Assessment of soil erosion rate and hotspot areas using RUSLE and multi-criteria evaluation technique at Jedeb watershed, Upper Blue Nile, Amhara Region, Ethiopia

Abstract

Soil erosion is a difficult forceful practice by which useful surface soil is removed, conveyed, and stored at a detached place causing the exposure of subsurface soil and siltation in reservoirs and natural streams. It also degraded different agricultural areas at different rates and different locations as well as created gulleys, but these degraded areas, degradation rates, and gulley locations were not well identified and quantified. Therefore; the core objective of this study is to evaluate soil erosion rate and to identify soil erosion hotspot areas as well as to identify gulley locations using Revised Universal Soil Loss Equation (RUSLE), Multi-criteria Evaluation Analysis Techniques, and Geographic Information System (GIS). Land Use/Land Cover (LU/LC) map, slope map, rainfall map, and Digital Elevation Model (DEM) were the necessary inputs used for this study. The results of this study indicated that the potential annual soil loss of the watershed ranged from 0.0 to 706.7 tons per hectare per year with an average annual soil loss rate of 27.7 tons per hectare per year. From the total area of the watershed (859.2 km2), the potential area for gully expansion is 63km2. The overall analysis indicated that 4.8% of the total watershed is highly sensitive; 54.24% is moderately sensitive; 17.69% is marginally sensitive while, 23.28% is currently not sensitive and the remaining 0.06% is a /constraint to erosion. Hence, the Areas which were categorized under highly and moderately sensitive classes needed direct mediation for better conservation planning. It is concluded that Gulley, LU/LC, Topographical wetness index, and soil types are factors that enable soil erosion from high to low, respectively. It is recommended that the concerned bodies should have to take care of the area from further soil erosion through creating awareness among the society about the sustainable use of natural resources and conservation methods.