Identification of hydrochemical processes of groundwater in Nekor-Ghiss plain (Morocco): using the application of multivariate statistics and Geographic Information Systems (GIS) to map groundwater

In arid and semiarid zones, groundwater is a vital and indispensable natural resource. Indeed, these water resources have become extremely limited due to several factors, including climate change, salinization, and overexploitation. This study covers the hydrochemical characterization of groundwater in the Nekor-Ghiss plain which is located in northern Morocco. To achieve this objective, a set of 79 water samples was analyzed, for various physical and chemical parameters of the samples, including E.C, pH, TDS, HCO₃⁻, SO₄²⁻, Ca²⁺, Mg²⁺, Na⁺, K⁺, PO₄³⁻, NO₃⁻, NO₂⁻ and NH₄⁺. Several methods were used to interpret the hydrochemical data, namely graphical methods, principal component analysis (PCA), hierarchical ascending classification, and ion exchange indices. A detailed geochemical study of groundwater is described to identify the origin of the chemical composition of groundwater. The results show that the samples studied are characterized by very high mineralization (> 1500 mg/l), with the predominance of Na⁺, Cl⁻ and SO₄²⁻ ions. The interpretation of geochemical signatures of groundwater in the Nekor-Ghiss plain shows sulfate-sodium (Na–SO₄) and chloride-sodium (Na–Cl) facies. Natural geochemical processes are responsible for water regulation, while human activities exert a limited influence on this control. Marine intrusion, evaporation, and the ion exchange process largely control the chemistry of the aquifer. Using PCA to confirm controlled water chemistry processes revealed three homogeneous groups. The study contributes to a better understanding of the quality and mineralization of groundwater in the Nekor-Ghiss plain, and it will serve as a reference for other plains with similar characteristics.