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Abstract

This paper investigates the hydro-climatic reasons behind the desiccation of the Hamun Lakes in the Iran-Afghanistan border. We analyzed changes in the flow of the Hirmand River (90 percent of the total inflow to the lakes) at the international border, and precipitation over this river’s sub-basin during 1960–2016 by calculating standardized indices for precipitation (SPI) and discharge (SDI). We applied Normalized Difference Spectral Indices using satellite images from 1987 to 2021 to observe monthly areal change of the lakes. The results show that the major cause of desiccation is upstream water regulation which severely reduced the Hirmand River inflow delivery to the lakes. Constructed reservoirs near the lakes by Iran in 2008, compounded the effect of Afghanistan water regulation to aggravate the situation. There is a discernible shift in the relation between the Hirmand River flow at the border and upstream precipitation before and after 2004. In 1960–2003, high Hirmand River inflows were expected due to high precipitation, while the flow declined after 2004 despite large amounts of upstream precipitation. Although a long period of drought from 1998 to 2004 decreased the lakes’ area, the lake system is primarily falling victim to anthropogenic flow reduction recently. Increased regulation of flows and use of water for irrigation in Afghanistan and Iran underscores the necessity of bilateral dialogues between the two countries to consider environmental flow for the lakes. The lakes’ shrinkage places socio-economic stress on an already-vulnerable region with public health implications as the exposed lake beds turn into major sources of dust storms.