Thursday 25 August 2005

P3
1400-1520 hours

405
Aral Sea water and salt budget estimations using a coupled groundwater-seawater model
Schrum, Corinna¹, Alekseeva, Irina², Jarsjö, Jerker³, Destouni, Georgia³
1 Schrum&Wehde Ecosystem Modeling GbR, Hamburg, Germany
2 University Hamburg, Germany
3 Stockholm University, Sweden
Author email: corinna.schrum@hamburg.de
The Aral Sea is located in Central Asia on the territories of the republics of Kazakhstan and Uzbekistan. In the 60s of the XX century the Aral Sea was the fourth out of the biggest lakes all over the world. In the following decades the water budget equilibrium was disturbed by increasing irrigation and resulting in dramatic volume loss und sea level decrease. At present, the sea water surface shrank down to 19000 square km what is approximately only 28 percent of the initial sea water surface area. Consequences of the environmental changes in the Aral Sea region were enormous. Economic, health and water resource problems of local inhabitants are the most dramatic ones. With decreasing river runof the groundwater has become an increasingly important contribution to the Aral Sea water balance. Aiming in a quantitatively understanding of regional and local role of groundwater, a coupled dynamic model for groundwater-seawater interactions has been implemented to govern the Aral Sea shrinking process. An interactive wetting and drying scheme has been implemented in the sea model to simulate the dramatic volume and surface area changes and their consequences for the Aral Sea water budget. The high resolution model was interactively coupled to a groundwater model and successfully applied to hindcast the Aral Sea water and salt budget on decadal time scales. For the first time high resolution groundwater inflow and evaporation time series were estimated which contributed to the understanding of the natural and human made environmental catastrophe. Furthermore the coupled groundwater-seawater model developed contributes to the predictive capacity and provides a powerful tool for risk management and closer investigation of water balance and regional groundwater flows on different time scales.

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