The impact of climate change on the water resources of the Amu Darya Basin in Central Asia

Central Asia is facing an unprecedented juxtaposition of regional climate- and water-related issues, emphasised by a changing climate. We investigate the potential impact of long-term climate change on the availability of water resources in the Amu Darya River, one of the two major rivers that feed the Aral Sea, and its effect on irrigation in the region. Using a water balance accounting model developed for the Amu Darya basin, we find that projected increases in summer temperatures of up to 5 °C by 2070–2099 under a high-emission scenario, combined with likely shifts in the seasonality of precipitation, would lead to an increase in crop water consumptive demand of between 10.6 and 16 % (or between 3.7 and 5.5 km³ y⁻¹) relative to 1961–1990. By the end of the century, 34 to 49 % of the basin’s existing 3.4 million ha of irrigated land would go unirrigated in a 1:20 year drought. Runoff is also expected to decline by between 10 and 20 % on current levels, however contributions to river flows from unsustainable glacial retreat and snow-melt are likely to remain small. While the uncertainty surrounding the precipitation projections is high, the effect of increased temperatures on irrigation practices in the basin is more robust in the long-term.