Spatial Estimation of Soil Erosion Using Rusle Modelling: A Case Study of Muger River Watershed, Ethiopia

Soil erosion poses a severe environmental challenge in Ethiopian highlands, threatening agricultural productivity, water quality, and rural livelihoods. This study evaluated soil erosion dynamics over 24 years (2001–2025) in the Muger River Watershed using the revised universal soil loss equation (RUSLE) model integrated with geographic information systems (GIS) and remote sensing. The assessment incorporated rainfall erosivity (R), soil erodibility (K), slope length-steepness (LS), cover management (C), and conservation support practice (P) factors derived from multisource geospatial datasets. Multitemporal analysis revealed a substantial decrease in soil erosion rates, with mean annual soil loss declining from 4.80 Mg·ha⁻¹·yr⁻¹ in 2001 to 2.18 Mg·ha⁻¹·yr⁻¹ in 2025, representing a 54.7% reduction. Areas classified as low erosion risk (0–5 Mg·ha⁻¹·yr⁻¹) expanded from 70.6% to 88.0% of the watershed, while zones exceeding 10 Mg·ha⁻¹·yr⁻¹ decreased from 13.7% to 3.8%. The most pronounced improvement occurred on steep slopes (>25°), where erosion rates declined by 72.8%. Climate variability analysis confirmed no significant rainfall-trend over the study period (p = 0.262), indicating that the observed reduction is attributable to land cover change and conservation interventions rather than shifts in precipitation. Sensitivity analysis revealed that the spatial distribution of erosion is primarily governed by topography, while temporal changes are associated with improvements in the cover management factor, which decreased from 0.183 to 0.119. These findings provide a quantitative basis for evaluating conservation effectiveness and informing soil conservation planning in the Ethiopian highlands.