Changing Water Resources in the Indus Basin: A Multi‐Model Budyko‐Based Analysis

ABSTRACT Assessing hydroclimatic variability and future water availability is crucial for sustainable water‐resource management. This study utilised the Budyko framework to explore baseline (1962–2005) and projected shifts in the water‐energy distribution across the Indus Basin, including the Upper Indus, Kabul, Jhelum, and Chenab sub‐basins. Future changes in hydroclimatic conditions were assessed using climate projections from multiple models under the RCP4.5 and RCP8.5 scenarios. Our findings highlight significant spatial variability across the Indus sub‐basins: The Upper Indus demonstrated lower evaporative efficiency, whereas Chenab experienced water partitioning primarily through runoff with the highest precipitation. Kabul and Jhelum were more responsive to atmospheric evaporative demand. In both emission scenarios, all sub‐basins showed noticeable changes in the Budyko space over the 21st century, mainly due to warming‐induced increases in potential evapotranspiration, particularly in the Upper Indus and Chenab. The projected directions of these shifts indicate a move towards more energy‐limited hydroclimatic conditions, driven by warming‐induced increases in atmospheric evaporative demand across the Indus sub‐basins. Ensemble projections further indicate increased hydroclimatic variability and greater sensitivity of basin‐scale water distribution to the partitioning between evapotranspiration and runoff under high‐emission scenarios. These results highlight the importance of effective water resource management in the Indus Basin under climate change.