hydrology” (Article 2, paragraph 2). As per Article 3,
paragraph 1 of the Convention, the Parties are under the obligation to “formulate and
implement their planning so as to promote the conservation of the wetlands included in
the List, and as far as possible the wise use of wetlands in their territory.”
4
96
En el articulo 3 parrafo 2 de la Convenci6n, se estipula que cada Parte Contratante tomara las
medidas necesarias para informarse lo antes posible acerca de las modificaciones de las condi ciones
eco16gicas de los humedales situados en su territorio e incluidos en la Lista, y que se hayan producido
o puedan producirse coma con secuencia del desarrollo tecnol6gico, de la contaminaci6n ode
cualquier otra intervenci6n del hombre. Las informaciones sabre dichas modifica ciones se
transmitiran sin demora a la Secretaria en el marco del Articulo 8.
En el anterior sentido, las Partes Contratantes se comprometen con la designaci6n de los sitios
Ramsa r a administrar dichos sitios de forma tal que se mantengan las caracteristicas eco16gicas de
cada uno de ellos y, de esa manera, mantener las funciones eco16gicas e hidro16gicas esenciales que
redundan en ultima instancia en sus "productos, funciones y atributos" .
El Registro de Montreux es un registro de los humedales inscritos en la Lista de Humedales de
lmportancia Internacional, en los que se estan produciendo, se han producido o pueden producirse
cambios en las caracteristicas eco16gicas coma consecuencia del desarrollo tecno16gico, la
contaminaci6n u otra intervenci6n del ser humano. El Registro se lleva coma parte de la Lista de
Ramsar.
1.2. Los conceptos de cambio en las caracteristicas ecol6gicas, uso racional y servicios
ecosistemicos
El cambio en las caracteristicas eco16gicas esta definido en el contexto de la Convenci6n coma el que
se produce en cualquiera de los componentes (biol6gico, quimico, fisico), procesos ecol6gicos o
servicios del humedal inducidos por la acci6n humana.
Por su parte, el concepto de uso racional es uno de los tres pilares de la Convenci6n y hace referencia
al mantenimiento del caracter eco16gico a traves de la implementaci6n de un enfoque por
ecosistemas en el contexto del desarrollo sostenible.
En el marco de la Convenci6n Ramsar las Partes Contratantes, aprobaron mediante la Resoluci6n IX.1
Anexo A.j los aspectos referentes a los servicios ecosistemicos de los humedales de la Evaluaci6n de
Ecosistemas del Milenio. En este contexto se definen coma los beneficios que las personas obtienen
de los ecosistemas Tabla 1. Estos incluyen la provision de servicios tales coma alimentos, agua,
servicios de regulaci6n coma control de inundaciones, sequias, degradaci6n de tierras y
enfermedades. Servicios de soporte coma formaci6n de suelos y ciclos de nutrientes; servicios
culturales coma recreaci6n, espirituales o religiosos asi coma otros beneficios no materiales.
:..ummIsiro, oe se rv1,c1os HegmacIon ae se rvIa os ::iervIaos ,crn1uraIes
Produc10s ctxenidoo de loo Bemficios oblenidos d0 los Bllneficioo no materiales
ec osistemas i:x-o:: esoo de rngulac ion de los . ooteni dos de kls ocosistemas Alim ento ecosistern as . . Espiritualas y rs! igi ooos Agua potable . Aag ulac i6n del clima . . Rocreooi6n y tuns mo Ccrn bustible . Control de en!Grm edades . . Estcitico Fl bra vegetal . Rag ulac i6n del agu a . . lnsr:;i rac i6nal Bioqu fmicos . Puri1caci6n del agua . . EdJc ativo Rec U ISOS gen eh:: 00 . Polin izaci6n . . S6111klo de dentidad Patrim onio cultural
Se rvi ciosde sopone
SeNcioo nec esari os para laprodu:: ci6n de todos las otros servicios del ec osistema
Form aci6n de susloo Cic I ado de nutri entes Pioouccion prim aria
Tabla 1. Servicios ecosistemicos de los humedales, definidos en la Evaluaci6n de Ecosistemas del
Milenio (2005).
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Article 3, paragraph 2 of the Convention provides that each Contracting Party is
to take the necessary measures to be informed the soonest possible of the changes
occurring in the ecological conditions of the wetlands located within their territories
and included in the List—changes that may have taken place, or are likely to, as a
result of technological development, pollution, or any other human interference. The
information on such changes must be transmitted without delay to the Secretariat, as
specified under Article 8.
In keeping with the above provisions, the Contracting Parties undertake, by
designating Ramsar sites, to manage such sites in a way that preserves their ecological
characteristics and, in this way, to maintain the ecological and hydrological functions
that ultimately result in their “products, functions, and attributions”.
The Montreux Record is a register of the wetlands included in the List of Wetlands of
International Importance where changes in the ecological character have occurred, are
occurring, or are likely to occur as a result of technological developments, pollution,
or any other human intervention. This Record is maintained as part of the Ramsar List.
1.2 The concept of change in the ecological characteristics, rational use, and
ecosystem services
The concept of change in ecological characteristics is defined in the context of the
Convention as that which occurs in any of the (biological, chemical, or physical)
components, ecological processes, or wetland services induced by human actions.
The concept of rational use, for its part, is one of the three pillars of the Convention
and refers to the maintenance of the ecological character through the implementation
of an ecosystem approach in the context of sustainable development.
In the framework of the Ramsar Convention, the Contracting Parties approved, by
way of Resolution IX.1, Annex A. j, the aspects related to the ecosystem services
of wetlands contained in the Millennium Ecosystem Assessment. The benefits that
people obtain from ecosystems are defined in Table 1 and include the provision of
services such as alimentation, water, and regulation systems such as flood, drought,
land degradation, and disease control; including support services such as soil formation
and nutrient cycles, cultural services such as amusement, spiritual, and religious, as
well as other non-material benefits.
Table 1. Wetland ecosystem services, as defined in the Millennium Ecosystem
Assessment (2005).
5
Service provision
Products obtained from
ecosystems
Alimc ntation
Drinking water
Fuds
Vegetable fibers
Biochemical
products
Genetic
resources
Service regulation
Benefits obtained from
ecosystem regu lntion
processes
C limate regulation
Disease contro l
Waler rcgulalion
Water purification
Pollination
Support Services
Cultural services
Non-material benefits
obtnined from ecosystems
Spiritual, or
religious benefits
Entertainment
and tourism
Esthctic
Lnspiratio nal
Educational
Sense of identity
C ultural heritage
Services necessary for the production of other ecosystem services
Soil formation Nutrient cvcles Primarv oroduction
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1.3 Misiones Ramsar de Asesoramiento (MRA)
En el parrafo 18 de la Resolucion X.13 (2008), las Partes Contratantes reafirmaron el compromiso "de
aplicar plenamente los terminos del Artfculo 3.2 relativos a la obligacion de informar sobre las
modificaciones y conservar o restablecer las caracterfsticas ecologicas de sus sitios Ramsar, incluso
mediante todos los mecanismos apropiados para abordar y resolver tan pronto como sea posible los
asuntos por los que un sitio haya podido ser objeto de un informe en cumplimiento del Artfculo 3.2;
y, una vez resueltos dichos asuntos, presentar un nuevo informe para que las influencias positivas en
los sitios y los cambios en las caracterfsticas ecologicas puedan reflejarse fielmente en los informes
presentados a las reuniones de la Conferencia de las Partes, a fin de exponer con claridad el estado y
las tendencias de la red de sitios Ramsar."
En el marco de la Convencion, se concede especial atencion a la prestacion de asistencia a las Partes
Contratantes en el manejo y la conservacion de los sitios designados de la Lista cuyas caracterfsticas
ecologicas se vean amenazadas. Esta labor se lleva a cabo mediante la Mision Ramsar de
Asesoramiento (MRA), un mecanismo de asistencia tecnica adoptado oficialmente mediante la
Recomendacion 4.7 de la Conferencia de las Partes de 1990. El principal objetivo de este mecanismo
es ofrecer asistencia a los pafses desarrollados yen desarrollo indistintamente con el fin de que
resuelvan los problemas o las amenazas que hicieron o hacen necesaria la inclusion del sitio en el
Registro de Montreux.
Tras recibir una solicitud de una Parte Contratante, la Secretarfa conviene en organizar la MRA con
las autoridades competentes y determina el tipo de experto que hara falta incluir en el equipo de la
mision. El proyecto de informe de la Mision que consigna conclusiones y recomendaciones se
transmite a las autoridades competentes que han solicitado la MRA para su revision y la version
revisada definitiva del mismo se convierte en documento publico, que puede servir de base para
tomar medidas de conservacion en el sitio.
1.4 La aplicacion de la Convencion Ramsar en Bolivia
La Convencion Ramsar entro en vigor en Bolivia el 27 de Octubre de 1990 e incluye como primer
Humedal de lmportancia Internacional Los Lipez (originalmente Laguna Colorada). A la fecha cuenta
con 11 sitios Ramsar o Humedales de lmportancia Internaciona l que cubren 14, 842,405 hectareas,
convirtiendose en el pafs con mas area de Humedales designados de lmportancia Internacional en la
Convencion.
El Viceministerio de Medio Ambiente, Biodiversidad, Cambios Climaticos y de Gestion y Desarrollo
Foresta I es la Autoridad Administrativa de la Convencion y agenda implementadora en Bolivia.
A traves del Fondo de Humedales para el Futuro, Bolivia ha recibido apoyo financiero por un valor de
USD$116,727 para la implementacion de proyectos orientados hacia el fortalecimiento de
capacidades y designacion de sitios Ramsar. lgualmente, por el Fondo de Pequef\as Subvenciones se
han financiado proyectos por un valor de CHFl00,600.
En cuanto a otros procesos de implementacion regional, Bolivia hace parte de las lniciativas
Regionales que operan en el marco de la Convencion: Humedales Alto Andinos, Amazonas y Cuenca
del Plata.
2. Programa de Trabajo de la Mision
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1.3 The Ramsar Advisory Missions (RAM)
Under Paragraph 18 of Resolution X.13 (2008), the Contracting Parties reaffirmed
their commitment “to implement fully the terms of Article 3.2 on reporting change,
and to maintain or restore the ecological character of their Ramsar sites, including
employing all appropriate mechanisms to address and resolve as soon as possible the
matters for which a site may have been the subject of an Article 3.2 report; and, once
those matters have been resolved, to submit a further report, so that both positive
influences at sites and changes in ecological character may be fully reflected in the
reporting to meetings of the Conference of the Parties in order to establish a clear
picture of the status and trends of the Ramsar site network.”
In the framework of the convention, special attention is paid to the provision of
assistance to the Contracting Parties in the management and preservation of the List
sites whose ecological characteristics are threatened. This task is carried out by means
of the Ramsar Advisory Missions (RAM), a technical assistance mechanism adopted
officially under Recommendation 4.7 of the Meeting of the Conference of the Parties
held in 1990. The main objective of this mechanism is to offer assistance to developed
and developing countries, indistinctively, with a view to resolving the problems or
threats that had made the inclusion of their sites into the Montreux Record necessary,
or that are likely to make it necessary.
After receiving a Contracting Party’s request, the Secretariat arranges a RAM with the
competent authorities and determines the particular expert needed for the mission’s
team. The Mission’s draft report, including conclusions and recommendations, is
transmitted to the competent authorities that requested a Ramsar Advisory Mission for
them to examine it, and the final version of the report becomes a public document that
can serve as the basis to take preservation measures in the site.
1.4 Application of the Ramsar Convention in Bolivia
The Ramsar Convention entered into force in Bolivia on 27 October 1990 and
includes Los Lipez (originally Laguna Colorada—Red Lagoon) as Bolivia’s first
Wetland of International Importance. To date, Bolivia has registered 11 Ramsar sites,
or Wetlands of International Importance covering an area of 14,842,405 hectares,
making it the country with the largest extent of Wetlands designated as Wetlands of
International Importance under the Convention.
The Vice-Ministry of Environment, Biodiversity, Climate Change, and Forest
Management and Development is the Convention’s Administrative Authority and the
implementing agency in Bolivia.
Through the Wetlands for the Future Fund, Bolivia has received financial support
equivalent to an amount of 116,727 USD for the implementation of projects directed
toward strengthening its capacities and designation of Ramsar sites. Similarly, through
the Ramsar Small Grants Fund, projects have been financed with a value of 100,600
CHF.
Concerning other regional implementation projects, Bolivia is part of the Regional
Initiatives that operate within the framework of the Convention: High Plateau wetlands,
the Amazon River, and La Plata Basin.
2. The Mission’s Working Program
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2. 1 Objetivo de la Misi6n
En nota diplomatica del 29 de Julio de 2016 la Misien Permanente del Estado Plurinacional de
Bolivia, transmite comunicacien del Viceministro de Relaciones Exteriores mediante la cual informa a
la Secretaria de Ramsar de cambios en las caracteristicas ecolegicas del Sitio Ramsa r los Lipez
(incluye bofedal del Silala y areas conexas del sitio Ramsar Los Lipez) y solicita oficialmente una
Misien Ramsar de Asesoramiento en dicho sitio.
Como respuesta a la solicitud del Gobierno de Bolivia y de acuerdo a las competencias de la
Secretaria, la Misien Ramsa r de Asesoramiento se realize del 7-11 de noviembre de 2016 con el fin
de proporcionar recomendaciones al Gobierno de Bolivia respecto a la problematica ambiental
que presenta el sitio y que permitan el mantenimiento de sus caracteristicas ecolegicas.
Con base a la informacien tecnica suministrada por el Ministerio del Medio Ambiente y Agua,
complementada por las presentaciones tecnicas y visita al Sitio Ramsar, el presente informe presenta
una serie de conclusiones y recomendaciones a los estamentos de gobierno de Bolivia y tomadores
de decisiones para el mantenimiento de las caracteristicas ecolegicas en el contexto de la
Convencien.
2. 2. Programa de Actividades
La Misien se realize del 7-11 de Noviembre de 2016 y conto con el apoyo del personal directivo del
Ministerio de Relaciones Exteriores en cabeza del Viceministro asi como profesionales del Ministerio
de Medio Ambiente y de diferentes instancias gubernamentales nacionales y regionales. La
Secretaria de Ramsar agradece al gobierno de Bolivia a traves de los anteriores estamentos sus
oficiales y expertos tecnicos todo el apoyo prestado para el desarrollo de la Misien.
La Misien estuvo coordinada por la Secretaria de la Convencien Ramsar a traves de la Consejera
Regional para las Americas, e hicieron pa rte de la misma un experto en hidrogeologia. El gobierno de
Bolivia asigne un grupo de expertos tecnicos del Ministerio de Medio Ambiente y otros estamentos
para acompaiiar la Misien.
La Misien reviso la informacien provista por el Gobierno de Bolivia durante la visita asi como la
proporcionada a partir de las reuniones tecnicas con los expertos. Los documentos consultados se
encuentran listados en la bibliografia y el programa de la Misien en el anexo 1. lgualmente, se realize
una visita por carro al sitio Ramsar.
3. Aspectos de Linea Base del Sitio Ramsar
3.1 Aspectos generales, criterios de designaci6n, otros aspectos
El Sitio Ramsar los Lipez (originalmente Laguna Colorada) fue designado el 27 de Junio de 1990
con un area de 1,427,717 ha. Esta localizado en el Altiplano Boliviano entre 4,200 a 6,000 m. El
sitio original se extendie significativamente en el 2009 e incluye un complejo de lagunas Alto
Andinas endorreicas hipersalinas asi como bofedales y humedales geotermicos. Estos
humedales sustentan aves migratorias tales como el Pholoropus tricolor y Colidris boirdii los
cuales usan estos humedales como sitio de parada y alimentacien. Adicionalmente, 25% y 50%
de las poblaciones globales del flamenco andino (Phoenicoporrus ondinus) y flamenco de James
(Phoenicoporrus jomesi), se concentran en esta area. Debido a su belleza paisajistica y
atractivos naturales es el area protegida mas visitada en Bolivia (Apro. 70,000 turistas por ano)
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2.1 The Mission’s Objective
Through Diplomatic Note of 29 July 2016, the Deputy Foreign Minister of the
Permanent Mission of the Plurinational State of Bolivia sent a communication
informing the Ramsar Convention Secretariat of changes occurring in the ecological
characteristics of Los Lipez Ramsar Site (which comprises the Silala wetlands and
related areas of Los Lipez Ramsar Site) and officially requested a Ramsar Advisory
Mission for the site.
Responding to the request made by the Government of Bolivia, and in accordance
with the competences of the Secretariat, the Ramsar Advisory Mission was carried
out from 7 to 11 November 2016 for the purpose of providing recommendations to the
Government of Bolivia in regard to the environmental problems occurring in the site
and to allow maintaining its ecological characteristics.
On basis of the technical information provided by the Ministry of Environment
and Water, which was complemented with the technical presentations and site visit
made to the Ramsar Site in question, this report presents a series of conclusions
and recommendations for the different governmental levels and decision-makers of
Bolivia to maintain the ecological characteristics of the site within the context of the
Convention.
2.2 Activity Program
The Mission was carried out from 7 to 11 November 2016 and was supported by
the management staff of the Ministry of Foreign Affairs, led by the Deputy Foreign
Minister, as well as by professionals of the Ministry of Environment and of different
national and regional government instances. The Ramsar Secretariat thanks the
Bolivian Government, through its officials and expert technicians, for the support
provided to carry out the mission.
The Mission was coordinated by the Secretariat of the Ramsar Convention through the
Regional Advisor for the Americas and had the participation of an expert hydrologist.
The Government of Bolivia appointed a group of expert technicians of the Ministry of
Environment and other Government institutions to accompany the Mission.
The Mission examined the information provided by the Government of Bolivia
during the visit, as well as that provided in technical meetings held with experts. The
documents consulted are listed in the bibliography and Mission’s Program found in
Annex 1. Likewise, a site visit by car was made to the Ramsar site in question.
3. Baseline Aspects of the Ramsar Site
3.1 General Aspects, designation criteria, and other aspects
The Los Lipez Ramsar site (originally, Laguna Colorada—Red Lagoon) was designated
on 27 June 1990, with an area of 1,427,717 hectares. It is found in the Bolivian High
Plateau, between 4,200 and 6,000 m. The original site was significantly extended in
2009 and now includes a complex of high Andean endorheic and hypersaline lagoons, as
well as geothermal wetlands and highland wetlands. These wetlands sustain migratory
birds such as Phalaropus tricolor and Calidris bairdii, which use these wetlands as
stop and feeding sites. Additionally, 25% and 50% of the global population of Andean
flamingoes (Phoneicoparrus andinus) and James’s flamingoes (Phoenicoparrus
james) are found in this area. Due to its beautiful landscapes and natural attractions,
this is the protected area that is visited the most in Bolivia (receiving approximately
70,000 tourists per year).
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El sitio Ramsar cubre dos de los 14 sitios prioritarios de la red de humedales de importancia
para la conservacion de los flamencos alto andinos en Argentina, Bolivia, Chi le y Peru . Una pa rte
del sitio esta protegido por la Reserva Nacional de Fauna Andina Eduardo Ava roa.
De acuerdo a la Ficha lnformativa Ramsa r, 2009 el sitio fue incluido en el listado de Humedales
de lmportancia Internacional de la Convencion atendiendo a 6 de los siguientes criterios:
Criteria 1:
Son complejos de lagos permanentes sa linos/hipersa linos/a lcalinos, turberas coma bofedales y
humedales geotermicos, ubicados en una zona arida o semiarida y de caracter endorreico.
Criteria 2
Dos de las tres especies de flamencos presentes en el sitio, Phoenicopterus andinus se
encuentra vulnerable (VU) y P. jamesi como casi amenazada de acuerdo a las categorfas de la
UICN (2008).
Otras especies en categoria de casi amenazada son el avestruz andino andino (Pterocnemia
pennata), el condor andino (Vultur gryphus), Fulica cornuta yen bofedales Phegornis mitchellii.
Ent re los felinos el gato andino (Oreailurus jacobita o Leopardus jacobita)
y el gato del pajonal (Leopardus colocolo) corresponden a las categorfas "en peligro" y "casi
amenazado" de la IUCN 2008.
Criteria 3: El sitio alberga algunas especies endemicas restringidas coma el anuro Telmatobius
huayro. Entre los lacertilios estan presenten algunas especies del genera Lio/oemus con endemismos
regionales coma Lio/aemus isu/gensis erguetae y L. jamesi pachecoi (Ergueta, P., H. Gomez y 0 .
Rocha. 1997 citado en FIR 2009).
En plantas existe una alta proporcion de generos y especies endemicas. Los generos endemicos de
esta porcion de la Puna son Parostrephia, Lampaya, Chersodoma y Anthobryum (Frankenia) (Cabrera
y Willink 1973 citado en FIR, 2009). Las especies Chersodoma candida, Ch. jodopappa (Cabrera 1978
citado en FIR, 2009) y Chaetanthero sphaeroidalis (Navarro 1993, citado en FIR, 2009), son propias
de las regiones aridas y frias que crecen en las acumulaciones de rocas o en los tolares, bajo la
proteccion de los arbustos (Garcia, 2006 citado en FIR, 2009). Entre las cactaceas en cojin, coma
Opuntia cf. backebergii, es una endemica poco conocida.
Entre las gramineas endemicas se encuentran: Jarava {Stipa) methei, Festuca petersonii, F.
potosiana, especies effmeras de Hoffmannseggia y Nototrichie (lbisch et al, 2003 citado en FIR,
2009).
Criteria 4: El complejo de lagunas son sitios de parada y alimentacion para aves acuaticas migratorias
boreales que se encuentran en importantes concentraciones. Entre las especies mas abundantes
estan Phalaropus tricolor y Calidris bairdii.
Laguna Colorada es el sitio de nidificacion mas importante para el Flamenco de James (P. jamesi) en
toda su area de distribucion (Hurlbert y Keith 1979 citado en FIR, 2009).
Criteria 5: De acuerdo a los censos de Aves Acuaticas Neotropicales (Rocha y Aguilar no publicado),
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This Ramsar Site covers two of the fourteen priority sites of the network of wetlands
relevant for the preservation of high Andean flamingoes in Argentina, Bolivia, Chile,
and Peru. A part of this site is under the protection of the Eduardo Avaroa Andean
Fauna National Reserve.
In accordance with the Ramsar Information Sheet (RIS) of 2009, the site was included
in the List of Wetlands of International Importance of the Convention due to the
following criteria:
First,
these wetlands comprise permanent saline/hypersaline/alkaline lakes, and peatlands,
such as wetlands and geothermal wetlands, found in an arid or semiarid endorheic
zone.
