GIS-based RUSLE modeling for soil erosion risk assessment, sediment yield estimation, and area prioritization in the Hamassa Watershed, Ethiopia

Abstract Soil erosion is a significant environmental concern in Ethiopia, particularly in agricultural landscapes. This study assesses soil erosion risk and sediment yield using GIS-based Revised Universal Soil Loss Equation (RUSLE) modeling in the Hamassa Watershed, Southern Ethiopia. The region receives an average annual rainfall of approximately 1,293.5 mm, with rainfall erosivity (R-factor) values ranging from 668.98 to 763.15 MJ mm ha −1 h −1 yr −1 . Soil erodibility (K-factor) varies between 0.13 and 0.30 t ha h ha −1 MJ −1 mm −1 , with Chromic Vertisols covering 76.3% of the watershed. The slope length and steepness (LS-factor) range from 0.072 to 148.37, highlighting high erosion risks in steeper areas. Land cover and management (C-factor) values range from 0.023 to 0.05. The model estimates an average annual soil loss of 14.75 t ha −1 yr −1 , with severity levels classified as very slight (47.8%), slight (29.4%), moderate (11.3%), severe (5.5%), and very severe (6.0%). The sediment delivery ratio (SDR) is calculated at 0.28, resulting in a sediment yield of 3.25 t ha −1 yr −1 . Five sub-watersheds (SWS3, SWS6, SWS8, SWS10, and SWS1) were identified as erosion hotspot areas, accounting for 73.8% of the total erosion in the watershed. These findings provide valuable insights for prioritizing conservation efforts and managing soil and water resources in the Hamassa Watershed, offering actionable recommendations for sustainable land management practices. Furthermore, this finding is crucial for advancing key sustainable development goals (SDGs) by supporting efforts to ensure clean water and sanitation, life on land, and climate action.