Corrigé
Corrected
CR 2015/12
International Court Cour internationale
of Justice de Justice
THE HAGUE LA HAYE
YEAR 2015
Public sitting
held on Friday 24 April 2015, at 10 a.m., at the Peace Palace,
President Abraham presiding,
in the cases concerning Construction of a Road in Costa Rica along the San Juan River
(Nicaragua v. Costa Rica); Certain Activities carried out by Nicaragua
in the Border Area (Costa Rica v. Nicaragua)
____________________
VERBATIM RECORD
____________________
ANNÉE 2015
Audience publique
tenue le vendredi24 avril 2015, à 10 heures, au Palais de la Paix,
sous la présidence de M. Abraham, président,
dans les affaires relatives à Construction d’une route au Costa Rica le long du fleuve San Juan
(Nicaragua c. Costa Rica) ; Certaines activités menées par le Nicaragua
dans la région frontalière (Costa Rica c. Nicaragua)
________________
COMPTE RENDU
________________ - 2 -
Present: President Abraham
Vice-President Yusuf
Judges Owada
Tomka
Bennouna
Cançado Trindade
Greenwood
Xue
Donoghue
Gaja
Sebutinde
Bhandari
Robinson
Gevorgian
Judges ad hoc Guillaume
Dugard
Registrar Couvreur
- 3 -
Présents : M. Abraham, président
M. Yusuf, vice-président
MM. Owada
Tomka
Bennouna
Cançado Trindade
Greenwood
Mmes Xue
Donoghue
M. Gaja
Mme Sebutinde
MM. Bhandari
Robinson
Gevorgian, juges
MM. Guillaume
Dugard, juges ad hoc
M. Couvreur, greffier
- 4 -
The Government of Nicaragua is represented by:
H.E. Mr. Carlos José Argüello Gómez, Amba ssador of the Republic of Nicaragua to the Kingdom
of the Netherlands,
as Agent and Counsel;
Mr. Stephen C. McCaffrey, Professor of International Law at the University of the Pacific,
McGeorge School of Law, Sacramento, former Member and former Chairman of the
International Law Commission,
Mr. Alain Pellet, Professor at the University Paris Ouest, Nanterre- La Défense, former Member
and former Chairman of the International Law Commission, member of the Institut de droit
international,
Mr. Paul S. Reichler, Attorney-at-Law, Foley Hoag LLP, member of the Bars of the United States
Supreme Court and the District of Columbia,
Mr. Andrew B. Loewenstein, Attorney- at-Law, Foley Hoag LLP, member of the Bar of the
Commonwealth of Massachusetts,
as Counsel and Advocates;
Mr. César Vega Masís, Deputy Minister for Foreign Affairs, Director of Juridical Affairs,
Sovereignty and Territory, Ministry of Foreign Affairs,
Mr. Walner Molina Pérez, Juridical Adviser, Ministry of Foreign Affairs,
Mr. Julio César Saborio, Juridical Adviser, Ministry of Foreign Affairs,
as Counsel;
Mr. Edgardo Sobenes Obregon, Counsellor, Embassy of Nicaragua in the Kingdom of the
Netherlands,
Ms Claudia Loza Obregon, First Secretary, Embassy of Nicaragua in the Kingdom of the
Netherlands,
Mr. Benjamin Samson, Researcher, Centre de droit international de Nanterre (CEDIN), University
of Paris Ouest, Nanterre-La Défense,
Ms Cicely O. Parseghian, Attorney -at-Law, Foley Hoag LLP, member of the Bar of the
Commonwealth of Massachusetts,
Mr. Benjamin K. Guthrie, Attorney -at-Law, Foley Hoag LLP, member of the Bar of the
Commonwealth of Massachusetts,
Mr. Ofilio J. Mayorga, Attorney-at-Law, Foley Hoag LLP, member of the Bars of the Republic of
Nicaragua and New York,
as Assistant Counsel; - 5 -
Le Gouvernement du Nicaragua est représenté par :
S. Exc. M. Carlos José Argüello Gómez , ambassadeur de la République du Nicaragua auprès du
Royaume des Pays-Bas,
comme agent et conseil ;
M. Stephen C. McCaffrey, professeur de droit international à la McGeorge Sch ool of Law de
l’Université du Pacifique à Sacramento, ancien membre et ancien président de la Commission
du droit international,
M. Alain Pellet, professeur à l’Université de Paris Ouest, Nanterre- La Défense, ancien membre et
ancien président de la Commission du droit international, membre de l’Institut de droit
international,
M. Paul S. Reichler, avocat au cabinet Foley Hoag LLP, membre des barreaux de la Cour suprême
des Etats-Unis d’Amérique et du district de Columbia,
M. Andrew B. Loewenstein, avocat au cabinet Foley Hoag LLP, membre du barreau du
Commonwealth du Massachusetts,
comme conseils et avocats ;
M. César Vega Masís, ministre adjoint des affaires étrangères, directeur des affaires juridiques, de
la souveraineté et du territoire au ministère des affaires étrangères,
M. Walner Molina Pérez, conseiller juridique au ministère des affaires étrangères,
M. Julio César Saborio, conseiller juridique au ministère des affaires étrangères,
comme conseils ;
M. Edgardo Sobenes Obregon, conseiller à l’ambassade du Nicaragua au Royaume des Pays-Bas,
Mme Claudia Loza Obregon, premier secrétaire à l’ambassade du Nicaragua au Royaume des
Pays-Bas,
M. Benjamin Samson, chercheur, Centre de droit international de Nanterre (CEDIN), Université de
Paris Ouest, Nanterre-La Défense,
Mme Cicely O. Parseghian, avocate au cabinet Foley Hoag LLP, membre du barreau du
Commonwealth du Massachusetts,
M. Benjamin K. Guthrie, avocat au cabinet Foley Hoag LLP, membre du barreau du
Commonwealth du Massachusetts,
M. Ofilio J. Mayorga, avocat au cabinet Foley Hoag LLP, membre des barreaux de la République
du Nicaragua et de New York,
comme conseils adjoints; - 6 -
Mr. Danny K. Hagans, Principal Earth Scientist at Pacific Watershed Associates, Inc.,
Mr. Robin Cleverly, Geographical and Technical Consultant,
Ms Blanca P. Ríos Touma, Ph.D., Assistant Professor at Universidad Tecnología Indoamérica in
Quito, Ecuador,
Mr. Scott P. Walls, Master of Landscape Architecture Environmental Planning, Sole Proprietor
and Fluvial Geomorphologist at Scott Walls Consulting, Ecohydrologist at cbec ecoengineering,
Inc., and Chief Financial Officer and Project Manager at International Watershed Partners,
Ms Victoria Leader, Geographical and Technical Consultant,
as Scientific Advisers and Experts.
The Government of Costa Rica is represented by:
H.E. Mr. Manuel A. González Sanz, Minister for Foreign Affairs and Worship of the Republic of
Costa Rica;
H.E. Mr. Edgar Ugalde Álvarez, Ambassador on Special Mission,
as Agent;
H.E. Mr. Sergio Ugalde, Ambassador of Costa Rica to the Kingdom of the Netherlands, Member of
the Permanent Court of Arbitration,
as Co-Agent, Counsel and Advocate;
Mr. Marcelo Kohen, Professor of International Law at the Graduate Institute of International and
Development Studies, Geneva, member of the Institut de droit international,
Mr. Samuel Wordsworth, Q.C., member of the English Bar, member of the Paris Bar, Essex Court
Chambers,
Mr. Arnoldo Brenes, Senior Adviser to the Ministry of Foreign Affairs and Worship, member of
the Costa Rican Bar,
Ms Kate Parlett, Solicitor admitted in Queensland, Australia, and in England and Wales,
Ms Katherine Del Mar, member of the English Bar, 4 New Square, Lincoln’s Inn,
as Counsel and Advocates;
Mr. Simon Olleson, member of the English Bar, 13 Old Square Chambers,
as Counsel; - 7 -
M. Danny K. Hagans, spécialiste principal des sciences de la terre de Pacific Watershed
Associates, Inc.,
M. Robin Cleverly, consultant dans les domaines géographique et technique,
Mme Blanca P. Ríos Touma, Ph.D., professeur adjoint à l’Universidad Tecnología Indoamérica
de Quito (Equateur),
M. Scott P. Walls, titulaire d’une maîtrise en architecture paysagère et en planification de
l’environnement, propriétaire unique et géomorphologue fluvial de Scott Walls Con sulting,
spécialiste en écohydrologie de cbec ecoengineering, Inc., directeur financier et chef de projet
pour International Watershed Partners,
Mme Victoria Leader, consultante dans les domaines géographique et technique,
comme conseillers scientifiques et experts.
Le Gouvernement du Costa Rica est représenté par :
S. Exc. M. Manuel A. González Sanz, ministre des affaires étrangères et des cultes de la
République du Costa Rica ;
S. Exc. M. Edgar Ugalde Álvarez, ambassadeur en mission spéciale,
comme agent ;
S. Exc. M. Sergio Ugalde, ambassadeur du Costa Rica auprès du Royaume des Pays -Bas, membre
de la Cour permanente d’arbitrage,
comme coagent, conseil et avocat ;
M. MarceloKohen, professeur de droit international à l’Institut de hautes étu des internationales
et du développement de Genève, membre de l’Institut de droit international,
M. Samuel Wordsworth, Q.C., membre des barreaux d’Angleterre et de Paris, Essex Court
Chambers,
M. Arnoldo Brenes, conseiller principal auprès du ministère de s affaires étrangères et des cultes,
membre du barreau du Costa Rica,
Mme Kate Parlett, solicitor (Queensland (Australie), Angleterre et pays de Galles),
Mme Katherine Del Mar, membre du barreau d’Angleterre, 4 New Square, Lincoln’s Inn,
comme conseils et avocats ;
M. Simon Olleson, membre du barreau d’Angleterre, 13 Old Square Chambers,
comme conseil ; - 8 -
Mr. Ricardo Otarola, Adviser to the Ministry of Foreign Affairs and Worship,
Ms Shara Duncan, Adviser to the Ministry of Foreign Affairs and Worship,
Mr. Gustavo Campos, Minister Counsellor and Consul General of Costa Rica to the Kingdom of
the Netherlands,
Mr. Rafael Saenz, Minister Counsellor at the Costa Rican Embassy in the Kingdom of the
Netherlands,
Ms Ana Patricia Villalobos, Official at the Ministry of Foreign Affairs and Worship,
as Assistant Counsel;
Ms Elisa Rivero, Administrative Assistant at the Ministry of Foreign Affairs and Worship,
as Assistant. - 9 -
M. RicardoOtarola, conseiller auprès du ministère des affaires étrangères et des cultes,
Mme Shara Duncan, conseillère auprès du ministère des affaires étrangères et des cultes,
M. Gustavo Campos, ministre-conseiller et consul général du Costa Rica auprès du Royaume des
Pays-Bas,
M. Rafael Saenz, ministre-conseiller à l’ambassade du Costa Rica au Royaume des Pays-Bas,
Mme Ana Patricia Villalobos, fonctionnaire du ministère des affaires étrangères et des cultes,
comme conseils adjoints ;
Mme Elisa Rivero, assistante administrative au ministère des affaires étrangères et des cultes,
comme assistante. - 10 -
Le PRESIDENT : Veuillez vous assoir. La Cour entendra maintenant les experts cités par le
Costa Rica, qui sont au nombre de deux. Le premier d’entre eux est Monsieur Cowx, que je prie de
bien vouloir prendre place à la barre. Bonjour, Monsieurle professeur. Je vous invite à faire la
déclaration solennelle prévue pour les experts et dont l’énoncé figure à l’alinéa b) de l’article 64 du
Règlement de la Cour.
