The problematic area selected is finding in the East Wollega Zone, Western Ethiopia calledrnupper Anger River Catchment of Abay Basin. The total surface area of the catchment is 7159.21rnKm2. The purpose of this study has to understand the Regional Groundwater flow and thernresponse of groundwater system to different scenarios with the help of numerical groundwaterrnflow modeling. One layer and unconfined Aquifer system simulated under steady state flowrncondition by using MODFLOW.rnThe boundary of the study area delineated from ASTR DEM with the 30m resolution by usingrnArc SWAT (Soil Water Assessment tool) software. The input parameters for the model gatheredrnfrom the well completion reports. SWAT software used to calculate the regional recharge rate ofrnthe upper Anger River Catchment. Annual recharge to the deep and shallow aquifer calculatedrnby the model is 388.84 mm/year.rnThe general Groundwater flow direction is from the north- east to south- west by following therntopographical trend and structural orientation. The model calibrated by Trial and Error methodrnusing groundwater contours produced from different heads collected from 7 observation wells.rnThe calibration shows that about 97.75% of the simulated heads with the calibration targets andrnthe overall water of the simulated model result show 8889163.3130. Model sensitivity analysesrnconducted with changing of the hydraulic conductivity and recharge the model is more sensitivernto them. Change in the hydraulic head by 20%, 30%, 40%, 50% result for the RMSE changes inrnthe head from the calibrated value. In addition, the same change happens in the recharge like therndifference in hydraulic head.rnThe result of the numerical simulations indicates while increasing well withdrawals by 25%,rn50%, 75% and 100% respectively it also resulted to the change of RMSE heads by 8%. WaterrnBudget results of the model shows that the reviled groundwater recharge comprise by 0.5% andrn97.75% by river leakage of the total water input for the total study area. The spatial distributionrnof groundwater decline is limited towards the river. However, there is hydraulic connectionrnbetween the sediment bed and Anger River.