Integrated biophysical assessment and erosion hotspot mapping for land degradation prioritization in the Megele washa watershed, Ethiopia

Land degradation remains a critical environmental and agricultural challenge in the Ethiopian highlands due to steep terrain and intensive cultivation. This study conducted an integrated assessment of the Megele Washa experimental Watershed using advanced geospatial techniques and R software. To achieve this, the research combined biophysical characterization (agro ecology, slope, land use/land cover and field-based soil quality evaluation) and soil erosion estimation through the Revised Universal Soil Loss Equation (RUSLE) with hotspot identification of the greatest risk. Analysis confirmed that 90% of the watershed falls within the Dega agro-ecology, while nearly half (47%) of the watershed is characterized by steep slopes (> 15%). Agricultural land dominates the watershed (58.1%), with 49% of steep areas actively under cultivation and 11.5% of the watershed classified as severely degraded land. Furthermore, soil physicochemical analysis indicated clay-dominated textures and widespread fertility decline, evidenced by spatially low levels of Total Nitrogen (TN) and Organic Carbon (OC), while pH and EC were within non-constraining ranges. Crucially, spatial analysis estimated an average annual soil loss of 26.5 t ha−1yr − 1, significantly beyond the tolerable limit, with localized losses reaching a maximum of 164.5 t ha−1yr − 1. While 78% of the area faces low-to-moderate risk, a significant 22% of the watershed is highly degraded (≥ 20 t ha−1yr − 1), constituting the critical erosion hotspots. To reduce the current average soil loss below the tolerable limit, these hotspots require targeted interventions. Implementing afforestation on steep slopes, rehabilitating degraded lands, and applying Integrated Soil Fertility Management are essential steps to restore ecological stability and enhance land productivity.