From water stress to livelihood stress: agricultural decline and migration risks in the lower Amu Darya basin under climate change and the Qosh Tepa Canal

Water security in the lower Amu Darya Basin is increasingly shaped not only by hydrological change but also by governance and allocation frameworks among riparian states. The Qosh Tepa Canal (QTC) in northern Afghanistan represents a major new diversion of the Amu Darya River, raising concerns about downstream water security in Uzbekistan and Turkmenistan. Combined with the projected 10–15% climate-induced reduction in river flow, QTC is expected to alter water availability across the administrative regions of the lower Amu Darya Basin with significant socio-economic implications. This study applies a scenario-based socio-hydrological framework that evaluates three levels of hydrological stress: QTC diversion alone and QTC combined with 10% and 15% flow reductions, under two contrasting allocation logics: equity-based distribution in which reductions are distributed proportionally to irrigated area and hydro-hegemony-based distribution favouring upstream users and downstream regions absorb the largest share of shortages. The results show that available water declines by ~28-43% across equity scenarios, with the largest absolute losses in Ahal (Turkmenistan) and Kashkadarya (Uzbekistan). Under hegemony-based allocation, the impacts concentrate downstream, with Dashoguz and the Republic of Karakalpakstan facing near-complete losses in agricultural viability. If livelihoods collapse, projected migration reaches 2.5–3.8 million under equity scenarios and 2.6-4.2 million under hegemony scenarios, highlighting the strong link between water scarcity, agriculture, and human mobility in the region. These estimates should be interpreted as indicators of relative migration pressure across regions and allocation regimes, rather than precise forecasts, which show the strong link between water scarcity, governance, agricultural decline, and human mobility in the region.