Water-rock interaction and geochemistry of groundwater from the Ain Azel aquifer, Algeria

Hydrochemical, multivariate statistical, and inverse geochemical modeling techniques were used to investigate the hydrochemical evolution within the Ain Azel aquifer, Algeria. Cluster analysis based on major ion contents defined 3 main chemical water types, reflecting different hydrochemical processes. The first group water, group 1, has low salinity (mean EC = 735 mu S/cm). The second group waters are classified as Cl-HCO3-alkaline earth type. The third group is made up of water samples, the cation composition of which is dominated by Ca and Mg with anion composition varying from dominantly Cl to dominantly HCO3 plus SO4. The varifactors obtained from R-mode FA indicate that the parameters responsible for groundwater quality variations are mainly related to the presence and dissolution of some carbonate, silicate, and evaporite minerals in the aquifer. Inverse geochemical modeling along groundwater flow paths indicates the dominant processes are the consumption of CO2, the dissolution of dolomite, gypsum, and halite, along with the precipitation of calcite, Ca-montmorillonite, illite, kaolinite, and quartz.