This study investigates the regional groundwater flow patterns in the Rambukpotha Oya micro-catchment within the Badulu Oya basin by integrating Geographic Information System (GIS) techniques with numerical groundwater flow modeling. Despite the lack of previous studies on the groundwater flow system in this micro-catchment, the research utilized existing data and information to build a comprehensive groundwater model. GIS was employed for preprocessing hydrogeological data and creating various data layers of the study area, which were then imported into groundwater modeling software for simulation. MODFLOW-NWT, coupled with ModelMuse for the graphical user interface, was used to conduct the flow simulations. The study generated regional groundwater flow patterns and examined their sensitivity to variations in recharge rates, evapotranspiration, and hydraulic conductivity. The results, presented through detailed graphical representations, provide valuable insights for future groundwater management and research in the Rambukpotha Oya micro-catchment.