Second,
of the three species of flamingoes present in the site, the Phoenicopterus andinus is
vulnerable (VU) and the P. Jamesi is classified as nearly threatened on the IUCN’s Red
List (2008).
Other species classified as nearly threatened are the Andean ostrich (Pretocnemia
pennata), the Andean condor (Vultur gryphus), the Fulica cornuta, and, within the
wetlands, the Phergonis mitchellii.
Concerning feline species, the Andean mountain cat (Oreailurus jacobita or Leopardus
jacobita) and the colocolo (Leopardus colocolo) are classified as “endangered” and
“nearly endangered” on the IUCN’s Red List for 2008.
Third,the site is home to some restricted-range endemic species such as the anuran,
Telmatobius huayra. Among the lizard species, the site is home to some species of the
Liolaemus genus with regional endemic species as the Liolaemus isulgensis erguetae
and L. Jamesi pachecoi (Ergueta, P., H. Gomez, and O Rocha, 1997, quoted in the RIS
of 2009).
Concerning plant families, there is a high amount of endemic genus and species.
The endemic species of this portion of the Puna are the Parastrephia, Lampaya,
Chersodoma, and Anthobryum (Frankenia) (Cabrera and Willink, 1973, quoted in
the RIS of 2009). The Chersodoma candida, Ch. Jodopappa (Cabrera 1978, quoted
in the RIS of 2009) and Chaetanthera sphaeroidalis (Navarro, 1993, quoted in the
RIS of 2009) species are characteristic of the arid and cold regions and grow on rock
accumulations or on tola plants (Parastrephia lepidophylla), protected by bushes
(Garcia, 2006, quoted in the RIS of 2009). Among the pincushion cacti species, the
Opuntia, cf. backebergii, is a little-known endemic genus.
Among the grass species, the following are present in the site: Jarva (stipa) methei,
Festuca petersonii, F. potosiana, together with the ephemeral species of Hoffmannseggia
and Notorichie (Ibisch, et al. 2003, quoted in the RIS of 2009).
Fourth, the lagoon complex is a stop and feeding site for boreal migratory waterbirds
that are found in considerable concentrations. The Phalaropus tricolor and Calidirs
bairdii are among the most abundant species.
Red Lagoon is the most important nesting site for the James’s Flamingo (P. jamesi)
genus throughout its area of distribution (Hurlbert and Keith, 1979, quoted in the RIS
of 2009).
Fifth, in accordance with the Census of Neotropical Waterbirds (Rocha and Aguilar,
unpublished),
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104
Caziani et al. (2007), Rocha (1997 y 2006), Rocha y Quiroga (1997), Valqui et al. (2000), citados en
FIR, 2009 y otras publicaciones, el sitio sustenta de manera regular una poblaci6n de 20.000 o mas
aves acuaticas.
Las especies mas abundantes son las tres especies de flamencos (Phoenicoparus jamesi, P. andinus y
Phoenicopterus chilensis) y dos playeros migratorios boreales (Pha/aropus tricolor y Calidris bairdii).
Criterio 6: El complejo de lagunas alberga una concentraci6n estival del 44-64% de la poblaci6n total
estimada de Flamenco de James (P. jamesi) y 22-28% de la poblaci6n total estimada de Flamenco
Andino (P. andinus) (Rocha 2006 citado en FIR, 2009).
Entre las especies aviares tambien esta presente la gallareta cornuda (Fulica cornuta) yes posible
que el sitio concentre a un 35% de la poblaci6n total de la especie que se estima en 7.669 individuos
(Rocha y Quiroga en prensa).
Caracteristicas ecol6gicas
El sitio esta conformado por un complejo de lagunas endorreicas permanentes, salinas, hipersalinas
y alcalinas, con abundante presencia de tres especies de flamencos y otras aves acuaticas residentes
y migratorias boreales, sitios prioritarios de nidificaci6n regular de flamencos altoandinos
(Phoenicoparrus james y P. andinus), con presencia de algunas especies casi amenazadas como la
gallareta cornuda (Fulico cornuta). Asimismo, se presentan turberas o bofedales con agua fresca,
altamente productivos de materia vegetal para forraje de ganado camelido. En este sitio existen
ademas humedales geotermicos subterraneos interconectados. El sitio se situa en un paisaje
esencialmente volcanico en una zona semidesertica, especialmente vulnerable al cambio climatico.
El sitio se ubica en una de las regiones mas pobres en especies de Bolivia y se caracteriza por la
presencia de bosques relictuales de Poly/epis tarapacana, asi como por fumarolas, aguas termales, y
lagunas de colores (FIR, 2009).
La vegetaci6n es tipica de la region biogeografica de la Puna Semiarida que esta caracterizada por
condiciones progresivas de aridez hacia el sur. Las condiciones de elevada salinidad, determinan la
presencia de una cobertura vegetal resistente a suelos halinos. La vegetaci6n crece de forma aislada,
ocupando grietas y lugares protegidos hasta los 4.800 y 5.000 ms.n.m., dominan las matas de
gramfneas de los generos Calamagrostis y Festuca con crecimiento en forma de semicirculo, debido
a la muerte de la rafz principal y por los fuertes vientos (Tropico- Swedeforest 1998, citado en FIR,
2009).
En las laderas con rocas volcanicas se observa los cojines de yareta (Azorella compacta) y pequeiias
comunidades de keiiua (Polylepis tarapacana). Se observan extensos pajonales abiertos con
gramfneas en mata que se distribuyen en laderas y planicies, en un rango altitudinal amplio. La
especie dominante es Festuca ortophylla, acompaiiada de Stipa y Ca/amagrostis y los cojines suaves
y amarillos de Pycnophyllum mo/le (Tropico- Swedeforest 1998 citado en FIR, 2009).
Las formaciones mixtas de pastizal-matorral, con diferentes especies de tola como Bacharis incarum,
Parastrephia lepidophylla, acompaiiadas de cactus en cojfn, como Opuntia cf backebergii, endemica
poco conocida. Los matorrales estan constituidos principalmente por la kh'iru thola (Parastrephia
/epidophyl/a), ph'ulica thola (P. quadrangularis) y la thola (P. lucida). Los matorrales mas abiertos
presentan Baccharis incarum, y arbustos aislados de Adesmia y Lampaya castellani (Lampaya), en
alturas menores. Los bofedales estan constituidos por cojines duros de la juncacea andina Oxych/oe
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Caziani et al (2007), Rocha (1997 and 2006), Rocha and Quiroga (1997), Valqui et al
(2000), quoted in the RIS of 2009 and other publications, the site regularly sustains a
population of 20,000 or more waterbirds.
The most abundant species in the site are the three flamingo species (Phoenicoparus
jamesi, P. andinus, and Phoenicopterus chilensis) along with two boreal migratory
shorebirds (Phalaropus tricolor and Calidris bairdii).
Sixth, the complex of lagoons is also home to a summery concentration of 44-64%
of the total population of the James’s flamingo (P. jamesi) and 22-28% of the total
estimated population of the Andean flamingo (P. andinus) (Rocha, 2006 quoted in the
RIS of 2009).
Among the avian species, there is also the presence of the gallareta cornuda (Fulica
cornuta) and the site is likely to concentrate a 35% of the total population of the species,
which is estimated in 7,669 specimens (Rocha and Quiroga, in the press).
Ecological characteristics
The site comprises a complex of permanent endorheic, saline, hypersaline, and alkaline
lagoons, characterized by an abundant presence of three flamingo species, as well as
other residing and boreal migratory waterbirds. These are regular nesting sites for
high Andean flamingoes (Phoenicoparrus james and P. andinus), with the presence
of some species that are classified as nearly threatened, such as the gallareta cornuda
(Fulica cornuta). Similarly, the site is also characterized by the presence of freshwater
peatlands, or wetlands, that produce high amounts of forage for camelid livestock. The
site also comprises interconnected underground geothermal wetlands and is located in
an essentially volcanic landscape that is found in a semiarid zone which is particularly
vulnerable to climate change.
The site is located in one of the most species-poor areas of Bolivia and is characterized
by the presence of relict forests of polylepis tarapacana, as well as fumaroles, hot
springs, and colored lagoons (RIS, 2009).
The vegetation is typical of the biogeographic region of the Semiarid Puna, which is
characterized by progressive conditions of aridness towards the south. The conditions
of high salinity result in the presence of haline-soil resistant vegetation, which grows
in isolation, occupying cracks and protected areas up to 4,800 and 5,000 m.a.s.l; there
is a higher presence of gramineous of the genus of Calamagrostis and Festuca, which
grow forming semicircles owing to the death of their main roots and the strong winds
(Tropico-Swedeforest, 1998, quoted in the RIS of 2009).
On the slopes characterized by volcanic rocks, it is possible to observe yareta cushions
(Azorella compacta) and small communities of keñua (Polylepis tarapacana).
Extensive open grasslands can also be observed, with forest gramineous that are
distributed in the slopes and plains, in a wide altitudinal range. The dominant species
is Festuca ortophylla, accompanied by Stipa and Calamagrostis and soft and yellow
cushions of Pycnophyllum molle (Tropico-Swedeforest 1998, quoted in the RIS of
2009).
The mixed formations of grassland-shrubs are characterized by different tola
species, such as Bacharis incarum, and Parastrephia lepidophylla, accompanied
by pincushion cacti as Opuntia cf. backebergii—which is endemic but little
known. The shrubs mainly consist of kh’iru thola (Parastrephia lepidophylla),
ph’ulica thole (P. quadrangularis) and thola (P. Lucida). The most open shrubs
are characterized by Baccharis incarum and isolated bushes of Adesmia and
9
106
andina y Distichia muscoides, acompaiiadas par gramineas de Calamagrostis (Tropico- Swedeforest
1998 citado en FIR, 2009).
En cuanto a la fauna ademas de las abundante presencia de tres especies de flamencos y otras aves
acuaticas, se encuentran mamfferos coma vicuiias, zorro andino, gato andino, vizcachas, tuco tuco
(Ptenomys spp.) y lagartijas del genera Lio/aemus y ranas del genera Tefmatobius (FIR, 2009).
3.2 Servicios eco-sistemicos
De acuerdo a la propuesta de Ecosistemas del Milenio, las servicios ecosistemicos/ambientales
son los bienes y beneficios que obtienen las personas de las ecosistemas. Estos incluyen las
servicios de regulacion, provision y culturales que directamente afectan a las personas, ademas
de los servicios necesarios para mantener los procesos ecologicos (soporte).
Entre las servicios ecosistemicos mas relevantes del humedal Los Lipez podemos destacar las
siguientes (FIR, 2009):
Las evidencias arqueologicas y actuales muestran claramente la fuerte dependencia de los
pobladores "lipeiios" a los recurses estrategicos de la region. Estos recurses estrategicos en la region
de Lipez son: el agua dulce -escasa en la region-, porciones de tierras cultivables para quinua y papa,
pastizales, bofedales y arbustales para la crianza de ganado camelido. Se hace evidente desde
tiempos milenarios que los asentamientos humanos en la region dependen fuertemente de
actividades ganaderas -cuidado de camelidos- que son desarrolladas principalmente en zonas de
bofedales y serranias.
Hoy en dia las actividades economicas se han diversificado y podemos encontrar ganaderia
camelida, produccion textil a partir de la lana de llama, la explotacion de recurses minerales no
metalicos - Ulexita y acido borico- en las riberas de las salares y la oferta de servicios turisticos que
en la ultima decada se ha incrementado exponencialmente, considerando que esta region junta al
Salar de Uyuni es la region con mayor afluencia turistica en todo el pais (alrededor de 70000
personas/aiio).
Sintesis de los servicios ecosistemicos del Sitio Ramsar Los Lipez
Suministro de servicios Regulaci6n de servicios Servicios culturales
Productos obtenidos Beneficios obtenidos de Beneficios no
de los ecosistemas los procesos de material es
regulaci6n de los obtenidos de los
ecosistemas ecosistemas
Alimento (Quinua y Regulacion del clima Recreacion y turismo
papa) Regulacion del agua Estetico/paisajistico
Agua potable Purificacion del agua Patrimonio cultural
Combustible (turba) Patrimonio
Fibras vegetales arqueologico
(totorales) Educative
Foresteria (Yareta,
Queiiua, Tholas)
Plantas medicinales
Ganado Camelido
10
107
Lampaya castellani (Lampaya), at lower altitudes. The wetlands consist of harder
cushions of the Andean Juncaceae, Oxychloe and Distichia muscoides, accompanied
by gramineous of Calamagrostis (Tropico-Swedenforest, 1998, quoted in the RIS of
2009).
In respect to the fauna, asides from the abundant presence of the three flamingo species
abovementioned and other waterbirds, it is also possible to find mammals as vicunas,
Andean foxes, Andean cats, viscachas, tuco tuco (Ptenomys spp.), lizards of the genus
Liolaemus and frogs of the Telmatobius genus (RIS, 2009).
3.2 Ecosystem services
Under the Ecosystems for the Millennium proposal, ecosystem/environmental systems
comprise the goods and benefits that people obtain from ecosystems. These include
regulation, provision, and cultural services that directly affect the people, as well as the
necessary services to maintain ecological processes (support).
Among the most relevant ecosystem services of Los Lipez wetlands, the following can
be highlighted (RIS, 2009):
Archeological and present-day data clearly evidence a strong dependence of the Lipez
inhabitants on the strategic resources of the region. These strategic resources found in
the Lipez region comprise fresh water—scarce in the region—, portions of arable lands
for quinine and potatoes, grasslands, wetlands, and shrubs to raise camelid livestock.
It is evident that, since millennial times, human settlings in the region are strongly
dependent on livestock activities—camelid raising—which are mainly carried out in
the wetland and highland zones.
To date, business activities have diversified and it is possible to find camelid livestock,
textile production of llama wool, and non-metallic mineral exploitation—ulexite and
boric acid—in the sides of salt flats, together with the offer of touristic services, which
has increased exponentially in the last decade—bearing in mind that this region, as
well as that of the Uyuni salt flat, is the one marked with the most tourist inflow in the
whole country (approximately 70,000 people per year).
Synthesis of the ecosystem services of Los Lipez Ramsar Site
10
Service Provision Service Regulation Cultural Services
Products obtained from the Benefits obtained from the Non-material Benefits
ecosystems ecosystem regulation obtained from the
processes ecosystems
Alimentation (quinine and Climate regulation Recreation and
potatoes) Water regulation esthetic/picturesque
Drinking water Water purification tourism
Fuels (peat) Cultural heritage
Vegetal fibers (cattail stands) Archeological and
Forestry (Yareta, Quenua, educational heritage
and Tho/as)
Medicinal plants
Camelid livestock
Non-metall ic mineral
resources-ulexite and boric
acid
Support Services
Services that are necessarv for the nroduction of all the o ther ecosvste1n services
Soil formation Nutrient cycles Prin1arv production
108
Recursos minerales no
I I
metalicos - Ulexita y
acido borico
Servicios de soporte
Servicios necesarios para la produccion de todos los otros servicios del ecosistema
Formacion de suelos I Cicio de nutrientes I Produccion primaria
3.3 Aspectos Fisicos
En esta seccion se presenta el analisis de los aspectos ffsicos iniciando el mismo con un area mas
extensa que la zona del Sitio Ramsar Los Upez; en lo subsecuente el analisis cubre mas detalles en
escalas cada vez mas focalizadas en el sitio Ramsar, yen particular la zona del Silala.
Un analisis de esta naturaleza permite ver la integracion de los aspectos ffsicos mas relevantes del
Altiplano Bolivia no y sus efectos a escalas regionales, intermedias y locales.
3.3.1 Clima y geomorfologia
Clima
Escala regional (ca 200'000 km2)
El clima de la region del sudeste de Bolivia (Fig. 3.1) es de altura, seco y frio, precipitacion baja,
radiacion solar intensa y fuertes vientos. La region occidental del Altiplano Sur esta caracterizada por
su bajisimo nivel de precipitacion pluvial, la cual se presenta generalmente en los meses de
diciembre, enero y febrero, el resto del afio la precipitacion es nula.
En algunas estaciones meteorologicas se han medido precipitaciones promedios, que varian
sensiblemente de Norte a Sur del Altiplano, los valores mas altos hacia Norte, varian entre 500 y 600
mm anuales, disminuyen paulatinamente hacia el sur con medidas inferiores a los 100 m anuales.
Las temperaturas registradas en la zona de analisis son las mas bajas de Bolivia, las minimas de
invierno (mayo a agosto) descienden en la noche a valores extremos de -25°C hasta -30°C, subiendo
en el dia hasta los 15°C (Fig. 3.2)
11
109
3.3 Physical Aspects
This section comprises an analysis of the physical aspects of the Site, starting from a
larger area than the Los Lipez Ramsar Site, and followed by an analysis that covers
more details on scales that increasingly focus on the Ramsar site, particularly the
Silala area.
An analysis of this kind allows the integration of more relevant physical aspects of
the Bolivian High Plateau and their effects on regional, intermediate, and local scales.
3.3.1. Climate and geomorphology
Climate
Regional Scale (ca 200’000 km2)
The climate of the southeast region of Bolivia (Fig. 3.1) is high, dry, and cold,
characterized by low precipitation, intense solar radiation, and strong winds. The
western region of the southern High Plateau is characterized by its very low level of
rainfall, which generally occurs in the months of December, January, and February;
precipitation is nil the rest of the year.
Average precipitations have been measured in some meteorological stations, and have
presented significant variations from the North to the South of the High Plateau. The
highest values towards the North vary between 500 and 600 mm annually and decrease
gradually towards the South with measures lower than 100 m annually.
The temperatures recorded in the area analyzed are the lowest in Bolivia. The lowest
temperatures recorded in winter (May to August) fall at night to extreme temperatures
of - 25° C, dropping to - 30° C, and rising in the day to 15° C (Fig. 3.2).
11
110
12'S
18'S
20'$
24·s ,
72'1/11 "N)'W 611"W El!,'1/11 ~"W 62VI 60-V/ 58-W 58"\!/
Fl&ura 3.1 Region de amilisis e,n el sudeste de Bo livia.
Figura 3.2 Mapas de i$otermas v d'e isoyetas del $1.Jdeste de Bolivia.
Lm, meses de veraoo son m~s mmlef"ados, pero de toda:s m.-ineras las heladas pueden s11cederse
rnn 1iacil"idad v el clima sigue slendo fria, presemandose dfferencias tennicas de enlre-3"Ca
20"C. El fenomeno dlimatico de incfdencia especial en, la ion,a es srn duda el viento,
especlalmente en los mese~ lnvernales don de las pioporciones se elev,ari a ni\'eles pelig rnsos di!:
hasta 6□ km/h de velocidad. Los vlentll s tienen un;i direroi6n p redom i na r1te noresoe-sud oeste,
.1,iendo una caracterrs1ica mUy espedal lo~ cambios de intensiclad y direcci6n segun la hma de-I
dia, 1ma vez pasadas las :16 horas este p rob1em;i se acentila.
111
Figure 3.1. Analysis region of the southeast of Bolivia
Figure 3.2. Isotherm and Isohyet Maps of the southeast of Bolivia
Summer months are more moderate, but frosts are still likely to happen and the climate
is still cold, with temperatures ranging from -3° C to 20° C. The climatic phenomenon
of distinctive incidence in the area is undoubtedly the wind, especially in the winter
months, when the winds rise to dangerous levels of up to 60 km/h of speed. The winds
have a predominant northeast-southwest direction and are characterized by changes in
intensity and direction, which depend on the time of the day. This problem worsens
after four o’clock.
112
Otro aspecto digno de mencionarse es el de insolacion e irradiacion solar, segun las apreciaciones
hechas por el programa ERTS esta zona poseen uno de los niveles de radiacion solar mas alto del
planeta . "Por la altura en que se encuentra el Altiplano, se supone que este soporta solo las 2/3
partes de la masa atmosferica que toleran las regiones a nivel del mar, par lo tanto permiten una
mayor insolacion y tambien una mayor irradiacion del suelo. Par tal motivo, existen oscilaciones
diarias, queen promedio estan dentro el orden de las 20°C. (Estudio socio-economico integral del
Altiplano Sur. Ministerio de Mineria y Metalurgia - Bolivia).
Con respecto a la evaporacion se puede decir que esta es intensa, debido en gran parte a la
radiacion solar, las productos generados par la escasa precipitacion seven disminuidos par la
evaporacion, que presenta valores extremos de hasta 6 mm diarios. Cabe notar que estos valores se
ven incrementados par la existencia casi continua de fuertes vientos.
Otra caracteristica interesante, e importante en el analisis a la escala regional, es queen realidad no
hay una altura de evaporacion anual definida y constante para toda la zona. Cada Iago se evapora de
manera particular debido a dos factores que controlan esa evaporacion: la temperatura minima de
la zona y la salinidad del Iago. Mientras mas salada sea una laguna, menos se evapora. Par ejemplo,
par cada 10 g/1 de NaCl la evaporacion se reduce en 1% en relacion a la de una laguna de agua dulce.
Par ejemplo una salmuera de 350 g/1 tiene una evaporacion reducida de 35%. Esta proporcion de 1%
puede aumentar con el contenido en magnesia (Turk, 1970). Par ello es queen la estimacion de la
evaporacion de cada laguna siempre de debera efectuar una correccion para las caracteristicas de
cada una de el las. Pero otro factor fundamental es la temperatura de la atmosfera; mientras mas
frio hace, mas tiempo se congela el agua y menos se evapora . Asi mismo, mientras mas salada sea
una agua, mas baja sera su temperatura de congelamiento y menos tiempo quedara esta congelada.
Como resumen, se puede decir que el analisis del clima en la region tiene una importancia
considerable par cuanto a su influencia debido a la interaccion de sus variables coma son la altitud,
el frio, las precipitaciones mini mas pero localizadas, coma tambien la radiacion, la insolacion, etc., se
constituyen en efectos vitales para comprender la meteorizacion y erosion de las rocas, cuyos
productos son los que definen la calidad de las depositos evaporiticos formados y las cuerpos de
agua intermitentes o permanentes coma las lagunas, las escurrimientos superficiales (muy raros), y
el agua subterranea.
Escalas intermedias y locales (10,000 km2 a 1,000 km2)
Auna escala mas intermediaria y mas local, las caracteristicas del clima y de la morfologia son
similares a la escala regional pero tambien tienen sus propios rasgos particulares, tales el caso
de la zona cubierta par el sitio Ramsar Los Upez (figura 3.3).
A esas escalas se distinguen las siguientes rasgos:
Altura : 6,000 y 4,200 m
Puna arida a semiarida.
Presencia de Lagunas salinas/hipersalinas/alcalinas, de bofedales, de humedales
geotermicos y de cuerpos de agua endorreicos en zona desertica.
