Etude hydrogéologique et hydrochimique du bassin d’Illizi

Abstract

The main objective of this work is to identify the different groundwater layers that characterize the Illizi basin and to determine their hydrochemical characteristics.Part of several studies, the Illizi basin occupies a strategic location from a hydrogeological point of view (capturing the two major aquifer systems of the SASS the Intercalary continental and the Terminal complex). It is located in the southeast of the Algerian Sahara, covers an area of 108,424 km2 and most of the wilaya of Illizi, which is subject to a dry and arid climate expressed by high temperatures, rare precipitations and above all the importance of evaporation due to dry air. From a geological point of view, this basin is affected by tectonics with a large radius of curvature; it is devised in a succession of depressions by a series of major axes that are generally found in NE-SW and NW-SE directions, accompanied by important faults. It is also characterized by the existence of several aquifer levels, the most important are the intercalary continental (CI) and the terminal complex (CT) each has its hydrodynamic properties. The chemical analysis of water samples (hydraulic wells) with the application of different diagrams shows the hydraulic relationship between the different aquifers and the abundance of sodium sulphate and chloride facies, which is mainly, linked to the presence of the carbonate and gypsum formations of the Senonien. .