Empirically based modeling of soil loss and sedimentation of Shewa Robit watershed, Awash River Basin, Ethiopia
摘要
This study examines soil erosion and sedimentation in the Shewa Robit watershed, a part of the central Awash River basin in Ethiopia, which faces significant issues with land degradation. The study presents a spatial analysis of soil loss and sediment yield using GIS technology combined with the Revised Universal Soil Loss Equation (RUSLE) model. Using the RUSLE framework, soil loss rates were calculated by integrating data from topography, rainfall, soil types, and land use. As of 2023, the average annual soil loss was 48.9 t ha⁻1 yr⁻1. This rate exceeds the acceptable limits for soil erosion in the country, underscoring the urgency of implementing erosion control measures. According to this study, the central, western, and southern parts of the watershed were identified as hotspots for erosion, with steep slopes and disturbed vegetation significantly increasing the risk of erosion. More than 60% of eroded material is carried downstream as a sediment, with a sediment delivery ratio (SDR) of 0.599, resulting in sedimentation issues that affect river water quality and reservoir capacity. These findings demonstrate that sustainable soil and water management practices are crucial for maintaining soil fertility and reducing sediment loads in the watershed. Generally, the study provides a basis for informed conservation planning to safeguard vulnerable areas and improve land productivity.