Numero limitado de fuentes de agua dulce para consumo humano.
Condiciones climaticas aun mas extremas que a la escala regional, lo cual inhibe, entre
otras cosas, la agricultura.
13
113
Another worth mentioning aspect is the insolation and solar irradiation. According
to the assessments made by the ERTS program, this zone has one of the highest
levels of solar radiation on the planet. “Owing to the altitude of the High Plateau,
it is assumed that the latter supports only two thirds of the atmospheric mass
tolerated by the regions at sea level, therefore allowing greater insolation and also
a greater irradiation of the soil. For this reason, there are daily oscillations, which
on average are within the order of 20° C.” (Comprehensive socio-economic study
of the Southern High Plateau, Ministry of Mining and Metallurgy—Bolivia).
Evaporation can be said to be intense, due in large part to solar radiation. The
products generated by the low precipitation are diminished by evaporation, which
presents extreme values of up to 6 mm per day. It should be noted that these values
are increased by the almost continuous presence of strong winds.
Another interesting and important feature of the regional analysis is that there is in
fact no annual, defined, and constant evaporation mean for the whole area. Each
lake evaporates in a particular way due to two factors that control evaporation: the
minimum temperature of the zone and the salinity of the particular lake. The saltier
a pond is, the less it evaporates. For example, for every 10 g/l of NaCl, evaporation
is reduced by 1%, in relation to that of a freshwater lagoon. For example, a
brine of 350 g/l has a reduced evaporation of 35%. This proportion of the 1%
may increase with the magnesium content (Turk, 1970). That is why corrections
must always be made on basis of the particular characteristics of each lagoon in
estimating evaporation. Another fundamental factor is, however, the temperature
of the atmosphere; the colder it is, the longer the water stays frozen and the less
time it takes to evaporate. Likewise, the saltier the water, the lower its freezing
temperature and the less time it will remain frozen.
As a summary, it can be said that the analysis of the climate in the region is of
considerable importance because its influence in the interaction of the region’s
variables—such as altitude, cold, minimum, yet localized, precipitation, as well
as radiation and insolation, etc.,—results in vital components to understand the
weathering and erosion of rocks, the products of which define the quality of the
evaporation deposits formed and the intermittent or permanent bodies of water, as
lagoons, surface runoffs (which are quite rare), and groundwater.
Intermediate and local scales (10,000 km2 to 1,000 km2)
At a more intermediate and local scale, the characteristics of the climate and
morphology are similar to those presented at the regional scale, but are also marked
by particular features, as is the case of the area covered by the Los Lipez Ramsar
site (figure 3.3).
The following features are distinguished at these scales:
• Altitude: 6,000 and 4,200 m.
• Arid to semiarid Puna.
• Presence of saline/hypersaline/alkaline lagoons, highland wetlands, geothermic
wetlands, and endorheic bodies of water in the desert region.
• Limited number of sources of fresh water for human consumption.
• More extreme climate conditions than at the regional scale, which impede, among
other activities, agriculture.
13
114
"...'
:,:
u
REFEREHCIAS
-SitiORbmSllt
~ I LlmH mun1e1pal
~ D RNFA EduardoAvaroa
- C\lefPOSde agua
/'V Qnos de a1,,1ua
■ comunld~s
11is1
SITIO RAMSAR "LOS LiPEZ"
POTOSI - BOLIVIA
I'°
Figura 3.3 Localizaci6n del Sitio Ramsar "Los Upez"
""
A la escala del sitio del sitio Silala, los dates de la estaci6n meteoro16gica mas cercana ubicada
en la Laguna Colorada a 38 km del area de estudio y para el periodo 1985-1997 son:
• Precipitaci6n: 59 mm de diciembre a marzo, con un maximo de 21.4 mm en enero, la
sequfa es entre abril y noviembre;
• Temperatura: promedio anual 14.2 C; promedio anual de las mfnimas -15;
• Evaporaci6n: mas alta entre septiembre y marzo (78 mm en septiembre y 113 mm en
diciembre), los valores mas bajos son entre abril y agosto (la mas baja con 36 mm en
junio); y
• Evaporaci6n Promedio: 914 mm.
Geomorfologfa
De la misma manera que para el clima, los aspectos de geomorfologfa de la region de analisis
tendra una mejor comprensi6n en su contexto general de la unidad morfo-estructural llamada
Altiplano, o sea de la escala regional a las escalas intermediarias y local.
Dentro del Sitio Ramsar el area del Silala se localiza entre el paralelo 22Q de latitud sur y 68Q de
longitud oeste a 4300 m sobre el nivel del mar. Esta area forma un valle que se extiende en
14
115
Figure 3.3. Location of Los Lipez Ramsar site
At the scale of the Silala site, the data obtained from the closest meteorological
station, found on Laguna Colorada, at 38 km from the area of study, and for the period
extending from 1985 to 1997, is the following:
• Rainfall: 59 mm from December to March, with a maximum of 21.4 mm in
January. Droughts are recorded between April and November.
• Temperature: the annual average is of 14.2 C; the annual average of the minimal
temperatures is of -15;
• Evaporation: it is higher between September and March (78 mm in September
and 113 mm in December); evaporation is the lowest between April and August (the
lowest evaporation rate, of 36 mm, is recorded in June); and
• Average evaporation: 914 mm.
Geomorphology
In the same way as for the climate, the geomorphological aspects of the region analyzed
will be understood better in the general context of the morpho-structural unit termed
the High Plateau (Altiplano); that is, starting from the regional scale and then moving
on to the intermediary and local scales.
Within the Ramsar site, the Silala area is located between the 22nd parallel south and the
68th parallel west, at 4,300 m.a.s.l. This area forms a valley extending from east to
14
i
.. ...
:z:
"
REFERENCIAS
-SlloRMIHI
u,,, ....... c,p,,1
0 Rt1FA Edl.iwdo..,_o.
- 0.Pl»Ge~ · ~"""-"-
smo RAMSAR "LOS LiPEZ ..
POTOSI - BOLIVIA
ARGENTI NA
__ j______.~
116
direcci6n este a oeste (fotografia no 1). Par sus caracterfsticas, el area corresponde a una zona
desertica de alta montaf'ia, en donde la flora y la fauna son muy restringidas.
El area del Silala se caracteriza par tener una topografia plana-ondulada, ligeramente inclinada hacia
el oeste rodeado de domos y estratovolcanes (fotografia 2). Las altitudes dentro del area varfan
desde las 4278 metros sabre el nivel del mar (msnm), en el If mite fronterizo que cruza en la
Quebrada Principal de Silala, hasta las 5701 msnm, cumbre del Volcan Silala (fotografia 2).
Tiene un clima tfpico de una zona desertica de alta montaf'ia con variaciones extremas diurnas y
nocturnas. La flora y la fauna es muy limitada y caracterfstica de la Cordillera Occidental y Altiplano
Boliviano. Los bofedales de alta altura de Silala tienen una flora y fauna tfpica de las mismos. Es una
region deshabitada con la poblaci6n mas cercana de Laguna Colorada (22 habitantes en 2001)
ubicada a 38 Km al SE del Silala. Actualmente la poblaci6n mas cercana al Silala es Quetena con mas
de 850 habitantes (SERNAP 2006), ubicada al Este a unos 60 Km aproximadamente.
Fotografia no 1 Collage de fotos Google Earthy satelital.
Ceno ¥ can Sllala NW
Bollvla ~
Qda.Sllala
Fotograffa no 2 Vista panoramica del Silala, vista Sureste (Bolivia) noroeste (Chile) (fuente: Urquidi
Barrau, 2003)
117
west (picture n° 1). Due to its characteristics, the area corresponds to a high-mountain
desert-like area, where flora and fauna are limited.
The Silala area is characterized by a flat-wavy topography, slightly inclined towards
the west, and surrounded by domes and stratovolcanoes (picture n° 2). Altitudes vary
within this area from 4,278 m.a.s.l., on the boundary line that crosses the Quebrada
Principal de Silala [Main Silala Ravine] to 5,701 m.a.s.l. on the summit of Silala
Volcano (picture nº 2).
It is characterized by a climate typical to high-mountain desert-like regions with
extreme variations in the day and night. The flora and fauna are very limited and
characteristic of the western Andes mountain ranges and Bolivian High Plateau. The
Silala high-altitude wetlands feature a flora and fauna typical to wetlands of this kind.
It is an uninhabited region, where the closest population is found in Laguna Colorada
(22 inhabitants in 2001), 38 km to the southeast of Silala. Currently, the community
that is closest to the Silala is Quetena, which comprises more than 850 inhabitants
(SERNAP, 2006) and is located to the east, at 60 Km approximately.
Picture nº 1: Google earth and satellite pictures
Picture nº 2. Panoramic view of Silala, southeast sight (Bolivia), northeast (Chile)
(Source: Urquidi Barrau, 2003)
Bolivl•
Qda. Sllala
nSllala
~ Chile
Cerro Sllal• Chlc:o
NW
,, .
118
Los aspectos geomorfologicos de la region se muestran en la figura 3.4. Esos efectos muestran los
diferentes procesos y agentes geomorfologicos que han modelado el relieve del area desde hace 7.8
Mo. Todo el paquete estructural regional fue posteriormente levemente solevantado hace
aproximadamente 1.7 a 1.9 Mo (Ministerio de Medio Ambiente y Agua, 2016) inclinandolo
suavemente hacia el Oeste, paralelamente a lo intrusion de conos volcanicos ya la formacion de
estratos volcanes. Por las edades obtenidas estos rasgos geomorfologicos alterados pudieron
haberse realizado hace 1.4 Mo.
Durante las glaciaciones de hace 14,500 afios BP, Ultimo Maximo Glaciar de la Cordillera Central de
los Andes, los rasgos geomorfol6gicos fueron fuertemente alterados por el movimiento y deshielo
de los glaciales que dieron lugar a la formacion de lagos, lagunas y salares en lado del Altiplano
Boliviano, asf como a la formacion de valles profundos, entre ellos el valle del Silala.
La actividad del deshielo de lo glaciacion es otro de los rasgos geomorfologicos mas notorios sobre la
formacion de la Quebrada de Silala. Rasgos que se formaron hace 10,000 afios BP o mas. A fines de
este episodio glaciar (tardi glaciar) se formaron las quebradas que son un ejemplo tfpico de la acci6n
del agua de deshielo aprovechando zonas de debilidad en la roca aflorante, en este caso la falla Silala
y las fallas transversales E-W de ajuste. Sin embargo, el disefio actual de la Quebrada Principal con
un corte transversal geomorfologico en "U" con paredes laterales verticales (15 o 100 m de altura y
40 m de ancho) y un piso piano es la combinacion de varios factores de meteorizacion y no solo a la
accion fluvio-glacial. Es importante sefialar que desde el Holoceno, la Quebrado de Silala no tiene
ninguna proporci6n entre la profundidad y ancho del mismo con lo cantidad de agua que pod fa fluir
en el, o sea que existe una desproporcion geomorfologica notable.
Los rasgos geomorfologicos modelados durante el Holoceno hasta nuestros dfas son mas por lo
accion eolica y por diferencia termica diaria y casi nulos por accion fluvial.
Respecto al area de Laguna Colorada y la Reserva Nacional de Fauna Andina Eduardo Avaroa, Segun
Navarro (2002) las principales unidades geologicas y morfologicas son las siguientes:
• Meseta ignimbritica riodacftica a riolftica (Formacion Alota): constituye en la mayor parte del
distrito la superficie topografica fundamentalmente, siendo parcialmente homologa a la
formacion Perez del Altiplano Norte ya la formacion Quemez del Altiplano Central. Con una
altitud promedio entre 4.000-4.500 m. Se le atribuye una edad Mioceno-Plioceno.
• Estratovolcanes andesftico-dacfticos, de edad Plioceno-Pleistoceno, constituyen muchos de los
volcanes que sobresalen del nivel de la meseta ignimbritica.
• Edificios volcanicos antiguos, domos y coladas de lava andesftico-dacfticos, junto a brechas
volcanicas, tobas andesfticas, areniscas, conglomerados y margas. Edad Mioceno-Plioceno.
• Afloramientos sedimentarios poco extensos, situados generalmente en las laderas orientales del
val le del Rfo Grande de Upez. Constituidos por areniscas y lutitas rojo bermellon con yesos, de la
formacion Potoco (Oligoceno).
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119
The geomorphological characteristics of the region are depicted in figure 3.4. These
effects evidence the different geomorphological processes and agents that have
modelled the relief of the area 7.8 million years ago. The structure of the region was
then slightly altered approximately 1.7 to 1.9 million years (Ministry of Environment
and Water, 2016), inclining to the west, simultaneously to the intrusion of volcanic
cones and the formation of stratovolcanoes. Based on the ages recorded in the area,
these altered geomorphological features are likely to have taken place 1.4 million
years ago.
During the glaciation periods occurring 14,500 years before the present—the Last
Glacial Maximum of the Andes Central Mountain Range—the geomorphological
features were strongly altered by the movement and melting of glaciers, resulting in
the formation of lakes, lagoons, salt flats, and deep valleys—as the Silala valley—all
over the Bolivian high plateau.
Melting, or glaciation is another one of the most notorious geomorphological features
in the formation of the Silala Ravine and were formed 10.000 years before the present.
The ravines, on the other hand, were formed at the end of this glacial period (the lateglacial).
These constitute a typical example of the action of meltwater on weaker zones
where rocks outcrop, in this case the Silala fault and the E-W cross-section adjustment
faults. However, the current design of the Main Ravine, presenting a geomorphological
U-shaped cross-section with vertical lateral walls (15, or 100 m of height and 40 m
of width) and a flat surface, is the result of the combination of several weathering
factors and not only of fluvio-glacial action. It must be noted that since the Holocene,
the depth and width of Silala Ravine does not correspond to the amount of water that
might influence it, i.e. there is a notorious geomorphological disproportion.
The geomorphological features modeled from the Holocene to the present time are
mainly the result of eolian action, the daily temperature differences, and rainfall.
According to Navarro (2002), the main geological and morphological units in the Red
Lagoon and the Eduardo Avaroa Andean Fauna National Reserve are the following:
• Rhyolitic to rhyodacitic ignimbrite plateau (Alota formation): it constitutes
most of the district of the topographical surface and is partially homologous to
the Perez formation of the Northern High Plateau and the Quemez formation of
the Central High Plateau, with an average height between 4,000 and 4,500 m. It
is said to date back to the Miocene-Pliocene.
• Andesitic-dacitic stratovolcanoes, dating back to the Pliocene-
Pleistocene; these constitute many of the volcanos that raise in the ignimbrite
plateau.
• Ancient andesitic-dacitic volcanic structures, domes, and lava flows,
together with volcanic breccia, andesitic tuffs, sandstones, conglomerates, and
loams dating back to the Miocene-Pliocene.
• Sediment outcrops of relative extent, generally found in the eastern
sides of the Rio Grande de Lipez valley. These are constituted of vermillionred
sandstones and lutite with gypsum, dating back to the Potoco formation
(Oligocene).
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120
Figura 3.4 Aspectos geomorfologicos del area (Ministerio de Media Ambiente y Agua, 2016)
3.3.2 Geologia
Escala regional
El Altiplano presenta una estratigrafia distinta segun las sectores (Mapa Geologico de Bolivia, 1978,
YPFB-GEOBOL), par ejemplo, el Altiplano Norte, esta caracterizado par presentar diferentes tipos de
rocas devonicas, constituidas par areniscas y lutitas. En las alrededores del Iago Titicaca es facil
encontrar rocas del carbonffero, constituidas par una intercalacion de areniscas y limos. Tambien
alrededor del Lago Titicaca se han identificado calizas fosiliferas de color gris claro, en alternancia
con lutitas gris oscuras correspondientes al Permico.
El Terciario se encuentra ampliamente difundido en el Altiplano Norte, rocas sedimentarias de la Fm.
Umala son caracteristicas en el area del rio Desaguadero, areniscas, arcillas y conglomerados son las
sedimentos mas tipicos. En el sector NO, las ignimbritas de composicion riodacitica de la FM Perez,
se encuentran cubriendo superficies muy amplias.
El sistema Cuaternario tambien se encuentra ampliamente difundido en el Altiplano Norte, ca pas
sub-horizontales de tobas, ignimbritas, coladas de lava, etc., son de amplia difusion. Sedimentos
lacustres de la Fm. Ulloma con fosiles de vertebrados , han sido descritos par numerosos autores.
Ademas fuera de la litologia anteriormente indicada, en este sector de la altiplanicie, se identifican
sedimentos finos compuestos de calizas, margas, arenas finas, arcillas y limos, correspondientes a las
hoyas lacustres conocidas coma Ballivian, Minchin y Tauca.
Es de acotar que tambien se han identificado cuerpos de naturaleza magmatica de edad mesozoica y
cenozoica, que se encuentran flanqueando el Altiplano, flanco oriental, pero con gran influencia
sabre este, son rocas que corresponden petrograficamente a granitos, granodioritas, monzonitas,
fonolitas y otras.
En el Altiplano media, en la zona de Sevaruyo y alrededores se han reconocido calizas cretacicas y
cuerpos yesiferos masivos, que juntamente con las rocas paleozoicas aflorantes al Este del Iago Poopo,
tienen una gran influencia sabre la cuenca mencionada.
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121
Figure 3.4. Geomorphological aspects of the area (Ministry of Environment and Water,
2016)
3.3.2. Geology
Regional scale
The High Plateau presents a stratigraphy that varies depending on its sectors (Geological
map of Bolivia, 1978, YPFB-GEOBOL); for instance, the northern High Plateau is
characterized by different types of Devonian rocks that are made up of sandstones
and lutites. In the outskirts of Lake Titicaca, it is easy to find carboniferous rocks
formed by an intercalation of sandstones and silts. Light gray fossiliferous limestones,
alternating with dark gray lutites that correspond to the Permian period, have also been
identified in this region.
The Tertiary period is widely spread in the northern High Plateau; sedimentary
rocks of the Umala formation are characteristic in the area of the Desaguadero
River. Sandstones, clays and conglomerates are the most typical sediments. In the
northwestern area, ignimbrites of rhyodacitic composition of the Perez formation
cover very lengthy surfaces.
The Quaternary system is also widely spread in the northern High Plateau; subhorizontal
layers of tuffs, ignimbrites, lava flows, etc., are widely distributed. Lake
sediments of the Ulloma formation, with vertebrate fossils, have been described by
numerous authors.
In addition to the above lithology, in this area of the plateau, fine sediments composed
of limestones, loam, fine sands, clays, and silts corresponding to the lacustrine basins
known as Ballivian, Minchin and Tauca are identified.
It is worth noting that bodies of magmatic nature of the Mesozoic and Cenozoic age
have been identified flanking the High Plateau, to the east; however, a great influence on
the latter is exerted by rocks that petrographically correspond to granite, granodiorite,
monzonite, phonolite, and others.
In the mid-High Plateau, in the area of Sevaruyo and the surrounding ones, Cretaceous
limestone and massive gypsum bodies have been identified; these, together with the
Paleozoic rock outcrops east of Lake Poopo, have a great influence on the said basin.
17
----
----·------ ___ . .--'.-..'.-• --
122
Antes de empezar una descripcion mas completa del Altiplano Sur, nos referiremos forma muy
general al sector SE del Altiplano. Esta region tiene una geologia que contrasta efectivamente con el
Oeste; mientras que este sector es eminentemente volcanico, el Este presenta afloramientos de
rocas sedimentarias correspondientes al Paleozoico bajo y especialmente areniscas, conglomerados,
arcillas, yeso con intercalaciones de tobas y lavas correspondientes al Terciario que cubren grandes
areas (Mapa Geologico de Bolivia, 1978).
El Cuatemario
La geologia superficial de toda el area predominantemente es producto de una actividad volcanica
del Miocene al Reciente, las distintas geoformas observables hoy en dia en el area estan modelados
desde hoce 7.8 Mo, iniciandose en el Miocene Superior con la deposicion de las tobas sobre rocas
presumiblemente del basamento Paleozoico o rocas del Miocene inferior.
Los procesos de meteorizacion, erosion y deposicion estan representados por sedimentos no
consolidados Cuaternarios y Recientes que cubren superficies extensas del area. Los materiales
depositados forman las depositos glaciales, fluvio-glaciales, coluviales y aluviales consolidados
por bloques o bolones poligenicos, clastos de diferentes rocas y tamaiios, y sedimentos finos
coma arenas y limos.
Mesetas ignimbriticas, es una de los caracteristicas mas notables, se inicio con la deposicion de los
tobas de las ignimbritas Silala, posiblemente, ha tenido lugar durante el Miocene Superior sobre
rocas presumiblemente del basamento Paleozoico o rocas del Miocene inferior, construyendo
mesetas ti picas con paredes verticales y con sistemas de drenaje que no son perceptibles en la
actualidad. Estas mesetas sufrieron bruscas alteraciones geomorfologicas, por el intense
diaclasamiento y el grado de soldadura de las ignimbritas, y por supuesto, por la accion
meteorizante de los agentes de movimiento y deshielo de glaciares, cambios extremos de
temperatura y viento. Esto dio lugar a la formacion de farallones que regionalmente en algunos
casos pasan de 100 metros de altura. Tambien dieron lugar a la formacion de paleosuelos de color
rojizo. Flujos de lava, son las que cubrieron las mesetas ignimbriticas ya toda geoforma original
creada por las ignimbritas y paleosuelos.
Las mesetas tipicas con paredes verticales y con sistemas de drenaje que no son perceptibles en
la actualidad. Estas mesetas sufrieron bruscas alteraciones de tipo fisico, por el intense
diaclasamiento y el grado de soldadura de las ignimbritas, y por supuesto, por la accion
meteorizante de las agentes de movimiento y deshielo de glaciares, cambios extremes de
temperatura y viento. Esto dio lugar a lo formacion de farallones que regionalmente en algunos
casos pasan de 100 metros de altura. Tambien dieron lugar a lo formacion de paleosuelos de
color rojizo. Estas mesetas fueron posteriormente cubiertas por fluidos de lavas que
enmascaran algunos rasgos originales de las ignimbritas y paleosuelos.
