The large Aral Sea water balance: a future prospective of the large Aral Sea depending on water volume alteration

The Aral Sea is the biggest saline lake in Central Asia. The Amu Darya and Syr Darya rivers flow into the Aral Sea. These rivers were heavily used for irrigation fields after 1960 because of Soviet Union plans. Consequently, the Aral Sea separated into two parts: Large Aral Sea to the south and a small Aral Sea in the north in 1987. The current study estimated the evaporation and precipitation rates of the Large Aral Sea by examining Aral Sea observed records from 1987 to 2011. As a result, the precipitation decreased exponentially from 5.8 km3 in 1987 to 2 km3 in 2011. Evaporation exponentially reduced from 34.2 km3 in 1987 to 5 km3 in 2011. The Nash–Sutcliffe model was used to predict the water volume by using previously observed and estimated data of the large Aral Sea precipitation, runoff, and evaporation from 2001 to 2025. The estimations indicate the large Aral Sea water volume will decrease to approximately 21.1 km3 in 2025 (R2 = 0.9654). The forecasted value of the water volume in the Large Aral Sea after 2025 will slowly decrease and eventually diminish to zero by 2057 if all variables remain unchanged.