|
OBJE BACKGROUND AND JUSTIFICATION
Lake Sarez is one of the largest mountain lakes in Central Asia, whose drainage of water endangers sustainable development of the mid- and low stream of the Amu-Darya river with the population over 5.5 million people. The lake is located in the Gorny Badakhshan autonomous region of the Republic of Tajikistan, in the Amudarya river basin, on the right hand tributary of the Pianj river - Bartang (Murgab) river.
Lake Sarez was formed as a result of a big landslide that blocked the Murgab river flow after a severe earthquake that occurred on February 18, 1911. As a result of the earthquake a huge piece of mountain rock of the volume equal to 2.2km3 blocked the Murgab river. The landslide formed a blockage dam in the mid stream of the Murgab river and buried under itself the whole Usoy village (kishlak). Behind the resulted blockage a large lake began to form, which in October 1911 engulfed the Sarez kishlak, after which the newly formed lake was named. The blockage itself got the name Usoy dam. The lake remained still until 1914 and then the water started to filtrate through the Usoy dam. The amount of water leaking through the Usoy dam varies from 35 and 70 cubic m/sec and depends on the water level in the lake. The height of the dam from the lake bottom is 567m; the height above the water surface is 38m. The average width of the dam is 3.2km and its length is 5km.
The analysis of the multiannual hydrological observations and the results of the research done during the targeted expeditions proved that as of today, 97 years after the formation of the Lake Sarez, its hydro meteorological and hydrological regimes have not yet stabilized. The total amount of water accumulated in the lake during the period of 97 years accounts for more than 17km3 with the maximum depth exceeding 500m and the water surface area of about 80km2. The water level in the lake continues to increase, the filtration characteristics of the dam are changing, and the level of mineralization is increasing at the bottom level. The lake area is in real danger of having new large-size and slide blockages.
 |
Despite the availability of enormous amount of data the issue of Sarez Lake and stability of the Usoy dam still give rise to numerous
debates. A number of researchers share the same view stating that the Usoy dam is a stable
formation, which cannot be destroyed under the pressure of the lake
water, and the water overflow from the dam that might occur as a result of an increased water level will not be
disastrous.
|
The so-called right-bank slope, which is situated at a distance of 4 km towards the east of the
dam, whose total volume is estimated at 0.9km3 is still considered to be the major problem of Lake
Sarez, and remains a debatable point. The available research papers contain data about its
structure, mechanism of shift, calculations of the volume and velocity of
shift, the dimension of the wave of flow over the Usoy dam as a result of the fall of this landslide into the
lake, etc. However, there is no instrumental data proving the existence of the surface of
sliding, neither are available sufficiently grounded calculations of the volume of the shifting
masses, velocity of their shift, or the volume of the overflowing wave. The data is rather contradictory even when provided by the same
authors. Comprehensive scientifically proved scenarios (simulations) on the development of the situation around Lake
Sarez, with due consideration to hydrological, geological and seismic long-term
forecast, do not exist as yet. For this reason, the issue of Lake Sarez safety remains
unresolved.
Another concern is degradation of snow-caps and glaciers in the zone of flow formation of the Central Asia rivers. Global warming is accompanied by constant degradation of mountain glaciation. It is known that the Pamiro-Alai mountains have witnessed glaciers degradation at least since the beginning of the 20th century. According to the international sources, the glaciers of the Pamir mountains has reduced by 30 to 35 per cent in the end of the 20th and beginning the 21th centuries. This is an issue of great concern for the whole Central Asian region, which is already faced with a stressed situation in the water sector, caused by scarcity of water and its irrational usage. For this reason, development of a scenario on rational usage of Lake Sarez water resources is a very timely matter.
The problem of ensuring safety of Lake Sarez is in the focus of attention of the Central Asia states and international donors have been invited to join the process. More than once the Tajikistan President, Emomali Rahmon, called the international community to render assistance in ensuring safety of Lake Sarez, and to undertake specific actions in this regard. At the 1st Asia-Pacific Water Summit (December 3-4, 2007, Bepu, Japan) and at the 5th World Water Forum (March 16, 2009, Istanbul, Turkey) President Emomali Rahmon put forward a proposal to establish the International Consortium for construction of a water pipe from Lake Sarez till the border with Uzbekistan, as a result of which the risk of breaking off the Sarez Lake dam would be diminished, and the population of the Central Asian region would be provided with ecologically sound freshwater.
A number of projects on studying Lake Sarez and associated problems have been implemented over the last decade. In particular, these projects were financed and implemented by the Government of the Republic of Tajikistan, by the NGO Focus - the humanitarian assistance provided by the US, World Bank, the Government of Switzerland .
Assessment of current state of lakes, rivers, glaciers, and other sources of freshwater, development of long-term measures for their protection and rational use are becoming urgent because of the aggravating crisis in the Aral Sea basin. Besides, these kind of activities will promote the implementation of the International Decade for Action “Water for Life”, 2005-2015 and practical realization of President Emomali Rahmon’s proposals on rational use of water resources of Lake Sarez for provision of the Central Asian population with safe drinking water.
In order to further increase awareness of the international community of the problems related to the lakes with a failure risk, and other water-related natural disasters the Government of Tajikistan, in cooperation with UNESCO, UNDESA, OSCE, UNDP and other international agencies, held the International Conference entitled Water-Related Disasters Reduction on June 27-29, 2007 in Dushanbe.
Development of actual practical measures to ensure Lake Sarez safety requires not only involvement of local experts but also constant exchange of information, study of world experience in management of similar situations in other regions and countries of the world.
|
