Developing GIS-Based Soil Erosion Map Using RUSLE of Andit Tid Watershed, Central Highlands of Ethiopia

Soil erosion is a common phenomenon and major threat in many parts of Ethiopian highlands and it remains difficult to quantify and measure the amount of soil erosion. Geographic Information System (GIS) provides spatial information to identify erosion potential areas and useful tools to estimate the annual soil loss based on Universal Soil Loss Equation (USLE). This research was conducted in Central Highlands of Ethiopia, Andit Tid watershed which is 180 Km far from Addis Ababa north direction and covers 475 ha area. The aim of this research was to estimate the annual soil loss from the watershed and to map the topographic and anthropogenic factors for the planning and implementations of sustainable soil conservation and management system in the watershed. A Revised Universal Soil Loss Equation (RUSLE) preferred for Ethiopian conditions and GIS was used to estimate soil losses and identify potential effect of erosion factors. We employed IDW- interpolation map for rainfall erosivity (R) factor, soil map for soil erodibility (K) factor, a 30m*30m Digital Elevation Model (DEM) for topography (LS) factor, satellite image for vegetation cover (C) factor, land use and slope class map for management (P) factor. We also made the long-term correlation matrix among discharge, sediment loss and rainfall of the watershed. The result revealed that the annual soil erosion potential of the watershed ranges between 0-291 ton.ha-1yr-1with an average of 22.3 ton.ha-1yr-1. Therefore, GIS-based soil erosion model is a cost-effective method to estimate soil erosion as well as to identify priority area for sustainable land management practices.