Soil erosion-prone area identification using multi-criteria decision analysis in Ethiopian highlands

Soil erosion is a very complex natural process that refers to the detachment and transportation of topsoil from the land surface by natural agents like water, wind, and others. This process has an effect on the environment including loss of soil fertility, reduction of water bodies' depth (lakes, ponds, reservoirs, etc.), increase in water turbidity, flood hazard problems, etc. Identifying the erosion hotspot areas using different techniques is an essential tool for sustainable natural resources management. This study focusses on the mapping of soil erosion-prone areas of Ribb watershed, Upper Blue Nile, Ethiopia. This study aimed to identify the erosion of hotspot areas for the setting of effective soil and conservation strategies. Different soil erosion contributing factors, viz. Slope, land use, soil, rainfall, and stream power index, were integrated on ArcGIS 10.3 environment for determining the erosion-prone areas. Multi-criteria decision analysis (MCDA) technique was used to develop erosion hotspot areas using thematic layers pair-wise comparison tool. The weights for each thematic layer and feature were decided based on the expert's judgment and review of the literature. Hence, the results of soil erosion map showed very high, high, moderate, low, and very low vulnerability to erosion with areal coverage of 7.04%, 20.40%, 17.60%, 32.01%, and 22.95%, respectively. The findings of this study will help decision-makers to plan and carry out effective soil and water conservation practices in highly vulnerable areas to soil erosion. MCDA was found as a basic tool for determining erosion-prone areas coupled with GIS. The spatial distribution map indicated that most of the erosion-prone areas were found in northern, eastern, and northeastern parts of the watershed due to the steep slope and agricultural practice which needs integrated soil and water conservation practice.