Quantitative Assessment of Water Resources: Empirical Methods and Mapping Recharge Zones: Case Study (Eastern Tunisia)

Abstract

Abstract Groundwater is considered the primary water resource for drinking, irrigation, and industrial purposes. Excessive groundwater pumping, driven by increasing water demand, particularly in the agricultural sector, leads to groundwater scarcity. Groundwater recharge is the most important process contributing to water sustainability. In this paper, two approaches have been combined to establish a groundwater recharge susceptibility map. The first approach is based on empirical formulas used to estimate quantitative groundwater recharge, namely Chaturvedi, modified Chaturvedi, Sehgal, Krishna Rao, and Bhattacharya, applied to the El Fahs Plain aquifer. The second approach, used to map sustainable groundwater recharge areas, is based on Analytic Hierarchy Process (AHP) multicriteria analysis. To delineate aquifer suitability for groundwater recharge, eight parameters were considered: soil type, land cover, drainage density, lithology, Normalized Difference Vegetation Index, slope, transmissivity, and rainfall. The impact of each factor was weighted, and this method was applied to the El Fahs Plain shallow aquifer. Results indicate that the recharge coefficients obtained from the empirical formulas are 0.143, 0.130, 0.114, 0.010, and 0.089 for Chaturvedi, modified Chaturvedi, Sehgal, Krishna Rao, and Bhattacharya, respectively. The findings suggest that 37% of the aquifer area has very good and good recharge suitability. The results were validated by the Receiver Operating Characteristics curve, with an accuracy of prediction reaching 89.3%. The primary benefit of this research is to enhance the efficiency of mapping groundwater recharge zone suitability.