Investigation of groundwater hydrochemical characteristics using the multivariate statistical analysis in Ain Djacer area, Eastern Algeria

The hydrochemical and multivariate statistical techniques such as the factor analysis (FA), the principal component analysis (PCA), and the cluster analysis (CA) were used to determine the main factors and mechanisms controlling groundwater chemistry of Ain Djacer Mio-Plio-Quaternary aquifer, Eastern Algeria. Twenty-one groundwater samples of this aquifer were monitored, during March 2013, with the objective of identifying the geochemical processes and their relation with groundwater quality as well as to get an insight into the hydrochemical evaluation of groundwater. The Piper diagram showed that water facies are of a Ca-HCO3-type near limestone limits and SO4-Na in the center part of the plain. The FA and the PCA revealed two factors that explained 65.1% of the total variance in water quality dataset. The first factor is salinization, which shows strong associations between total dissolved solids (TDS), , Cl-, Ca2+, Mg2+, and Na+. The second factor is mostly associated with chemical fertilizers and represents the high positive load of and K+ and the high negative load of pH andHowever, the CA, based on major ion contents, defined three main groups, reflecting different hydrochemical processes. The first group has low salinity (TDS<1,000mg/l) and a Ca-HCO3 water type. Samples of this group are mostly located in recharge areas and suggest dissolution of carbonate rocks. The third group has high salinity (TDS>2,000mg/l) and a SO4-Na water type. Samples from this group are mostly located in the center part of the plain which constitutes the discharge area. The second group has intermediate salinity (1,000<TDS<2,000mg/l) and Ca-Na water type. These three groups present a salinity increasing with groundwater flow direction. The chemical monitoring allowed relating the presence of nitrates in the study area to agricultural activity. This study highlights that reactions responsible for the hydrochemical evolution in this area are of three categories: (1) dissolution of evaporite minerals, (2) precipitation of carbonate minerals, and (3) anthropogenic action.