For a Better Understanding of Recharge and Salinization Mechanism of a Cenomanian–Turonian Aquifer

Abstract

The Cenomanian–Turonian aquifer of the Ouazzi basin is the source of drinking water for the local population, as well as irrigation water for agricultural needs. The aim of the present work was to understand the origin, geochemical evolution of deep groundwater by using a group of years of piezometric, hydrochemistry and isotopic data. The deterioration in groundwater quality of the study area is explained by the decrease in the precipitation due to climate change and overexploitation. The hydrochemical study shows that the chemical composition of groundwater in the study area consists of Cl-Ca-Mg, HCO₃-CaMg, Cl-Na, and SO₄Ca chemical facies for the years 1995, 2007, 2012, and 2019. Results show that electrical conductivity increased from 1995 to 2019, and this could be explained by a decrease in annual precipitation, in relation to climate change and the characteristics of water–rock interaction. Geochemical and environmental isotopic data show that the water–rock interaction and cation-exchange process are the major geochemical mechanisms controlling hydrochemical evolution of groundwater in the Cenomanian–Turonian aquifer. The diagram of δ²H = f (δ¹⁸O) shows that the isotopic contents are close or above to the Global Meteoric Water Line, which suggests that the aquifer is recharged by precipitation of Atlantic origin.