A Comparative Study of Groundwater Recharge Mapping Using Analytical Hierarchy Process, Fuzzy-Analytical Hierarchy Process, and Frequency Ratio Models: A Case Study from Quetta Region, Pakistan

Abstract

Groundwater is an essential resource in arid and semi-arid regions, where water scarcity and droughts are common. The Quetta region of Pakistan is one such area that requires effective groundwater recharge zone mapping to manage groundwater resources adequately. This study aimed to delineate groundwater recharge zones using analytical hierarchy process (AHP), fuzzy-AHP, and frequency ratio (FR) models. Additionally, it aimed to compare the effectiveness of these models in groundwater recharge potential zone mapping. To achieve the objectives, nine groundwater influencing factors were considered: geology, soil types, lineament density, elevation, slope, topographic wetness index, drainage density, land use land cover, and rainfall. Thematic maps for all these factors were generated using satellite and conventional data in the ArcGIS environment. All thematic layers were combined using AHP model-l (Weighed overlay), AHP model-ll (Weighted sum), fuzzy-AHP overlay, and FR-based model using ArcGIS. The findings revealed that 15% and 39% of the study area have high recharge potentials according to AHP-based model-l and model-ll, respectively. The FAHP model demarcated 43% of the area as high recharge zones, while the FR model demarcated 42% as high recharge zones. The majority of high groundwater recharge areas were found in the central part of the study area, while the southern part was demarcated as a moderate recharge zone. The eastern and western parts were demarcated as low recharge potential zones. To validate the accuracy of the models, the study used receiver operating characteristic (ROC) validation curves. The ROC curves revealed that AHP model-ll had the highest accuracy (AUC=89%), followed by the FAHP model (AUC=88%), AHP model-l (AUC=84%), and FR (AUC=81%). In conclusion, the AHP model-ll was more effective in recharge zone demarcation than the FAHP and FR models in the current study. The results of this study can benefit decision-makers in groundwater resource management and future planning in land use for urban extension, particularly in water-scarce regions of the country.