Evolving hydroclimate of Indus river basin exposes asymmetric transboundary risks

The Indus River Basin (IRB) is a vital transboundary system in South Asia that sustains one of the world’s largest irrigation networks. IRB supports extensive agricultural and socio-economic activities for over 300 million people across India and Pakistan. The Indus Waters Treaty, signed in 1960 with mediation by the World Bank, established a legal framework for allocating the Indus River water between India and Pakistan. The treaty allocated the three western rivers to Pakistan and the three eastern rivers to India. It is widely regarded as a successful model for transboundary water sharing. However, the treaty was designed under mid-20th-century hydro-climatic and geopolitical conditions that differ significantly from present-day conditions. Despite substantial changes in the Indus River Basin since the treaty’s formation, there remains a limited understanding of how climate-driven shifts have altered hydrological conditions across the two countries. In this study, we examine changes in precipitation, groundwater availability, reservoir inflows, and contributions from snow and glacier melt to the total inflow. Our results reveal a persistent drying trend in the Chenab, Ravi and Sutlej basins, with more than 16% decline in precipitation, while the western basins remain largely stable. Sharp groundwater declines exceeding 10 meters in the Sutlej and Ravi basins highlight the unsustainable dependence on groundwater. We also observe a significant reduction in annual inflow to several major Indian reservoirs, indicating a shift toward greater hydroclimatic variability. Overall, declining storage trends in major Indian dams, altered inflow regimes, intensifying climatic stressors, and evolving meltwater dynamics underscore the need to re-evaluate the existing water-sharing framework to ensure long-term sustainability.