Mapping the potential of groundwater is important for managing water resources in a way that will last, especially when the climate changes, land use changes, and water demand rise. This study examines the integration of Geographic Information Systems (GIS) and Multi-Criteria Decision Analysis (MCDA) methodologies, focusing on the Analytical Hierarchy Process (AHP), and illustrates their implementation in the Fork Fish Creek watershed, a humid Appalachian headwater basin in West Virginia, USA. Although GIS–AHP methodologies are extensively utilized in semi-arid areas, their efficacy in humid, structurally intricate mountainous environments is still inadequately investigated. Using expert-based AHP weighting and GIS-based weighted overlay analysis, six thematic parameters were combined: rainfall, geology and soil characteristics, slope, drainage density, land use and land cover (LULC), and lineament density. The appropriate AHP consistency ratio (<0.1) showed that the weights were reliable. The resulting groundwater potential map divided the watershed into three zones: Good (6.7%), Moderate (76.5%), and Low (16.8%). The prevalence of Moderate potential indicates the impact of fragmented topography and drainage configuration, which limit groundwater storage despite sufficient precipitation. Validation encompassed an evaluation of hydrogeomorphic consistency and an additional comparison with USGS monitoring-well depth data, so offering empirical corroboration for the Moderate-dominated distribution. The results show that groundwater potential patterns vary greatly from one place to the next. They also show how useful GIS–MCDA frameworks may be for assessing groundwater in humid, data-poor mountainous areas.
