Hydrochemical equilibrium and statistical approaches as effective tools for identifying groundwater evolution and pollution sources in arid areas

Abstract

Hydrochemical investigations, including geochemical analyses, multivariate statistics and geostatistics, were conducted to assess the factors that influence groundwater geochemistry and pollution potentiality in Luxor area, Upper Egypt. A total of thirty-one groundwater and surface water samples from the Quaternary aquifer and the River Nile were analyzed for fourteen physical and chemical variables for each sample. Spatial variations in total dissolved solids and nitrate concentration were mapped. Piper and Durov diagrams indicate that the hydrochemistry of groundwater is influenced by the secondary processes; mixing with fresh water from the River Nile and El Kalabia Canal, irrigation return flow, and sewage leakage, and reverse ion-exchange process. The hydrochemical modeling of mineral phase saturation indices shows that nearly all of the groundwater points are undersaturated with reference to calcite, aragonite, dolomite, anhydrite, gypsum, and halite. Correlation coefficients of the different variables are consistent with the saturation indices. Cluster analysis was used to identify four significant, distinct groundwater zones where the original groundwater was influenced differently by mixing processes. Factor analysis showed four mutually interfering factors reveal the chemical characteristics of the groundwater; these factors are caused by rock-water interactions, mixing of waters of different origins, and anthropogenic effects. Integration of hydrochemical and statistical analyses approach can be applied for the better management of water resources at a regional scale and in areas with comparable conditions.