Transboundary hydropolitical conflicts and their impact on river morphology and environmental degradation in the Hirmand Basin, West Asia.

The Hirmand Transboundary River Basin (HTRB), shared by Afghanistan, Iran, and Pakistan, is a hydrologically critical and politically sensitive region. This basin sustains livelihoods, ecosystems, and agriculture in a region plagued by climatic variability and geopolitical tensions. The Hirmand River, which forms the heart of this basin, faces severe morphological and discharge changes due to upstream water management, climatic shifts, and land use changes, directly impacting downstream ecosystems and human populations. This study examines the morphological changes in the Hirmand River and disentangles natural and human-induced drivers behind these shifts. Using the TWINS framework, the study assesses cooperation and conflict in hydropolitical relations, alongside the environmental repercussions of upstream activities on downstream ecosystems. Landsat imagery analysis (1987-2022) via Google Earth Engine reveals significant morphological changes, with 43% of river arcs shifting by 500-1200 m and an annual width reduction of three meters, even during wet periods. Further, prolonged droughts and upstream water diversions have desiccated the Hamoun Lake, obliterating ecosystems, displacing residents, and transforming exposed lakebeds into major dust sources. The TWINS analysis highlights hydropolitical dynamics as the predominant driver of these changes, outweighing climatic influences, and underscores the need for cooperative frameworks to address escalating environmental and social challenges in the basin.