Comparative AHP and Fuzzy-AHP Modeling with GIS for Groundwater Potential Zone Mapping in a Hilly-Coastal Region of Bangladesh

Groundwater potential zone mapping in the hilly coastal regions is becoming a prerequisite for sustainable groundwater resource management. The groundwater potential zones of Chattogram District were delineated by the integrated GIS-based Analytical Hierarchy Process (AHP) and Fuzzy Analytical Hierarchy Process (Fuzzy-AHP) approach. Ten groundwater-controlling thematic layers were prepared and reclassified, weighted with the AHP method and fuzzy-AHP, and integrated using weighted overlay analysis in ArcGIS. The AHP model reveals that the most extensive area in the study, spanning 2882.2 km² or 68% of the total, is classified as having moderate groundwater potential. This is followed by the suitable groundwater potential zone, which covers 877.4 km² or 20% of the area. The Fuzzy-AHP model, however, categorized the areas as moderate (2414.7 km² or 57%), suitable (1395.1 km² or 33%), less suitable (452.8 km² or 10%), and negligible (0.1002 km²) very suitable areas. Both models were found to be valid by model validation, which yielded AUC values of 0.738 and 0.762 for AHP and Fuzzy-AHP, respectively. The slight difference in numbers (ΔAUC = 0.024) suggests that Fuzzy-AHP gives some improvement in predictive performance by being able to incorporate uncertainty in the expert judgments while not necessarily offering a significant increase in reliability.