E.Chub, Sergey MYAGKOV

Central Asian Research Hydrometeorological Institute (SANIGMI) 72, K. Makhsumov str., Tashkent, Uzbekistan

e-mail : uzhymet@meteo.uz Abstract

On the base of trends of mean yearly values of the Central Asian rivers runoff the analysis of inter-yearly runoff variability has been conducted. The analysis has revealed the water content decrease for a majority of the Aral Sea basin rivers what can be treated as one of the factors of the Aral Sea level reduction.

Introduction

In many countries of the world, especially in the Asian and African countries with the dry climate, the problem of the water resources exists. It is forecasted that in the conditions of the crucial need in water in the course of the industrial and agricultural development and substantial population growth, the problem of the water resources deficit will be more acute. These expected forthcoming climate changes can deepen the water deficit. The developing countries and the states with the economy in transition, located in the dry and semi-dry areas, are very vulnerable to the climate change impact and have a lot of technical and financial problems. The after-effects of the climate change depend on the initial conditions of the water-supply system and on the organization of the water resources management.

The surface water resources of the Central Asia are formed, mainly, in the mountainous part due to atmospheric precipitation of the cold period, the long-term distribution of which is determined by the specific features of the synoptic processes and orography. The interaction between the moisture-bringing flows and the complex relief determines the high spatial resolution of precipitation and flow of some rivers. The main flow amount is concentrated in the transboundary rivers, used by the Central Asian states. The biggest rivers of the Central Asia – Amudarja and Syrdarja – which are the main sources of the surface water and inflowing directly into the Aral Sea, belong to the Aral Sea basin.

The length of Amudarja river, which is formed by the confluence of Vakhsh and Pyandj rivers, is more than 1400 km. Such rivers as Kafirnigan, Surkhandarja with Sherabad, Kashkadarja and Zeravshan, are also included into Amudarja river basin. Amudarja river basin is divided into the mountain part – the flow formation zone- and the plain one – the flow distribution zone. In the mountainous part Amudarja gains a lot of tributaries. In the plain part the river does not take the tributaries, and some part of flow is lost for infiltration, evaporation and water intake, used for the national economy purposes (mainly for irrigation). The water regime of Amudarja river depends on the melt of the alpine snow cover, glaciers and on the rainfall, and it is characterized by the high summer flow and the low winter one. The highest discharge values are recorded in July-August, and the lowest ones – in January-February.

Syrdarja river is formed by the confluence of Naryn and Karadarja rivers, and its length is more than 2000 km. The mountain part of Syrdarja basin is made up by the complex system of the Pamir-Alai and Tien-Shan mountainous ranges, and it is the flow formation area. Such rivers as Naryn, Karadarja, Angren, Chirchik, Keles, Arys and the rivers, flowing down the ranges of Fergana valley, from the northern slope of Nuratau range and south-western slope of Karatau range, belong to Syrdarja basin.

This basin is characterized by the substantial glacial alimentation, and only in the upstream it is fed by the glaciers and snow. About 80-82% of the river flow pass through Syrdarja from March up to September.

The natural flow regime is significantly distorted by the water-intake for irrigation, by the drainage water discharge and by the water storages which breaks their hydrodynamical and hydrochemical regimes.

The amount of water resources in the lakes of the mountain part of Amudarja basin is 46 km³, and that of Syrdarja is 4 km³. The amount of water in the lakes on the plain area (not including the Aral Sea) is 70 km³, approximately. The amount of ice in the glaciers of the Hissar-Alai area is 88 km³ and 465 km³ - in the Pamir glaciers.

The lakes are located mainly in the river valleys. The mountain lakes are usually of the landslide or ice-moraine origin, while the plain ones are formed by the drainage water. The irrigation and discharge lakes are formed on the margins of the irrigated territories in the natural relief lowerings. The lakes of the Arnasai network, Sarykamysh in their contemporary state were formed as the result of the drainage water discharge in the sites of the temporary water bodies.

The underground water of the Aral Sea basin is formed by the precipitation, filtration from the water objects, river channels, canals, lakes and from the irrigated territories, as well. The return water is formed by the collector and drainage flow. They form rather substantial part of the water resources, but at the same time, they are the important pollution source.

The main consumer of the water resources is the irrigated land-use, which takes more than 90% of all available water resources in the region. At present about 3,6 mln. ha. are irrigated. The amount of the collector and drainage water during the high-water years is 10 km³/year, while the non-productive water losses in the basin raised up to 32-33 km³/year, which is the half of the long-term average flow value.

Presumably, the flow increase in Syrdarja river basin began in 1891 and continued up to 1973, and afterwards the decrease of the flow was observed. However, the periods of the flow decrease, considering the general behavior of its increase up to 1973, were of some other character. If the period trend observed in 1914-1920 corresponded to the same one in Amudarja basin, then the next continued from 1924 up to 1944. The flow decrease since 1973 was not interrupted with its increase,

as it was observed in Amudarja basin, where after the beginning of the flow decrease since 1961, the periods of its increase were also registered.

There are also another differences in the variation of flow in the above mentioned basins. Thus, if 1969 was the wettest one for Amudarja basin, then 1921 and 1969 were the wettest ones for Syrdarja basin. The average annual discharge values in these years were 1430 and 1420 m³, respectively. For Amudarja basin, the flow value was almost the average one in 1921. The flow value was 2100 m³/s.

The annual discharge values in the basin were higher in 26 years of 85-year series.

Conclusion

The common feature for all basins is the occurrence of a very substantial low-water period after many high-water years. Thus, after 1969, the period of the flow decrease continued during 22 years up to 1991 in Amudarja river basin. In Syrdarja river basin the period of the flow decrease after the high-water 1969 had continued for 17 years – up to 1986.

