Mapping of potential areas for aquifer recharge in arid regions using the IF model and the fuzzy AHP method: the case of southeastern Tunisia

In arid areas in southern Gabes (SE Tunisia) with low precipitation and scarce surface water resources, the exploitation of groundwater remains the only way to meet the various needs of development. Indeed, with economic development, these water resources are becoming increasingly degraded and exploited. The identification of appropriate zones for aquifer recharge (PGWRZs)—the goal of the current study—constitutes an effective management tool to compensate for these losses and limit this degradation without hindering development. The proposed methodology focuses on influencing factor (IF) and the fuzzy analytical hierarchy process (fuzzy AHP) models, which use weights and rating coefficients for the major factors: density of drainage, altitude, soil slope, permeability, density of lineaments and land use/land cover (LULC). These weights and rating coefficients depend on the degree of involvement of the factor in the recharge process. This was only possible with the functionalities offered by satellite imagery (RS) and geographic information systems (GIS). Results obtained using multi-criteria decision-making (MCDM) approaches showed that the PGWRZs obtained via the IF model could be classified into three categories: good, moderate and low recharge classes covering 38%, 46% and 16% of the research area, respectively. The fuzzy AHP model allowed us to validate the obtained results and to improve the management proposals and decision-making within the research region. The recharge potential index ranged from 297 to 689, implying the presence of three classes: poorly favorable (297–347), moderately favorable (347–416) and highly favorable (420–689). The most favorable zones for recharge are distributed around the wadis and in the southeastern parts, where the aquifer is mainly composed of highly porous and permeable materials, a high number density of lineaments, and relatively gentle slopes, indicating that a considerable quantity of rainwater can infiltrate the subsoil. The fuzzy AHP's spatial distribution of PGWRZs provides more precise suggestions for the choice of suitable recharge sites. The obtained results could be considered for use to support decision-making, particularly in water resource management. Preferential recharge areas deserve special attention from the authorities through the implementation of protection measures.