Spatial assessment of soil erosion risk in menz mama midir district, central Ethiopia

Abstract

Soil erosion is one of the major agricultural problems in the highlands of Ethiopia. Identification of erosion areas on a regional scale can be very useful for appropriate soil and water conservation measures and can help reduce land degradation. The aims of this study were to assess soil erosion risk areas and to estimate annual soil loss rates of Menz Mama Midir District using Geographic Information System (GIS) and Remote Sensing (RS). In this study, annual soil loss rates are estimated using the Revised Universal Soil Loss Equation (RUSLE) Model that has been used all over the world. Rainfall data, soil data, and satellite image and Digital Elevation Model data were used as input data sets to generate RUSLE factor values. Five principal factors were used to calculate soil loss per year, such as rainfall erosivity (R), soil erodibility (K), slope length and slope steepness (LS), land use/cover factor (C) and Conservation practice or erosion control practice factor (P). Based on the analysis, the model final result shows that the current annual soil loss of the study area ranges from 0 to 23,790.1ton/ha/year with the mean annual value of 32.2 ton/ha/year from 65,101 hectare of land. These values were categorized into four priority classes depending on the calculated soil erosion amount to provide site specific conservation interventions. According to the study result, areas which are classified as severe erosion class covers an area of 18,759ha which is about 28.89% of the total study area , high erosion risk class covers an area of 8447ha (13.01%), moderate erosion risk class covers an area of 5,809ha (8.94%) and the remaining 31,928ha (49.16%) are under low erosion risk classes. A majority of the high erosion risk sites are on the banks of rivers and on the steep slope land of the study area. This is due mainly to the high steep slopes along the river banks and the practice of agricultural activities in this area. As a result, the areas that have high erosion risk should be conserved and requires effective soil conservation measures.