Mr. COWX:
“I solemnly declare upon my honour and conscience that I w ill speak the truth,
the whole truth and nothing but the truth, and that my statement will be in accordance
with my sincere belief.”
Le PRESIDENT : Merci. Je me tourne maintenant vers le conseil du Costa Rica, qui va vous
demander de confirmer l’exposé écrit qui se trouve devant vous. Madame.
Ms PARLETT: Good morning, Professor Cowx. Thank you very much for being here. I
understand you flew in yesterday evening from Vietnam. Could I ask you to confirm whether the
two documents in front of you that is, your summary prepared for the purposes of this hearing
and your report of 11 December 2014, prepared in the context of this case reflect your honest,
expert views?
Mr. COWX: They do.
Ms PARLETT: I believe counsel for Nicaragua now has some questions for you.
Le PRESIDENT : Merci. Je vais maintenant donne la parole à Monsieur Loewenstein,
conseil pour le Nicaragua pour le contre-interrogatoire. Monsieur Lowenstein, vous avez la parole.
Mr. LO EWENSTEIN: Good morning, Mr. President, and good m orning to you,
Professor Cowx. It is a pleasure to meet you. If I may, I would like to begin by discussing the
ways in which elevated levels of sediment may impact fish.
Professor Thorne provided expert testimony in the Certain Activities case in which he listed
a number of effects that elevated sediment levels can have on fish. I understand that whether
elevated levels of sediment will have impacts, and to what extent, may depend upon the specific - 11 -
species of fish under consideration. But I would like to see whether you agree with
Professor Thorne about what types of impacts might occur.
Would you agree that sediment can clog and damage the gills of fish?
Mr. COWX: I do, at very high levels of sediment, yes.
Mr. LOEWENSTEIN: Would you agree that s ediment can reduce the ability of fish to
recover from wounds?
Mr. COWX: Mostly, but many fish are able to recover regardless because they have
antiseptic in their skin which helps them to recover anyway, irrespective of sediment load.
Mr. LOEWENSTEIN: Would you agree that sediment can disrupt reproduction in some fish
by damaging or smothering eggs or larvae?
Mr. COWX: It is less so eggs and larvae, it is more some of the gravel spawning areas or
habitats that are affected.
Mr. LOEWENSTEIN: Would you agree that sediment can affect adult fishes’ reproductive
behaviour, for instance, by impacting visual mate recognition?
Mr. COWX: In very, very few species this occurs. Mostly the multiple species groups, such
as in Lake Victoria, where they use col our recognition for identifying their mate, but very rarely in
riverine fisheries.
Mr. LOEWENSTEIN: Would you agree that sediment can impair the ability of certain fish
to locate food as a result of decreased visibility?
Mr. COWX: Many fish are adapted to high sediment loading and are able to seek their food
by sensing their movements, by using organs within the body that help them detect it, so it is very
unlikely that in high sediment loading, unless it is unusually high, massively beyond clear water
colourations, that you will get that effect.
Mr. LOEWENSTEIN: But you agree that, in some circumstances, it can have that effect? - 12 -
Mr. COWX: It has to be huge sediment loading and the systems usually have to be clear
water before that takes any impact, so always clear water.
Mr. LOEWENSTEIN: Would you agree that sediment can result in loss or reduction of
macroinvertebrate populations?
Mr. COWX: They can do. Again, under circumstances of high loading, many invertebrates
are adapted to sediment loading and sediment levels.
Mr. LOEWENSTEIN: Would you agree that some species of fish, during at least some part
of their life cycle, are dependent upon macroinvertebrates for food.
Mr. COWX: Very much so. They are dependent on macroinvertebrates but als o during the
juvenile, very small life stages, they are dependent on what is called zooplankton and
phyto-plankton, which are found in the water column and not the benthic macroinvertebrates which
is what is being addressed here.
Mr. LOEWENSTEIN: Would you agree that sediment can alter the balance of fish species
present in a given location?
Mr. COWX: Very rarely have I encountered that situation.
Mr. LOEWENSTEIN: Regardless of whether you have personally encountered that
situation, would you agree that elevated levels of sediment can have an impact as Professor Thorne
testified in his expert report?
Mr. COWX: Under extreme conditions, yes and I am talking about extreme conditions of
change in the environment, as opposed to small level changes.
Mr. LOEWENSTEIN: Would you agree that it is important to protect the balance of fish
species present in Ramsar sites?
Mr. COWX: Very much. If the Ramsar site is set up for fish species which very, very rarely
they are. They are usually set up for other types of organisms and habitat types. - 13 -
Mr. LOEWENSTEIN: So you disagree with the statement that it is important to protect the
balance of fish species in Ramsar sites, unless those conditions you mentioned are present?
Mr. COWX: Unless the Ramsar site is establ ished for fish species, it is unlikely that any
change in fish species will impact on the ecosystem as a whole.
Mr. LOEWENSTEIN: But as a general proposition, would you agree that it is important to
protect the balance of fish species in Ramsar sites?
Mr. COWX: It is important to protect the balance of fish species in any site.
Mr. LOEWENSTEIN: OK. You stated in your summary report that, in total, 81 species
have been described in the San Juan River basin, of which 54 are exclusively freshwater. Do you
still agree with that statement?
Mr. COWX: That is based on the best available information, based on Bussing and other
colleagues from Costa Rica.
Mr. LOEWENSTEIN: I see, so best available information. Does that give you some doubts
as to the quality of the information?
Mr. COWX: Far from it, in fact I think it is excellent information, provided by the leading
expert on Central American fish species Dr. Bussing.
Mr. LOEWENSTEIN: You listed 11 species of fish found in the San Juan River as bei ng
vulnerable or threatened. Do you still agree with that?
Mr. COWX: Can I refer to the particular place, please?
Mr. LOEWENSTEIN: Yes, that was in table 2 of your full report.
Mr. COWX: These lists, I have no doubt, have not changed. Most of these species are
estuarine species, certainly the top one, Carcharhinus, is a shark. So it is not particularly going to - 14 -
be found in fresh waters, Centropomus is found in the estuarine areas, totally away from the area
associated by the row.
Mr. LOEWENSTEIN: Professor Cowx, the question before you was whether you agree that
there are 11 species of fish down in the San Juan that are either listed as vulnerable or threatened?
Mr. COWX: Well, according to the ICN List, which is the internationally -recognized list,
there are only six and two of them are classed as “least concern”, which means that they are not
considered vulnerable. One is considered vulnerable, the VV, which is the Megalops.
Mr. LOEWENSTEIN: Why did you list 11 species on your table?
Mr. COWX: These are provided by the environmental diagnostic assessment and I was just
providing and updating, or providing that information for completeness.
Mr. LOEWENSTEIN: Whether the species of fish that are present in the San Juan River are
vulnerable to one or more of the impacts that we discussed before, would need to be determined on
a species by species basis, taking into account each species’ habitat and environmental tolerances.
Do you agree with that?
Mr. COWX: That would be the classical way of doing it, yes.
Mr. LOEWENSTEIN: No studies have been done on any of the specific species of fish
found in the San Juan to determine their sensitivity to sediment. That is correct, isn’t it?
Mr. COWX: To my knowledge that is correct.
Mr. LOEWENSTEIN: Now, Professor Cowx, if you don’t mind, I would like to ask you to
turn to tab 26 of the judge’s folder which I believe you have been provided by the Court. This is an
article entitled “ The role of catchment scale environmental management in freshwater fish
conservation” that you co-authored in the journal Fisheries Management and Ecology . I would be
grateful if you could turn to page 309 of that article. - 15 -
In the section entitled “Importance of freshwater fish conservation for the environment ” you
state in the highlighted part, in regard to fisheries protection measures:
“The main problems with existing measures are the lack of baseline information
on which to manage the fishes, lack of public awareness and weak integration of
conservation in water resource management planning.”
You then state in the next paragraph:
“Although a lack of baseline data is an issue, the urgency for direct management
intervention is so great for many species that decisions should be based upon the best
available science and existing experience to support management options. Where
information on which to make a decision remains inadequate, the precautionary
approach must be adopted. This is particularly important where development schemes
are likely to impact on fish communities about which little is known.”
Do you still agree with this statement?
Mr. COWX: I do agree with the statement . . .
Mr. LOEWENSTEIN: Thank you very much.
Mr. COWX: It was written some time ago but it is still highly relevant.
Mr. LOEWENSTEIN: Thank you very much. Mr. President, I have no further questions for
Professor Cowx. With you permission we can now proceed with the re-examination.
Le PRESIDENT : Merci. Je me tourne vers le conseil du Costa Rica, Madame Parlett qui
va conduire, si elle le souhaite, l’interrogatoire complémentaire.
Ms PARLETT: Professor Cowx, Mr. Loewenstein asked you questions about the
importance of protecting fish in Ramsar sites. In your expert opinion as an aquatic ecologist, do
you have an opinion as to whether the fish in this particular Ramsar site are likely or not to suffer
the kind of effects that Mr. Loewenstein put to you?
Mr. COWX: There are two issues here. The first is that we do not know the species in the
Ramsar site as such, and the second is that we do not know the tolerances of the species that may
be there, but it is highly likely that those species are tolerant to sediment anyway, because the San
Juan River system is a naturally tropical river which has got high sediment loading, particularly - 16 -
during the flooding period. And therefore, these species are adapted to those conditions in any
case.
