Ethiopia has altered natural ecosystems through experiencing a huge amount of land use change has effect on the hydrological condition. Therefore, this study was initiated to compare the past and potential future change of land use with its effect the hydrological response of the Weib catchment which is found in the upper Genale Dawa River basin which covers a total area of 7407.42km2. The Soil and Water Assessment Tool model was used to compare the impact of land use change on stream flow of

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... e study area. The study was used model by using readily available spatial and temporal data and calibrated against measured discharge. The analysis of land use change has shown that the Settlement area has increased from 12.8% to 30.8%, cultivated land from 10.8% to 39.1% between 1986 and 2010, while area of Forest has reduced from 32.5% to 9.4 % and Grassland from 20.9% to 12.3%. The performance of the model was evaluated based on performance rating criteria, coefficient of determination, Nash and Sutcliff efficiency values for monthly runoff were 0.85 and 0.81during calibration, 0.88 and 0.87 during validation, respectively. The evaluation of the model response to changes indicated that the mean wet monthly flow for 2010 land cover enlarged by 40.7 % from 1986 land cover. Similarly, the 1986 land cover mean month flow was higher by 10% than the 1995 land cover flow for wet months. The dry average monthly flow was less by 45.2 %, for 2010 and 26 % for 1995 land covers when compared to that of 1986 land cover. The rapid conversion of Forest and Grassland cover to Urban and cultivated land resulted in higher peak flow and less base flow on Weib river hydrology.