Trnhe main goal of this study is to identify the impact of land use/ land cover changes on thernhydrology of Megech Watershed S pecifically, the study was analyzed the histor ical landrncover changes at (2000, 2010 and 20018 years) that have occurred in the ca tchment and itsrnimpact on stream flow of watershed because the recent input data gives more accurate results.rnPopulation growth, deforestation and higher demand for farm lands have eff ect on naturalrnresource of the M egech river catchment of A bbay River basin. Assessing the problem andrnfinding solution at catchment level is use full to minimize the effect of the problem. Decisionrnsupport tools are need ed for successful assessment for impact of land use on stream flow andrnapplication of soil and water conservation measures at upstream of watershed . Land coverrnchange analysis has shown that the settlement (town) area has increased from 2.21% torn9.13%, agricultural land increased from 46.3% to 70.49% and forest area has been decreasedrnfrom 6.43% to 0.8% between 20 00 2018 years . In this study the effect of land use and landrncover changes on stream flow was observed. Soil & water assessment tool (SWAT model setrnup were run to evaluate the impacts of land use changes o n stream flow using three landrncover year s of 2000, 2010 and 2018.rnSensitivity, calibration, validatrnion and uncertainty analysis were also conducted usingrnsequential uncertainty fitting version 2 (SUFI 2) in SWAT CUP (C a libration and U ncertaintyrnpr ogram ) using stream flow historical data. Model calibration and v al idation were conductedrnfor land use 2000, 2010 and 2018 years by using measured (gauged) data near to watershedrnby using SWAT CUP. For 2000 land use, calibration from 1999-2001 and validation from 2002-2003, for 2010 land use, calibration from 2008-2010 & validation from 2011-2013, for 2018 land use, calibration from 2014-2016 & validation from 2017-2019 years was conducted. The Results from calibration for three land use show acceptable range (0.82, 0.63 and 0.71 for NSE and 0.82, 0.79 and 0.74 for R2) between observed and simulated stream flow respectively. The results of validation were also acceptable range (0.66, 0.78 and 0.75 for NSE and 0.71, 0.84 and 0.78 for R2) respectively.rnThe mean monthly stream flow for both dry and w et season were decreased by 3.31 m 3 /s andrn1.88 m 3 /s due to land use/land cover changed in the catchment from 2000 2018 yearsrnrespectively.