The Aral SeaThe Devastation and Partial Rehabilitation of a Great Lake /

XII, 453 p. 78 illus., 31 illus. in color.online

Evolution of Sea Level of the Big Aral Sea from Satellite Altimetry and Its Implications for Water Balance

The Aral Sea, one of the biggest lakes in the world, started to shrink in the 1960s because water was withdrawn for irrigation. The lowering of the Aral Sea level led to the separation of the lake into two basins – the Small Aral in the north, and the Big Aral in the south. For several decades there were no continuous observations of sea level, and the few data that exist are fragmentary or unavailable. We present observations of the Big Aral Sea level estimated from the TOPEX/Poseidon (T/P) altimetry with high temporal resolution over the last decade (1993- 2004). Since the sea volume is one of the key parameters for the studies of water balance, we use the T/P-derived time series of sea level to reconstruct, using a dedicated digital bathymetry model (DBM), associated changes in the sea surface and volume. We introduce variations of the sea volume as the new constraint for the water budget of the Big Aral Sea. This is an important step forward towards estimating detailed seasonal and interannual changes of the water budget. We assess various existing components of the water budget of the Aral Sea and discuss the quality of the existing data and their applicability for establishing detailed water balance. In particular, large uncertainties in estimating the evaporation and underground water supply are addressed. Desiccation of the Aral Sea resulted in dramatic changes in the salinity regime and, consequently, affected marine ecosystems. We also discuss changes in the aquatic fauna and its possible evolution under continuing desiccation of the Big Aral Sea. Combination of satellite altimetry with other parameters of the water budget show that this approach offers promising potential for the assessment of the temporal evolution of the water budget in arid or semi-arid conditions, even with poor ground monitoring network