Identifying Soil Erosion Hotspots Using Integrated RUSLE and GIS-Based Multi-Criteria Decision Analysis: Evidence from the Adag Watershed, Ethiopian Highlands

Abstract In Ethiopia, the pressing issue of soil erosion and land degradation is exacerbated by the rugged and steep topography, intensifying the rate of erosion. This study aimed to pinpoint soil erosion hotspot within the Adag watershed by employing the Revised Universal Soil Loss Equation (RUSLE) and Multi-Criteria Decision Analysis (MCDA) methodologies. Based on RUSLE model, the average annual soil loss of Adag watershed was reaches up to 382.4 ton ha − 1 yr − 1 . In the Adag watershed 52%, 26%, 18%, 5% of the total watershed area predicted soil loss ranges between 0 to 15, 15 to 50, and 50 to 200 and above 200 t ha − 1 respectively. On the other hand, the GIS based MCDA technique considered five major factors land use, soil type, topographic wetness index, stream power index and potential location of gullies. The factors were weighted using pair-wise comparison matrix and weights were combined using Weighted Overlay Tool of ArcGIS Spatial Analyst Toolbox to obtain the final erosion hotspot map. In Adag watershed 4.7%, 50.7%, and 44.6% of the total watershed area was highly, moderately, and slightly sensitive to soil erosion respectively. Based on validation, field level observation, MCDA model prediction was more accurate than RUSLE. Thus, bottomlands of the watersheds under highly sensitive areas for erosion therefore immediate attention for soil and water conservation practice. Therefore, both tools should be applied for planning and targeting of watershed intervention.