Résumé
In Central Asia, the Pamir-Alay mountain range (mainly located in Tajikistan and Kirghizstan) provides the essential of the water resources for the endorheic basin of the Aral Sea, through two main rivers, Amu Darya and Syr Darya, which have their source there. Those mountains culminate at a height over 7000 in with numerous glaciers. As in most places of the world, these glaciers are in a phase of shrinking. However, it is not so much the deglaciation, but the impact of climate change on the snow cover genesis and melting that influences most the flow regimes of the two Main water courses of the region, the Vakhsh and the Pyandj Rivers. The study was conducted on 6 sub-basins of both rivers, with areas ranging from 1,890 to 7,580 km(2), and various hydrological and climatic behaviors. The spatial information used includes two types of data : (I) the altimetry was extracted from the SRTM mission at a 3 '' arc resolution, and provided the physical characteristics of the basins (hypsometry, slope, orientation); (2) the dynamics of snow cover was studied through the "snow product" of the MODIS sensor with a 500 m-resolution for 48 scenes during the period 2000-2002. This spatial dynamic information was crossed with the local hydroclimatic data (precipitation, temperature and water discharges) obtained from the local official monitoring agencies, as well as with the reanalysis data from NCEP-NCAR.