Estimation of Soil Loss Using the RUSLE Model Integrated with GIS Tools: A Case Study of the Ribb Dam Catchment, Upper Blue Nile Basin, Ethiopia

Abstract Soil erosion is a major environmental challenge, particularly in watersheds such as the Ribb Dam catchment, which contributes to sediment deposition in reservoirs and reduces the lifespan of dams. This study estimates the total soil loss from the Ribb Dam catchment using the Revised Universal Soil Loss Equation (RUSLE) model, integrated with Geographic Information Systems (GIS). The RUSLE model evaluates soil erosion based on five factors: rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), land cover (C), and conservation practices (P). Input data for these factors were collected from Landsat satellite images, soil maps, rainfall data, and a 12.5m resolution Digital Elevation Model (DEM). The model was used to identify erosion hotspots and assess the severity of soil loss across the catchment. The estimated annual soil loss ranged from 0 to 50 tons per hectare per year, with an average of 25 t/ha/yr. Approximately, 96% of the watershed experienced slight to very slight soil loss, while 4% of the area faced moderate to severe erosion, predominantly in the northern and central regions. The findings indicate that these areas require urgent conservation efforts to mitigate soil loss and ensure the long-term sustainability of the Ribb Dam. The integration of the RUSLE model with GIS provides a powerful tool for soil erosion prediction and conservation planning in erosion-prone watersheds.