This is spelt out in fact in Bussing’s review of the fishes of Costa Rica; he clearly states that
the fishes of the San Juan are adapted to these high levels of sediment loading. That is quoted in
my statement.
Ms PARLETT: You said, Professor Cowx, that the fish in this particular Ramsar site are
highly likely to be tolerant to sediment, and you referred to the study of Dr. Bussing. In your
expert opinion, is there any other relevant information, or not, as to what species there are in this
part of the river, and whether they are likely to suffer the kind of impacts that Mr. Loewenstein put
to you?
Mr. COWX: I am afraid the problem I have is that I am not fully familiar with the Ramsar
site and its extent and all the other aspects of the Ramsar site, and how it floods, how the sediment
loading is delivered to it; so therefore I cannot really respond to that question.
Ms PARLETT: I think I can probably put to you that the San Juan River is included in the
Nicaraguan Ramsar site and I think that is uncontested.
Mr. COWX: Then it is highly unlikely that any species in the Ramsar site will be affected
by the sed iment loading because they are adapted to the natural sediment loading patterns that
occur in the river.
Ms PARLETT: Mr. Lowenstein took to you Appendix 2 of your report, just in front of you.
Could you explain to the Court how you produced this appendix?
Mr. COWX: The appendix is produced from the Environmental Diagnostic Assessment
2014, verbatim, and that is also based on information from Bussing, and so it just provides both the
international conservation status and the national conservation st atus, which suggest that only a
couple of species are really threatened two, three species are “endangered”, as we call them in
conservation level terms. - 17 -
Ms PARLETT: And on the basis of the information that you have looked at that is
underlying in this appendix, do you have an opinion as to whether or not fish in this Ramsar site
that is, in the San Juan River are likely or not to suffer this kind of adverse impact s that
Mr. Loewenstein put to you?
Mr. COWX: Unlikely. The threatened species t hat you have got here, the A gonostomus,
basically lives in mountain streams, away from the main San Juan River. So it lives in the smallest
tributaries and then will go down, right to the estuary, as part of its life cycle, life history. So, it is
unlikely that will be affected. The other species, the R ivulus species, is a similarly migratory
species but it will be found mostly in the estuarine conditions, so probably below the Ramsar site
area.
Ms PARLETT: Mr. Loewenstein asked you whether or not in your view, fish in the San
Juan River are likely to suffer impacts as a result of a degradation in macroinvertebrates in the
river. Are you aware of any relevant information before the Court about the impact of any
degradation in macroinvertebrates on fish?
Mr. COWX: The information that I have received, the various documents that I have read as
a result of this case, clearly state that there is very, very little impact on macroinvertebrate fauna
and food. The scale of the impact is so small in comp arison to the size of the San Juan River, it is
inconsequential.
Ms PARLETT: You mentioned that you’ve seen studies on this: could you direct the Court
to them, to those studies?
Mr. COWX: In terms of?
Ms PARLETT: In terms of any impact on macroinvertebrates that you just mentioned.
Mr. COWX: There are some good studies in what is called the Ok Tedi mining system
which is on the Sepik River in Papua New Guinea, where the sediment loading from the mining - 18 -
activity is so huge that you could almost walk across the river, it is that thick with sediment. A
completely different level of what is going on in this river.
Ms PARLETT: And have you seen any relevant studies relating to the impact on
macroinvertebrates in this river? In the context of this case, or otherwise.
Mr. COWX: In the Ok Tedi? Yes, I have seen some studies done by a colleague of mine
who worked for the company for a number of years, and he was saying that the impact is so huge
that basically [they have] written off the river because the damage is so great the economic
importance to Papua New Guinea is so great that they are reconciled that they . . .
Ms PARLETT: And are you aware of any studies that show the impact in this particular
river, whether or not in the context of this case? On macroinvertebrates.
Mr. COWX: In the Ok Tedi’s. . .? Sorry?
Ms PARLETT: In the San Juan River.
Mr. COWX: No. There is nothing in the San Juan River to indicate that there is a loss of
macroinvertebrate fauna to justify any impact on fisheries or the food web at all.
Ms PARLETT: Thank you very much. Costa Rica has no further questions on
re-examination.
Le PRESIDENT : Merci, Madame Parlett. L’un des membres de la Cour souhaite poser une
question à l’expert. Je vais donc mai ntenant lui donner la parole et je demande à l’expert de bien
vouloir répondre à la question qui lui sera posée aussitôt après qu’elle aura été posée. Je donne la
parole à M. le juge Bhandari.
Judge BHANDARI: Professor Ian Cowx, I have a question for you. It regards 14 and 23 of
your written statement. You appear to suggest that increased sediment delivery in the San Juan
River could in fact have positive rather than negative impacts on the fish species in that river. In
support of this proposition, y ou cite a number of scientific publications. My question to you is, - 19 -
could you briefly, and in plain terms, explain the scientific basis, for why increased sediment
delivery into the San Juan River could actually improve living conditions for the fish in that river?
Mr. COWX: This is based on the fact that the sediment is just not material. It actually
carries with it nitrates and phosphates which are nutrients that help develop, what we call “primary
production” and then “secondary production”. So they build up the algae populations, and then the
macroinvertebrate populations, which then become the food of the fish. And that is ca rried in
sediment loading. Traditionally it would carry about 20 per cent of the nitrates for the river, and
about 80 per cent of the phosphates. And the phosphates are the limiting factor, so it is very
important. It is bringing more of those sorts of nutrients to improve production. Starvation in
rivers where you have had starvation of sediments the fish production ha s gone down, almost
proportionally to the reduction in the delivery of sediments, and therefore nutrients. I have just
come back from Vietnam as Kate has informed you and that is one of the big issues we are
looking at there.
Judge BHANDARI: Thank you, Professor.
Le PRESIDENT : Merci. S’il n’y a pas d’autres questions pour l’expert, je le remercie.
Ainsi s’achève, Monsieur Cowx, votre déposition. Je vous remercie encore d’avoir bien voulu
comparaître devant la Cour. Vous pouvez quitter la barre. Merci.
Mr. COWX: Thank you.
Le PRESIDENT : Le second expert cité par le Costa Rica et qui sera entendu par la Cour est
le professeur Thorne. La Cour souhaite éviter autant que possible d’interrompre l’audition du
professeur Thorne. C’est la raison p our laquelle elle va procéder à la pause- café habituelle à un
moment inhabituellement précoce dans la matinée. Elle va donc se retirer maintenant pour
15 minutes et l’audience reprendra avec l’audition du professeur Thorne. L’audience est
suspendue.
L’audience est suspendue de 10 h 25 à 10 h 40. - 20 -
Le PRESIDENT : Veuillez-vous asseoir. La Cour va proc éder maintenant à l’audition du
professeur Thorne, second expert cité par le Costa Rica. Je l’invite à s’approcher de la barre.
Bonjour, Monsieur le professeur. Je vous invite maintenant à faire la déclaration solennelle
prévue pour les experts dont l’énoncé figure à l’alinéa b) de l’article 64 du Règlement de la Cour.
Nous vous écoutons.
Mr. THORNE: Good morning, Mr. President. Good morning, Judges.
“I solemnly declare upon my honour and conscience that I will speak the truth,
the whole truth and nothing but the truth, and that my statement will be in accordance
with my sincere belief.”
Le PRESIDENT : Merci, Monsieur Thorne. Je m’adresse à présent au conseil du
Costa Rica, M. Wordsworth, qui va vous demander de confirmer l’exposé écrit qui se trouve devant
vous. Monsieur Wordsworth.
Mr. WORDSWORTH: Thank you, Mr. President. Professor Thorne, in the folder before
you, I think you have four repo rts: your written statement of March 2015, your report annexed to
the Rejoinder of Costa Rica of February 2015, your report of November 2013, annexed to
Costa Rica’s Counter-Memorial, and a report prepared by you during proceedings on Nicaragua’s
Application for provisional measures in November 2013. Can I ask you to confirm that these
reflect your honest expert views?
Mr. THORNE: Yes, they do.
Le PRESIDENT : Merci. Je donne maintenant la parole à M. Reichler pour le
contre-interrogatoire. Monsieur Reichler.
Mr. REICHLER: Thank you, and good morning, Mr. President and Members of the Court,
and good morning to you, Professor Thorne.
Mr. THORNE: Good morning.
Mr. REICHLER: We meet again. Since our last meeting, I hope you at least had an
opportunity to go to the Keukenhof and see the tulips? - 21 -
Mr. THORNE: Sadly, not yet!
Mr. REICHLER: Be sure to do that when you are done with the case. They are glorious.
Yesterday, we heard from Costa Rica’s counsel about Costa Rica’s mitigation efforts in
regard to various sites along the road. I intend to ask you questions about three distinct subjects
this morning and I would like to begin by asking you some questions about the subject of
Costa Rica’s remediation.
Costa Rica’s counsel did not addre ss this chart yesterday. This chart is from your
February 2015 report that accompanied Costa Rica’s Rejoinder. Is that correct?
Mr. THORNE: That’s correct.
Mr. REICHLER: Please tell me if I am reading it correctly. There are a total of 127 sites
where the road crosses watercourses?
Mr. THORNE: It might be 128. I think Dr. Weaver found one that Dr. Mende missed.
Mr. REICHLER: Of these, there were 24 where it was determined that no mitigation was
necessary, is that correct?
Mr. THORNE: That’s correct.
Mr. REICHLER: And there were 28 sites where mitigation has been reported as having
been completed at the time of yourreport. Is that correct?
Mr. THORNE: That’s correct. The inspection wouldn’t have been undertaken at the time
the report was written. It would have been taken some time before and so the statistics wouldn’t be
fully up to date at the time that the report was issued because it is based on information gathered in
some preceding months. But with that, yes.
Mr. REICHLER: I appreciate that clarification.
Mr. THORNE: Well, because the mitigation is an ongoing process and of course we can’t
be absolutely up to date. - 22 -
Mr. REICHLER: Are you able and I understand if you cannot, but since you raised the
subject are you able to update this as you stand here? In other words, do you have a number in
mind of additional sites that have been completely mitigated since this report was prepared?
Mr. THORNE: I don’t have such a number in mind at this moment, no.
Mr. REICHLER: And, as of the time of this report and according to it, again if I am correct,
there were 23 water crossings where mitigation was in progress but was not completed. Is that
correct?
Mr. THORNE: That’s correct.
Mr. REICHLER: And there were a nother 31 watercourse crossing sites where mitigation
was required but, as described in the chart, it had been scheduled but not yet undertaken, is that
correct?
