In the often discussed Aral Sea basin (Central Asia), water availability depends essentially
on the high mountains located in its eastern part, especially from the Pamir Alay
Range where the Vakhsh and Pyandj Rivers, the main tributaries of the Amu Darya
5 River, flow. In this region, the cryosphere, glaciers, and snow cover significantly impact
the water cycle and the flow regime, which could be deeply modified by climate
change. The present study, part of a project funded by the EU FP6, analyzes the hydrological
situation in six benchmark basins covering areas between 1800 and 8400 km2
,
essentially located in Tajikistan, with a variety of topographical situations, precipitation
10 amounts, and glacierized areas. Four types of parameter are discussed: temperature,
glaciers, snow cover, and river flows. Two time periods are considered: (i) a long time
series ending in the 1990s with the collapse of the Soviet Union and based on field
observations and data collection; (ii) a May 2000 to May 2002 interval, using scarce
monitored data and satellite information to follow snow cover dynamics. The results
15 confirm the global homogeneous trend of temperature increase in the mountain range
and its impacts on the surface water regimes. Concerning the snow cover, significant
differences are noted regarding the location, the elevation, the orientation and the morphology
of the respective basins. Finally the expected changes in the flow river regime
are regulated by the combination of the snow cover dynamics and the increasing trend
20 of the air temperature. It confirms the high sensitivity of this region to the warming as
identified by the 4rd IPCC Assessment Report.