Impact of climate change on water resource potential and sediment yield of the Gibe III watershed, Omo-Gibe Basin, Ethiopia

Abstract The impact of climate change on the water resource potential of the Gibe III watershed, Omo-Gibe Basin, Ethiopia, was investigated using the Soil and Water Assessment Tool (SWAT) model and selected climate models of Coupled Model Intercomparison Project Phase 5 (CMIP5) for future projection. Because the Omo-Gibe Basin in general and the Gibe III watershed in particular was the source of hydropower generation, more work toward updating knowledge of climate change impact on it is required so as to manage the sustained use of the water resource and prevent sedimentation of the reservoir. High-resolution (0.25° × 0.25°) datasets of some general circulation models (GCMs) such as GFDL-ESM2M, MPI-ESM-MR, CSIRO-MK3-6-0, NorESM1-M, and MIROC5 were downloaded for six stations. After calibrating and validating the Soil and Water Assessment Tool (SWAT) model, the impact of climate change was simulated. Accordingly, the annual precipitation was expected to increase by 8.4 and 21.1% during 2050 and 2080, respectively; mean temperature was projected to increase by 1.85 and 2.8 °C in 2050 and 2080, respectively; the stream flow was expected to increase by 55.5 and 81% by 2050 and 2080, respectively, from the base period (1990–2017). The scenario of mean annual sediment yield would increase by 64.5 and 138% by 2050 and 2080, respectively. Therefore, actions toward reducing excess runoff production in the catchment and timely removal of sediment from the reservoir are required.