This study combined downscaled CMIP6 climate projections with hydropower modeling to assess the future potential of hydropower in the Indus basin and its ability to meet changing energy demands. We show that all four classes of hydropower potential (theoretical, technical, financial and sustainable) is projected to increase under the majority of climate change scenarios, with variations across the basin and subbasins in terms of magnitude and portfolio characteristics (plant sizes, configurations and costs). Historical theoretical potential of 1565 TWh yr−1 increases by 3.9–56 % while technical potential at 300 TWh yr−1 changes between -2.3–46.8 %, financial potential at 266 TWh yr−1 between -8.8–50.4 % and sustainable potential at 90 TWh yr−1 between -6.1–49.7 %. Only RCP 4.5 shows some decline. The monsoon-dominated discharge in the southeastern subbasins results in stronger increases in hydropower potential, larger plants that have lower costs and higher variability in the future than in the westerlies-dominated northwestern subbasins. Such spatial differences highlight the importance of a high-resolution localized assessment of hydropower potential. We also confirmed our hypothesis that using future hydro-climatology improves hydropower planning by designing plants that utilize the spatially varying impacts of climate change. Additionally, sustainable potential portfolios are more stable than technical portfolios under climate change with higher increases in performance and lower variations over time.
The sufficiency of the increasing hydropower potential depends on the future changes in energy demands. While the sustainable potential can contribute to energy security within the basin, meeting downstream energy needs will require development beyond sustainable potential, which comes at the risk of conflict with other water and land users, including the environment, and higher exposure to geo-hazard risks. The spatial mismatch between increase in potential and population growth further increases the disparity in energy self-sufficiency between the southeastern and the northwestern subbasins of the Indus basin. The Satluj subbasin shows a consistent increase in per capita potential while the Kabul subbasin shows a decline even in the wettest future. The spatial disparities in availability, affordability and sufficiency of hydropower potential add complexity to the upstream-downstream and transboundary resource sharing in the Indus basin. A socio-hydrological approach is necessary to ensure sustainable and equitable development and allocation of hydropower potential within and across the riparian countries. Our hydropower cost curves provide an initial step toward identifying the hydropower development pathways in the Indus basin, revealing optimal locations, size and configurations for plants. Ultimately, the realization of these hydropower portfolios within the overall energy supply mix will depend on riparian countries' aspirations for energy self-sufficiency, equitability, sustainability, carbon neutrality and energy demand management.