Delineation of the Optimal Groundwater Recharge Zone in Taif Basin, Western Saudi Arabia: Implication for Groundwater Sustainability

The escalating demand of drinking water, coupled with increasing agricultural and industrial needs, has imposed a significant strain on groundwater sources worldwide, which is further exacerbated by the implications of climate change. The current research aims to identify the groundwater potential zones (GPZs) and the optimal sites for artificial recharge in the Wadi Waj watershed, Taif, Saudi Arabia. An integrated approach using remote sensing (RS), GIS, multi-criteria decision analysis (MCDA), and the analytic hierarchy process (AHP) was utilized. Seven hydrological and geological factors have been weighted and analyzed using AHP and GIS-based weight overlay approaches. Five GPZs have been mapped with the range from very high to very low where the very high, high, moderate, low, and very low GPZs were 0.046, 33.5, 31.3, 35.1, and 0.023 percent of the basin, respectively. The high GPZs were found in the downstream region, while the low GPZs were located in the upstream region with impermeable rock and steep slopes. A total of 27 locations have been identified as optimal sites for constructing artificial recharge facilities. These sites are positioned strategically to both catch and encourage the infiltration of rainwater into the ground. The findings were verified with the agricultural farms and wells demonstrating the alignment with moderate to high GPZs. The GPZs were also verified with the groundwater depth data obtained from the global model “GLOBGM v1.0,” and the findings showed comparable trends. The findings will support water resources management to enhance regional water security and maintain sustainable groundwater resources.