Land use land cover change is the central form of global environmental change that occurs at spatial and temporal scales. This study aimed to evaluate the impacts of land use/land cover (LULC) changes on the streamflow of the Beressa watershed. The study used three times series of Landsat images Landsat 5 TM 1990, Landsat ETM+ 2000, and Landsat 8 OLI-TIRS 2013. The study used ERDAS EMAGINE 2014 software through maximum likelihood classification techniques to classify Landsat images with the help of Google Earth for the preparation of LULC maps for 1990,2000 and 2013 years. The SWAT CUP semi-automated Sequential Uncertainty Fitting (SUFI2) was used to calibrate and validate the model parameters of streamflow. Three SWAT models set up were run to evaluate the impacts of land-use changes on the streamflow of Beressa watershed using three differentyears 1990, 2000, and2013. Sensitivity, calibrationvalidation, and uncertainty analysis were conducted using Sequential Uncertainty Fitting–version 2 (SUFI-2) in SWAT-CUP (Calibration and Uncertainty Program) using streamflow historical data.Land cover change analysis showed that the agriculture land increased by 6.3%,barren land increased by5.5%, the water bodies increased by 158.8% and the urban areas increased by 195%, whereas the forest decreased by32% and the grassland decreasedby 26.1% from 1990 to 2013. Model calibration and validation were conducted for both land use using measured data at the Beressa gauge calibration approach in a monthly basis. In the 1990’s land use calibration was from 1991-1995 and validation was from1996-1998, for 2000’s land use calibration was from 1999- 2003 and validation was from 2004-2006, and for the 2013 calibration was from 2006 -2011 and validation was from 2012 -2014. Results from calibration for both land use showed a good result (0.62 to 0.82 for NSE and 0.77 to 0.82 for R2) between observed and simulated stream flow on a monthly base. The results of validation were acceptable (0.65 to 0.80 for NSE and 0.76 to 0.86 for R2). Average monthly stream flows of the Beressa watershed decreased from the year 1990 to 2000 by 1.46 m3/s and increased from the year 2000 to 2013 by 0.40m3/s. Keywords: Beressa Watershed, LULC, stream flow, SWAT, SUFI2