Impacts of climate change on soil erosion and sediment yield in the beressa watershed upper Blue Nile Basin Ethiopia

Abstract

Climate change is intensifying soil erosion and sedimentation, particularly in vulnerable regions like the Ethiopian highlands. This study assesses the impacts of climate change on soil erosion and sediment yield in the Beressa Watershed, Upper Blue Nile Basin, Ethiopia, using the Soil and Water Assessment Tool (SWAT). Historical climate data and bias-corrected CMIP6 projections under SSP245 and SSP585 scenarios were used to simulate future conditions. The Mann–Kendall (MK) trend analysis of precipitation and minimum and maximum temperatures revealed increasing trends for both scenarios. The SWAT model showed good agreement between observed and simulated streamflow and sediment data, confirming reliable performance during calibration and validation. The sub-watersheds' Sediment delivery ratio (SDR) value ranged from 0.152 to 0.523. Results indicate a substantial increase in soil erosion and sediment yield under projected climate scenarios, accompanied by significant spatial shifts in hotspot areas. Compared to the baseline, sediment yield is projected to increase by 32% and 27.9% under near- and far-term SSP245, and by 19.2% and 45.4% under near- and far-term SSP585, respectively. The area generating sediment within tolerable soil loss limits decreased by 29.3% in the near term, and by 41.7% and 44.9% in the far term under the SSP245 and SSP585 scenarios, respectively. These findings enhance understanding of climate-driven erosion processes and provide a basis for adaptive soil and water conservation strategies.