Escalas intermediaria y local
El area de los Manantiales de Silala se halla localizada en el bloque sur de la Cordillera
Occidental y forma pa rte de la Zona Volcanica Central de los Andes. La geologia regional esta
dominada por los productos de una actividad volcanica del Miocene al Reciente y el paisaje fue
modelado por procesos resultantes de las glaciaciones Pleistocenicas-Holocenicas. El Mapa de la
figura 3.5 muestra el mapeo geologico realizado en el area en una escala 1:50,000 y la Tabla No. 3.1
el detalle de la columna estratigrafica (SERGEOMIN, 2003). Los procesos de meteorizacion, erosion y
deposicion estan representados por sedimentos no consolidados Cuaternarios y Recientes que
cubren superficies extensas del area . Los materiales depositados forman las depositos glaciales,
18
123
Before turning to a more complete description of the South High Plateau, general
reference must be made to the southeastern sector of the High Plateau. Said region
presents a geology that is in sharp contract with the western region—while the latter is
the most notoriously volcanic one, the East region presents sedimentary rock outcrops
corresponding to the lower Paleozoic era and manly sandstones, conglomerates, clays,
and gypsum interspersed with tuffs and lavas from the Tertiary, which cover vast areas
(Geological map of Bolivia, 1978).
The Quaternary
The surface geology of the area is chiefly the result of volcanic activities dating
from the Miocene era to the present. The different geoforms currently observable in
area were modelled 7.8 million years ago, and began in the Upper Miocene with the
deposition of tuffs on rock surfaces from the Paleozoic basement, or rocks from the
lower Miocene.
Weathering, erosion, and deposition processes are represented by unconsolidated
sediments from the Quaternary and the Recent eras, covering vast surfaces of the
area. The materials deposited formed glacial, pluvial-glacial, colluvial, and alluvial
deposits, consolidated by polygenic blocks or quarry stones, clasts of different rocks
and different rock sizes, and fine sediments as sands and silt.
Ignimbrite plateaus are one of the most notorious characteristics. Their formation
began with the deposition of tuffs from the Silala ignimbrite, which possibly occurred
in the Upper Miocene on rocks of presumably Paleozoic basement, or rocks from the
lower Miocene, forming average plateaus with vertical walls and drainage systems
that are imperceptible at present. These plateaus endured sharp geomorphological
alterations owing to intense fractures and welding of the ignimbrites, and extreme
changes in the temperature and winds. These resulted in the formation of rock outcrops
that regionally surpass the 100 meters of altitude, together with the formation of red
paleosols. These plateaus were then covered by lava flows that have hidden some of
the original features of the ignimbrites and paleosols.
The typical plateaus with vertical walls and with drainage systems that are not
perceptible at present. These plateaus endured sharp geomorphological alterations
owing to intense fractures and welding of the ignimbrites, and extreme changes in the
temperature and winds. These resulted in the formation of rock outcrops that regionally
surpass the 100 meters of altitude, together with the formation of red paleosols. These
plateaus were then covered by lava flows that have hidden some of the original features
of the ignimbrites and paleosols [sic].
Intermediary and local scales
The area of the Silala springs is found in the south block of the Western High Plateau
and forms part of the Central Volcanic of the Andes. The regional geology is dominated
by the products of volcanic activities that date back to the Miocene and Recent epochs.
The landscape was modelled by the processes resulting from glaciations that date back
to the Pleistocene-Holocene. The map presented in figure 3.5 depicts the geological
mapping carried out in the area at a scale of 1: 50,000 and Table No. 3.1 shows the
detail of the stratigraphic column for the area (SERGEOMIN, 2003). The weathering,
erosion, and deposition processes are represented by unconsolidated sediments from
the Quaternary and Recent epochs and cover vast regions of the area. The deposited
materials form glacial,
18
124
fluvio-glaciales, coluviales y aluviales constituidos por bloques o bolones poligenicos, clastos de
diferentes rocas y tamafios, y sedimentos fines como arena y limo.
El tectonismo del area del Sitio Ramsar esta influenciado por el solevantamiento y fallamiento del
bloque regional de Upez, conocida como la Cuna Occidental. La mayor manifestaci6n de este
tectonismo en el area es el sistema de Fallamiento de Khenayani que cruza el area con un rumbo
regional ENE, y por fallas de ajuste con el mismo rumbo y por fallas transversales de ajuste con
rumbos EW y WNW. Estas ultimas tienen una extension limitada pero profunda, que facilitaron la
efusi6n de los volcanes con la consiguiente deposici6n de rocas fgneas efusivas y debris piroclastico y
la fracturaci6n de las rocas ignimbrfticas basales.
Por otra pa rte, el tectonismo, manifestado como fallamiento y diaclasamiento de las rocas efusivas
del area, es de suma importancia en cuanto a la ubicaci6n de los afloramientos de las descargas de
agua en forma de manantiales del Silala.
Los bofedales se encuentran sobre rocas ignimbriticas recubiertas por dep6sitos superficiales no
consolidados de tipo coluvial. En el margen derecho del bofedal Norte existen diferentes
alumbramientos de agua que son canalizados, en este sector se observ6 afloramiento de roca con un
nivel de piroclastos, que emergieron del volcan lnacaliri. Esta lava con algunos metros de espesor,
relativamente reciente, reposa en pa rte sobre las lavas descritas antes, pero ante todo sobre el
sustrato ignimbritico del Miocene. Las ignimbritos tienen una coloraci6n grisacea a rosado naranja
(con alteraci6n).
El bofedal sur, esta controlado por el diaclasamiento y fallamiento en la roca ignimbrftica que fluye
hacia sedimentos o suelos recientes hasta su intersecci6n con aguas del bofedal Norte.
Actividad Voldmica
La actividad volcanica en el area es muy importante y se inicia en el Cicio Andino del Miocene
Superior. Durante este ciclo se edificaron varias calderas, centres y domes volcanicos, entre ellos el
de Agua de Perdiz (ubicado fuera del area de estudio) que se manifiesta con la erupci6n y deposici6n
de un manto ignimbrftico regionalmente extenso denominado lgnimbritas Silala. Estas ignimbritas
estan muy bien expuestas en el area y se encuentran parcialmente cubiertas por flujos de lavas de
los estratovolcanes intruidos a traves de las mismas (Fotograffa No. 2). Esta es la primera fase
efusiva en el area de estudio. Las estructuras volcanicas mas evidentes, dentro y circundando el
area, son los domes volcanicos del Cerro Silala Chico y Torito, y los estratovolcanes lnacaliri y Silala
desarrollados por la acumulaci6n de productos de fases extrusiva y efusivas. La primera fase
extrusiva esta representada por la formaci6n de los domes volcanicos. La segunda fase efusiva esta
representada por coladas de lavas andesfticas y lavas de composici6n andesfticas-dacfticas.
A fines del Pleistocene se inicia la edificaci6n de otros centres volcanicos como el Volcan Cerro
Negro, cuyo volcanismo efusivo desarro116 dep6sitos de lavas andesfticas, las cuales llegan a cubrir
relieves preexistentes.
19
125
fluvial-glacial, colluvial, and alluvial deposits made up of polygenic blocks or quarry
stones, clasts of different rocks and of different rock sizes, and fine sediments such as
sand and silt.
Tectonism of the Ramsar Site area is influenced by geological uplifting and faulting of
the regional block of Lipez, known as the Cuña Occidental. The major manifestation
of this tectonism in the area is the Khenayani Fault system, which crosses the area
with a regional ENE course, and is characterized by faults of adjustment that follow
the same course and cross-section faults of adjustment that follow EW and WNW
directions. The latter have a limited, yet deep, extent, which facilitated the effusion
of volcanoes and the consequent deposition of effusive igneous rocks and pyroclastic
debris, as well as the fracturing of basal ignimbrite rocks.
Tectonism, on the other hand, manifested by the faulting and jointing of effusive rocks
found in the area, is of utmost importance for the outflows of water discharges that
form the Silala springs.
The wetlands are found on ignimbrite rocks covered by unconsolidated surface deposits
of a colluvial type. In the right edge of the north wetland, there are different water
sources that are channeled; in this sector, rock outcrops with a level of pyroclasts that
emerged from Inacaliri volcano have been observed. This lava, which is a few meters
thick and relatively recent, rests partly on the lava described above, but above all
on Miocene ignimbrite substrate. These ignimbrites have a grayish to pinkish orange
coloration (with alterations).
The south wetland is controlled by the joints and faults of ignimbrite rocks that flow
towards the recent sediments, or soils, until their intersection with the waters of the
north wetland.
Volcanic activity
Volcanic activity in the area is very important and begins in the Andean Cycle of
the Upper Miocene. During this cycle, several craters, centers, and volcanic domes
were formed, including the Agua de Perdiz (located outside the study area), which is
manifested by the eruption and deposition of a regionally extensive ignimbrite mantle
known as Silala ignimbrites. These ignimbrites are highly exposed in the area and are
partially covered by lava flows that come from the stratovolcanoes interloped among
them (Picture Nº 2). This is the first effusive phase in the study area. The most evident
volcanic structures, found within and surrounding the area, are the volcanic domes of
the Silala, Chico, and Torito hills, together with the Inacaliri and Silala stratovolcanoes
formed by the accumulation of extrusive and effusive phase products. The first extrusive
phase is represented by the formation of volcanic domes. The second effusive phase
is represented by andesitic lava flows and andesitic-dacite composition lava. At the
end of the Pleistocene, the formation of other volcanic centers such as Cerro Negro
Volcano began, the effusive eruption of which formed deposits of andesitic lava, which
have come to cover preexisting reliefs.
19
126
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20
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128
3.3.3 Hidrologfa superficial
La hidrologia superficial del sitio Ramsar se caracteriza por la presencia de pocos rios
intermitentes, algunos riachuelos y lagunas con deficits hidricos a escalas locales, regionales y
probablemente globales (el conj unto del sitio Ramsar).
Una de las caracteristicas hidrol6gicas mas importantes del sitio Ramsar es la presencia de una gran
cantidad de lagunas saladas que forman pequefias unidades endorreicas, donde las lagunas ocupan
la parte mas baja de sus respectivas cuencas. En su mayoria, los rios son de caracter temporal y de
muy escaso caudal, producto de la extrema aridez del clima de la region. Sin embargo, existen
manantiales que permiten que algunos cursos de agua tengan un caudal permanente. Como es
frecuente en regiones de origen volcanico, existen afloramientos termales. La perdida de agua se da
principalmente a la evaporaci6n producto de la intensa radiaci6n solar.
La calidad del agua de esas lagunas es altamente variables, con un pH que va desde 7,9 hasta 10.8,
son aguas cloruro-s6dicas (las mas frecuentes), sulfatadas-s6dicas y carbonatadas-s6dicas. Las aguas
son predominantemente alcalinas, salobres e hipersalinas, con Nay Cl como iones dominantes, yen
algunos casos Cay K. Destacan tambien los niveles altos de sustancias t6xicas como As y algunos
metales como Fey Pb, una alta conductividad y valores altos de s61idos totales. La laguna que
generalmente presenta mayor concentraci6n de Sodio, Cloruros, s61idos totales ya su vez una
mayor conductividad y alto valor en s61idos totales disueltos es Laguna Colorada y entre aquellas
que presentan menor concentraci6n en los mismos para metros esta Totoral (Rocha 2006).
Estas lagunas, generalmente poco profundas, son alimentadas por rios y manantiales de agua
subterranea. La ubicaci6n geografica y altura de las 37 lagunas inventariadas en el sitio Ramsar
se enlistan en la tabla 3.2 (ver Anexo 1).
Existen tres factores que controlan la existencia de una laguna salada ode un salar (Eugster y Hardie,
1978):
una cuenca cerrada,
infiltraciones reducidas,
evaporaci6n superior a las lluvias.
Las cuencas cerradas pueden ten er varios origenes, entre los cuales se pueden citar:
La tect6nica: Graben, rift. Es el caso de la cuenca altiplanica, tomada globalmente;
La actividad volcanica. Los flujos de lavas pueden cerrar pequefias cuencas entre los
volcanes (caso de Lipez);
La acci6n del viento: la deflaci6n. Puede ser la causa de algunos salares pequefios del SurLipez
(Laguna Kollpa, numero 14 en la tabla 3.1); y
La acci6n de los glaciares.
En cuanto a la evaporaci6n superior a las lluvias, es evidente que si esto no fuese asi se tendria un
factor de diluci6n permanente debido a las lluvias. El clima y la tect6nica son los dos factores que
controlan la intensidad de la evaporaci6n en relaci6n con las lluvias.
Las principales zonas climaticas en las que la evaporaci6n es superior a las lluvias son las zonas
subtropicales y las zonas polares. En cuanto al control tect6nico, son los altos relieves que pueden
proteger ciertos terrenos de las lluvias, y almacenar las aguas que caen en las cumbres para despues
redistribuidas en cuencas aridas con fuerte evaporaci6n como se muestra esquematicamente en la
figura 3.6. Este es probablemente el caso general del Altiplano Boliviano.
21
129
3.3.3. Surface Hydrology
The surface hydrology of the Ramsar site is characterized by the presence of intermittent
rivers, streams, and lagoons that present water deficits at the local, regional, and
probably global (the whole of the Ramsar site) scales.
One of the most important hydrological characteristics of the Ramsar site is the
presence of a great amount of saline lagoons that form small endorheic units, where
the lagoons occupy the lowest sections of their respective basins. Most of the rivers
are ephemeral in nature and have a low volume of water owing to the extreme aridity
of the region’s climate. However, there are springs that allow some watercourses to
have a permanent flow. As is common in volcanic-origin regions, there are thermal
water outcrops. Water is lost mainly to evaporation, which caused by the intense solar
radiation.
The water quality of these lagoons is highly variable, with a pH that ranges from
7.9 to 10.8; these are chloride-sodium (the most frequent ones), sulphate-sodium,
and carbonate-sodium waters. The waters are predominantly alkaline, brackish, and
hypersaline, with Na and Cl as the dominant ions, and Ca and K in some cases. There
are also high levels of toxic substances, as A, and some metals, as Fe and Pb, with a
high conductivity and high values of total solids. The lagoon that generally presents
the highest concentration of sodium, chloride, total solids and, in turn, a higher
conductivity and higher level of total dissolved solids is Laguna Colorada and among
those that present an inferior concentration of these values is that of Totoral (Rocha,
2006).
These lagoons, which are generally shallow, are fed by rivers and groundwater springs.
The geographical location and altitude of the 37 lagoons reported in the Ramsar site
are both listed in table 3.2 (see Annex 1).
There are three factors that control the existence of a saline lagoon, or a salt flat
(Eugster and Hardie, 1978):
- A closed basin
- Reduced infiltrations
- Evaporation that exceeds rainfall
The closed basins possibly have several origins, among which the following can be
mentioned:
- Tectonic origin: Graben, rift. This is the case of the Altiplano basin, taken as a
whole;
- Volcanic activity. Lava flows are likely to close small basins among the volcanos
(this is the case of Lipez);
- Wind action: deflation. This is likely to be the cause for some small salt flats in
Sur Lipez (Kollpa lagoon, No. 14 in table 3.1); and
- The action of glaciers.
In regard to evaporation exceeding rainfall, it is evident that if this were not the case,
there would be a permanent dilution factor resulting from rainfall. The climate and
tectonics are the two factors that control the intensity of evaporation in relation to
rainfall.
The main climatic zones where evaporation exceeds rainfall are subtropical and
polar areas. As for the tectonic control, high reliefs can protect certain lands from the
rains, and store the waters that fall in the peaks to then redistribute them in dry basins
characterized by strong evaporation, as shown schematically in Figure 3.6. This is
probably the general case of the Bolivian Altiplano.
21
130
Una vez reunidos esos factores las aguas se van a concentrar por evaporacion hasta precipitar las
sales segun el orden de sus solubilidades crecientes.
{"'""""'~"' Clllfllrvl llS !f.J
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Figura 3.6 Representacion esquematica del control morfo-climatico en la formacion de las lagunas
saladas y salares.
El unico rio permanente localizado en el sitio Ramsar es el rio Grande de Lipez. Este rio nace en el
sitio Ramsar Lipez Sur y escurre esencialmente hacia el norte formando una cuenca importante
mostrada en la figura 3.5 con la cuenca numero 17. Este rio tiene una importancia mayor en la
region pues representa el mayor aporte de aguas dulces al salar de Uyuni. Es un rio permanente que
desemboca en el Sureste del salar, infiltrandose en los sedimentos deltaico-lacustres de ese borde.
Finalmente, se puede afirmar que el origen de las aguas tanto superficiales como subterraneas
(ver tambien seccion 3.3.4) que entran en las cuencas pueden ser:
Las lluvias por precipitacion directa en las lagunas y/o salares;
Por torrentes y rios intermitentes. Una parte de las aguas de lluvia escurren en
superficie hasta la laguna o el salar; y
Por manantiales y rios permanentes. Una pa rte de las aguas de lluvias al infiltrarse
alimenta capas de aguas subterranea, que se descargan continuamente alimentando asi
directamente al salar por los manantiales o alimentando rios cuando los manantiales
estan lejos de las orillas.
3.3.4 Hidrologfa subterranea
No existen datos sobre la disponibilidad de aguas subterraneas a la escala regional, pero las
caracteristicas geologicas y morfologicas de la region hacen suponer que son recursos de gran
importancia.
A escalas intermediarias y locales, aunque no hay un acuifero dominante por su tamaiio y/o
volumen de almacenamiento, la region alberga un gran numero de pequeiios acuiferos los
cuales en muchos casos representan las unicas fuentes de agua a las lagunas, salares, o rios
intermitentes, ademas del uso domestico que se puede hacer de ellos.
22
131
Once these factors have been collected, the waters concentrate because of evaporation
and then precipitate over the salts, according to the order of their increasing solubility.
Figure 3.6. Schematic representation of morpho-climatic control in the formation of
saline lagoons and salt flats.
The only permanent river found in the Ramsar Site is the Grande de Lipez River,
which originates in the Sur Lipez Ramsar site and flows towards the north forming
a very important basin—as shown in figure 3.5, basin Nº 17. This river has a higher
importance in the region inasmuch as it provides the most freshwater to Uyuni salt flat.
This is a permanent river that discharges in the southeast of the salt flat, infiltrating into
the deltaic-lacustrine sediments of that edge.
Finally, it is possible to affirm that the surface waters and groundwater (see also,
section 3.3.4) that enter the basins possibly constitute:
- Rainwaters, resulting from direct precipitation on the lagoons and/or salt flats;
- Waters originating from torrents and intermittent rivers. A part of the rainwaters
flow on the surface until they reach the lagoon or salt flat; and
- Waters originating from springs and permanent rivers. When they infiltrate, a part
of the rainwaters feeds groundwater layers, which are continuously discharged and
feed directly the salt flat due to the springs formed, or feed rivers when the springs are
far from the riverbanks.
3.3.4. Groundwater hydrology
There is no data on the availability of groundwater at the regional scale, but the
geological and morphological characteristics of the region suggest that these are
resources of high importance.
At the intermediate and local scales, albeit there are no dominating aquifers, be for
their size or/and their storage volume, the region comprises a great number of small
aquifers, which are, in many cases, the only sources of water for lagoons, salt flats, or
intermittent rivers, as well as for domestic use.
22
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132
Los acufferos, o pequei'ias napas subterraneas que existen en la zona del sitio Ramsar pueden
ser muy antiguos, y haberse establecido en una epoca en que los niveles de los lagos eran mas
altos. Aunque cabe hacer notar que tambien son las lluvias que las alimentaron, o queen
muches casos continuan alimentandolos. Esos acufferos se manifiestan en ocasiones por
manantiales que, por diferencia de presiones, hacen surgir las aguas subterraneas de las napas
mas someras.
En la zona existen dos tipos principales de manantiales:
los manantiales francos, cuyas aguas escurren visiblemente. 0 sea sus sa lidas estan bien
determinadas (ese es el caso de los manantiales del Silala);
Los manantiales difusos, es decir, el agua sa le muy lentamente a todo lo largo de una
orilla produciendo una zona pantanosa con vegetaci6n (lo cual se manifiesta por la
presencia de bofedales). En este segundo caso, nose nota el escurrimiento del agua
subterranea. Esas aguas son generalmente mas concentradas que las aguas de los
manantiales francos, parque ya se han evaporado antes de salir a la superficie.
Con respecto al area del Silala, yen particular en la zona desertica de alta montai'ia nacen
manantiales con un caudal estimado de alrededor de 200 1/s. El acuffero que origina esos
manantiales esta formado por ignimbritas bien fracturadas de edad miocenaica (16 a 12 Ma) que
tienen una gran distribuci6n al este de los manantiales. La figura 3.7 es un croquis esquematico
propuesto por SERGEOTECMIN en 2004 para explicar este proceso en el sitio de las quebradas del
Silala. La cuenca de captaci6n superficial alcanza solamente 32 km', mientas la extension de la
cuenca subterranea, de acuerdo a la situaci6n geo16gica y morfol6gica, se estima en 200 km'. Sin
embargo, esta area no es suficiente para explicar el caudal de las vertientes en una zona con una
precipitaci6n de apenas 60 mm/a. Estos aspectos y la ausencia de tritio en las aguas llevan a la
conclusion, que las aguas son mas antiguas y han sido recargadas probablemente en un tiempo
pluvial mas antiguo (Neumann-Redlin y Torres, 2003).
Ni.rel f,eo.tico d,, las
O.';luo..s su.bt:~rrcl' nea.s
\. I I ' I -'-. I I ;
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Figura 3.7 Situaci6n hidrogeo16gica en el area del Silala. Segun investigaciones en los Manantiales del
Silala, SERGEOTECMIN (Diciembre 2004).
3.3.5 Suelos
23
133
The aquifers, or groundwater sources that exist in the area of the Ramsar site are
possibly very old and are likely to have been established at a time when the lake levels
were higher. Although it should be noted that it was also the rains that fed them, or
in many cases continue to feed them. These aquifers sometimes manifest with the
formation of springs that, depending on pressure differences, cause the groundwater of
the shallower lagoons to emerge.
There are two kinds of springs in the area:
- Open springs, the waters of which flow visibly; i.e. their outflows are well
determined (this is the case of Silala springs);
- Widespread springs, in which the water flows slowly covering a bank and
producing a swampland with vegetation (which is manifested by the presence of
highland wetlands). In this case, the flow of groundwater is not perceptible. These
waters are generally more concentrated than the waters of open springs, because they
evaporate before emerging to the surface.
In the Silala area, and particularly the high-mountain desert zone, the springs originate
with an estimated flow of approximately 200 l/s. The aquifer that gives origin to these
springs is formed by fractured ignimbrites of the Miocene (16 to 12 Myr), which
are widespread to the east of the springs. Figure 3.7 presents a schematic sketch
proposed by SERGEOTECMIN in 2004 to explain this process in the site of the Silala
ravines. The surface intake basin has an extent of only 32 km2, while the extent of the
groundwater basin, based on its geological and morphological situation, is estimated
at 200 km2. However, this area is not sufficient to explain the flow rate of the springs,
in a region characterized with a precipitation of barely 60 mm/a. These aspects and
the absence of tritium in the waters lead to the conclusion that the waters are older and
had probably been recharged in a more ancient pluvial period (Neumann-Redlin and
Torres, 2003).
