Impacts of Management Scenarios on Sediment Yield Simulation in Upper and Middle Awash River Basin, Ethiopia

Abstract

Sediment transport is a complex hydrological phenomenon that influences water resources, ecosystems, soil and water quality. The evaluation of sediment yield and mitigation practices are the mechanism to enhance the water resource potential. The study was aimed at simulating the sediment yield and the impact of three best management scenarios in the Upper and Middle Awash River Basin (UMARB). The Soil and Water Assessment Tool (ArcSWAT 2012) was used to simulate and identify high sediment yield prone areas in the catchment by the implementation of three management practices such as filter strips, terraces, and grassed waterways. The model results indicated a good agreement between observed and simulated streamflow and sediment yield in the baseline scenario. The mean annual sediment yield was 21.43 ton/ha/yr. The implementation of 5 and 10 m filter strips reduced the mean annual sediment yield by 31.68% and 46.6%, respectively. Terraces and grassed waterways were showed a reduction of sediment yield by 19.56% and 16.64%, respectively. Filter strips were found to provide the highest reduction of sediment yield in each sub-basin and the outlet of the catchment. Besides, the combination of the three management scenarios has reduced the values of sediment yield by 50.88% from the baseline, and the mean annual sediment yield becomes 10.53 ton/ha/yr. In these results, the efficiency of soil conservation practices would increase by applying more than two sediment management scenarios in the study area. The study delivered important information for the reduction of sediment yield and implementation of sustainable watershed management in the UMARB.