Soil and Water Assessment Tool (SWAT) simulation has been developed forrnstudying the complex hydrological watershed and their impacts. This study wasrnconducted in Watershed of Legedadi Reservoir in North Western Shoa Zone Alelturnand Bereh district. The objective of this study was to assess the impacts ofrnhydrological, climate variability and land use/land cover on Legedadi reservoirrnWatershed. The simulation was calibrated from 1989 to 2000 and validated fromrn2001 to 2012. Based on the simulation performance criteria the variation ranges fromrn1.0 to 0.95 and Nash-Sutcliffe Efficiency index range from 0.58 to 0.51. On averagernthe annual evaporation is decreasing by 0.0005 mm of water/ year. Annual averagernmaximum Surface runoff is 654.27 mm of water /year and Annual average minimumrnvalue of Surface runoff is 518.86 mm of water /year, Annual average maximumrnGroundwater is 413.76 mm of water /year. The annual average sediment load 175.28rnton/ ha/year is maximum while 36.7ton/ha/year is the minimum in sub-basin 2 and 22rnrespectively. Due to land use land cover change the Sediment yield is changed fromrn49% of 100% to 51 %, of 100%, runoff changed from 51% of 100% to 49% of 100%rnand water yield is changed from 54% of 100% to 46 % of 100% in 1997 and 2012rnrespectively. Depending on the findings of the study , further study need for detailrnstudy due to the variation of surface runoff, evapotranspiration, ground waterrncontribution , sediment yield and inflow rate from sub-basin to sub-basin. Properrnfarming practices should be essential.rnKey Words: sediment yield, water yield, LULC Change, runoff, inflow rate