Water is a scarce resource in many regions of the world. In all Central Asian countries, the society depends on the availability of water either for hydro-power generation or irrigation. Since the collapse of the Soviet Union and the separation into independent countries, water resources management became a critical and political issue. Public information on water resources is now unavailable for many lakes and reservoirs and the data exchange about in- and outflows or actual storage volumes is limited. While the initial purpose of radar altimetry has been to measure sea surface topography and sea level changes, it proved to be a suitable tool for inland water body monitoring and to partially provide data about lake and reservoir level changes. Using this technology, the water levels of the Toktogul, Kairakum and Shardara Reservoirs and Lake Aydarkol have been extracted from 1995 onward. Using external information the derived water levels have been converted into water volume changes. This study shows that since 2011 the available water volume decreased and the water from the Toktogul and Shardara Reservoirs are overused. In 2015 the stored water volume of the Toktogul Reservoir was almost at its lowest possible amount. Merely the Kairakum Reservoir with a smaller storage capacity is replenished every year. Likewise, a decrease of water level and volume of Lake Aydarkol is clearly visible for the past years.
