Climate change impacts on Seti Gandaki River flow from hydropower perspectives, Nepal

This study delves into the intricate relationship between climate change and hydrological dynamics in Nepal’s Seti Gandaki River, with a specific focus on its implications for hydropower potential. Utilizing IPCC AR6 scenarios, the well-calibrated HEC-HMS model integrates data from four Global Climate Models (GCMs) and two Shared Socioeconomic Pathways (SSPs). The study enhances GCM precipitation outputs using quantile mapping bias correction and evaluates mean monthly and peak flow changes through continuous and event-based simulations across three future periods: the Near Future (2023–2042), the Mid Future (2043–2062), and the Far Future (2063–2082), with a base period reference of 1995–2014. The findings indicate no significant changes in mean flow over future periods. However, in the Far Future under SSP245 scenario, wet months fluctuate marginally (− 2.1% to + 0.86%). The decrease in flow, particularly in December (− 8.35%), January (− 15.69%), and February (− 11.86%), suggests a future drought risk. Whereas, March, April, and May show notable increases of 18%, 28.5%, and 20.3%, hinting at a potential early monsoon onset. The design discharge for hydropower do not show any trend under SSP245 but slight increment (1.95%) is observed under SSP585 for Far Future. Flood analysis shows an increasing trend for different return periods. The baseline flood of 6740.44 m³/s rises to 7742 m³/s and 9066.76 m³/s for Far Future under SSP245 and SSP 585 scenario, respectively. These findings furnish valuable insights into the potential risks and opportunities posed by climate change on water resources and hydropower.