Impact of climate change on the full spectrum of future low flows of Budhigandaki River Basin in Nepal using Gumbel distribution

Climate change (CC) will most likely alter the future low flows and adapting to its impact is the key to successful management of water resources. This study investigates CC impact on the full spectrum of low flows by taking the case of Budhigandaki River Basin under RCP 4.5 and RCP 8.5, considering baseline flows (1983–2012) and ensembled future flows (2021–2099). Gumbel distribution is found to be the best fit for 1-day, 7-day, 30-day, and monthly low flow series and the same is used to compare the future 2, 5, 10, 20, 25 and 50-year return period low flows against the corresponding baseline flows for three time windows: Near (2021–2050), Mid (2046–2075) and Far Future (2070–2099). Our results analyzing 72 scenarios show that future low flows are expected to increase compared to the corresponding baseline flows for all return periods, emission scenarios and time windows. It can be attributed to higher anticipated future rainfall in the basin. The respective changes are higher under RCP 8.5 than under RCP 4.5. The change in the projected low flows compared to the baseline for different durations increases with the return period under both RCPs in all the time windows. Contrary to the popular belief, CC is expected to have positive implications on low flows in this region. © The Author(s), under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University 2022. Springer Nature or its licensor holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.