Megersa Olumana Dinka
University of Johannesburg
Title: Soil Erosion and Sediment Yield Estimation for Lake Basaka Catchment using RUSLE and GIS
Biography
Biography: Megersa Olumana Dinka
Abstract
The soil and water resources of Ethiopia, although still rich, are degrading quickly. Topography, soil types, and agro-ecological parameters play a significant role in the degradation processes influenced by man. According to the Ethiopian Highlands Reclamation Study soil erosion is estimated to cost the country 1.9 billion US$ between 1985 and 2010. The aim of this work was to estimate the soil loss and sediment yield within Lake Basaka catchment from limited available dataset in distributed manner using the RUSLE model in GIS environment. This study is the first attempt to estimate the soil erosion and sediment yield in the entire Lake Basaka watershed using combined use of RUSLE, RS and GIS. Accordingly, all the RUSLE factors for the lake catchment were formulated and prepared in raster format. The raster layers were then ovarlayed in GIS and then the soil loss was estimated. The result indicates that the annual soil loss varies from 0 to 309 tons/ha, with average value of 108 tons/ha. Areas highly contributing to soil loss are those areas where the slope steepness is high. About 21 cm of the economically productive top soil is lost since 1973 from the catchment. The computed sediment yield indicates that about 14% of the lake incremental volume and depth in recent periods is due to sedimentation. The study result indicated the potential areas highly contributing to erosion and sedimentation and hence gives clue where land use/cover practice has to be done to reduce, if not avoided, the impacts of erosion and the subsequent sedimentation in the lake.