Figure 3.7. Hydrological situation of the Silala area. Based on research made on the
Silala springs, SERGEOTECMIN (December, 2004)
3.3.5. Soils
23
,
134
Los suelos son de baja fertilidad y con un alto contenido de piedras, gravas y afloramientos rocosos,
no aptos para la agricultura, exceptuando las suelos de la cuenca del rfo Quetena (Ergueta, 2002).
Los suelos presentan las siguientes caracteristicas:
Canas volcanicos, do mos o volcanes en escudo y sabre flujos de lava andesitica y dacitica
asociada con rocas piroclasticas.
Mesetas de lavas ignimbriticas riodaciticas, disectadas par canales sub-paralelos con
superficie irregular y pendientes variables.
Materiales deposicionales de arena, arcilla y limo fluvio-lacustre del cuaternario en lugares
pianos o alga inclinados (pendientes de hasta de un 3%).
3.4 Uso del suelo
En el Sitio Ramsar Los Upez, el uso del suelo esta practicamente ausente de la agricultura o el
pecuario; las actividades agricolas son minimas o inexistentes. Muy cerca del sitio existe una
importante produccion de quinua. En el periodo 2014-2015 la produccion de quinua llego a 110,000
toneladas metricas. En las ultimas 5 ai'ios, la superficie cultivada ha crecido y se estima actualmente
en mas de 170 mil hectareas en el altiplano boliviano. La mayor parte de la produccion del sector de
la quinua se concentra alrededor del Salar de Uyuni al norte del sitio Ramsar, con aproximadamente
70,000 pequei'ios productores.
Otro aspecto relevante del uso del suelo es el hecho que durante milenios, la poblacion de la region
utiliza las bofedales para el pastoreo del ganado camelido teniendo el cuidado de no sobrecargar
con unidades animales estas areas de gran productividad pero muy fragiles en su equilibria. Sin
embargo el crecimiento de la poblacion de camelidos y la creciente perdida de areas disponibles
para el pastoreo -bofedales, hacen que estos lugares sean sobrecargados especialmente cuando se
encuentran cerca de las poblados.
Actualmente, en algunos sectores coma el bofedal del rio Quetena se realiza el pastoreo extensivo
de llamas (FIR, 2009).
En la zona no existe un sistema de tenencia de la tierra para usos agricolas en lo que se refiere a las
pocas familias que viven en el area. La actividad se reduce a la ganaderia de camelidos y permite un
uso de la tierra que es considerado, de modo generico, coma un bien comunitario, al cual es libre de
acceso toda la poblacion de la region.
En la region del SO de Potosi en las ultimas ai'ios, se han desarrollados proyectos de ecoturismo en
las que se ha involucrado activamente a las comunidades originarias y se ha desarrollado una
interesante oferta de servicios turisticos, muchos de ellos asociados a las lagunas mas atractivas de
la region. (FIR, 2009).
Dentro y en las alrededores de la Reserva Eduardo Avaroa existen operaciones mineras
principalmente de borax, ulexita, azufre y carbonato de sodio (Tropico-Swedeforest 1998, Ergueta
2002) .
4. Estado actual del sitio (factores de deterioro naturales/antropogenicos pasados presentes)
En el Sitio Ramsar de acuerdo a la FIR, 2009 se indican a continuacion las principales factores de
afectacion:
24
135
The soils are of low fertility and present a high content of stones, gravel, and rock
outcrops. These soils are not suitable for agriculture, with the exception those of the
Quetena River basin (Ergueta, 2002).
The soils present the following characteristics:
• Volcanic cones, shield volcanoes, domes formed on flows of andesitic and dacitic
lava associated with pyroclastic rocks.
• Plateaus of rhyodacitic ignimbrite lava, dissected by sub-parallel canals with an
irregular surface and varying slopes.
• Pluvial-lacustrine sand, clay, and silt depositions from the quaternary found in
plains and slopes (of up to 3% of inclination).
3.4. Land use
The use of the land for agricultural or farming purposes in the Los Lipez Ramsar site
is practically nil; agricultural activities are either minimal, or inexistent. Close to the
site, however, there is an important quinine production—which reached the 110,000
metric tons for the 2014-2015 period. The cultivated surface has increased in the past
five years—it is estimated that it covers more than 170 hectares of the Bolivian High
Plateau. Most of the quinine production is concentrated around the Uyuni salt flat,
north of the Ramsar site, covering approximately 70,000 small producers.
Another relevant aspect connected with the use of the land is the fact that the inhabitants
of the region have used the wetlands for camelid livestock grazing for thousands
of years, taking the precaution of not overburdening these areas, which are highly
productive but fragile also. This notwithstanding, the growing number of camelids and
the recent loss of areas available for grazing—wetlands—have caused these zones to
be overburdened, especially where these zones are found near populated areas.
Llama grazing, is currently carried out extensively at certain areas, as the wetland of
Quetena River (RIS, 2009).
Land tenure systems for agricultural purposes for the few families that inhabit the
area have not been implemented. Agricultural activities are limited to camelid raising,
allowing for a use of the land that is regarded, in general, as a community asset, to
which anyone can secure access.
In the past years, the southwestern part of Potosi has seen the implementation of
ecotourism projects in which the indigenous communities have taken active part and
an interesting tourist product offer has developed, much of which is connected with the
most attractive lagoons of the region (RIS, 2009).
Within and in the surroundings of the Eduardo Avaroa Andean Fauna National Reserve,
mining activities are carried out, particularly concerning borax, ulexite, sulfur, and
sodium carbonate (Tropico–Swedeforest 1998, Ergueta 2002).
4. Current state of the site (past and present natural/anthropogenic factors of
deterioration)
The following main affectation factors in the Ramsar site concerned here can be
pointed out (based on the RIS, 2009):
24
136
Actividad minera. La actividad minera para la extraccion de minerales no metal icos como ulexita,
borax, calizas marmoleras, sal y otros en algunas lagunas como Capina, Koll pa y Salar de Chalviri es
considerable. Las cooperativas explotan los yacimientos de forma manual y rudimentaria a cielo
abierto, luego el material extraido es secado al sol y transportado en camiones de mediano y alto
tonelaje a puntos especfficos para su exportacion. El tran sporte de estos minerales no metalicos
produce en la zona cercana a los caminos ya las lagunas contaminacion atmosferica por la emision
de una importante cantidad de polvo producido. Tambien es probable que se esten contaminando
los cuerpos de agua, por derrame de aceites y combustibles.
Usos de aguas subterraneas. El uso de las aguas subterraneas en el Sitio Ramsar se da en la
actividad minera y por los albergues para el turismo.
Proyecto geotermico. En la FIR del 2009, se mencionaba la existencia de un proyecto de ley para
impulsar el aprovechamiento de energia geotermica en Sol de Mariana (dentro del sitio Ramsar), la
cual se constituye en una de las estrategias del gobierno boliviano para el aprovechamiento de los
recursos no renovables alternativos. La planta geotermica de acuerdo a las prospecciones tiene un
potencial de 280 MW y un periodo de vida de 40 afios. A la fecha el Estado Plurinacional de Bolivia
no ha previsto darle continuidad.
Se menciona igualmente que si bien esta alternativa pretende mejorar las caracteristicas
socioeconomicas de una de las regiones mas pobres del pais, los impactos ambientales tambien
seran de gran escala, desde la modificacion del paisaje - efecto sobre la actividad turistica-,
modificacion de las lagunas -por utilizacion de agua de las cuencas y otras subterraneas de la region,
efectos sobre la fauna silvestre -avifauna y otros vertebrados-, contaminacion del aire y del agua de
la region.
Durante la Mision se informo que El Ministerio de Hidrocarburos y Energia, junto a la Empresa
Nacional de Electricidad (ENDE) hicieron posible el financiamiento del Proyecto Piloto Planta
Geotermica en la Laguna Colorada, con 5 (MW) de potencia.
Actividades turisticas. En los ultimos afios el turismo intensivo, mas de 70.000 visitantes en el 2007,
que llega a la RNFA Eduardo Avaroa y su area de influencia (www.bolivia-rea.com), originan ciertos
impactos en la region yen particular en las lagunas, que son el principal habitat para los flamencos.
Por lo tanto, la presencia del turismo intensivo en algunas lagunas (Colorada, Hedionda Norte,
Cafiapa, Polques y Verde) puede ser un factor de alto riesgo para los humedales puesto que los
turistas se aproximan demasiado a las orillas con el objeto de fotografiar a los flamencos, o realizan
su "pic-nic" en lugares muy proximos a las orillas dejando basura o lavando los utensilios de cocina
con detergentes en las lagunas.
La construccion de albergues o alojamientos para el turismo muy proximos a las lagunas como
Colorada, Verde y Hedionda Norte, probablemente pueden estar contaminando los cuerpos de agua
por carecer de sistemas adecuados de tratamiento de aguas servidas, asimismo estas
infraestructuras no estan acordes con el paisaje porno utilizar material local o estar mal ubicados.
Por otro lado, los servicios basicos para alojamiento demandan cada vez mas agua en un area donde
este elemento es muy escaso. El uso de vehiculos "todo terreno" fuera de las rutas establecidas
dejan huellas en el suelo arenoso modificando el paisaje y compactando el terreno. Por otro lado, el
establecimiento de albergues improvisados como en el caso de Laguna Colorada, Huayllajara y
Laguna Verde, que no tienen sistemas adecuados de evacuacion de aguas servidas, las cuales
pueden filtrarse contaminando las fuentes de agua o directamente los mismos cuerpos de agua, y
finalmente el uso excesivo del agua de los manantiales, para servicios turisticos, que son los
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Mining activities. Mining activities carried out to extract non-metallic minerals,
such as ulexite, borax, limestones, salt, and others in some of the lagoons, as Capina,
Kollpa, and Chalviri salt flat, are considerable. The cooperatives exploit the deposits
manually and rudimentary in the open. The extracted materials are then dried in
the sun and transported in trucks of medium and high tonnage to specific points for
their exportation. The transport of these non-metallic minerals produces atmospheric
pollution in the areas close to roads and lagoons due to the emission of a significant
amount of dust. It is also probable that waterbodies are being contaminated by oil and
fuel spills.
Uses of groundwater. The groundwater in the Ramsar Site is used in mining activities
and to provide lodges for tourism.
Geothermal project. In the RIS of 2009, mention was made of a draft law to promote
the utilization of geothermal energy in Sol de Mañana (found within the Ramsar site),
which is one of the most strategic energy sources for the Government of Bolivia for
the utilization of alternative, non-renewable resources. According to the projections
for this initiative, the geothermal plant has a potential of 280 MW and a duration of
40 years. To date [however], the Plurinational State of Bolivia has not contemplated
implementing this initiative.
Mention was also made of the fact that, whereas this alternative purports to improve
the socioeconomic characteristics of one of the poorest regions of the country, the
environmental impacts would also be of a great scale, ranging from modifications to
the landscape (and their effect on tourist activities), to modifications of the lagoons
(owing to the utilization of basins and groundwater of the region), effects on wildlife
(avifauna and other vertebrae), and air and water contamination of the region.
During the mission, it was reported that the Ministry of Hydrocarbons and Energy,
together with the National Electricity Company (ENDE) made possible the financing
of the Pilot Project labelled Geothermal Plant in Laguna Colorada, with 5 (MW) of
power.
Tourism activities. In recent years, intense tourism—more than 70,000 visitors in
2007—in the Eduardo Avaroa Andean Fauna National Reserve and its area of influence
(www.bolivia-rea.com) has had certain impacts in the region and particularly in the
lagoons, which are the main habitat for flamingoes. Therefore, the presence of intense
tourism in some lagoons (Colorada, Hedionda Norte, Cañapa, Polques and Verde) is
likely a high-risk factor for wetlands, as tourists approach the banks excessively to
photograph flamingos, or perform picnics in places that are very close to the banks, and
litter, or wash kitchen utensils with cleansing agents in the lagoons.
The construction of lodges, or hostels for tourism in areas that are too close to the
lagoons, as Colorada, Hedionda Norte, Cañapa, Polques and Verde, are probably
contaminating the bodies of water, inasmuch as these lack the proper systems to
dispose of wastewater. Additionally, these infrastructures do not befit the landscape,
insofar as they do not use local materials, or are wrongly located.
Furthermore, basic services for lodging increasingly demand more water in a region
where this element is very scarce. The use of off-road vehicles outside of the established
routes leaves tracks on the sandy soil, altering the landscape and downsizing the area. In
addition, the establishment of improvised lodges—as it occurs in Colorada, Huayllajara,
and Verde lagoons—, which lack adequate systems to dispose of wastewaters, and
which might in turn leak out and contaminate water sources, or the bodies of water
themselves, and the excessive use of water that upwells from the springs for touristic
services might possibly be reducing the
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afluentes de los cuerpos de agua, pueden estar disminuyendo el caudal de recarga que necesitan,
considerando que se trata de una zona semidesertica con muy poca precipitacion.
Pastoreo de ganado camelido. En el area la actividad principal radica en el manejo de ganado
camelido, particularmente de llamas. El pastoreo de llamas y ovinos se realiza mayormente al borde
de las lagunas yen los bofedales, aunque en las lagunas nose pudo detectar un sobrepastoreo, pero
si sobre los bofedales.
La vulnerabilidad de los humedales del altiplano es aun mayor si consideramos su variabilidad
natural y la ocurrencia de ciclos secos-humedos interanuales, el clima seco y las condiciones de alta
evaporacion contribuyen a grandes variaciones espaciales y temporales {Caziani et al. 2001).
Recoleccion de huevos de flamencos. Existe presion de las comunidades locales para hacer uso
tradicional de los huevos de flamencos como se hacfa antes de la implementacion del area
protegida. Se estan analizando las posibilidades de hacer experiencias piloto de aprovechamiento de
los huevos de flamencos para consumo local. No obstante hubo cosechas de huevos ilegales por
pa rte de las comunidades locales, lo cual genera impacto sobre las colonias de reproduccion en
Laguna Colorada que no han sido cuantificables.
Caceria furtiva. Se presentan algunos hechos aislados sobre la caceria ilegal de vicufias fuera de los
limites del area protegida.
En la zona circundante del sitio Ramsar se producen las mismas actividades que generan efectos
adversos a la salud de los humedales en la region, actividad minera poco controlada, actividades
turisticas mal reguladas, impacto sobre el paisaje generandose caminos o huellas por todo lado
producido por vehiculos de empresas turisticas, actividades ganaderas poco eficientes.
Sin embargo, el uso de aguas subterraneas a una mayor escala es una de las principales amenazas
para la conservacion y permanencia del complejo de lagunas, puesto queen la region del suroeste
de Potosi, actualmente se esta emprendiendo la extraccion a cielo abierto de yacimientos de plata,
plomo y zinc a gran escala por la Empresa Minera San Cristobal - la mayor inversion en este rubro en
las ultimas tres decadas-. Las actividades mineras de esta empresa estan previstas para los
siguientes doce afios y demandaran 40 000 m3 agua/dia durante la fase de operacion, lo que
equivale a 4651/s de caudal continuo, aguas que solo estarian disponibles de fuentes subterraneas
(Molina 2007).
Registro de Montreux
Por la propuesta del Proyecto geotermico el sitio ingreso al Registro de Montreux el 16 de Junio
de 1993 y fue retirado del mismo el 7 de agosto de 1996.
Otros procesos de afectacion.
Canalizaci6n de los bofedales del Silala. En 1908 la prefectura de Potosi otorga las aguas del Silala
en concesion a la FCAB para el uso de locomotoras y aprueba el permiso de construccion de canales
e infraestructura para surtir de agua a los ferrocarriles del FCAB.
A continuacion se describen el estado de los componentes fisicos y ecologicos del sitio Ramsar.
4.1 Componente fisico
4.1.1 Geomorfologia
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recharge rate these bodies need, bearing in mind that this is a semi-desert region with
very little rainfall.
Grazing camelid livestock. In the area, the main activity is the handling of camelid
livestock, particularly llamas. Grazing of llamas and sheep occurs mostly at the edges
of the lagoons and in the wetlands; although it was not possible to detect overgrazing
in the lagoons, it was possible to identify it in the wetlands.
The vulnerability of the High Plateau wetlands is even higher if its natural variability
and the existence of dry-humid interanual cycles are borne in mind. The dry climate
and the high evaporation conditions contribute to high spatial and temporal variations
(Caziani, et al, 2001).
Collection of flamingo eggs. There is pressure from local communities to make
traditional use of flamingo eggs, as was done before the implementation of the
protected area. The possibilities of pilot experiments on the use of flamingo eggs
for local consumption are being analyzed. However, illegal egg harvests by local
communities have been evidenced, resulting in an impact on the breeding colonies of
Laguna Colorada that has not been quantified yet.
Poaching. Only isolated facts about illegal vicuña hunting outside the boundaries of
the protected area are available.
In the area surrounding the Ramsar Site, the presence of the same activities that cause
adverse effects on the wetland health of the region has been identified, i.e. poorly
controlled mining activities, poorly regulated tourism activities with impacts on the
landscape—the vehicles of tourist enterprises create roads or leave tracks on the soil—
, and inefficient cattle-raising activities.
Nevertheless, the use of groundwater at a higher scale is one of the major threats to the
preservation and permanence of the complex of lagoons, given that, in the southwest
region of Potosi Department, extraction activities of silver, lead, and zinc are currently
being undertaken at great scales in the open by San Cristobal mining enterprise—
which is the greatest investment in this field in the last three decades. This enterprise’s
mining activities have been calculated for the coming twelve years and will demand
40,000 m3 of water per day in its operation phase, which is equivalent to a continuous
flow rate of 465 l/s—these waters, however, would only be available from underground
sources (Molina, 2007).
Montreux Record
Due to the Geothermal Project proposal, the site was registered into the Montreux
Record on 16 June 1993 and it was then withdrawn from it on 7 August 1996.
Other processes of affectation
Canalization of the Silala Wetlands. On September 23, the Prefecture of Potosi
Department awarded the waters of Silala in concession to the FCAB to power its
locomotives and to this end also approved the permit for the construction of canals and
infrastructure to channel the waters.
Below is a description of the state of the physical and ecological components of the
Ramsar Site.
4.1 Physical component
4.1.1 Geomorphology
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Geomorfol6gicamente, el area tiene variadas geoformas que corresponden a sectores donde existen
depresiones (lagunas), planicies y zonas con imponentes elevaciones y temperaturas extremas; es
ahi en donde se encuentra el mayor potencial hidrogeol6gico. Por todos estos aspectos, sumado a
razones de tipo logistico y tecnico como la distancias, vias de acceso deterioradas, dificultades en lo
operatividad de los metodos de trabajo han impedido realizar estudios en detalle para cuantificar de
manera precisa los cambios de deterioro naturales y/o antropogenicos pasados; hace cerca de dos
decadas se inici6 la observaci6n de cambios en el area por medio de la utilizaci6n de imagenes
satelitales de Landsat.
4.1.2 Hidrologia superficial
Una de las caracteristicas basicas del sitio Ramsar Los Lipez son los deficits hidricos a escalas locales
regionales y probablemente globales (el conjunto del sitio Ramsar). Los deficits hidricos son el
resultado del deterioro natural desde el holoceno (miles de afios) cuando el area era todavia mas
humeda.
Aun con esas caracteristicas desfavorables, la presencia de las lagunas es muy importante pues son
ecosistemas clave para la presencia de flora y fauna en la region. Estas lagunas poco profundas son
alimentadas por rios y agua subterranea, por lo cual aun y cuando sean minimas, las fuentes
existentes de agua deben conservarse.
El drenaje superficial en la pa rte suroeste del sito Ramsar Los Upez es de tipo radial en las
cabeceras yen las partes bajas nose evidencian cursos de agua naturales definidos, a pesar de
la amplia variaci6n de altura. La red de drenaje principal se manifiesta a partir de manantiales,
cuyas aguas han sido canalizadas generando un flujo artificial, con direcci6n oeste. Los aforos
realizados por SERGEOTECMIN (2004) muestran flujos de entre 421/s y 1291/s para un total de
1641/s.
No obstante, estudios mas recientes de geofisica e isotopia han demostrado que los flujos de
drenaje del agua subterranea que surgen desde los manantiales en direcci6n oeste, ya se
habian establecido desde tiempos geo16gicos dada la presencia de valles, vaguadas, talwegs, o
cou/ees, los cuales se formaron por el derretimiento y drenaje glacial.
4.1.3 Hidrologia subterranea
Desde inicio de los afios 2000, SERGEOTECMIN realiz6 estudios de investigaci6n de campo y de
calculo para establecer el origen y las caracteristicas de flujo de las aguas en el Silala y continuar
adquiriendo conocimientos sobre los acufferos y las aguas subterraneas en la cordillera occidental.
Con esos estudios se concluy6 que la ocurrencia del agua en el Silala se debe a la descarga natural de
un acuifero constituido por ignimbritas fracturadas. La ocurrencia de las aguas es producto del flujo
del agua a traves de las fracturas de las ignimbritas por porosidad secundaria. Ese acuffero aflora en
la zona y, por diferencias topograficas, crea manantiales que descargan en varias puntos de la zona y
alimenta los bofedades localizados en la misma.
En diciembre de 2004 SERGEOTECMIN realiz6 estudios adicionales en el sitio del Silala con el objeto
de cuantificar la descarga de los manantiales y establecer unbalance hidrico de los bofedales.
El balance hidrico se elabor6 como sigue:
• Superficie de los bofedales del Silala:
• Evapotranspiraci6n real:
108,700 m'
3,000 mm/a
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Geomorphologically, the area has varied geoforms that correspond to sectors where
there are depressions (lagoons), plains, and zones of imposing elevations and extreme
temperatures; this is where the greatest hydrogeological potential is to be found.
Owing to all these aspects, in addition to logistical and technical reasons, such as
distances and deteriorated access routes, the difficulties in the operability of working
methods have prevented the conduction of detailed studies to quantify precisely the
natural deterioration and/or earlier anthropogenic changes; about two decades ago,
the observation of natural deterioration changes began in the area through the use of
LandSat satellite images.
4.1.2 Surface Hydrology
One of the basic characteristics of Los Lipez Ramsar site is the water deficits at local
and probably global scales (at the whole Ramsar site). Water deficits are the result of
natural deterioration from the Holocene (from thousands of years ago) when the area
was still more humid.
Even with these unfavorable characteristics, the presence of lagoons is very important
because they are key ecosystems for the presence of flora and fauna in the region.
These shallow lagoons are fed by rivers and groundwater; as a result, even if they are
minimal, existing water sources must be preserved.
