Geospatial Assessment of Hydrogeochemical Factors Controlling Groundwater Evolution of the Eocene Limestone and Clastic Quaternary Aquifers, Eastern Desert, Egypt

Hydrochemical studies, involving groundwater analysis, multivariate statistics, and geospatial element distributions, were carried out to understand the factors influencing groundwater geochemistry and potential pollution in an arid area (Eastern Desert, Egypt). A total of 104 groundwater samples were analyzed for twenty-three physical and chemical variables. Spatial mapping was conducted to depict variations in the concentration of several variables. A spatial pattern revealed an increasing water table depth from south to north, correlating with a rise in groundwater salinity. The correlation coefficients for various variables were found to align with aquifer mineral saturation indices. Hydrochemical facies identified three main zones with six facies in the first sub-area, five in the second, and the third sub-areas. Specific processes, including evaporite/carbonate rock dissolution and ion exchange, dominate. The results support meteoric groundwater recharge in the first sub-area, influenced by the Nile water and rainfall. The second and third sub-areas indicated groundwater mixing from diverse sources, emphasizing evaporite/carbonate rock dissolution and ion exchange. Negative saturation indices for anhydrite, halite, and gypsum suggested under-saturation conditions, while dolomite and calcite indicated upper saturation, implying secondary mineral precipitation. Factor analysis demonstrated that six interrelated factors elucidate the chemical attributes of the groundwater. These factors arise from interactions between rock and water, blending of waters from diverse sources, and, to some extent, anthropogenic influences. Utilizing cluster analysis, notable and distinct groundwater zones were identified, where the original groundwater was uniquely influenced by mixing processes. Therefore, integration of hydrochemical and geospatial statistical analysis methods can be employed to enhance water resource management on a regional scale and in areas with similar conditions.