Investigation of the climate and Land use/land cover change impacts on the optimal reservoir operation of the Nashe reservoir, Blue Nile River Basin, Ethiopia

The management of water resources and inflows into reservoirs has been directly impacted by the uncertainties underlying climate change and land use changes. This study explores the impact of climate and land use/land cover (LULC) changes on the Nashe Reservoir's inflow and hydropower operations using the SWAT and HEC-ResPRM models. Climate projections under RCP 4.5 and RCP 8.5 scenarios indicate that, the reservoir's average annual elevation and storage will increase by 6.40 % and 5.16 % under RCP 4.5, and by 19.04 % and 20.39 % under RCP 8.5 in the near future (2021–2050). In the mid-future (2051–2080), these increases are expected to be 6.72 % and 7.65 % under RCP 4.5, and 16.85 % and 20.64 % under RCP 8.5. Optimal power capacity is projected to grow by 24.21 % and 23.72 % in the near future and by 28.76 % and 34.00 % in the mid-future under RCP 4.5 and RCP 8.5, respectively. These findings suggest that climate and LULC changes will significantly enhance reservoir inflows and power generation but may also lead to fluctuations in monthly power output. The study emphasizes the need for updated reservoir operation strategies of future water management and optimize hydropower generation, providing valuable insights for water resource planners.