The surface drainage in the southwestern part of Los Lipez Ramsar Site is radial in
the headwaters and there is no evidence of defined natural watercourses in the lower
parts, despite the wide altitude variations. The main drainage network manifests in the
upwelling of springs, the waters of which have been channeled generating an artificial
flow, in direction to the west. The measurements completed by SERGEOTECMIN
(2004) show flow rates ranging between 42 l/s and 129 l/s for a total of 164 l/s.
However, more recent geophysical and isotopic studies have shown that the flows of
drained groundwater from springs, which move in direction to the west, had already
been established since geological times owing to the presence of valleys, troughs,
thalwegs, or coulees, which were formed by melting and glacial drainage.
4.1.3 Groundwater hydrology
Since the beginning of the 2000s, SERGEOTECMIN has carried out field research and
calculation studies to establish the origin and flow characteristics of the waters of the
Silala and to continue acquiring knowledge on the aquifers and groundwater found in
the western mountain range.
With these studies, the conclusion was reached that the occurrence of water in the
Silala is the result of the natural discharge of an aquifer constituted by fractured
ignimbrites. The occurrence of the water is the product of water that flows through the
fractures of ignimbrites by secondary porosity. This aquifer upwells in the area and,
due to topographical differences, creates springs that discharge at various points of the
area and feed the wetlands located therein.
In December 2004, SERGEOTECMIN carried out additional studies in the Silala site
in order to quantify the discharge of the springs and establish a water balance for the
wetlands.
The water balance was elaborated as follows:
• Surface of the Silala wetlands: 108,700 m2;
• Actual Evapotranspiration: 3,000 mm/a;
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• Evapotranspiracion real Silala : 326,100 m3/a
• Oferta de aguas subterraneas Silala : 2001/s = 6,307,200 m3/a
• Oferta de agua menos evapotranspiracion: 6,307,200 - 326,100 = 5,981,100 m3/a ~ 190 1/s
Como resultado de ese analisis se concluyo que alrededor de 10 1/s, o 5 % del agua subterranea que
nace en Silala, evapotranspira, el resto de 1901/s escurre superficialmente en direccion oeste.
Convertida en volumen, la evapotranspiracion real en el Silala, es mucho menor con respecto a la
oferta del agua descargada par el acuifero. Par eso existe un escurrimiento superficial en direccion al
oeste.
A la escala local (bofedales y manantiales del Silala) esos datos de balance hidrico parecen ser las
unicos que existen. Nose sabe si el volumen total de las manantiales, de 2001/s, ha cambiado con el
tiempo, pero dadas las caracteristicas hidrogeologicas del sitio, y coma primera hipotesis
conceptual, se puede concluir que se trata de manantiales, u ojos de agua de origen subterraneo con
un volumen relativamente estable. La Mision fue informada que el Estado Plurinacional de Bolivia
esta realizando estudios a fin de contar con datos actuales.
Par otro lado, segun estudios mas o menos recientes (Neumann-Redlin y Torres, J., 2003) de las
aguas de las manantiales del Silala realizados con isotopos estables (6180, 62H, 3H y 14(), las aguas
que afloran en esos manantiales son aguas f6siles de mas de 10,000 arias. Es decir son aguas que no
se renuevan par recarga natural de aguas meteoricas en el acuifero local. Baja las condiciones
climaticas actuales, esto significa que esos recursos hidricos estan almacenados en el acuifero
ignimbritico bien fracturado desde hace miles de arias, el cual se vacia natural y paulatinamente a
traves de las siglos.
4.1.4 Suelos
Los factores de deterioro mas adversos que afecten a las caracteristicas del sitio son las cambios en
el uso del suelo (incluyendo el aprovechamiento del agua) y de proyectos de desarrollo, son
principalmente las concesiones para la mineria.
La actividad minera para la extraccion de minerales no metalicos coma ulexita, borax, calizas
marmoleras, sal y otros en algunas lagunas coma Capina, Koll pay Salar de Chalviri es considerable.
Estas actividades de extraccion son realizadas par una empresa privada y par varias pequerias
cooperativas constituidas par las pobladores de la region . Estas cooperativas explotan las
yacimientos de forma manual y rudimentaria a cielo abierto, luego el material extraido es secado al
sol y transportado en camiones de mediano y alto tonelaje a puntos especificos para su exportacion.
Ademas de impactos di rectos sabre las lagunas -par presencia humana y cambios en las orillas y
espejo de agua; el transporte de estos minerales no metalicos produce en la zona cercana a las
caminos ya las lagunas contaminacion atmosferica par la emision de una importante cantidad de
polvo producido. La extraccion de material es de forma artesanal par las cooperativas y con
maquinaria pesada par parte de la empresa privada, par lo cual existe la probabilidad que se
contaminen las cuerpos de agua, principalmente en el segundo caso par derrame de aceites y
combustibles. Este aspecto no ha sido estudiado en detalle (FIR, 2009).
4.2 Componente ecosistemico
4.2.1 Flora y vegetacion
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• Actual Evapotranspiration Silala: 326,100 m3/a;
• Supply of Silala groundwater: 200 l/s = 6,307,200 m3/a;
• Water supply excepting evapotranspiration: 6,307,200 - 326,100 = 5,981,100
m3/a = 190 1/s
As a result of this analysis, it was estimated that about 10 l/s, or 5% of the groundwater
that originates in Silala evapotranspires, while the remainder, amounting to 190 l/s
flows superficially to the west.
Converted to volume, the actual evapotranspiration in the Silala is much smaller with
respect to the supply of water discharged by the aquifer. That is why there is a surface
runoff in direction to the west.
At the local scale (Silala springs and wetlands), these water balance data seem to be
the only ones available. It is not known if the total volume of the springs, amounting
to 200 l/s, has changed over time, but due to the hydrogeological characteristics of the
site, and as the first conceptual hypothesis, it can be concluded that these springs or
water outflows originate from groundwater and have a relatively stable volume. The
Ramsar Mission has been informed that the Plurinational State of Bolivia is carrying
out surveys in order to obtain updated data.
On the other hand, according to relatively recent studies (Neumann-Redlin and Torres,
J., 2003) of the waters of the Silala springs, which were carried out with stable isotopes
(δ18O, δ2H, 3H and 14C), the waters that surface in those springs are fossil waters dating
back to more than 10,000 years. In other words, these are waters that are not renewed
by natural recharges of meteoric waters in the local aquifer. Under the current climatic
conditions, this means that these water resources are stored in the well-fractured
ignimbrite aquifer for thousands of years, emptying naturally and gradually over the
centuries.
4.1.4 Soils
The most adverse deterioration factors that affect the characteristics of the site are
changes in the use of the soil (including the utilization of water) and development
projects, mainly mining concessions.
Mining activities to extract non-metallic minerals, as ulexite, borax, limestones, salts,
and others in Capina and Kollpa lagoons, and in the Chaviri salt flat is significant.
These extraction activities are carried out by a private company and by several small
cooperatives set up by the inhabitants of the region. These cooperatives exploit the
reservoirs manually and rudimentarily in the open. The extracted materials are then
dried in the sun and transported in trucks of medium and high tonnage to specific
points for their exportation. In addition to direct impacts on the lagoons—caused by
human presence and changes in the banks and water mirrors—the transport of these
non-metallic minerals produces atmospheric pollution in the area that is close to the
roads and lagoons due to the emission of a significant amount of dust produced. The
extraction of material is handmade by cooperatives and with heavy machinery by the
private company, which is why it is likely that the water bodies will be contaminated,
mainly by the latter company due to spillage of oils and fuels. This aspect has not been
studied in detail, though (RIS of 2009).
4.2 Ecosystem component
4.2.1 Flora and vegetation
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Varias especies vegetales estan sometidas a explotaci6n a gran escala por su caracter combustible
como la yareta, las tholas, la tara y otras mas. La mayor presi6n proviene de las minas de ulexita,
campamentos mineros y caleras. En el caso de la yareta (Azore/lo compocta), se produce una
explotaci6n en gran escala, extracci6n hist6rica de cojines completos, disminuyendo grandemente
las posibilidades de producci6n de semi I las. Es la especie considerada mas vulnerable en la zona
sobre todo por su uso en minerfa (FIR, 2009).
4.2.2 Fauna
De las especies presentes en el Sitio Ramsar, los flamencos son especies altamente especializadas
cuya capacidad para adaptarse a condiciones cambiantes es limitada y cuya vulnerabilidad a
interferencias por humanos es especialmente alta, particularmente debido a que los ambientes
salinos que habitan son explotados para la extracci6n de sal, sulfatos y boratos (del Hoyo 1992).
5. Evaluaci6n del cambio en las caracterfsticas eco16gicas
De acuerdo a la informaci6n suministrada por el gobierno de Bolivia, como parte de solicitud de la
Misi6n se indic6 queen el Sitio Ramsar Los Lipez (bofedal Silala y areas conexas), se estan
presentando cambios en sus caracterfsticas ecol6gicas debido a la canalizaci6n artificial de sus
manantiales. En este sentido se mencion6 que las aguas no renovables del Silala se han visto
disminuidas, que los suelos se han daiiado y que el sistema de aguas y de vida interconectado a
dicho bofedal se han visto negativamente afectados.
En el marco de la Convenci6n, el caracter eco16gico de un sitio Ramsar es la combinaci6n de los
componentes, procesos y beneficios/servicios que caracterizan al humedal en un punto dado del
tiempo.
En el contexto de implementaci6n del Artfculo 3.2 cambio en el caracter eco16gico, son las
alteraciones humanas adversas de cualquier componente, proceso yo beneficio/servicio del
ecosistema.
De acuerdo a lo anterior a continuaci6n se realiza una evaluaci6n del estado del caracter eco16gico
del Sitio Ramsar Los Lipez como un todo en base a la informaci6n suministrada y la visita de cam po
al sitio.
5.1 Aspectos ffsicos
5.1.1 Hidrologfa superficial
Se describen brevemente algunos cambios considerados como importantes, producidos en las
caracterfsticas hidro16gicas superficiales y subterraneas a las escalas regional, intermediaria y local
del sito Ramsar Los Lipez.
A la escala del sitio Ramsar Los Lipez, con un area total de 14,277 km', nose observan cambios
hidrol6gicos notables desde la denominaci6n del toda el area como sito Ramsar.
A la escala intermediaria y local, se observa un desarrollo intensivo del turismo en el Sitio, con el
establecimiento de infraestructura para alojamientos en lugares poco adecuados y pr6ximos a los
cuerpos de agua (lagunas, bofedales), lo que origina cierta contaminaci6n porno contar con
sistemas adecuados de evacuaci6n de aguas servidas. Asimismo, se esta utilizando cada vez mas
agua de los afluentes que llegan a Laguna Colorada. Otros albergues se han establecido cerca de los
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Several plant species are subject to large-scale exploitation because they can be
used as fuels; this is the case of the yareta, the tholas, the tara and others. These are
predominantly exploited in ulexite mines, mining camps, and lime fields. The yareta
(Azorella compacta) is exploited at a large scale; whole yareta cushions have been
historically extracted, greatly diminishing the possibilities of seed production. This
species is considered the most vulnerable in the area, mainly because of its use in
mining (RIS of 2009).
4.2.2 Fauna
From among the species present in this Ramsar Site, flamingoes are a highly specialized
genus. Their capacity to adapt to changing conditions is limited and their vulnerability
to human interferences is remarkably high, particularly due to the exploitation of salt,
sulphate, and borates in the saline environments they inhabit (del Hoyo, 1992).
5. Assessment of changes in ecological characteristics
According to the information provided by the Bolivian Government, as part of the
Mission’s request, it was indicated that the Los Lipez Ramsar Site (Silala wetland
and related areas) are showing changes in their ecological characteristics due to the
artificial channeling. In this sense, it was mentioned that the non-renewable waters of
the Silala have decreased, that the soils have been damaged, and that the system of
waters and life interconnected to said wetland have been adversely affected.
Within the framework of the Convention, the ecological character of a Ramsar site is
the combination of the components, processes, and benefits/services that characterize
the wetland at a given point in time.
In the context of implementing Article 3.2, changes in the ecological character occur
when there have been adverse human alterations of any component, process, and/or
ecosystem benefit/service.
In light of the foregoing, an evaluation of the ecological status of the Los Lipez Ramsar
Site as a whole is carried out on basis of the information provided and the field visit
to the site.
5.1. Physical aspects
5.1.1. Surface hydrology
Some important changes occurring in the surface and underground hydrological
characteristics are described briefly at the regional, intermediate, and local scales of
the Los Lipez Ramsar site.
At the scale of the Los Lipez Ramsar site, covering a total area of 14,277 km2, no
noticeable hydrological changes are observed since its inclusion as a Ramsar site.
At the intermediate and local level, there is a concentrated development of tourism
activities in the site, with the establishment of infrastructures for accommodations in
places that are not suitable and that are close to the waterbodies (lagoons, wetlands),
which causes a certain degree of contamination resulting from the lack of adequate
wastewater disposal systems. Similarly, waters from the tributaries that reach Laguna
Colorada are increasingly being used. Other lodging sites have been established near other
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146
cuerpos de agua como en Laguna Verde y laguna Hedionda Norte y el impacto de la infraestructura
que rompe el paisaje, basura y otros aspectos es cada vez mas evidente.
A la escala de los bofedales del Silala, no existen cuerpos de agua superficial, excepto aquellas que
afloran de los manantiales en los bofedales descritos antes. Las denominadas Laguna Blanca y
Laguna Chica son depresiones topograficas secas sin agua. La Laguna Blanca esta cubierta en su
superficie por clastos de 2 a 20 cm de chert o cuarzo amorfo, que dan lugar a ese tono blanquecino
que se observa en la imagen satelital y fotografias aereas
El cuerpo de agua superficial mas cercano a los bofedales del Silala es la Laguna Khara que se
encuentra a 5.5 Km al NE y la Laguna Colorada, localizada a 38 Km al sur del area de Silala.
Por ultimo, no existe ningun efluente contaminante en toda el area de estudio.
5.1.2 Hidrologfa subterranea
La zona esta conformada por numerosas cuencas endorreicas constituidas por subcuencas, lagunas,
corrientes de agua superficial y afloramientos de agua subterranea. Esta zona es considerada muy
arida con escasas precipitaciones (<100 mm anuales en Laguna Colorada) y un alto nivel de
evaporacion (> 500 mm), produciendose un deficit hfdrico permanente que contrasta con la
presencia de numerosas lagunas que, como oasis en el desierto son ecosistemas clave para la
presencia de flora y fauna en la region. Estas lagunas poco profundas son alimentadas por rios y
manantiales de agua subterranea (Alurralde 2006).
No obstante, el agua subterranea tiene un valor inestimable sobre los humedales locales (bofedales)
pues los desniveles de la presion del agua subterranea permiten a la vez la resurgencia de
manantiales quienes escurren de manera superficial y alimentan los bofedales; al mismo tiempo
estos desniveles alimentan los bofedales directamente por emergencia vertical sobre los mismos
(ver croquis en la figura 3.7). De hecho, los bofedales deben su existencia al agua subterranea.
Estudios realizados por el SERGEOMIN (2001) revelan la fntima relacion entre las aguas superficiales
y subterraneas que definen las caracterfsticas hidrologicas de la region; es decir, que la formacion de
lagunas y bofedales en la superficie terrestre dependen del aporte de las aguas subterraneas, y estas
son bastante antiguas (Alurralde 2006). El sistema de aguas subterraneas constituye un tejido
interno regulador que sostiene la humedad en el suelo externo con la manifestacion de manantiales,
vertientes, rios, cuencas y formacion de humedales que sirven de habitat de poblaciones de avifauna
y poblaciones humanas asentadas en la region (SERGEOMIN 2001, citado en Alurralde 2006).
Estudios realizados en la zona coinciden en que la recarga de acufferos en la region es muy debil o
casi inexistente. La recarga de los acufferos pudo haberse producido entre algunos cientos y varios
miles de afios, cuando las caracterfstica climaticas eran diferentes a las actuales. Por lo tanto, se
puede considerar al agua como un recurso no renovable f6sil y bastante limitado del que dependen
las actividades antropicas realizadas en la region.
El uso de las aguas subterraneas en el Sitio Ramsar se da en la actividad minera y por los albergues
para el turismo. En el primer caso las aguas de los manantiales del Silala se desvfan hacia Chile para
su uso en las mineras y la empresa Tierra Ltda tambien hace uso de agua subterranea de un pozo de
energia geotermica para el procesamiento de acido borico. Los albergues de turismo utilizan agua de
los manantiales de agua subterranea y aguas termales (FIR, 2009).
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147
waterbodies as the Verde and northern Hedionda Lagoons, and the impact of these
infrastructures—disrupting the landscape—, garbage, and other components is
increasingly evident.
At the scale of the silala wetlands, there are no surface water bodies, with the exception
of those that well up from the springs located in the wetlands described above. The socalled
Laguna Blanca and Laguna Chica are dry topographic depressions. The surface
of Laguna Blanca is covered by clasts of chert, or amorphous quartz of 2 to 20 cm,
which give place to that whitish tone that can be observed in satellite images and aerial
photographs.
The surface waterbody that is closest to the Silala wetlands is Khara lagoon, which is
found at 5.5 Km to the northeast, and Laguna Colorada, found at 38 km to the south
of the Silala area.
Finally, there is no polluting effluent in the whole of the area studied.
5.1.2 Groundwater hydrology
The area is formed by numerous endorheic basins constituted by sub-basins, lagoons,
surface water currents, and outcrops of groundwater. This area is considered very
arid with little rainfall (<100 mm per year in Laguna Colorada) and a high level of
evaporation (> 500 mm), resulting in a permanent water deficit that contrasts with the
presence of numerous lagoons which, like oases in the desert, are key ecosystems for
the presence of flora and fauna in the region. These shallow lagoons are fed by rivers
and groundwater springs (Alurralde, 2006).
However, groundwater has an invaluable importance on local wetlands, inasmuch as
the unevenness of the groundwater pressure allows the resurgence of springs that runoff
on the surface and feed the wetlands, and, at the same time, feeds the wetlands directly
by vertical emergence over them (see diagram in figure 3.7). In fact, the wetlands owe
their existence to groundwater.
Studies carried out by SERGEOMIN (2001) reveal the intimate relationship between
surface and groundwater, which defines the hydrological characteristics of the region;
that is, the formation of lagoons and wetlands on the surface depends on the inputs
of groundwater, and these are quite old (Alurralde 2006). The groundwater system is
an internal regulating tissue that maintains the humidity in the external soil with the
manifestation of springs, slopes, rivers, basins, and the formation of wetlands that
serve as the habitat for bird and human populations settled in the region (SERGEOMIN
2001, quoted in Alurralde 2006).
Studies carried out in the area agree that the recharge of aquifers in the region is very
weak, or almost inexistent. The recharge of the aquifers might have occurred between
several hundred and several thousand years, when the climatic characteristics were
different to the present ones. Therefore, water can be considered as a rather limited
and non-renewable fossil resource on which anthropic activities in the region depend.
The groundwater in the Ramsar Site is mainly used in mining activities and lodging
for tourism. In regard to the former, the waters of the Silala springs are diverted to
Chile and are used by mining companies. Tierra Ltd. Company also makes use of
groundwater obtained from a geothermal well to process boric acid. Tourist lodges,
on the other hand, use waters from groundwater springs and thermal waters (RIS of
2009).
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Otro uso de aguas subterraneas en la region del suroeste de Potosi, es la extraccion a cielo abierto
de yacimientos de plata, plomo y zinc a gran escala par la Empresa Minera San Cristobal- la mayor
inversion en este rubro en las ultimas tres decadas. Las actividades mineras de esta empresa estan
previstas para las siguientes dace aiios y demandaran 40 000 m3 agua/dfa durante la fase de
operacion, lo que equivale a 4651/s de caudal continua, aguas que solo estarian disponibles de
fuentes subterraneas (Molina 2007).
lndependientemente de la utilizaci6n de este recurso para actividades mineras de gran escala, el uso
de estos recursos en esta fragil region puede causar impactos coma la disminuci6n de las niveles de
agua subterranea y el volumen de agua almacenados en las acuiferos, degradacion y/o desecaci6n
de bofedales, la desecaci6n de lagunas alto-andinas, efectos negativos sabre la avifauna que
depende de estas lagunas (flamencos), reducci6n de las hatos de camelidos, impactos
socioecon6micos y culturales en las poblaciones humanas, la desaparici6n o degradaci6n de fuentes
de agua utilizadas para consumo humano (Molina 2007).
La totalidad de las manantiales que afloran en forma artesiana en el area de Silala son descargas del
acuifero de las lgnimbritas Silala. En muchos casos se observan manantiales surgentes directamente
de las diaclasas y fisuras. Los sedimentos finos Cuaternarios y Recientes que cubren las ignimbritas
son alimentados y saturados par el agua del acuifero ignimbritico subyacente formando bofedales.
El acuifero de Silala es de escala intermediaria cuya area se estima a aproximadamente 320 km2, el
acuifero puede ser confinado o de condicion freatica dependiendo de la cobertura de materiales del
Cuaternario. Se requeririan la perforacion de par lo menos dos pozos exploratorios para definir su
real origen, el espesor de las ignimbritas y las rocas infrayacentes. Asi coma la determinacion del
nivel o niveles de las acuiferos y el bombeo necesario para determinar las niveles de descarga
permisibles.
Segun la hidro-quimica y las para metros ffsicos de las aguas, se deduce la existencia de dos niveles
de acuiferos ignimbriticos. Uno superior que forma el bofedal del Sur con afloramientos a las 4450
msnm y conductividad promedio de 257 μS/cm, y mayor contenido de Ca, Li y 504. El segundo nivel
acuifero inferior, aflora a las 4400 msnm y tiene una conductividad promedio de 109 μS/cm, y mayor
contenido de Na. Este nivel es el que aflora en el Bofedal Norte o Cajones.
Nose ha detectado ningun tipo de contaminaci6n en las aguas surgentes del acuifero.
Desde el punto de vista de la recarga natural al acuifero par media de la infiltracion de la
precipitaci6n en el area, se observa que esta es de menor importancia pues corresponde a las
aportes de la precipitacion, queen promedio, son menores de 100 mm/aiio, ademas, es muy
variable de un aiio a otro: hay aiios en que ha superado las 250 mm, mientras queen otros esta par
debajo de las 50 mm.
De esas observaciones se puede deducir que la recarga neta al acuifero es casi nula, debido o
perdidas par evaporaci6n y sublimaci6n. Eso lo ubica en un acuifero de tipo no-renovable a la escala
geologica. El origen y cantidad de esas aguas es unicamente el volumen almacenado en el acuifero,
el cual se vacia natural y paulatinamente a traves de las siglos.