Mr. THORNE: That ’s correct. That ’s based on my conversations with the person at
CONAVI. CONAVI are the Government organization doing the works. Based on what she told
me, they had 31 that they were scheduled to work on as soon as they could mobilize the people and
provided the weather permitted.
Mr. REICHLER: And in the case of those 31 sites, do you know when that mitigation is
scheduled to be performed?
Mr. THORNE: Only in general terms. S he assured me it would be performed as soon as
possible. But given the weather and given the circumstances, she was not able to give me a precis e
date, no.
Mr. REICHLER: So if my arithmetic is correct, according to this chart, out of a total of
127 water crossings and for the moment we will leave out the extra one that you acknowledged
that Dr. Weaver found out of a total of 127 water crossings, there were 54 where mitigation was
either required but not completed, including 31 where it had not yet been commenced, but were
scheduled to begin at some at least for you uncertain time? - 23 -
Mr. THORNE: That’s correct, yes.
Mr. REICHLER: You m entioned Dr. Mende earlier in your answers to m y questions.
Would it be correct to say that you personally did not visit all 127 of these water crossings and
decided in each case whether it was completely mitigated, mitigation in progress, mitigation was
scheduled or no mitigation was necessary, or it belonged in any of these categories?
Mr. THORNE: I did not visit them physically. I visited quite a few of them physically, not
all. What I did do with Dr. Mende was took a virtual tour in the Mende repor t, the inventory of
water crossings; those pictures and maps of all of them, I went through those with Dr. Mende.
And, in that regard, I visited them, but not physically on the ground, that was not possible.
Mr. REICHLER: Would it be fair to say that, in addition to your actual personal
involvement as you have just described it, that you relied on Dr. Mende’s work in this regard?
Mr. THORNE: I relied on it once I had discussed in depth the status and conditions as he
observed it. I did not accept his initial classification of water crossing sites. I suppose the best way
to describe it would be that it was negotiated, because I wanted to be sure that the tables in his
records, they wouldn’t be the same if I had done it myself but they would be as cl ose as possible,
and in that regard I am content to rely upon them.
Mr. REICHLER: Can we look at the other chart that comes from your February 2015 report
that accompanied the Rejoinder? This has to do with the mitigation status of slopes rather than
watercourses. Is that correct?
Mr. THORNE: That is correct. These are cut slopes and fill slopes, not differentiated.
Mr. REICHLER: And I am asking this, it is a slightly compound question in order to save
time, but if you feel uncomfortable answe ring it just tell me and I will break it up into several
questions. Is that fair enough?
Mr. THORNE: OK. - 24 -
Mr. REICHLER: Would the same be true for this chart on slopes as was true on your chart
for watercourses in the sense that the work of observing a nd classifying the different sites was
performed by Dr. Mende, you relied on his work but you also engaged in some personal
observation and some, I think you called it, virtual observation, to assure yourself that the numbers
in this chart were reliable. Is that correct?
Mr. THORNE: That is correct.
Mr. REICHLER: And again, just to be sure I am reading this chart correctly, in the same
way that you do, it was determined by Dr. Mende and yourself that there were 201 locations where
there were cut slopes or fill slopes, is that correct?
Mr. THORNE: Correct.
Mr. REICHLER: And of those 201 slopes may I just call them “slopes” to make it
easier?
Mr. THORNE: Yes.
Mr. REICHLER: OK. Of those 201 slopes, mitigation was not required at 11?
Mr. THORNE: Correct.
Mr. REICHLER: So, at 190 of the 201 locations where there were cut slopes or fill slopes,
mitigation was required?
Mr. THORNE: Correct, the slopes are the heart of the matter. They are the source of, by
Dr. Kondolf’s survey, 75 per cent of the sediment. It is quite correct to focus on the slopes
primarily.
Mr. REICHLER: And of these 190 locations where mitigation was required, according to
this report and at the time the information was gathered, only 25 were considered as completely
mitigated? - 25 -
Mr. THORNE: At the time we compiled the data, that is correct. We were quite assiduous
in making sure that if we put it as done, then it was done. There is a very large body of work in
progress and I am sure that those numbers have changed now , but I cannot tell you exactly how
much. I am sure that the 107 has come down and the 25 has come up, but I do not know how
much.
Mr. REICHLER: Are you aware that, according to Dr. Mende’s report 2014, Annex 3 to
the Rejoinder, Appendix B that, of the 25 sites that he classified as completely mitigated, the
only mitigation that he reported at 13 of those 25 sites was the natural regrowth of some vegetation
and there was no physical activity performed by Costa Rica by way of mitigation at these 13 sites.
Is that correct?
Mr. THORNE: I believe so. The story that this tells us is that nature is quite resilient and
that sometimes it moves faster than the Costa Rican Government.
Mr. REICHLER: Well, I already talked about your credibility and I certa inly am aware that
governments sometimes move slowly and I am sure Costa Rica is no exception in that regard. And
they have my utmost respect.
Mr. THORNE: Well, indeed, and I find that as frustrating as I am sure everybody else does.
Mr. REICHLER: Still referring to this chart thank you mitigation was regarded as still
in progress and not yet completed at 107 slopes, as of the time of this report, correct?
Mr. THORNE: Yes, there was a huge effort being made in the latter third of 2014,
continuing into early 2015.
Mr. REICHLER: And do you know when the mitigation that is in progress at these
107 slopes requiring mitigation, do you know when that mitigation will be completed? Can you
give me a date? - 26 -
Mr. THORNE: I cannot. I probed CONAVI quite hard about this and quite honestly, it does
depend on the weather, it does depend on the funding being continuous. There are factors that are
beyond their control. I am reassured they are doing it as fast as they can.
Mr. REICHLER: And there are, according to the chart, if I am reading it correctly, there are
58 slopes that require mitigation, where mitigation has been scheduled but, as of the time of this
chart, the mitigation had not yet commenced. Is that correct?
Mr. THORNE: That is correct. C ONAVI are rushing, I am not sure that is entirely a good
thing, their agenda is being driven by the need to complete this work very quickly. When I visited
some sites, the last time I visited some of the active sites was in November, and they were working
very hard and under the kind of health and safety regulations that I am used to in the
United Kingdom and the United States, the work would not be allowed. They are taking chances to
get the work done at a time when I would have suspended the work becaus e of the wet season
weather. Haste may not be absolutely the best thing here. Sorry, that is a long answer.
Mr. REICHLER: At these 58 sites, these particular 58 sites that require mitigation, and
where it says that mitigation has been scheduled, do you know when mitigation at these 58 sites is
scheduled to commence?
Mr. THORNE: I do not.
Mr. REICHLER: And, would it also be correct that you do not know when that mitigation
will be completed?
Mr. THORNE: I do not know that either.
Mr. REICHLER: You mentioned budget or financing a moment ago, I would just like to ask
you a question about that. Do you know what budget has been established by Costa Rica to
complete the mitigation in progress at these water crossings and slopes, and to carry out mitig ation
at the sites where it is scheduled, do you know what budget has been established to do all that
work? - 27 -
Mr. THORNE: I do not know the sum in colones or dollars. I could quote one or two
figures for individual sites where I have discussed them with t he individual engineers when I have
been on site, as you do. What I do know about the budget is that it is continually having to be
increased because this work is expensive. It was underestimated; the budget is being increased
and each time it is increased there is a slight delay whilst the paperwork is done. I find that just as
frustrating, I am sure, as the people who want to do the work on the ground.
Mr. REICHLER: Thank you. I would like to recall for you a statement that you made in
your December 2013 report that accompanied Costa Rica’s Counter-Memorial, and since you are
opening it let me give you the site, it is at paragraph 11.19.
Mr. THORNE: Sorry, could you say that again?
Mr. REICHLER: It is paragraph 11.19 of that document. I will gi ve you a moment to find
it.
Mr. THORNE: 11.19?
Mr. REICHLER: That is correct.
Mr. THORNE: Yes, got it.
Mr. REICHLER: Right. I am not going to read the whole paragraph, but if you need to do
so for context I do not want to read the whole thing because it would take too long you are
allowed to refer to anything in any of your reports if it would assist you, and I do not mean to stop
you from doing that.
Mr. THORNE: I understand.
Mr. REICHLER: The words that I am particularly going to ask yo u about are these: “these
are temporary works that mitigate but do not permanently solve erosion problems, and a permanent
solution will not be achieved until design, planning and construction of the Road are completed”.
Do you still agree with that statement? - 28 -
Mr. THORNE: Absolutely.
Mr. REICHLER: How do you, as an expert, distinguish between mitigation works that are
temporary, on the one hand, and mitigation works that are permanent, on the other?
Mr. THORNE: There is a huge difference: in terms of the mitigating works CONAVI are
using standard designs; so they have a design for a road -crossing culvert; they have a design for
these gutters that they put at the base of slopes; they have designs that they use for stabilizing the
slopes themselves, in the way that Dr. Del Mar showed you yesterday.
Mr. REICHLER: My question, Professor Thorne, is simply: can you give us examples of
what are temporary mitigation works, what are they, and what are permanent works? Just to recall,
you have just toldme that you agree with your statement in your December 2013 report referring to
Costa Rica’s mitigation works: “these are temporary works that mitigate but do not permanently
solve erosion problems and a permanent solution would not be achieved until des ign planning and
construction of the road are completed”. So, I wanted you to tell the Court some examples of the
kinds of mitigation works that you consider temporary and contrast those with the kinds of
mitigation works that you would consider permanent.
Mr. THORNE: I understand. Those standard designs are just taken out of a manual and
used because there isn’t time to do the hydrological analysis for a micro basin, so each micro basin
may be 1 km sq and a culvert has been put there to replace a log bridge or a fill segment, and that
culvert will work for a couple of years but it’s a standard sized culvert; it’s whatever they’ve
got on the van, basically, that they are using.
The permanent solution will be to use a hydrological analysis to calculat e the design flood
for a culvert; perhaps it’s the 100- year event Dr. Weaver knows a lot more about this than I
do but you would then have a different sized culvert at each road crossing that is correctly
designed to handle the run-off at that road crossing. That’s part of detailed designed; that’s part of
the permanent solution, which is proceeding but, again, slower than we would all like. But they
have to get it absolutely right, you will appreciate. - 29 -
Mr. REICHLER: Thank you, Professor Thorne. Can you also give us again you can
refer to what Costa Rica is doing or you can answer the question generally, I will leave it up to you.
