Boudjema1, AGuettaia, SBrinis, N2023-05-282023-05-282019-05-01A. Boudjema1*, S. Guettaia1,N.Brinis,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) . Journal of Fundamental and sciences. vol.11, no 2. May 2019. Faculty of exact sciences. university of el oued. [visited in 01/May/2019]. available from [baryte2003@yahoo.fr]https://dspace.univ-eloued.dz/handle/123456789/24491ArticleThe 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 SO42-, 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.enChott El Gharbi; multilayer; system hydro-geochemical; analyzes statistical study, saturation index.Author Correspondence, e-mail: baryte2003@yahoo.frdoi: http://dx.doi.org/10.4314/jfas.v11i2.16Journal of Fundamental and Applied SciencesISSN 1112-9867Available online at http://www.jfas.infoResearch ArticleArticle