Climate change poses significant challenges to hydropower development and management in mountainous basins. This study examined the impact of climate change, and the associated risks, on the energy production of the Upper Tamakoshi Hydropower Project, which is located in the Tamakoshi basin of Nepal. The outputs of three GCMs—namely MIROC-ESM, MRI-CGCM3, and MPI-ESM-M—under the Representative Concentration Pathways (RCP) scenarios were used for the projection of precipitation and temperature in the future. The minimum and maximum temperatures of the basin are projected to increase by 6.33 °C and 3.82 °C, respectively, by 2100. The projected precipitation varies from -8% to +24.8%, which is expected to alter the streamflow by -37.83% to +47% in the future. Based on the streamflow output, the risk for energy production was calculated with respect to the baseline energy production of 1963 GWh and 2281 GWh. Using the three GCMs, the risk associated with annual hydropower production under altered runoff was analyzed. The risk percentage in the future periods shows a mild risk varying from 0.69% to 6.63%. MPI-ESM-M GCM projects a higher percentage of risk for energy production during the same future periods, as compared to the baseline energy production of 1963 GWh. A mild to moderate risk of 13.24% can be expected when energy production in the future is compared to the baseline energy production of 2281 GWh.