But, you very helpfully explained for the Court the difference between temporary remediation
works, as Costa Rica i s doing, and permanent remediation works as Costa Rica hopes to do in
regard to mitigation of the watercourse crossings. I wonder if you could help us in regard to slopes,
cut slopes and fill slopes, mitigation again the question, just to be clear; I am not trying to limit
you, but I just want to make sure that you answer the question properly I know you are trying to
give responsive answers; I have no problem with anything you were saying; I just want to make
sure that my question is clear to you on the record and so that it will be clear to the judges, if they
decide to consult the transcript.
Mr. THORNE: I understand exactly.
Mr. REICHLER: So, the question is: can you give us some examples of the differences
between what you consider temporary mitigation works and permanent mitigation works in regard
to the mitigation at the slopes and cut slopes?
Mr. THORNE: So, if we took an example of the fill slopes, where material has been
side-cast off the side of the road and it is not compacted, a temp orary solution may be to cover that
with coconut matting and protect it from raindrop impact and run-off. The permanent solution may
be to take it away because it hasn’t been properly compacted, it hasn’t been vibro -compacted and
built up in layers in the proper fashion, and the only thing you can do with that fill slope is take it
away and start again. So, that is the difference for a fill slope between protecting it for a year or
two and mitigating and then actually the cure for that site; it may not b e possible to stabilize that
fill slope in that location. In extremis, the permanent solution may be to re -route the road and,
again, Dr. Weaver I wouldn’t argue with a lot of his recommendations; he knows what he is
talking about.
Mr. REICHLER: I be lieve you have already said this but, just to be sure, in your
December 2013 report you said: “In my opinion, the necessary work should proceed as soon as
possible, with the work expedited to the greatest degree . . .” That remains your opinion? - 30 -
Mr. THORNE: That remains my opinion; it was stated at that time in the context of the
position of Nicaragua which was that all work should cease and I was keen to make it clear that all
work shouldn’t cease; the remediation should continue and, in my opinion, the completion of the
road, the permanent solution, should proceed as soon as possible.
Mr. REICHLER: In regard to the type of mitigation that you regarded as sufficient to
achieve a permanent solution to the problem?
Mr. THORNE: Well, the permanent solution wouldn’t mitigate it, it would permanently
solve the problem of instability on the road.
Mr. REICHLER: You are absolutely right, and I am sorry that I misspoke. What you are
recommending that Costa Rica do is not just mitigate, but perform the wo rks necessary to
permanently resolve the problems at these sites.
Mr. THORNE: Yes, Route 1856 should be brought to the same standard as all other
comparable roadways in Costa Rica, many of which are built to an extremely high standard and
this one should be too, but it’snot been built that way.
Mr. REICHLER: Yesterday, before we leave this subject and move on to my second
subject, counsel for Costa Rica, Ms Del Mar, said I must quote from the uncorrected version of
the transcript, so bear that in min d “the original dates . . . estimated for the conclusion of the
final designs . . . have been delayed”. And that CONAVI, the agency in charge, has still not even
received any designs for these works. Is that your understanding as well?
Mr. THORNE: Yes, in broad terms, yes.
Mr. REICHLER: Thank you, Professor Thorne. With your kind indulgence, I would like to
move on to the second topic of the three that I wish to ask you about today.
This topic I will call “suspended sediment concentrations, or sus pended sediment levels”.
Do you still agree with the statement that you made in your December 2013 report, which
accompanies Costa Rica’s Counter -Memorial, that “extreme natural variability in sediment - 31 -
concentrations, and associated levels of turbidity ar e characteristic of rivers in the Río San
Juan-Colorado system”? That is correct, isn’t it?
Mr. THORNE: Can we go to it, to just see the context.
Mr. REICHLER: Oh, of course, any time . . . I am referring to your December 2013 report
and particularly to paragraph6.31.
Mr. THORNE: Yes it is, and it is illustrated graphically in the scatter graph that
Dr. Kondolf referred to, figure 18, which shows that suspended sediment concentrations in parts
per million measured over a long period: 2,409 individual measurements range from less than ten
to more than 10,000.
Mr. REICHLER: And that is what you referred to as “extreme natural variability in
sediment concentrations”.
Mr. THORNE: Yes, it is not the most extreme that occurs these are just the measured
ones. A paper by my good friend Ian Douglas, from Manchester University, in 1996 reports
concentrations in excess of 100,000 parts per million in volcanic basins around the Pacific Rim,
just like Costa Rica, but not actually in Costa Rica.
Mr. REICHLER: And the data that has been at your disposal reveal that measurement
uncertainty, together with natural fluctuations in rainfall, discharges, catchment sediment yields
and suspended sediment concentrations (SSCs) mean that suspended sediment levels ( SSLs) are
likely to vary inter-annually by 5 and 10.5 million tons. That is correct?
Mr. THORNE: Yes, the sediment load and the sediment concentration are conditioned by
the water flow and the availability of sediment. They vary due to the weather, the y vary due to
seismicity, volcanoes; high variabilities are characteristic of this river. The problem is
compounded because we do not have very much data and it is also compounded because the data
we do have comes from the Río Colorado and then there is, what I think you referred to as a
“witches’ brew” of statistics to try and work out from the data that we have got on the Colorado, - 32 -
what the data for the Río San Juan would look like. I think a “witches’ brew” is a bit harsh, but
there are perhaps some analytical gymnastics that go on and that means the uncertainty . . .
Mr. REICHLER: I will accept your description and withdraw “witches’ brew” in deference
to you, Sir.
Mr. THORNE: Thank you.
Mr. REICHLER: When there is lower rainfall, that produces less catchment run -off and
generates less erosion and therefore a smaller suspended sediment load, that is correct?
Mr. THORNE: A smaller suspended sediment load, yes. Even in a light year, there will still
be very heavy downpours. We are in the tropic s. There will be some high SSCs, sediment
concentrations, but the annual load will be much lower as Dr. Andrews indicated for the
Jabillos Station in his very exhaustive mental and analytical gymnastics.
Mr. REICHLER: And because the post -road period that is, since the road construction
began has been drier than usual, meaning there has been lower rainfall than usual during this
3- or 4-year period, that would have the effect of reducing the annual sediment load?
Mr. THORNE: It has had that effect. The loads in 2012, 2013, 2014 are 8 million,
8.5 million, 6 and a bit. That is quite a big variability. It is nothing compared to the variability you
would find if we had 30 years of record.
Mr. REICHLER: Based on the natural variability in sediment loads and the other factors
that you have mentioned, you have concluded that “no possibility exists for using measured loads
to estimate how much sediment derived from erosion of the road has been added to the
Río San Juan due to the very high natural vari ability in those loads”. This is the same report, your
December 2013 report, paragraph 8.17.
Mr. THORNE: Yes, I thought it was a ways away. Yes, that is right but I think you have to
read 8.17 in conjunction with 8.12, where I was referring to measurem ents made prior to the road
in a joint programme between 1974 and 1976 and then measurements made by ICE in 2010 to - 33 -
2013. I agree with Dr. Andrews, and he was fairly hard on me in saying two years of records are
too short to draw big conclusions, and he i s right and I agree with him and I stopped doing it after
this. But, no, you cannot do it on the basis of such short records, especially not when you are
making these leaps of faith of taking Colorado data and trying to use it for the Río San Juan. If we
had really good data on the Río San Juan you could do it but that is not possible for Costa Rica.
Mr. REICHLER: And do you agree with Dr. Andrews that having really good data on the
Río San Juan would mean data collected over some years prior to the con struction of the road, let
us say numerous samples over a period of several years, say up to 2010, before the construction of
the road began, to use as a baseline and if you had those data, you might be able to draw some
conclusions from measurements of sediment loads after construction of the road, is that correct?
Mr. THORNE: No! Would you like me to tell you why?
Mr. REICHLER: Go ahead, I have no alternative, do I?
Mr. THORNE: Okay, so doing it that way would be great if we had a time machine and we
could go back and start data, but we do not. What we can do though is we can set up a measuring
station upstream of the road, which is completely unaffected by the road and we can collect data
there and we can take data downstream, in fact Nicaragua has done this at least on three occasions
when it has made measurements at El Castello and upstream of Boca San Carlos, and
Mr. Wordsworth discussed that with Dr. Kondolf. That is still going to be tough. If I were doing
this and I had a free hand, the fir st thing I would do is set up stations just upstream and just
downstream of the 17 severely eroding sites identified by Dr. Kondolf and I would expect to be
able to see a signal from that sediment that comes in between two stations, if there was indeed any
sediment coming in.
Mr. REICHLER: Fair enough. But you have concluded and I am not going to go into
your conclusions or your calculations, I am certainly no match for you there but you have drawn
conclusions that sediment is going into the river from the road and as a result of the construction of - 34 -
the road, just you and Dr. Kondolf have come to very different conclusions as to the amount, is that
correct?
Mr. THORNE: That is correct. We cannot both be right.
Mr. REICHLER: I am not going to ask you as to who is right or why, or how you got there,
my only question is that you have made your own determination that sediment, in whatever
amount, is coming into the river from the road.
Mr. THORNE: I think there is some actual sediment, yes.
Mr. REICHLER: That is all I am asking, thank you. Well Professor Thorne, I have saved
my third and most exciting topic for last: channel morphology. I am sure just the mention of those
two words will make hearts in this room beat faster.
Mr. THORNE: It is really important.
Mr. REICHLER: Well, I agree and I know that you are a fluvial geomorphologist, so this is
your stuff and my heart is beating faster too, I have become so interested in it. For purposes of
these questions, may we assume, as you have in some of your reports that, at the delta, 90 per cent
of the San Juan River’s waters flow into the Colorado River and 10 per cent of those waters flow
into the Lower San Juan? For the purpose of these questions, can we start there?
Mr. THORNE: No!
Mr. REICHLER: That is a pity. Let me refer you to your February 2015 report that
accompanied the Rejoinder and this is across several paragraphs. Let us start at paragraph 4.74.
Please let me know when you have found it.
Mr. THORNE: Yes.
Mr. REICHLER: In the fifth line down, there is a sentence that begins with these words and,
again, please feel free to look at the context. And it says “it is believed that about 90 per cent of the
discharge of the Rio San Juan passes to the Rio Colorado”. It is believed by you? Or by others? - 35 -
Mr. THORNE: Well, it definitely is not believed by Dr. Andrews because, again, he took
me to task after the 2013 report, and pointed out that the way that I had come to that conclusion by
comparing measurements from 1974 to 1976, to 2010 to 2013, was unfounded because they are
different periods, it is a different . . . Confucius said you cannot cross the same river twice, it is a
different river today to what it was then and he was right to do so, and I accept it. So, what we
did, and if you just turn the page, we did it for 95, 90 and 85, to reflect the fact that we do not
know. Ninety is a common wide -held belief, it is probably not bad, but it certainly is not 90, it
varies.
