Sediment Yield Modelling and Soil Erosion Hotspot Area Identification

Abstract Sediment movement is the most critical problem in Ethiopia, notably in the Ketar river watershed, which is located in the Rift Valley Basin. The Ketar River flows through rugged terrain with steep slopes and high sediment movement. The purpose of this research is to check Soil and Water Assessment Tool (SWAT) in simulating sediment yield and to identify soil erosion-prone sites. The SWAT model sediment simulation performance was evaluated using the coefficient of determination (R 2 ) and Nash-Sutcliffe Efficiency (NSE), with R 2 and NSE values of 0.69 and 0.55 for calibration and 0.73 and 0.51 for validation, respectively using SWAT Calibration and Uncertainty Program (SWAT-CUP). The sub-basins located at the upstream of the watershed have a high sediment yield rate. The sediment-prone area sub-basins have steep slopes and were mostly covered by cultivated land. Annual sediment yield from cultivated land was approximately 1872.12 t/y, while grass land with moderately cultivated yield was 171.45 t/y. Woodland and forest land have less soil erosion rate. The sub-basin highly covered by Eutric nitisols is found at very high soil erosion prone area. Sediment yield from a slight slope is almost zero, whereas sediment yield from steep and very steep slopes was very high. The slope of the sub-basin is an important factor in determining sediment yield, followed by land cover and soil types. The very high sediment yield rate area accounted for 39.64% of the total sub-basin.