Adaptation Against Climate Change Impacts on Hydropower Generation and Irrigation Supply of Naumure Multipurpose Project, Nepal

Abstract

Hydropower serves as a dependable and eco-friendly alternative to fossil fuels and a carbon-emission-free energy source has a crucial role in addressing climate change, yet the impacts of climate change on the hydropower project itself cannot be avoided. This study focuses on the impacts of climate change on hydrological variables (precipitation and temperature) and its implications for hydropower generation and irrigation supply in the Naumure Multipurpose Project, and the development of an adaptation strategy accounting for climate change impacts. Six different Coupled Model Intercomparison Project, Phase 6 (CMIP6) Global Climate Models (GCMs) were downscaled, bias-corrected using a linear scaling method, and then projected for three different periods of future i.e., Near of Future (NF) period of 2015-2040 AD, Mid of Future (MF) period of 2041-2070 AD and Far of Future (FF) period of 2071-2100 AD under two different Shared Socio-economic Pathways (SSPs) scenarios i.e., SSP245 and SSP585 scenario. Projections indicate that there will be a noteworthy rise in both the maximum and minimum temperatures up to 3.67 °C and 4.97 °C respectively across various periods in the future under both scenarios. Similarly, precipitation was projected to increase between 13.95% to 90.16% at different points in the future annually however, seasonally precipitation tends to decrease in post-monsoon season and increases in pre-monsoon and monsoon seasons while winter season has no specific trend. Hydrological model was used to project future discharge and reservoir model was used to simulate baseline and future energy generation. Flow projection reveals except in winter season of NF future under scenario SSP245 where flow decreases by up to 23%, in all other seasons, flow was projected to increase in all future periods. Hydropower generation was projected to increase up to 18% in futures, except for winter season where generation decrease by up to 5.8% while irrigation supply is projected to meet demand in all future under both scenarios. This slight decrease in energy generation during winter season suggests the need to adjust the rule curve to maximize winter energy generation while ensuring overall energy generation and irrigation supply. Eight modified rule curves were developed and simulated, showing potential for increased winter energy generation. This study 5 highlights the need for adaptive measures to mitigate the impact of climate change on hydropower generation and irrigation supply in the future