Mr. REICHLER: I appreciate that explanation. Since 90 per cent is not bad, let us use it for
the next few questions. And if you find that it is unfair to you, to continue using it for the purpose
of the next questions, just tell me and we will move on. But I think you will find that even your
characterization of 90 per cent is not bad, will be sufficient to make progress here.
Mr. THORNE: I agree. Absolutely.
Mr. REICHLER: Now, under that assumption, would it be the case that approximately
80 per cent approximately of the sediment that is carried by the San Juan River upstream of
the delta did I say 80 per cent?
Mr. THORNE: You said 80per cent.
Mr. REICHLER: I am sorry, my eyes started playing tricks on me, and I apologize for that.
Let me start the question again, with your indulg ence. So, under the assumption of the 90/10 split
in the flow between the Colorado and the Lower San Juan, would it be the case that approximately
80 per cent of the sediment carried by the San Juan River, which includes both coarse and fine
sediment of c ourse, would flow into the Colorado River, and approximately 20 per cent of the
sediment would flow into the Lower San Juan? Approximately.
Mr. THORNE: Well, based on diagram 4.14 and 4.15. - 36 -
Mr. REICHLER: Now, you will have to give me a second to cat ch up with you, if you do
not mind. I think that is called “equality of arms”, you get to look at your report, I get to look at it
also. Which figures are you talking about?
Mr. THORNE: On page 198, and you took me to page 196. So it is just very, ver y close,
and it is relevant to the text.
Mr. REICHLER: So, which paragraphs again?
Mr. THORNE: It is figures 4.14 and 4.15.
Mr. REICHLER: Oh, yes. OK, I am with you.
Mr. THORNE: There is a pie chart showing that the split of the water . . .
Mr. REICHLER: Pardon me, can I just, for the convenience of the Court, this figure 4.14 is
at paragraph 4.78, of your report of December 2013. And figure 4.15 is also in that paragraph, just
at the next page.
Mr. THORNE: Yes. And this is where we unpack th e fact that we do not actually know
how much water goes down each branch, and therefore we certainly do not know how much
sediment goes down each branch. But, we can model it, and that is what we have done.
Mr. REICHLER: Correct. And, in figure 4.14 which is at the bottom of the page, I think
this page is 198 of the Counter -Memorial, page 54 of your report and it has three models, (a),
(b) and (c), correct?
Mr. THORNE: Yes.
Mr. REICHLER: And under the model (b), which corresponds to a 90 per cent/10 per cent
distribution of the flow: this model shows that 84 per cent of the fine sediment goes to the
Colorado and 16 per cent of the fine sediment goes to the Lower San Juan.
Mr. THORNE: That is what the model shows. - 37 -
Mr. REICHLER: That is all I am asking.
Mr. THORNE: OK.
Mr. REICHLER: And then figure 4.15, again, figure (b) or item (b), shows how the coarse
sediment would be distributed between the Rio Colorado and the Lower San Juan. And, if I am
reading this figure in your report correctly , with a 90 per cent split that is, 90 per cent of the
water goes to the Colorado, 10 per cent to the San Juan then, 80 per cent of the coarse sediment
goes to the Colorado and 20 per cent of the coarse sediment goes to the Lower San Juan, according
to this model. Is that correct?
Mr. THORNE: According to the sediment transport model, that is correct.
Mr. REICHLER: So, somewhere, then, between 16 per cent which is the fine sediment
figure and 20 per cent which is the coarse sediment figure would go to the Lower San
Juan River under the model we are talking about, where 90 per cent of the river’s flow goes to the
Colorado and 10 per cent of the river’s flow goes to the Lower San Juan. Correct?
Mr. THORNE: According to the uncalibrated mode l, although Nicaragua’s measurements
indicate otherwise.
Mr. REICHLER: But this model has been developed by ICE of Costa Rica? Is that correct?
Mr. THORNE: Correct. By Costa Rica based on the available Costa Rican data for the
Colorado.
Mr. REICHLER : And you thought it was good enough to put in your report of
December 2013. I assume if you thought it was worthless, you would not have included it in your
report.
Mr. THORNE: I thought it was the best we had at that time.
Mr. REICHLER: Now, if 8 4 per cent of the fine sediment flows into the Colorado River,
and 16 per cent of the fine sediment flows into the Lower San Juan, and 20 per cent of the coarse - 38 -
sediment flows into the San Juan and 80 per cent of the coarse sediment flows into the Colorado ,
would it be correct to say that according to these models produced by Costa Rica’s ICE, and
reproduced in your report that roughly four times as much sediment flows into the Colorado
River as flows into the Lower San Juan?
Mr. THORNE: At least fourtimes, yes.
Mr. REICHLER: So, the magnitude of the sediment flowing into the Colorado River is at
least four times the magnitude of the sediment flowing into the Lower San Juan? Correct?
Mr. THORNE: According to the model, yes.
Mr. REICHLER: Now, w ould you agree that, despite the fact that it receives at least four
times as much sediment as the Lower San Juan, the Colorado River is not plagued by the
accumulation of sediment to such a degree, that navigation between the delta and the mouth of the
river is seriously obstructed? You would agree with that, wouldn’t you?
Mr. THORNE: Yes, I would. The Colorado is a much bigger river.
Mr. REICHLER: Now, by contrast, in the San Juan, although it receives less sediment than
the Rio Colorado does you said by less than one fourth of the sediment, according to the models,
than the Colorado does the San Juan by contrast with the Colorado we are talking about the
Lower San Juan is unable even to accommodate this load of sediment. That is correct, isn’t it?
Mr. THORNE: Can we go to that?
Mr. REICHLER: We can. Can you and I can take you right there but is it possible for
you to give me an answer to the question and then we go to it, or would you rather go to it?
Mr. THORNE: Now, you see, I w as not listening properly because I was thinking about
where was . . .
Mr. REICHLER: Did your counsel not tell you to always listen to the question ? You have
to listen carefully to the question, that is the first rule for every witness. - 39 -
Mr. THORNE: I apologize.
Mr. REICHLER: Well, let us then go to the data and I can ask the question again.
Mr. THORNE: Context is everything.
Mr. REICHLER: Context is everything, I agree with that. We go to. . . here . . . It is
actually your 2011 report that was submitted with Costa Rica’s Memorial in the Certain Activities
case, and this is II -27, the page is numbered II- 27. Is there a reason you are looking over there?
You need the report? I am sorry, I would be happy to furnish you with . . .
Mr. THORNE: I would like to read the paragraph that . . .
Mr. REICHLER: I am happy to provide it for you. Thank you, Costa Rican counsel for
facilitating this.
Mr. THORNE: And it is II, which page?
Mr. REICHLER: I think II-27.
Mr. THORNE: Got it.
Mr. REICHLER: OK? I refer you in particular to the next to last paragraph on that page
and, again feel free to explore the context, but the words that I am looking at are these:
“The situation in the R ío San Juan branch of the deltaic is quite different
[compared to the Colorado which is discussed in the previous paragraph] . Although
this river receives less of the sediment delivered to the D elta than the R ío Colorado
does, it is unable to accommodate even this load.”
True?
Mr. THORNE: In the context of the comparison between the Colorado and the Lower R ío
San Juan, that is correct. And in the context of accommodating sediment, yes.
Mr. REICHLER: You have described the Lower San Juan River as a “response reach”. Is
that correct? - 40 -
Mr. THORNE: Correct.
Mr. REICHLER: I am going to be asking you two or three questions, maybe two, about
your discussion of response reaches in your December 2013 report that was submitted with the
Counter-Memorial, in case you want to consult it. I am navigating between pa ragraphs6.12
and 6.15, in that general area. I will give you a moment. Mr. President, while the witness is
looking for the reference, is it possible for the Court to advise me of how much time I have left or
how much time I have used?
Le PRESIDENT : Vous disposez encore d’une demi-heure.
Mr. REICHLER: Thank you, Sir. I will finish well before that.
Mr. THORNE: 6.12?
Mr. REICHLER: Yes, it is again feel free . . .
Mr. THORNE: It begins with Professor Cowx?
Mr. REICHLER: Let me look at it, I h ave it here but let me just consult the actual page.
OK. I am looking in paragraphs . . .
Mr. THORNE: This is the 2013 report?
Mr. REICHLER: Yes, this is December 2013. And actually, you first discuss response
reaches between paragraph 6.12 and 6.14 and then you say, in paragraph 6.15, that you consider the
Lower San Juan River to be a response reach, is that correct?
Mr. THORNE: Yes, I do.
Mr. REICHLER: So now, we will let everybody in on the secret as to what a response reach
is. I believe you have defined a response reach as and you will find this at paragraph 6.12 a
“morphologically sensitive channel[ where] the actual rate of sediment transport is limited by the - 41 -
capacity to transport sediment rather than the supply from upstream and loca l sources”. That is
your view?
Mr. THORNE: That is my opinion, yes.
Mr. REICHLER: And, continuing in that paragraph, these “transport -limited conditions
mean that the river has no unfilled capacity to transport additional sediment and morphologic
adjustments are likely to occur in response to changes in sediment supply”. Do you see where you
wrote that?
Mr. THORNE: Yes.
Mr. REICHLER: And that is true?
Mr. THORNE: It is true of all response reaches of which there are three downstream of the
road, so two in the Río San Juan and one in the Lower RíoSan Juan.
Mr. REICHLER: Morphologically speaking, the bed of the Lower San Juan River is not flat
and smooth like a bowling alley, is it?
Mr. THORNE: No, it is not.
Mr. REICHLER: In fact, there are what you described as “continuous bed level changes
associated with the migration of ripples, dunes with amplitudes of up to half a metre, and bars with
amplitudes greater than one or even two metres”. Correct?
Mr. THORNE: Correct, and obviously we w ould now add to that, a 2- metre-deep,
30-metre-wide trapezoidal trench.
Mr. REICHLER: That is what Nicaragua has dredged?
Mr. THORNE: Has dredged.
Mr. REICHLER: So, it would be correct to say that when sediment accumulates in the
Lower San Juan River, it does not spread out evenly across the entire bed of the river, does it? - 42 -
Mr. THORNE: No, it does not. It mostly settles out in the two-metre-deep, 20-,
30-metre-wide trench.
Mr. REICHLER: But I believe you said that much of the sediment that flows into the Lower
San Juan is “deposited in and along a mainly meandering channel in the form of shoals, islands,
point bars and natural levees”, is that correct?
Mr. THORNE: That is correct, as long as everybody knows what a shoal, a levee, an island
and the other thing . . a point bar, everybody knows what a point bar is.
