Identification of Soil Erosion Hotspots in Jimma Zone (Ethiopia) Using GIS Based Approach

The objective of this research was to examine spatial patterns of soil erosion, identify erosion hotspots and investigate the impact of land use changes on spatial patterns of soil erosion in the Jimma zone, Western Ethiopia. The area is one of the regions that produce coffee which is an export commodity and known for its good forest cover and undulating topography. Additionally, the rivers in the area are currently being developed for hydropower generation and more hydropower projects have been proposed by government downstream. Universal Soil Loss Equation (USLE) coupled with GIS was used to identify areas that are susceptible for soil erosion and hotspots for erosion. The impact of land cover change was assessed through the analysis of readily available NDVI imagery. About 14.3 and 18.1 percent of the area fall in the very high erosion risk class (>50 metric tons ha-1yr-1) for the years periods (2001 and 2013) considered for this study respectively. Moreover, the total soil loss in the study area (1,824,878 ha) for the year 2001 and 2013 was found to be 90.2 x 10 6 and 115.9 x 10 6 metric tons respectively. The result of the analysis indicates that within 10 years period (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013), there was an increment in erosion potentials (susceptibility) and parts especially with undulating topography where crop production practiced is much susceptible for erosion. More interestingly, four out of five districts with very high erosion susceptibility levels are those that drain to a reservoir of one of the important hydro power plant that have cascading dams downstream and calls for immediate intervention.