It is anticipated that climate change will impact sediment yield in watersheds. The purpose of this study was to investigate the impacts of climate change on sediment yield from the Logiya watershed in the lower Awash Basin, Ethiopia. Here, we used the coordinated regional climate downscaling experiment (CORDEX)-Africa data outputs of Hadley Global Environment Model 2-Earth System (HadGEM2-ES) under representative concentration pathway (RCP) scenarios (RCP4.5 and RCP8.5). Future scenarios of climate change were analyzed in two-time frames: 2020–2049 (2030s) and 2050–2079 (2060s). Both time frames were analyzed using both RCP scenarios from the baseline period (1971–2000). A Soil and Water Assessment Tool (SWAT) model was constructed to simulate the hydrological and the sedimentological responses to climate change. The model performance was calibrated and validated using the coefficient of determination (R²), Nash–Sutcliffe efficiency (NSE), and percent bias (PBIAS). The results of the calibration and the validation of the sediment yield R², NSE, and PBIAS were 0.83, 0.79, and −23.4 and 0.85, 0.76, and −25.0, respectively. The results of downscaled precipitation, temperature, and estimated evapotranspiration increased in both emission scenarios. These climate variable increments were expected to result in intensifications in the mean annual sediment yield of 4.42% and 8.08% for RCP4.5 and 7.19% and 10.79% for RCP8.5 by the 2030s and the 2060s, respectively.

Climate change affects the availability of water resources by altering the pattern and magnitude of precipitation, temperature, and streamflow. The projection of climate change impact on the streamflow is used to identify the level of changes and desirable intervention measures. In this research, Soil and Water Assessment Tool (SWAT) model and the regional circulation model (RCM) outputs of CORDEX Africa climate model associated with mid and high-level Representative Concentration Pathways (RCP4.5 and RCP8.5) climate scenarios were used to evaluate the change in streamflow in two future projection scenarios (2041-2070 and 2071-2099). The study is directed to the Upper Wabe Bridge watershed found in the Wabe Shebele basin, Ethiopia. The result shows an increase in mean temperature by 3.46 and 5.15°C for RCP4.5; and 4.78 and 5.88°C for RCP8.5 in mid and long-term periods, respectively. The study also confirmed an increasing trend in annual precipitation by +26.3 and +31.85% for RCP4.5 and RCP8.5 climate scenarios, respectively, at the end of 21^st century. In Kiremt (rainy) season precipitation shows an increasing trend by +44.28% and +59.34% for RCP4.5 and RCP8.5 climate scenarios, respectively, but Bega (dry) season show decreasing trend. The future projected annual streamflow shows increase trends under both climate scenarios in both projection periods. The mean seasonally streamflow decreases in the Belg (short rainy) season by -10.91% and increases in the Kiremt (rainy) season by 17.4%. Hence, the increment trend in streamflow during the Kiremt season will have the utmost significance for the requirement of storage and rainwater harvesting structures for irrigation development during dry season. Therefore, incorporating the possible effect of climate change is vital during water resources planning and development.