Statistical and hydrochemical classification of underground waters in a multi-layer aquifer system in an arid zone :application to Chott El Gharbi basin (extreme west of Algeria)

Abstract

The studied area, so called Chott El Gharbi shelters a multilayer aquifer system. The hydro-chemical tool shows that the results of the groundwater analyzes of the aquifer system of the Chott El Gharbi region revealed that they are sulphated-calcium and magnesian. Water infiltrated at the Bajo-Bathonian and Mio-Plio-Quaternary carbonate formations is enriched with HCO3- and SiO2 along its underground route. Also, the presence of a Triassic evaporitic formation or the Cenomano- Turonian argilo-gypsum formation enriches these waters with SO₄^2-, Cl^-, K⁺, Mg²⁺, Na+ and Ca²⁺.
Thermodynamics has shown that these waters are under saturated evaporitic elements, which gives them a greater power of dissolution than that of carbonates which are in equilibrium or sometimes even supersaturated and tend to precipitate.