Groundwater Exploration Using Multi-Criteria Decision Analysis Method and Analytical Process in the Muda River Basin, Kedah, Malaysia

Groundwater serves as a critical freshwater resource in the Muda River Basin, Kedah, Malaysia, where increasing demand has exceeded the capacity of the surface water supply. This study delineates Groundwater Potential Zones (GWPZs) using a Geographic Information System (GIS) integrated with Multi-Criteria Decision Analysis (MCDA). Eight geoenvironmental factors─slope, lithology, drainage density, lineament density, soil media, soil thickness, rainfall, and land use─were selected as decision criteria. The Analytic Hierarchy Process (AHP) was employed to assign relative weights to each factor, ensuring consistency ratio (CR < 0.1). The weighted thematic maps were overlaid using a weighted linear combination in GIS to generate a groundwater potential index. The resulting map was classified into five zones, ranging from very low to very high potential. Validation against discharge data from 22 wells yielded an accuracy of 77%, confirming the model’s reliability. Results indicate that lithology, rainfall, and slope are the most influential parameters, with moderate-to-high potential zones covering nearly half of the basin. This integrated approach demonstrates that GIS-based AHP is a robust, cost-effective tool for groundwater exploration and sustainable water resource management under tropical monsoon conditions.