Para tener una idea de las tiempos de escurrimiento naturales asf coma de las volumenes
potenciales almacenados en el acuifero, en las secciones siguientes se presenta un analisis
cuantitativo, conceptual, basado en las conocimientos y datos actuales de las que se dispone,
recabados par la mision Ramsar (noviembre 2016- marzo 2017).
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149
Another use of groundwater in the southwest region of Potosi Department is the
open-pit large-scale extraction of silver, lead, and zinc deposits by the San Cristobal
Mining Company—the largest investment in this area in the last three decades. Mining
activities of this company are planned for the next twelve years and will demand
40,000 m3 water/day during its operation phase, which is equivalent to a continuous
flow-rate of 465 1/s; these waters would only be available from underground sources
(Molina, 2007).
Irrespective of the use of this resource for large-scale mining activities, the use of
these resources in this fragile region can cause impacts such as reductions of the
groundwater levels and the volume of water stored in the aquifers, degradation, and/or
desiccation of high-Andean lagoons, negative effects on the avifauna—which depends
on these lagoons (flamingoes)—, declines of camelidae herds, socioeconomic and
cultural impacts on human populations, and disappearance or degradation of the water
used for human consumption (Molina 2007).
The whole of the springs that appear artesianly in the area of Silala results from
discharges of the aquifer of the Silala ignimbrites. In many cases, springs arising
directly from the joints and fissures can be observed. The Quaternary and Recent
thin sediments that cover the ignimbrites are fed and saturated by the water of the
underlying ignimbrite aquifer, forming wetlands.
The Silala aquifer is of intermediate scale. Its area is estimated at approximately 320
km2. This aquifer might be a confined, or phreatic one depending on the coverage
of materials from the Quaternary. The drilling of at least two exploratory wells was
required to define its true origin, the thickness of the ignimbrites, and the underwater
rocks, together with the determination of the level, or levels, of the aquifers and the
necessary pumping to determine permissible discharge levels.
According to the hydro-chemistry and the physical parameters of the waters, the
existence of two levels of ignimbrite aquifers is deduced. A superior one that forms the
south wetland with emergences of water at 4450 m.a.s.l and an average conductivity
of 257 μS/cm, and higher content of Ca, Li, and S04.; and a lower one that emerges at
4400 m.a.s.l and has an average conductivity of 109 μS/cm, and a higher Na content.
This aquifer level is the one that emerges in the north wetland or Cajones.
No contamination has been detected in the waters that emerge from the aquifer.
As far as the aquifer’s natural recharge through the infiltration of precipitation in the
area is concerned, it is observed that this infiltration is of minor importance because
it corresponds to the contributions of precipitation, which on average amount to less
than 100 mm/year and varies from year to year: there are years when it has exceeded
the 250 mm, while in others it was below the 50 mm.
From these observations it can be deduced that the aquifer’s net recharge is almost nil,
due to losses resulting from evaporation and sublimation. This leads to its classification
as a non-renewable aquifer on the geological scale. The origin and quantity of these
waters comprises only the volume stored in the aquifer, which empties naturally and
gradually over the centuries.
To get an idea of the natural runoff times, as well as of the potential volumes stored in
the aquifer, the following sections present a quantitative, conceptual analysis, based on
current knowledge and data collected by the Ramsar Mission (November 2016–March
2017).
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Escurrimientos naturales
Para evaluar las escurrimientos naturales del agua subterranea contenida en el acuffero de
ignimbritas del Silala, se consideraron las If mites del mismo propuestos par SERGEOTECMIN {2002) .
La carta geoI6gica mostrada de la figura 5.1 indica en color rojo las lfmites del acuffero; mientras que
la figura 5.2 es un carte transversal suroeste-noreste del sitio del Silala con enfasis en la
hidrogeologfa, segun SERGEOTECMIN {2002). De igual manera se utiliz6 la figura 5.3 tambien
propuesta par SERGEOTECMIN (2002) mostrando las direcciones del flujo subterraneo en 2D
horizontal.
Con el uso esas figuras se aplic6 la ley de Darcy para estimar las flujos de agua subterranea que
ocurren el acuffero desde sus lfmites noreste hasta las If mites suroeste.
La formulaci6n de Darcy para medias porosos o porosos equivalentes (el caso de este acuffero) es:
Q=A · K· i
En donde: Q es el flujo volumetrico, en m3/s; K es la conductividad hidraulica del acuffero en m/s; e i
es el gradiente hidraulico, sin dimensiones.
Dada la falta de datos de parametros precisos del acuffero, se hizo una busqueda en la literatura
para materiales similares al acuffero del Silala el cual esta compuesto esencialmente de ignimbritas
fracturadas y se encontraron valores distintos de conductividad de hasta tres 6rdenes de magnitud,
entre lE-5 m/s y lE-7 m/s (Huang et al., 2014).
El area del acuffero se estim6 de la delimitaci6n propuesta en la figura 5.1; mientras que el gradiente
hidraulico se estim6 del carte transversal de la figura 5.2, las valores estimados son:
A=320 km'
i=0.02
Con esos valores y utilizando la gama de las tres conductividades, se obtienen gastos de
escurrimiento de entre 64'0001/s para K=lE-5 m/s, y 640 I/s para K=lE-7 m/s. El valor dado para
K=lE-7 m/s es el que mas se acerca al volumen total de las caudales que emergen en las
manantiales del Silala (2001/s). Dadas las incertidumbres en el area yen las conductividades
propuestas, se puede concluir que un valor de K= lE-7 m/s serf a el mas representante del acuffero
pues es el que reproduce el mismo orden de magnitud de las volumenes que emergen en las
manantiales.
Estas estimaciones son muy preliminares, las calculos pueden ser refinados y disminuir asf las
incertidumbres, con la obtenci6n de datos mas precisos.
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151
Natural runoff
To assess the natural runoff of the groundwater contained in the ignimbrite aquifer
of Silala, the limits set by SERGEOTECMIN (2002) were taken into account. The
geological map of figure 5.1 depicts the aquifer’s limits in red; while figure 5.2
depicts a southwest– northeast cross-section of the Silala site, placing emphasis on
hydrogeology, as per SERGEOTECMIN (2002). Similarly, figure 5.3—proposed by
SERGEOTECMIN also (2002)—was used to depict the directions of groundwater
flow in a 2D horizontal plane.
With the use of these figures, the Darcy law was applied to estimate the groundwater
flows that occur in the aquifer, stretching from its northeast limits to its southwest
limits.
The Darcy formula for porous media, or equivalent porous (in the case of this aquifer)
is:
Q = A • K • i
Where: Q is the volumetric flow, in m3/s; K is the hydraulic conductivity of the aquifer
in m/s; and i is the hydraulic gradient, without dimensions.
Owing to the lack of precise parameters for the aquifer, the literature was examined to
search for materials that are similar to those of the Silala aquifer, which is essentially
composed of fractured ignimbrites. Different conductivity values of up to three
magnitude orders were found, between 1E-5 m/s and 1E-7 m/s (Huang et al, 2014).
The area of the aquifer was estimated on basis of the delimitation proposed in figure
5.1; while the hydraulic gradient was estimated on basis of the cross-section presented
in figure 5.2, the values estimated are:
A = 320 km2
i: 0.02
With these values and using the range of the three conductivities, the result of runoff
rates obtained is between 64’000 l/s for K = 1E-5 m/s and 640 l/s for K = lE-7 m/s.
The value given for K = lE-7 m/s is the one closest to the total volume of the flows
that emerge in the Silala springs (200 l/s). Due to the uncertainties in the area and the
proposed conductivities, it can be concluded that a value of K = lE-7 m/s would be the
most representative for the aquifer because it reproduces the same order of magnitude
as the volumes that emerge in the springs.
These estimates are preliminary; the calculations can be improved and thus reduce the
uncertainties—once more precise data is obtained.
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152
Figura 5.1 Mapa geo16gico del area del Silala con enfasis en la hidrogeologia, segun SERGEOTECMIN
(2002).
so NE
A B
CaJTioo
Laguna IISAID
Khara t~ 4400
0 1 2 Jmi
L...J........L.
■ Oepisilosoocoo- ■ Lavasmk> •plo· ■ lll!mblilas
soid&YJI p~is1oceoo:is cericas IAaittero)
Figura 5.2 Corte transversal suroeste-noreste del area del Silala con enfasis en la hidrogeologia,
segun SERGEOTECMIN (2002) .
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153
Figure 5.1. Geological map of the Silala area with an emphasis on hydrogeology.
Based on SERGEOTECMIN (2002)
Figure 5.2. Transversal Southwest–Northeast cut of the Silala with an emphasis on
hydrology. Based on SERGEOTECMIN (2002)
33
so NE
A 8
Canm
l.l}!la lllt.
~111~ Valk~ ~
ll\lJOllNles
~
11:6
lltll ~
4!00 li.'Q
~ 11:t
IXll 3mi
UOJ l ' j
1)¢1tosl'Oall· 1 1.l,am-~• ■ ig,im
111daai1 V,,l'ms m (l,ol,n)
154
AgUJO N" 3: Mopo de zonitlcoci6n y d.rocci6n de llujo a nivel regional
,., ..... ..... -·P~
i.a ... , c:3 -,--.., -.. -z--~.~
. __,
I
Fufflf•: MMAyA
Figura 5.3 Direcciones del flujo subterraneo con vista en 2D horizontal, segun SERGEOTECMIN
{2002) .
Volumenes a/macenados y tiempos asaciados al escurrimiento
Una de las hip6tesis mas importantes en el area del Silala es el modelo conceptual adoptado del
acuffero ignimbrftico descrito en las secciones 3.3.4 y 4.1.3. Por ende, ademas de los escurrimientos
naturales estimados en la secci6n precedente, es imperative cuantificar los volumenes almacenados
y los tiempos asociados al escurrimiento natural, lo cual permitira evaluar los cambios en las
caracterfsticas ecoI6gicas (bofedales localizados en el sitio Silala), asf como cualquier otro evento
natural o antropogenico.
Los caudales de los manantiales del Silala han sido monitoreados desde los afios noventa, contando
a la fecha con 20 afios de dates cumulados con una frecuencia de una vez y hasta cuatro veces por
afio. El total de los caudales de todos los manantiales del sitio del Silalal se ha mantenido
relativamente constante. Los caudales medidos desde junio de 1996 muestran un valor promedio
anual de 187.51/s con un valor mfnimo de 155 I/s en junio de 1996, y un maximo de 280 1/s en abril
de 1999; la desviaci6n estandar es de 43 I/s. La figura 5.4 es una representaci6n grafica de los
caudales de los manantiales del Silala, se observa que los caudales aumentan ligeramente en el
periodo de verano, entre diciembre y abril.
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155
Figure 5.3. Directions of the groundwater flows in a 2D horizontal plane. Based on
SERGEOTECMIN (2002)
Stored volumes and times associated with runoff
One of the most important hypotheses concerning the Silala area is the conceptual
model adopted for the ignimbrite aquifer described in Sections 3.3.4 and 4.1.3.
Therefore, in addition to the natural runoff estimated in the preceding section, it is
imperative to quantify the volumes stored and the time associated with natural runoff,
which will allow assessing the changes in the ecological characteristics (wetlands
located in the Silala site), as well as any another natural, or anthropogenic event.
The flows of the Silala springs have been monitored since the 90s. To date, 20 years of
data, accumulated with a frequency of one to four times per year, is available. The total
flow of all the springs of the Silala site has remained relatively constant. Flowrates
measured since June 1996 show an annual average value of 187.5 1/s with a minimum
value of 155 1/s in June 1996, and a maximum value of 280 1/s in April 1999. The
standard deviation is of 43 1/s. Figure 5.4 is a graphical representation of the flows of
the Silala springs, which shows that the flows increase slightly in summer, between
December and April.
34
Figura N° 3: Mapa de zoniflcoci6n y direcci6n de ttujo o nive4 regk>nol
N C....
-.•·•,•~~
.... ,
-e:3 -,-------·-
J
\
lA> ----·- !4,
-t:IIWJD~
156
Caudales de los manantiales del Silala
•'3"00 ~======/==7===== ============================= ~:: __ "TA Va ~_A\ . W . -c y' v J 100
50
0
Figura 5.4 Caudales totales aforados en los manantiales del Silala; tomados del reporte de
SERGEOTECMIN (2002).
Siguiendo con la hip6tesis de acuifero con recarga infima, o nula, conteniendo aguas f6siles norenovables
a escala humana (secciones .3.4 y 4.1.3), se puede entonces deducir la importancia de los
manantiales como la unica fuente de agua del sitio del Silala con un volumen permanente pero norenovable.
Es por ello que resulta muy interesante hacer un analisis cuantitativo de los volumenes
potencialmente almacenados en el acuifero y de los tiempos asociados al escurrimiento subterraneo
que emerge en los manantiales.
Una manera de estimar esos volumenes es utilizando la ecuaci6n hidrogeo16gica:
V=S·A·b
En donde V es el volumen almacenado en m3; A es el area del acuifero en m2; S representa el
coeficiente de almacenamiento del acuifero para el caso de acuifero confinado, o rendimiento
especifico s, (conocido tambien como porosidad de drenaje, n,) si el acuifero es no-confinado; b
representa el espesor del acuifero, o el nivel de agua subterranea medido desde el fondo del
acuifero.
Una vez mas, utilizando las figuras 5.1 y 5.2 se deducen los valores del area y del espesor del
acuifero de manera aproximativa:
A= 2.22·108 m'
B= 100 to 175 m
S, ors,, or n, = variable
Los valores del coeficiente de almacenamiento para ese acuffero no son conocidos pero se pueden
estimar en un rango de entre 5% y 25% para ese tipo de roca de origen volcanico. Tomando el valor
mas bajo del ese rango, de 5%, se obtiene un volumen almacenado de 1.77·109 m3; y de 8.83·109 m3
para el valor mas alto del coeficiente de almacenamiento, 25%. La figura 5.5 muestra los volumenes
potencialmente almacenado en el acuifero ignimbritico del Silala con un rango aun mayor de
coeficientes de almacenamiento.
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157
Figure 5.4. Total estimated flow of the Silala springs, taken from SERGEOTECMIN
report (2002)
Following the hypothesis that this aquifer has very little, or no recharge, and that it
contains non-renewable fossil water on a human scale (Sections 3.4 and 4.1.3), the
importance of the springs as the only water source in the Silala site, with a permanent
yet non-renewable natural volume, can be deduced.
That is why it is quite interesting to make a quantitative analysis of the volumes
potentially stored in the aquifer and the times associated with the underground runoff
that emerges in the springs.
One way to estimate these volumes is to use the hydrogeological equation:
V = S • A • b
Where V is the volume stored in m3; A is the area of the aquifer in m2; S represents the
aquifer’s storage coefficient for the confined aquifer, or specific output Sy (also known
as drainage porosity, nd) in case the aquifer is unconfined; b represents the thickness
of the aquifer, or the level of groundwater measured from the bottom of the aquifer.
Again, using figures 5.1 and 5.2 the values of the area and the thickness of the aquifer
are deduced on an approximate basis:
A = 2.22 • 108 m2
B = 100 to 175m
S, or Sy, or nd = variable
The values of the storage coefficient for this aquifer are not known, but can be estimated
in a range between 5% and 25% for that type of volcanic origin rock. A stored volume
of 1.77 • 109 m3 is obtained for the lowest value of that range, 5%, and one of 8.83 •
109 m3 for the highest value of storage coefficient, 25%. Figure 5.5 shows the volumes
potentially stored in the Silala ignimbrite aquifer with an even greater range of storage
coefficients.
35
JOO
J<,(J ! 200
:a 150 s 100
,;o
0
Caud1lu de l~s m1n1ntl1les del S11111
158
0.45 ~------------------
0.4 +-----------------~ -
0.35 +----------------~__,,,, _
0.3 +----------------,,,-"~_,,,-, ---
0.25 +-----------.-.,,,,.=~--.-/' -----
0.2 +---------7"""'-----------
0.15 +-------~-.~/'----------
0.1 t--------:;-.~/'------------
0.05 +---=--__,,,, _____________ 0 +----~- -~-~-~-~-~-~-~-~
xr;j, xrS' .,,,<S" xr;g, xr;§J x,S, x'\,<.:,
,,,'?"'<; ...,')"<; ,,,'?"'<; ,,, ,,,,,,<; ".,f 'b'!f ..,el
Volumen almacenado (mA3)
Figura 5.5 Agua subterranea almacenada en el acuifero del Silala.
5.1.3 Suelos
Potencialmente, la actividad minera es la que mas puede producir cambios en las caracteristicas
naturales de los suelos; por otro lado, el incremento del turismo aunque tiene efectos menores
sobre los suelos, el uso de vehiculos "todo terreno" fuera de las rutas establecidas dejan huellas en
el suelo arenoso modificando el paisaje y compactando el terreno; sin embrago hasta ahora nose
han observado cambios substanciales en el mismo.
5.1.4 Geomorfologfa
El analisis detallado ya escala fina de las fotografias satelitales de alta resoluci6n, tomadas entre
2001 y 2011 (imagen 1 de noviembre 2001; imagen 2 de junio, 2004; imagen 3 de marzo, 2011), no
revelan ningun cambio geomorfol6gico notable durante ese periodo. Nose detectan modificaciones
en la configuraci6n geom6rfica del sitio que pudiesen ser atribuidas a orden antropogenico.
El uso de vehfculos "todo terreno" fuera de las rutas establecidas dejan huellas en el suelo arenoso
modificando el paisaje y compactando el terreno; sin embrago esto conlleva a un efecto mfnimo
sobre la geomorfologia del sitio. Desde el punto de vista geomorfol6gico, la huella del impacto,
magnitud y forma de las modificaciones humanas es muy reciente y dificil de cuantificar. La
geomorfol6gica de la region fue modificada durante miles de a nos (holoceno, ver secci6n 3.3.1),
mientras que los efectos antropogenicos solo son visibles a escala decadal.
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159
Figure 5.5. Groundwater stored in the Silala aquifer
5.1.3. Soils
Potentially, mining activity is the most likely to produce changes in the natural features
of the soils; on the other hand, the increase in tourism—albeit it has minor effects
on the soils—the use of “all-terrain” vehicles outside the established routes leave
tracks on the sandy soil, altering the landscape and diminishing the extent of the land;
nevertheless, substantial changes on the soil have yet not been detected.
5.1.4. Geomorphology
The detailed analysis, and at a fine-scale, of the high resolution satellite images, taken
between 2001 and 2011 (image No. 1, November 2001; image No. 2, June 2004;
image No. 3, March 2011) do not reveal any notorious geomorphological change in
this period. Modifications in the geomorphological configuration of the site can be
attributed to anthropogenic activities.
The use of “all-terrain” vehicles outside the established roads leave tracks on the
sandy soil, altering the landscape and diminishing the area of the land; this, however,
has minimal effects on the geomorphology of the site. From the geomorphological
viewpoint, the traces of the impacts, magnitude, and types of human alterations are
quite recent (Holocene, see section 3.3.1), while the anthropogenic effects are only
visible at decadal time scales.
36
0.45
0.4
0.35
... 0.3 j 0.25
~ 0.2
a. 0.15
0.1
0.05
0
~ ~ ~ ~ ~ ~ ~ ,;,~ ~~ s-~ <{J>~ ~~ ~~ ,;:,~
,,,. .,. '\. <t,· .,.. ..,,. .,..
Volumen almacenado (m"3)
160
Imagen 1 satelital tomada en noviembre de 2001.
Imagen 2 satelital tomada en junio de 2004.
Imagen 3 satelital tomada en marzo de 2011.
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161
Satellite image No. 1, taken in November 2001
Satellite image No. 2, taken in June 2004
Satellite image No. 3, taken in March 2011
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162
5.1.5 Salinidad
En terminos generales no se detectan cambios en la sa linidad con respecto a las concentraciones de
ba se, las cuales son consecuencia de las condiciones climaticas, geologicas e hidrologicas, tal y como
se describe en la seccion 3.3.3.
No obstante lo anterior, la disminucion del agua en los bofedales, especialmente en epoca seca hace
que las sales disueltas tengan mayor concentracion, por lo tanto se presentan afloramientos salinos
en los suelos de estos bofedales (principalmente en el bofedal sur) (Ministerio de Medio Ambiente y
Agua, 2016)
5.1.6 Calidad del agua
Como se indico en la seccion 4, el efecto mas evidente de cambios en la calidad del agua son las
actividades turisticas, aunque cabe decir que su impacto es dificil de cuantificar de manera objetiva a
escalas intermediarias y locales. En los ultimos aiios el turismo intensivo, de mas de 70,000 visitantes
en 2007, que llega a la RNFA Eduardo Avaroa y su area de influencia, originan ciertos impactos en la
region yen particular en las lagunas, que son el principal habitat para los flamencos.
Tambien es un hecho que todavia existen algunas lagunas que por su ubicacion o dificil acceso, no
tienen ningun impacto o presencia de actividad antropica hasta el presente y mantienen sus
caracteristicas ecologicas bien conservadas, entre ellas destacan Laguna Khara, Kalina, Guayaques y
Pelada.
Las muestras tomadas en los bofedales del Silala, por su pureza y bajisimo contenido de
sales, estan consideradas de muy alta calidad fisicoquimica (Ministerio de Medio Ambiente y Agua,
2016)
5.2 Componentes ecologicos
Respecto a los cambios en los componentes ecologicos, de acuerdo a los estudios realizados en 28
lagunas de 1990 a 2009 (Rocha, comms personal), se presenta una retraccion en el area del
complejo de lagunas en un 34.5%, lo cual implica la perdida de habitat para las especies que
dependen de estos sistemas especialmente aves acuaticas asi como para el suministro de agua.
Los bofedales de la region de Silala han sido altamente afectados con la construccion de
los canales recolectores de agua iniciada en 1908. En la actualidad quedan tan solo relictos de los
bofedales originales que cubrian un area de cerca de 141,200 m2 o 14.1 hectareas. La
superficie actual de bofedales es tan solo de alrededor de 6,000 m2 o 0.6 Ha. que se
ubican en el entorno de las captaciones de agua y canales artificiales (SERGEOMIN,2003). Este
proceso de degradacion progresiva se pudo constatar durante la visita al sitio Ramsar donde los
bofedales sur y norte presentan fuertes procesos de deterioro.
lgualmente, el Ministerio de Medio Ambiente y Agua (2016) realizo un analisis de los cambios en la
vegetacion en los bofedales del Silala utilizando imagenes de satelite (Land Sat TMs) en el cual se
encontro una disminucion de 1.08 ha en bofedales entre los periodos 1986 y 2010. De esto
resultados tambien se pudo observar la presencia de afloramientos de sales en la superficie del
suelo. Asi, la disminucion de lo cobertura vegetal predispone a la perdida de suelo por los frecuentes
vientos caracteristicos de la zona, especialmente en la epoca seca.