Mr. REICHLER: Maybe we can discuss this outside, I think we may be pressing the limits
of everyone’s patience in terms of fluvial geomorphology. Let me move on to the next question if I
may.
Mr. THORNE: Yes, and if. . .
Mr. REICHLER: If you would like to, again I am sorry if I . . .
Mr. THORNE: Just to clarify . . .
Mr. REICHLER: If you would like to say what a shoal is, what a sandbar is, what a . . .
Le PRESIDENT : Monsieur le professeur. Pardon. Monsieur le professeur, je m’adresse
également à vous. Si vos échanges sont trop rapides, si les questions et les réponses s’encînent
trop vite, les interprètes ont un peu de mal à suivre. Je ne voudrais pas enlever à ces échanges le
caractère vivant qui permet de soutenir l’attention de la Cour, mais il faut penser aussi un peu aux
interprètes. Donc, faites- en sorte qu’entre une réponse et la question qui suit, il y ait une toute
petite pause pour que les interprètes puissent suivre, sans ralentir à l’excès naturellement. Merci.
Mr. REICHLER: Thank you very much, Mr. President. My time is running out,
Professor Thorne, however, in the interest of fairness to you, if you would care to give a
hopefully brief description. . .
Mr. THORNE: Very brief. - 43 -
Mr. REICHLER: . . . description of a shoal, what is a shoal, what is a sandbar, what is a
point bar, what is a natural levee, if that is what you wish to do, I am happy to allow you to do it.
Mr. THORNE: Well, I would just like to focus a bit more because natural levees are not in
the channel, they are above the channel so they do not affect navigation. Island s are above the
water level, unless you are flying a flying boat they do not affect navigation. The shoals are the
problem. The point bars, as every geographer knows, are on the inside of the meanders; the
navigation channel is on the outside of the meanders. But the shoals are the problem.
Mr. REICHLER: As well as sandbars would you say?
Mr. THORNE: Well sa ndbars are mobile bed features. We call them sandbars or
megadunes, so ripples and dunes and sandbars form spontaneously in a mobile sand- bed, they
indicate that the bed is sand and they indicate that it is mobile. A shoal is the static feature that
gives you the problems.
Mr. REICHLER: And sometimes they merge, the dunes and the sandbars?
Mr. THORNE: Yes, they are wave forms and wave forms can interact and reinforce each
other or cancel each other out.
Mr. REICHLER: Thank you. Actually, that turne d out to be quite painless and I appreciate
your brevity as well as your clarity in describing them. You have referred to Dr. Andrews several
times. I would like to ask you if you would agree or disagree with this statement of his?
“Sediment will be not be distributed evenly along and across the delta channels. It will instead tend
to form bars, creating reach -wise instabilities and obstructions to navigation that will need to be
removed through dredging.” Do you agree with Dr. Andrews’s statement.
Mr. THORNE: No!
Mr. REICHLER: Why do you consider him wrong? - 44 -
Mr. THORNE: The evidence from field studies, some at Redwood Creek by learned
colleagues Mr. Hagans and Dr. Weaver, show that when there is an excess sediment load due to
say, large-scale deforestation, in Redwood Creek the first thing you do is you fill in the pools,
which is really, really bad for habitat. The bars do not grow in amplitude or riffles , as they are in
the Redwood Creek, the first thing you do is you fill in the pools. And, in the case of the sandbars,
when the flow goes over a sandbar, the depth reduces and the velocity increases and the top of the
sandbar, the elevation of the sandbar becomes self -limiting. It cannot grow out through the water
surface. The reason navigation is so difficult in the dry season is because it is the dry season, the
water depth reduces massively.
Mr. REICHLER: I think you also said the shoals are a problem for navigation?
Mr. THORNE: Now shoals are depositionary centres and they do accumulate sediment.
They are preferential sites and may be what Dr. Andrews was referring to was shoals, more than
bars but this is a nomenclature.
Mr. REICHLER: May I ask you, if we substituted the word “shoals” for “bars” in
Dr. Andrews’s statement, you would agree with that?
Mr. THORNE: I would agree entirely : in the three response reaches between the severely
eroding sites and the Lower Río San Juan. There are two other response reaches. In the last few
days I have looked: there are six major shoals, eac h of which will trap 60/70 per cent of the
bed load before you get to the delta, so, yes, shoals collect sediment. It is not a problem for
navigation because the Río San Juan is a much bigger river.
Mr. REICHLER: In the RíoSan Juan but not in the Lower.
Mr. THORNE: The LowerRío San Juan is a problem, I agree.
Mr. REICHLER: Would you agree that Nicaragua’s present dredging programme, at its
recent or current levels, has very little effect on the flow of the Lower San Juan River? In part
because, although Nicaragua keeps dredging sediment out of the river, just as much if not more - 45 -
sediment keeps arriving from upstream, accumulating in the channel Nicaragua was attempting to
maintain, requiring repeated dredging of the same areas?
Mr. THORNE: I woul d not agree, no. I think it has a highly deleterious effect on the
channel.
Mr. REICHLER: But my question is whether there is, to maintain the channel that you
described before, that is, the object of Nicaragua’s dredging programme, you would agree that that
requires repeated dredging just to maintain that channel?
Mr. THORNE: Yes, but there are much better ways of maintaining that channel than
repeatedly dredging it, which clearly is not working.
Mr. REICHLER: And the reason it is not working is bec ause the channel keeps filling up
with sediment as they dredge it?
Mr. THORNE: Yes! As I stated before, if there is a pool, if you dredge a deep hole in the
channel, it will refill very quickly.
Mr. REICHLER: Especially if there is a lot of sediment coming from upstream sources,
whatever they may be.
Mr. THORNE: Yes! We have got 11 live volcanoes putting sediment into the river. In my
opinion, the road-derived sand has not got there yet.
Mr. REICHLER: I had a feeling you would sneak that in at one point, so touché ! Do you
stand by the statement in your 11 October report that: “Maintaining navigation in the Río San Juan
for vessels with draughts greater than, say, about 1 m, will require not a single capital operation but
repeated dredging and the removal of hundreds of thousands of cubic metres of sediment year after
year.” You still agree with that?
Mr. THORNE: That would be the catastrophic result of trying to dredge this river to
maintain passage, yes. - 46 -
Mr. REICHLER: Well, in order to maintain passage for vessels with draughts greater than
1 m, whether you think it is a good idea or a bad idea . . .?
Mr. THORNE: I think it is a terrible idea.
Mr. REICHLER: OK, but it would require not a single capital operation but repeated
dredging and removal of hundreds of thousands of cubic metres of sediment, year after year? That
is what you said in your 2011 report in the Certain Activities case. Is there any reason why you
would disagree with your prior statement now?
Mr. THORNE: No, this is Sisyphean; they are going to be doing it forever.
Mr. REICHLER: Professor Thorne, once again I thank you immensely for your
co-operation, for your openness and your candour. Really and I say this with all sincerity it
has really been a pleasure get ting to know you and I hope that we will remain friends after this
session ends. Thank you very much.
Mr. THORNE: Thank you very much. That is my wish too and thank you for your
forbearance and for the Court’s forbearance. I am new to being an expert witness and I have not
followed the rules exactly. I apologize!
Mr. REICHLER: Thank you, Mr. President, Members of the Court.
Le PRESIDENT : Merci, Monsieur le professeur. Mais la Cour a encore beaucoup de
patience à sa disposition. Nous n’avons pas terminé. Et je vais maintenant donner la parole à
M. Wordsworth qui va me dire s’il souhaite procéder à un interrogatoire complémentaire et, dans
l’affirmative, qui va pouvoir maintenant procéder à cet interrogatoire complémentaire.
Monsieur Wordsworth… Monsieur Wordsworth, pouvez -vous parle r dans un micro qui soit
allumé? Pour l’instant, ce n’est pas le cas. On ne vous entend pas bien. Est -ce que le micro est
branché ? Oui ?
Mr. WORDSWORTH: Is it now working? Very good. Professor Thorne, in thefirst part of
that cross-examination, you will recall you were asked and shown various slides on mitigation - 47 -
works and you were asked questions in relation to mitigation works. Now, can you explain to the
Court how, or the extent to which, you have taken mitigation works into account in your estimates
of how much sediment is coming from the road?
Mr. THORNE: We have not taken them into account at all.
Mr. WORDSWORTH: And why is that?
Le PRESIDENT : Monsieur Reichler?
Mr. REICHLER: As you probably ha ve observed, I have not stood up to object to any
questions, yet either on cross -examination by counsel for Costa Rica, or re -examination. If
Mr. Wordsworth will recall, I asked the witness questions about three distinct subjects: the
mitigation efforts or mediation efforts; suspended sediment loads and concentrations; and channel
morphology. If Mr. Wordsworth is intending to take the witness into his calculations or
Dr. Kondolf’s calculations regarding sediment going into the river, I did not ask any questions
about that. Furthermore, I think you will recall that Mr. Wordsworth made a similar protest during
the re-examination of Professor Kondolf. So, in order to avoid having any difficulties as we go
forward, I just wanted to make clear for Mr. Wordsworth’s benefit, what the subject areas were and
our understanding that the subjects to be covered on re -examination should not be those other than
were covered on the cross-examination. Thank you, Mr. President.
Le PRESIDENT : Merci. Monsieur Wordsworth, vous pouvez poursuivre.
Mr. WORDSWORTH: Mr. President, thank you very much. I would just respond very
briefly to that, although I don’t see it in any way as a properly made objection. First of all,
Mr. Reichler has not stood up to object before but he has had no basis to object so that is hardly
surprising. Secondly, I asked Professor Thorne, quite correctly, a question about mitigation. He
was shown various slides on mitigation and the implication behind all those slides is that mitigation
may be important to the task before this Court. I am simply asking Professor Thorne a very
specific question about how he has taken mitigation works the fact of the mitigation works - 48 -
into account into the calculation of his estimates of sediment coming from the road. That is plainly
a question that comes out of cross-examination.
Le PRESIDENT : C’est une question à laquelle le professeur Thorne va maintenant pouvoir
répondre.
Mr. THORNE: I am sorry, Mr. President, this was not on.
Le PRESIDENT : Vous pouvez répondre à la question.
Mr. THORNE: No, we did not make any reduction in our estimate to account for the effect
of mitigation.
Mr. WORDSWORTH: Thank you very much. Now you were asked whether approximately
20 per cent of the sediment upstr eam of the delta goes into the Lower San Juan, with 80 per cent
going into the Río Colorado, and you referred to figures 4.14 and 4.15, and you said that this was
an attempt to model the division of flows and division of sediment as well, as I understand it. How
would you obtain actual figures as to where the flow and the sediment goes?
