Reproduction of historical water balance in the Aral Sea Basin: The physically-based framework to quantify water consumption components in endorheic lake

• The basin-scale hydrological model was developed for the endorheic lake basin. • The framework deepens understanding of basin water balance components. • The long-term desiccation of the Aral Sea was reproduced from 1961 to 2010. • Historical various water consumptions were quantified as human impact. • The model is physical, which can consider climate change and irrigation scenarios. The desiccation of the Aral Sea, a once vast endorheic lake, serves as a stark reminder of the consequences of unsustainable human water management. This study develops a modeling framework approach to quantify the impact of human activities on endorheic lake water balance. The model integrates a land surface model with an endorheic lake budget model based on basin water balance principles to reproduce past changes in the Aral Sea. We consider key human activities such as agricultural water supply, irrigation efficiency, inflow to terminal lakes, and external water withdrawals as main components impacting the lake. Our results reveal that increased water withdrawals for irrigation, particularly due to inefficient conveyance systems, are the primary drivers of the lake’s shrinkage. Specifically, total water consumption for irrigation in the Aral Sea Basin increased from 56.7 Gt/yr in the 1960 s to 81.1 Gt/yr in the 2000 s, with irrigation inefficiency contributing to 30 % of this usage. From 2001 to 2010, water requirements for irrigation, losses due to conveyance inefficiencies, withdrawals to the Karakum Canal, and drainage to Lake Sarygamysh were calculated at 39.0 Gt/yr, 26.3 Gt/yr, 9.4 Gt/yr, and 6.5 Gt/yr, respectively. These various water usages significantly influence the equilibrium states of the endorheic lake. Our integrated physical model effectively demonstrates the balance shift between inflow and evaporation from the lake surface. By considering the impacts of human activities and climate change on watershed terrestrial water circulation, our model offers valuable insights into the causes of change and can help predict future projections and hypothetical scenarios. This research provides a valuable tool for understanding and predicting the fate of similar water bodies facing growing human activities pressures.

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