Assessment Of Erosion Hazard And Prioritization For Treatment Using Rusle And Syi Models In Geo spacial Environments: A Case Of Kogawatershed, Upper Blue Nile Basin, Ethiopia

Abstract

Soil erosion and the subsequent sedimentation are the major watershed problems in Ethiopia. Removal of top fertile soil, siltation of Koga irrigation reservoir, clogging of irrigation canal by sediment and reduction of irrigated land are the major threat of Koga Watershed. Hence, this study attempted to prioritize 23 sub watersheds based on soil loss and sediment yield using RUSLE and SYI model in a GIS and remote sensing environment then after suggested appropriate soil and water conservation practice. To accomplish this research Mean annual precipitation, Abay Basin digital soil map, 30 m resolution Digital Elevation Model (DEM) and landsat 8 were used to determine the RUSLE and SYI values. Accordingly, the potential annual soil loss of the watershed ranges from 0.0 to 270 t/ha/yr and the mean annual soil loss rate is 37.72 t/ ha/yr and the potential sediment yield of the study area ranges from 0.0 to 120 t/ha/yr and the average annual sediment yield estimated was 23.92 t/ha/yr. In this study soil loss and sediment yield were determined at different elevation and slope zones to identify the relationship. In the current Study, found that 6694.513 hectare falls under the first priority zone among both the models that needs immediate action for the conservation purpose. Therefore, the conservation practices as per the slope of study area have been decided and suitable places for Check Dams were selected on the basis of slope, drainage and the result of soil loss. In the study, land use classification assessment and the erosion prone areas identified have been validated using high resolution Google Earth images (i.e. Google Earth pro).Based on the validation, 83.3% and 80% accuracy was achieved respectively.