Respecto a la vegetacion, tal vez las que presentan la mayor degradacion son las praderas nativas.
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163
5.1.5 Salinity
In general terms, no changes in the salinity are detected with respect to the basic
concentrations, which are a consequence of the climatic, geological, and hydrological
conditions, as described in section 3.3.3.
Nevertheless, the reduction of water found in the wetlands, especially in dry season,
causes the dissolved salts to have a higher concentration; therefore, saline outflows
occur in the soils of these wetlands (mainly in the south wetland) (Ministry of
Environment and Water, 2016).
5.1.6 Water quality
As indicated in section 4, the most obvious effect of the changes in water quality
concerns tourism activities, although it is difficult to quantify it objectively at the
intermediate and local scales. In recent years, concentrated tourism—amounting to
more than 70,000 visitors at the Eduardo Avaroa Andean Fauna National Reserve and
its area of influence in 2007—causes certain impacts on the region and particularly on
the lagoons, which are the main habitat for flamingoes.
It is also a fact that there are still some lagoons which, due to their location, or difficult
access, have received no impact, or influence of anthropic activities up to the present
and have preserved their ecological characteristics—among them, Khara, Kalina,
Guayaques and Pelada lagoons.
Due to their purity and low content of salts, the samples taken from the Silala wetlands
are regarded as having a very high physic-chemical quality (Ministry of Environment
and Water, 2016).
5.2 Environment components
Regarding changes in the environment components, according to the studies carried
out in 28 lagoons from 1990 to 2009 (Rocha, personal commission), there is a reduction
by the 34.5% in the lagoon complex area which implies a habitat loss for species that
depend on these systems, particularly waterbirds, as well as a loss of water provision.
The wetlands found in the Silala area have been highly affected by the construction
of the water-catchment canals started in 1908. At present, there are only vestiges of
the original wetlands that used to cover an area of about 141,200 m2, or 14.1 hectares.
The current surface area of the wetlands covers only about 6,000 m2, or 0.6 ha., which
are surrounded by the water catchment works and artificial canals (SERGEOMIN,
2003). This process of progressive degradation was verified during the visit made to
this Ramsar site, where the south and north wetlands have been affected by strong
deterioration processes.
Likewise, the Ministry of Environment and Water (2016) carried out an analysis of
the changes in vegetation in the Silala wetlands using satellite images (Land Sat TMs)
and found a reduction by 1.08 ha. in the wetlands between 1986 and 2010. From these
results, it was also possible to observe the presence of salt outcrops on the soil surface.
As such, this reduction in the vegetation leads to soil losses, owing to the frequent
winds that are typical of the area, especially during dry seasons.
As regards vegetation, native prairies are likely the ones that present the most severe
degradation.
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Su potencial forrajero esta en peligro de perderse como consecuencia de la combinacion de la falta
de un manejo adecuado y las condiciones climaticas y edaficas. El desequilibrio del ecosistema
produce la perdida de las especies forrajeras mas aceptadas por alpacas y llamas, yen muchos casos,
perdidas de agua por evaporacion y de suelo por erosion hfdrica y eolica, con la formacion de
arenales. Extensas superficies de comunidades vegetales son sometidas a extraccion drastica,
sobrepastoreo y extension de la frontera agrfcola, las cuales estan provocando una desertificacion
paulatina (Garcia, 2006).
Varias especies estan sometidas a explotacion a gran escala por su caracter combustible como la
yareta, las tholas, la tara y otras mas. La mayor presion proviene de las minas, ulexita, campamentos
mineros y caleras. Asimismo se identifica a Parastrephia lepidophylla como la especie combustible
con mayor cobertura en la zona.
En el caso de la yareta (Azore/la compacta), se produce una explotacion en gran escala, extraccion
historica de cojines completos, disminuyendo grandemente las posibilidades de produccion de
semi I las. Es la especie considerada mas vulnerable en la zona sobre todo por su uso en minerfa.
Respecta a la fauna de acuerdo al Plan de Manejo de la Reserva Nacional de Fauna Andina Eduardo
Avaroa (2010), algunas especies silvestres de fauna consideradas como recurso potencial se estarfan
recuperando satisfactoriamente gracias a los procesos de proteccion (flamencos, vicufia, suri,
yareta). Segun los datos de los censos de flamencos y la observacion de los guardaparques, las
poblaciones de especies silvestres se estarfan recuperando por la presencia del area protegida en la
region por lo que nose presentan cambios de fondo en este componente pero se requiere la
continuidad en las medidas de conservacion implementadas asf como en los monitoreos de las
poblaciones de las tres especies presentes en el sitio.
6. Conclusiones
1. En el sitio Ramsar Los Upez, con un area total de 14,277 Km' se presentan factores de
deterioro de caracter antropogenico que amenazan sus caracterfsticas ecologicas.
2. Los principales cambios en las caracterfsticas ecologicas se presentan en la reduccion en el
34.5 % del area de 28 de sus lagunas asf como en el deterioro de los bofedales del Valle del
Silala por la construccion de los canales recolectores de agua iniciada en 1908.
3. Existen algunos factores adversos que afectan, o que pueden afectar en el futuro, las
caracterfsticas ecologicas del sitio Ramsar en particular los suelos y el agua. Estos son
principalmente las concesiones para la minerfa y otros proyectos de desarrollo, e.g.,
proyecto piloto geotermico en la Laguna Colorada.
4. El proyecto piloto geotermico en la Laguna Colorada asf como propuestas futuras de
explotaci6n y/o aprovechamiento de las recursos hfdricos incluyendo aguas subterraneas
requieren de enfoques integrales teniendo en cuenta el estado de las caracterfsticas
ecologicas del sitio Ramsar y el mantenimiento de las mismas.
5. Los deficits hfdricos son el resultado del deterioro natural desde la epoca del Cuaternario
(miles de afios) cuando el area era todavfa mas humeda.
6. El agua subterranea tiene un valor inestimable sobre los humedales locales (bofedales) pues
los desniveles de la presion del agua subterranea permiten a la vez la resurgencia de
manantiales que escurren de manera superficial y alimentan los bofedales; y, al mismo
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165
Their forage potential is in danger of being lost owing to a combination of the lack of
proper management and the climatic and edaphic conditions. This imbalance in the
ecosystem results in losses of the forage species that are most accepted by alpacas and
llamas, and in many cases, also entails water losses to evaporation and soil losses to
water and wind erosion, resulting in the formation of sandbanks. Extensive areas of
plant communities are subject to drastic extraction, overgrazing, and extensions of the
agricultural frontier, which are causing gradual desertification (Garcia, 2006).
Several species are subject to large-scale exploitation because they can be used as fuels,
i.e. yareta, tholas, tara, and others. These are predominantly exploited in ulexite mines,
mining camps, and lime fields. The Parastrephia lepidophylla has been identified as
the ignitable plant species that is most present in the area.
The yareta (Azorella compacta) is exploited at a large scale; whole yareta cushions have
been historically extracted, greatly diminishing the possibilities of seed production.
This species is considered the most vulnerable in the area, mainly because of its use
in mining.
As far as fauna is concerned, according to the Management Plan of the Eduardo
Avaroa Andean Fauna National Reserve (2010), some wild species of fauna considered
potential resources are apparently recovering satisfactorily due to protection processes
(flamingoes, vicuna, suri, and yareta). According to the data obtained from flamingo
censuses and from observations made by park rangers, it appears that the populations of
wild species are recovering as a result of the region’s insertion into the protected area.
There seemingly are no fundamental changes in this component, but the preservation
measures implemented must continue, as well as population monitoring for the three
species present on the site.
6. Conclusions
1. The presence of anthropogenic deterioration factors has been confirmed in the
Los Lipez Ramsar site—which covers an area of 1,427,717 ha. This anthropogenic
deterioration threatens the site’s ecological characteristics.
2. The main changes in the ecological characteristics entail a reduction of 34.5% of
the area of 28 of the site’s lagoons, as well as in the deterioration of the wetlands of
Silala valley derived from the construction of abstraction canals begun in 1908.
3. There are some adverse factors affecting, or likely to affect in the future, the
ecological characteristics of this Ramsar site, particularly its soils and water; these
factors are related to mining concessions and other development projects, e.g., a
geothermal pilot project in Laguna Colorada.
4. The geothermal pilot project in Laguna Colorada, as well as the future prospects
for exploitation and/or utilization of the water resources of this site—including
groundwater—requires integral approaches that take into account the state of the
ecological characteristics in this Ramsar site and their preservation.
5. The water deficits are the result of natural deterioration occurring since the
Quaternary (thousands of years ago), when the area was even more humid.
6. Groundwater is of inestimable value to local wetlands inasmuch as the unevenness
of groundwater pressure allows the resurgence of springs that run off on the surface
and directly feed the wetlands,
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tiempo, estos desniveles alimentan los bofedales directamente por emergencia vertical. Los
bofedales deben su existencia al agua subterranea.
7. La formaci6n de lagunas y bofedales en la superficie terrestre dependen del aporte de las
aguas subterraneas. El sistema de aguas subterraneas constituye un tejido interno regulador
que sostiene la humedad en el suelo externo con la manifestaci6n de manantiales,
vertientes, rfos, cuencas y formaci6n de humedales que sirven de habitat de poblaciones de
avifauna y poblaciones humanas asentadas en la region
8. A la escala local (bofedales y manantiales del Silala) el volumen total de los manantiales es
de 2001/s, este volumen tiene variaciones menores, y no ha cambiado con el tiempo desde
que se iniciaron los aforos en 1996. Dadas las caracterfsticas hidrogeol6gicas del sitio, y
como primera hip6tesis conceptual, se puede teorizar que se trata de un volumen
permanente.
9. Estudios con is6topos estables han mostrado que las aguas que afloran en los manantiales
del Silala son aguas f6siles de mas de 10,000 afios. Es decir son aguas que nose renuevan
por recarga natural de aguas mete6ricas en el acuffero local. Bajo las condiciones climaticas
actuales, esto significa que esos recurses hfdricos estan almacenados en el acuffero
ignimbritico desde hace miles de aiios, el cual se vacfa natural y paulatinamente a traves de
los siglos.
10. No existe ningun efluente contaminante superficial en el area del sitio del Silala.
11. Aun existen algunas lagunas que por su ubicaci6n o diffcil acceso, no tienen ningun impacto
o presencia de actividad antr6pica hasta el presente y mantienen sus caracterfsticas
ecoI6gicas bien conservadas, entre ellas destacan Laguna Khara, Kalina, Guayaques y Pelada.
12. La presencia de cou/ees establecidos desde tiempos geoI6gicos por el derretimiento y
drenaje glacial en el sitio del Silala han causado un drenaje de agua subterranea en
direcci6n oeste.
7. Recomendaciones
1- Es importante que se prepare un Plan de Manejo para todo el Sitio Ramsar de manera
integral que incluya al area protegida de la Reserva Nacional de Fauna Andina Eduardo
Avaroa yen el que se especifiquen medidas concretas para el uso sostenible de las
actividades turfsticas y actividades mineras.
2. Dado los fuertes factores de cambio en las caracterfsticas ecoI6gicas de los bofedales norte y
sur del Sllala, es de caracter prioritario realizar acciones inmediatas para la mitigaci6n de los
impactos y la preparaci6n de un programa para su restauraci6n.
3. Es prioritario continuar con el monitoreo de los caudales de los manantiales, tanto por
separado (este y norte),
4. Serf a de una muy gran utilidad realizar estudios adicionales de cam po especfficos, con el
prop6sito de obtener valores reales de para metros hidrogeoI6gicos del acuffero ignimbrftico
del Silala, tales como la conductividad hidraulica y la porosidad.
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167
owing to vertical emergence over them. The wetlands owe their existence to
groundwater.
7. The formation of lagoons and wetlands on the surface depends on the inputs of
groundwater. The groundwater system is an internal regulating tissue that sustains the
moisture in the external soil with the manifestation of springs, slopes, rivers, basins,
and the formation of wetlands that serve as the habitat for bird and human populations
settled in the region.
8. At the local level (Silala springs and wetlands), the total volume of the springs is
200 1/s; this volume has minor variations and has not changed over the time since the
appraisals began in 1996. Given the hydrogeological characteristics of the site, and as
the first conceptual hypothesis, it can be theorized that this is a permanent volume.
9. Studies with stable isotopes have shown that the waters that emerge in the Silala
springs are fossil waters dating back to more than 10,000 years. In other words, these
are waters that are not renewed by natural recharges of meteoric waters in the local
aquifer. Under the current climatic conditions, this means that these water resources
have been stored in the well-fractured ignimbrite aquifer for thousands of years,
emptying naturally and gradually over centuries.
10. No superficial polluting effluent has been detected in the whole of the area studied.
11. There are still some lagoons which, due to their location or difficult access, have
received no impact or presence of anthropic activities up to the present, and have
preserved their ecological characteristics—among them, Khara, Kalina, Guayaques
and Pelada lagoons.
12. The presence of coulees established since geological times by the melting and
glacial drainage at the site of Silala have caused a drainage of groundwater to the west.
7. Recommendations
1. It is essential that a comprehensive Management Plan for this Ramsar site be
prepared; this ought to include the protected area of the Eduardo Avaroa Andean Fauna
National Reserve and detail specific measures for the sustainable use of tourism and
mining activities.
2. Given the strong factors of change in the ecological characteristics of the north
and south wetlands of Silala, it is essential that immediate actions be implemented to
mitigate the impacts and that a restoration program be prepared.
3. Priority should be given to the monitoring of the springs’ flow rates, both
separately (east and north), [sic].
4. It would be highly advantageous to carry out additional specific field studies to
obtain real values of hydrological parameters of the Silala ignimbrite aquifer, such as
hydraulic conductivity and porosity.
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168
5. Se recomienda construir un modelo numerico hidrogeo16gico a la escala local en dos
dimensiones vertical para simular los escurrimientos y las reservas de aguas subterraneas
del acuffero ignimbrftico del Silala, asf como para examinar diversos parametros e hip6tesis,
y simular escenarios diferentes.
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5. It is advisable that a hydrological numerical model, at the local scale and in two
vertical dimensions, be prepared to simulate the outflows and reserves of groundwater
of the Silala ignimbrite aquifer, as well as to examine different parameters and hypotheses,
and to simulate different scenarios.
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8. Referencias bibliograficas
Alurralde. J.C. 2006. Problematica de las aguas subterraneas. En Olivera, M., P. Ergueta, M. Villca
Samjines (eds.). Conservaci6n y desa rrollo sostenible en el sudoeste de Potosi, Bolivia. Prefectura del
Departamento de Potosf-Tr6pico. La Paz- Bolivia . Pag 377-391.
Del Hoya, J. 1992. Flamingos. P. 508-526 en: Del Hoyo, J., Elliot A., & J. Sargatal (eds.). Handbook of
the Birds of the World . Vol 1. ICBP. Lynx Edicions. Espana, 640 p.
Ergueta, P. 2002. Gufa de viaje - Reserva Nacional de Fauna Andina Eduardo Avaroa. TROPICO. La
Paz. 62 p.
EUGSTER, H.P. and HARDIE, L.A.-1978. Saline Lakes. In : Lakes, Chemistry Geology, Physics. (a.
Lerman, ed .. Springer Verlag, p. 237-293.
Huang YuLong, Yuhui Feng, and Pujun Wang, 2014. Characteristics and Cutoff of Porosity and
Permeability of the Effective Volcanic Gas Reservoirs of the Lower Cretaceous Yingcheng Formation
in Songliao Basin, Northeast China. Adapted from oral presentation given at 2014 AAPG Annual
Convention and Exhibition, Houston, Texas, April 6-9, 2014. AAPG © 2014 Serial rights given by
author.
Ministerio de Media Ambiente y Agua, 2010. Actualizaci6n Plan de Manejo de la Reserva Nacional de
Fauna Andina, Eduardo Avaroa.
Ministerio de Media Ambiente y Agua, 2016. Caracterizaci6n de las recursos hfdricos en el sudoeste
del Departamento de Potosi. Municipio de San Pablo de Lipez. Bofedaels del Valle del Sllala y
sectores colindantes.
Molina, J. 2007. Agua y recurso Hfdrico en el sudoeste de Potosi. FOBOMADE. La Paz- Bolivia. 74 p.
Navarro, G. 1993. Vegetaci6n de Bolivia: el Altiplano Meridional. Rivasgodaya 7:69-98
Neumann-Redlin y Torres, J., 2003). lnvestigaciones hidrol6gicas, hidroqufmicas e isot6picas en el
area de las manantiales del Silala.
Ramsar, 2009. Resoluci6n IX.l Anexo A.j. Marco conceptual para el uso racional de humedales y el
mantenimiento de su caracter ecol6gico.
Ramsar, 2010. Resoluci6n X.13. El Estado de las Sitios en el Listado de lmportancia Internacional.
Rocha, 0.0. 2006. Relacion de la abundancia de tres especies de flamencos del suroeste del
Altiplano de Bolivia con las caracterfsticas del habitat. Universidad Mayor de San Andres. Tesis de
Grado. La Paz. 83p.
Secretaria de Ramsar. 2009. Ficha lnformativa Ramsar Los Lipez.
SERGEOMIN. 2001. Estudios de Cuencas Hidrograficas. Cuenca Laguna Verde. La Paz.
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8. Bibliographic references
Alurralde J. C. 2006. Problematica de las aguas subterraneas [The problem of
groundwater]. In Olivera, M., P. Ergueta, M. Villca Sanjines (Eds.). Conservacion
y desarrollo sostenible en el sudoeste de Potosi [Preservation and sustainable
development of the southwest of Potosi Department], Bolivia. Prefecture of the Potosi
Department – Tropico. La Paz- Bolivia. Pp. 377-391.
Del Hoyo, J. 1992. Flamingos. P. 508-526 in: Del Hoyo, J., Elliot A., & J. Sargatal
(Eds.). Handbook of the Birds of the World. Vol. ICBP. Lynx Editions. Spain, 640 p.
Ergueta, P. 2002. Guia de viaje—Reserva Nacional de Fauna Andina Eduardo Avaroa
[Travel Guide—Eduardo Avaroa Andean Fauna National Reserve]. TROPICO, La
Paz, p. 62.
EUGSTER, H.P. and HARDIE, L.A.-1978. Saline Lakes. In: Lakes, Chemistry
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43
174
Anexo 1.
Tabla 3.2 Ubicaci6n geografica y altura de las principales lagunas del sitio Ramsar Los Lfpez en el
Suroeste de Potosi, Bolivia (Rocha 2006).
Ubicaci6n geografica Altura
No. Laguna 19K UTM msnm
1 Chulluncani 615833 7617362 4525
2 Pastes Grandes 627463 7598966 4458
3 Cachi 608268 7597239 4368
4 Khara Grande 615313 7578131 4526
5 Capina 647867 7574630 4260
6 Caiiapa 602493 7622072 4164
7 Hedionda Norte 597702 7612517 4166
8 Chiar Khota 597261 7608598 4111
9 Honda Norte 598141 7613026 4216
10 Ramaditas 595520 7605313 4160
11 Colorada 624832 7547943 4232
12 Chalviri Norte 647443 7516928 4445
13 Hedionda Sur 665123 7515515 4638
14 Kollpa 663106 7514095 4525
15 Salada o L. Polkes 639170 7507802 4487
16 Puripica Chico 653913 7510418 4479
17 Totoral 676137 7506164 4584
18 Catalcito 681117 7502573 4640
19 Herrera 653167 7504535 4449
20 Calina 680526 7498129 4575
21 Puripica Grande 652523 7487005 4742
22 Guayaques 652398 7484676 4767
23 Verde 623863 7477042 4425
24 Pelada 687368 7483614 4738
25 Cristal 684528 7523916 4520
26 Chojllas 697316 7526035 4577
27 Loromayu 682397 7521913 4468
28 Corante 710235 7543474 4381
29 Morejon 699914 7562594 4617
30 Coruto 704483 7516197 4550
31 Mama Khumo 696538 7537006 4589
32 Sombrerito 697282 7547754 4716
33 Chi papas 695217 7544817 4519
34 Penas Blancas 666192 7519018 4604
35 Luriqui 689140 7522958 4726
36 Celeste 695456 7541362 4500
37 Khastor 707636 7536798 4499
44
175
Annex 1.
Table 3.2. Geographical location and altitude of the main lagoons of the Los Lipez
Ramsar site in the southeast of Potosi (Rocha, 2006).
44
No. Lagoon Geographical location Altitude in
m.a.s.l
19K UTM
I Chulluncani 615833 76 17362 4525
2 Pastos Grandes 627463 7598966 4458
3 Cachi 608268 7597239 4368
4 Khara Grande 6153 13 7578131 4526
5 Caoina 647867 7574630 4260
6 Cai\apa 602493 7622072 4 164
7 Hedionda Norte 597702 7612517 4166
8 Chiar Khota 597261 7608598 4111
9 Honda Norte 598141 7613026 4216
10 Ramaditas 595520 7605313 4160
II Colorada 624832 7547943 4232
12 Chalviri Norte 647443 75 16928 4445
13 Hedionda Sur 665123 75 15515 4638
14 Kollpa 663106 7514095 4525
15 Salada o L. Polkes 639170 7507802 4487
16 Purioica Chico 653913 7510418 4479
17 Totoral 676137 7506164 4584
18 Catalcito 68 1117 7502573 4640
19 Herrera 653167 7504535 4449
20 Calina 680526 7498129 4575
21 Puripica Grande 652523 7487005 4742
22 Guavaaues 652398 7484676 4767
23 Verde 623863 7477042 4425
24 Pelada 687368 74836 14 4738
25 Cristal 684528 7523916 4520
26 Chojllas 697316 7526035 4577
27 Loromavu 682397 7521913 4468
28 Corante 710235 7543474 4381
29 Morei6n 699914 7562594 4617
30 Coruto 704483 7516197 4550
31 Mama Khumo 696538 7537006 4589
32 Sombrerito 697282 7547754 4716
33 Chioaoas 695217 7544817 4519
34 Pefias Blancas 666192 75190 18 4604
35 Luriaui 689140 7522958 4726
36 Celeste 695456 7541362 4500
37 Khastor 707636 7536798 4499
Translation prepared on basis of the Spanish source-text original by the Strategic Office for the Maritime
Claim, Sila la, and International Water Resources
176
Anexo 2.
Mapa de ubicaci6n Sitio Ramsar Los Lipez
UBICACION
45
177
Annex 2
Location map of the Los Lipez Ramsar site
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