Hydro-geochemical processes in the Complexe Terminal aquifer of southern Tunisia: An integrated investigation based on geochemical and multivariate statistical methods

Abstract

We analyze samples from the CT aquifer for chemical and isotopic compositions. Four water clusters are obtained by the multivariate statistical analyses. Groundwater chemistry is not controlled by the lithological facies of the aquifer. The random distribution of evaporates in the basin controlled water chemistry. The aquifer recharge occurred under different climatic conditions than present. Hydrochemical data from a total of 104 groundwater samples were used to investigate the main factors and mechanisms that control the chemistry of groundwaters in the Complexe Terminal (CT) aquifer of Chott region in southern Tunisia. Multivariate statistical techniques combining Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA) were applied to the dataset of 12 physicochemical parameters (i.e. pH, T°, depth, Na+, K+, Ca2+, Mg2+, HCO3-, NO3-, Cl-, SO42-, and TDS). The HCA using Ward's method and squared Euclidean distance classified the parameters into four clusters...