Similar situation was observed after another high-water years, but the period of the flow decrease was shorter. After 1921 the period of the flow decrease in Syrdarja basin was only 6 years. Also, the common trend is, that with a very rare exceptions, the historical (by the water content) years, after which the period of the flow decrease begins, are observed at the background of the general flow increase.

Refences

Agltseva N., Myakov S. : Dynamics of the river runoff changes in the Aral Sea basin (in Russian). Proceedings of SANIGMI, 2001 ; Vol. 163 : 244.

Chub V.: Climate change and its impact on the natural resources potential of the Republic of Uzbekistan (in Russian). Tashkent, 2000, 252p.

2.4- Le droit relatif aux cours d’eau internationaux de la République d’Haïti et de la République Dominicaine. Le cas de la rivière Artibonite

Jean André VICTOR

Juriste sp. en droit international de l‟environnement FSAE - Université Quisqueya, BP 796, Port-au-Prince, Haïti

E-mail : jeanandrev@yahoo.com

Résumé

Le problème des ressources en eau partagées est bien connu en droit international lacustre et fluvial puisque la moitié de tous les bassins hydrographiques du monde est partagée entre deux ou plusieurs pays différents. Boutros Boutros-Ghali eût à dire que « la sécurité nationale de l‟Egypte est aux mains de huit autres pays africains » en tenant compte du fait que le Nil était partagé entre neuf pays avec l‟Egypte comme Etat aval du cours d‟eau.

Ainsi, il n‟est pas interdit de penser que la sécurité nationale d‟Haïti est aux mains de la République Dominicaine qui contrôle la partie amont du fleuve Artibonite. Vu l‟importance de ce fleuve pour ces deux pays, ces derniers ont, sans doute, intérêt à devenir des Etats Parties à la Convention de 1997 sur le droit relatif à l‟utilisation des cours d‟ eau internationaux à des fins autres que la navigation. Ces deux Etats devraient se préoccuper également de passer des accords bilatéraux selon le vœu même de ladite convention en vue d‟adapter les dispositions de celle-ci aux caractéristiques particulières du fleuve Artibonite. N‟y a-t-il pas lieu également, en vue de renforcer la coopération inter-étatique, de créer une aire protégée transfrontalière au niveau du bassin versant considéré ?

Cette triple démarche juridique pourrait contribuer, d‟une part, à promouvoir la gestion intégrée de l‟unité hydrologique en question et d‟autre part, à trouver des réponses appropriées aux problèmes de rareté, de pollution et de partage équitable de la ressource en eau, problèmes qui ne manqueront pas de se poser dramatiquement dans un futur pas trop lointain.

Introduction

L‟eau est appelée à devenir une source de conflits ou un élément de coopération entre les Etats durant le 21^e siècle. Le Nil, l‟Euphrate et le Jourdain font déjà l‟objet de conflits répétés en Afrique du Nord, en Asie et au Moyen-Orient. L‟eau a été reconnue, par exemple, comme un élément central dans le conflit Israélo-palestinien. L‟hydropolitique ou la géopolitique des ressources en eau tend à devenir un nouveau centre d‟intérêt de plus en plus important pour la grande majorité des Etats du globe.

En Amérique, l‟eau demeure également une source de tensions malgré son abondance relative. Elle reste, toutefois, un élément de coopération entre les Etats qui partagent des cours d‟eau internationaux dans ce continent. C‟est le cas, notamment, des EUA et du Canada pour les grands lacs, des EUA et du Mexique pour le Rio Grande, le San Pedro ou la Santa Cruz. C‟est aussi le cas de la Colombie et du Venezuela pour l‟Orénoque et divers autres cours d‟eau, du Brésil et du Pérou pour l‟Amazone ou encore de l‟Argentine, de la Bolivie et du Paraguay pour le Pilcomayo. Le rapport du Secrétaire Général de l‟OEA sur la mise en œuvre du sommet de la Bolivie de 1998 a fait une

place très large aux opportunités de coopération qui se développent entre les Etats de l‟Amérique Latine et des Caraïbes pour les ressources en eau partagées.

Dans la Caraïbe insulaire, le seul cas connu de cours d‟eau internationaux concerne la République d‟Haïti et la République Dominicaine qui se partagent l‟île d‟Haïti, appelée aujourd‟hui par euphémisme, l‟île Quisqueya voire l‟île Hispaniola. Ces deux pays ont, en effet, en commun plusieurs cours d‟eau internationaux tout le long de la frontière haïtiano-dominicaine c‟est à dire des cours d‟eau dont les différentes parties se retrouvent des deux cotés de la frontière.

Parmi ces ressources en eau partagées, le cas de la rivière Artibonite mérite une attention spéciale en raison de ses fonctions écologiques, de son importance socio-économique et de sa signification politique. En ce qui concerne l‟Artibonite, Haïti constitue l‟état aval du cours d‟eau et pour parodier Boutros Boutros-Ghali qui disait que la sécurité de l‟Egypte par rapport au Nil est aux mains de huit autres pays africains, il n‟est pas osé d‟affirmer que la sécurité d‟Haïti est aux mains de la République Dominicaine.

Dans cette perspective, il s‟agit de montrer comment le droit international lacustre et fluvial pourrait contribuer à faire de la susdite unité hydrologique un élément de coopération plutôt qu‟une source de conflits entre la République d‟Haïti et la République Dominicaine. Il convient, pour cela, de présenter la problématique de la rivière Artibonite (section I), de montrer les limites des accords bilatéraux traditionnels sur le plan juridique (section II) et de faire ressortir, les apports possibles du droit international de l‟environnement à la promotion du développement durable dans ces deux Etats caribéens (section III).