Improved dam operation in the Amu Darya river basin including transboundary aspects

Glacial and snowmelt is essential for the well being of all the states of Central Asia and provides over 90% of their water requirements. Unfortunately, climate change is causing rapid recession of the glaciers, which in the short-term helps meet the states ambitious water requirements, but in the long term, will result in decreased runoff and increased evapotranspiration from higher temperatures. Because of the comparably geological young nature of the mountain ranges their instability result in rapid siltation of existing reservoirs and leading to very limited life expectances, also for potential reservoir sites. Vast quantities of water are wasted also by inefficient and poorly managed irrigation schemes in the entire basin. The water resources of the region are already overstretched and hence, in the foreseeable future the very existence of their agricultural economies is at stake. Large dams at the two Aral Sea tributaries, Amu Darya and Syr Darya, control and regulate the annual flow regime and water availability at the downstream regions. Results of past project studies for the Amu Darya river point out, that the multi-reservoir system of the Tuyamuyun Hydro Complex (6.8 km(3)) provide attractive capabilities to improve the availability of high quality water by applying modified release and filling strategies. The Nurek dam (10.5 km(3)) and the Rogun dam (under construction, height of the dam: 335 m) provide further options for improving the rational operation and sustainable management of water resources.However, the current rational management of transboundary water resources in the Amu Darya basin is hampered by difficulties to have reliable hydrological data and to predict the short and long term availability from the glacier run-off. Major uncertainty has been identified for knowledge on current capacity losses of dams, located in the upstream part of the basin. The development of risk-management strategies for securing future water supply under varying conditions of water shortage needs therefore (i) to revise the existing storage capacities, (ii) to improve the forecasting methods, (iii) to associate possible water saving mechanisms and improved crop growth patterns at the downstream areas, and finally (iv) to adapt the dam operation at upstream and downstream regions accordingly.