Assessment of Land Use Cover Change Impact on Stream Flow and Sediment Yield Case Study on Gilgel Gibe III Reservoir Omo Gibe Basin

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Addis Ababa University


Land use/land cover (LULC) change is an important landscape process capable of altering the fluxes of water, sediment, contaminants and energy. In this study, Soil and Water Assessment Tool (SWAT) model was used to examine the effects of LULC on the hydrological process of Gibe III Watershed in the Omo-Gibe basin. The performance of the model was evaluated through sensitivity, uncertainty analysis, calibration and validation. The LULC change analyses for two periods (2009 and 2019) were used for estimation of stream flow and sediment yield. The result has shown that during the study period most parts of the forest land were converted into cultivated land with an increase of cultivated land by 6.97%, which resulted in an increase of stream flow and sediment yield by 4.7 m3/s and 0.53 ton/ha/year respectively. The Nash sutcliff efficiency (NSE), coefficient of determination (R2) and percent of bias (PBIAS) were used for evaluating the model performance. The model results have shown a good and satisfactory agreement with the observed values with NSE > 0.51, R2 > 0.63, and PBIAS < 6.45. values. Based on the validated sediment yield results of 2019 land use, high potential source of spatial variability of sediment yield identified within the watershed. Hence, for the critical sub-watersheds, the design and development of three best management practices (BMPs) were performed. These best management scenarios include: S1 (filter strip), S2 (terrace/ bund) and S3 (reforestation). Based on these scenarios, the findings have shown a sediment yield reduction by 41.56%, 32.49% and 53.77% with the implementation of S1, S2 and S3 respectively. Therefore, based on the findings, implementing S3 is the best management strategy as compared to other options and hence, such intervention should be encouraged at a wider scale for efficient sediment reductions of Gibe III watershed



Arc SWAT, Land Use Cover Change, Sediment Yield, Omo Gibe, Gibe III Watershed