Mr. THORNE: They would be obtained using the USGS standard methods to which
Dr. Kondolf referred, with a section being measured upstream of the bifurcation and a section
being measured downstream of the bifurcation in each of the branches.
Mr. WORDSWORTH: And are there uncertainties in the model to which you referred at
figures 4.14 and 4.15?
Mr. THORNE: There are very large uncertainties.
Mr. WORDSWORTH: Why are those uncertainties there?
Mr. THORNE: The model is based on measurements made only in the Colorado branch.
We don’t know the approach sediment load or the sediment load in the Lower Río San Juan. If we
knew two of the three, we could calculate the third by continuity, but we only know one of the
three so we have to surmise what one of the other ones is. In the case of bed load, we have no - 49 -
measurements at all; that is purely a theoretical model. Since writing this report, I have looked at
Annex 16 in Nicaragua’s Counter -Memorial in Certain Activities, which does have measurements
made on the other two branches, in January 2011 and in May -April 2012. On those particular
days and they are only two measurements and Professor van Rhee is pretty happy to go with
three measurements, or two measurements I honestly wouldn’t be but they are what they are,
they’re snapshots: on those days when they measured those loads, the amount of sediment going
into the Lower Río San Juan was on the first occa sion 7 per cent and on the second occasion,
14 per cent, so rather lower than the model would predict. If we had more data and could calibrate
the model, the uncertainties would reduce enormously.
Mr. WORDSWORTH: Thank you. You were later on taken t o page II-27 of your report in
Certain Activities, and you were asked questions about whether the Río San Juan, particularly the
Lower Río San Juan, can accommodate its sediment load. And you were also taken to
paragraph 6.12 of your 2013 report on the road: in your response, you referred to response reaches
of which, as I understood it, two are in the San Juan proper and one is in the Lower San Juan.
Now, do those response reaches have any impact in terms of where sediment coming from the road
might go?
Mr. THORNE: For sediment coming from the road upstream of Boca San Carlos, which is
where most of the slopes we have seen quite a lot are located, that sediment must pass
through two response reaches before it reaches the delta. Within those response reaches are
innumerable sandbars, point bars, natural levees and channel marginal areas, all of which tend to
trap sediment. There are also six depositional centres we might call them shoals: each of those
has a trap efficiency of at least 50 per cent for coarse sediment moving as bed load or near bed
load. So do not think of the Río San Juan as a slurry pipe where actual sediment comes in and the
actual sediment goes out. Actual sediment comes in and it goes into a shoal and it stays there for a
year, five years; it goes into a marsh: it stays there for a thousand years. Now sediment comes out
of the other end but it is not the same sediment. In terms of the bearing on this case, what we did in
2013 and 2014 was look at quantum: we looked a t the sediment transport and we did not
differentiate between sediment derived from the road, or the Irazu volcano, or the Cinchona - 50 -
earthquake of 2009. We just said sediment is sediment). Really thanks to Mr. Reichler for
prompting this thought train, I started to think a lot more about the actual sediment and the fact that
both those response reaches also have a tendency to aggradation, just as does the Lower Río San
Juan: it is not as strong as it is in the Lower Río San Juan because of geology and that is why I say
the Lower Río San Juan cannot accommodate this sediment in the way that the other rivers can
because they are much bigger. They have more hotel rooms for sediment; the sediment can stop
there without clogging anything up. The Río San Juan is just small and it is pinched by geology.
Mr. WORDSWORTH: Now you were asked some questions about dredging and where
sediment would be settling in the Lower San Juan. You said that sediment is settling into the
trench dredged by Nicaragua. Now, can I understand it, by reference to the answer just given, what
sediment are you referring to there that is settling into the trench dredged by Nicaragua?
Mr. THORNE: The sediment I am referring to there, the actual sediment, 3,000,000 cubic
metres of it, comes from the San Carlos; 2,500,000 cubic metres of it comes from the Sarapiqui;
and particularly from rivers like the Sucio the Sulphur River the sulphur river drains a
volcano and it carries about a million cubic metres per year. Up until 1971 it confluenced with the
Rio Colorado, it then avulsed and now confluences upstream of the delta. It is putting in an
additional million tons per year. That is a sediment perturbation and that is going to give a problem
for navigation. It does not give a problem for the river because the Lower Rio San Juan is not a
sick river it is wrong to characterize it that way it is an old river, it is an old distributary, but
that does not mean it is sick. It just means that it accommodates its sediment in a dif ferent way to
the youthful and vigorous Colorado.
Mr. WORDSWORTH: Now, you were also taken to a passage from your 2011 report where
you say that sediment is settling in shoals, levees and the like. Now, what I want you to clarify is
that, on the one hand, you said to Mr. Reichler that sediment reaching the Lower San Juan is
settling into the trench dredged by Nicaragua. On the other hand, you said in 2011 that sediment is
settling in shoals, levees and so on. So, are you able to explain to the Court how those two
statements fit together? - 51 -
Mr. THORNE: Yes, I think so. When there is a heavy and variable sediment load, the river
cannot transport that material all at once. During high periods it accumulates sediment; during
lean periods when there is less sediment coming into the river because there has not been an
earthquake, or the volcano has not erupted, or sediment is not coming from 10,000 other sources in
this basin then the river quietly chips away at that store of sediment that is built up, and so the
bed aggrades and then it comes down and that is the natural rhythm of things. If you come and dig
a big hole in it, it will fill up very quickly. If you keep on digging that hole, it will fill up probably
more quickly. And if you disturb the width and I have read the EPN report on the dredging
programme to come, which involves clearing all vegetation from islands and banks that is
obstructing the natural flow of the river if you do that and the river widens, your bed will shoal
very significantly. My prediction would be and I was right with what I predicted in 2011, I
hope I am not right now that the wider shoaling of the bed due to its widening as more sediment
comes in, you unlock the natural levees, you unlock the stores of sediment in the islands, will
massively overwhelm the dredging capacity. The bed will aggrade, the Rio San Juan will become
not a perennial distributary, but a seasonal distributary. And that would be a disaster. So, digging
a hole actually has an unintended co nsequence. The problem with the Rio San Juan is navigation.
Let us deal with navigation, not try ing to change the river. Do we have to have boats with drafts
greater than 1 m? Couldn’t we use different boats?
Mr. WORDSWORTH: Thank you, Professor Thorne. I have no further questions in
re-examination. The Court may have questions for you.
Le PRESIDENT : Merci. Je me tourne vers mes collèges. Je ne crois pas qu’il y ait de
questions à adresser à l’expert. Si. Monsieur le jugeTomka, vous avez la parole.
Judge TOMKA: Thank you very much, Mr. President. First of all, I just wish some
clarification. I have understood one of your answers to maître Reichler’s question that dredging is
not the best way of dealing with, as he admitted, problems in t he San Juan, the lower part of the
San Juan, to be more precise. What, in your view, would be the appropriate way of maintaining - 52 -
navigability, if dredging is not the appropriate one, because, as I understand, you also see this as a
kind of Sisyphus work? Thank you very much.
Le PRESIDENT : Monsieur le professeur.
Mr. THORNE: Professor van Rhee is an expert on dredging and I have read his report very
carefully. His colleague, Professor Huib de Vriend, I know very well. He is not here this week.
Professor de Vriend has retired from Deltares; he is now the Director of Ecoshape, a foundation
utterly devoted to working with natural processes. I urge Nicaragua to talk to Professor de Vriend
about the alternatives, he is a Dutch expert. My recommendation would be to copy what happens
in other places and Professor van Rhee referred to some of them where in-stream training
structures are used to maintain a navigation channel that is open all year. Sometimes they are made
out of inappropriate materials, concrete and steel. I would not use those, I would use wood and
the wood, provided it is kept below the water level, does not rot. It would last for many decades. I
have not had access to look at the Rio San Juan in detail. I have seen it, I have be en there. I think
rather than pulling all the wood out, I might re-arrange it. I would re-arrange it in ways that created
shoals in places I did not want to navigate and which focused the remaining flow of the wet season,
which is still considerable it is still 150 cubic metres per second, that is a lot of water but
focus it in the navigation channel, as our friends at the Corps of Engineers do on the Lower
Mississippi. The dredging requirement on the Lower Mississippi in the 1970s was horrendous,
they were spending a billion dollars a year dredging the river, the outcome of that was to destroy
the Mississippi delta, because it starved of sediment. If you dredge out 730,000 cubic metres of
sand from this river, they will starve the delta. And if you look back at figure 2 in my summary in
Certain Activities, you will see the overlay of the maps. Just look at the coast, it has retreated 1 km
since 1840. The dredging programme, if it cuts off the sediment supply, will starve the delta, the
Caribbean Sea will take it away, we will lose hundreds of hectares of wetland due to coastal
erosion. We need that sediment. Every grain is precious. It needs to be kept in the river, but let us
move it on its way by appropriate river training works and spot dredging I am not saying there is
no dredging requirement, there is but spot dredging of the tops of the shoals during the low - 53 -
season when you just need to knock the top off to get your 2 m draft boat through. That is what I
would say.
Judge TOMKA: Thank you very much. Merci, Monsieur le président.
Le PRESIDENT : Merci Monsieur le professeur. S’il n’y a pas d’autres questions, je vais
remercier le professeur Thorne. Votre déposition s’achève et je v ous remercie d’avoir bien voulu
comparaître devant la Cour. Vous pouvez quitter la barre. Merci.
Mr. THORNE: Thank you very much , Mr. President. Thank you very much, judges,
Mesdames, Messieurs. It has been a privilege to be here and thank you for your forbearance with
me on this second occasion.
Le PRESIDENT : Merci. Le calendrier des audiences dont les Parties ont eu communication
prévoit que la matinée d’aujourd’hui est consacrée à l’audition des experts du Costa Rica. Tel a été
le cas et que les plaidoiries du Costa Rica pour le premier tour r eprendront cet après- midi à
15 heures. La Cour se réunira donc de nouveau cet après -midi à 15 heures pour entendre la suite
du premier tour de plaidoiries du Costa Rica. Je vous remercie. L’audience est levée.
L’audience est levée à 12 h 10.
___________
Public sitting held on Friday 24 April 2015, at 10 a.m., at the Peace Palace, President Abraham presiding, in the cases concerning Construction of a Road in Costa Rica along the San Juan River (Nicaragua v. Costa Rica); Certain Activities carried out by Nicaragua in the Border Area (Costa Rica v. Nicaragua)