Hydrodynamic, hydrochemical and isotopic characterization of the waters of the quaternary aquifer of Bahr-El-Ghazal, north central Chad.

Located in the middle of Sahel, study area is an integral part Bahr-El-Ghazal region. It crossed by a fossil valley, which has geological history similar to that rivers disappeared under influence climate change where evaporation phenomena were intense. From hydrogeological point view, free water table this region housed sedimentary formations different natures. passes from sand tablecloth fluviolacustrine clays. In some cases, latter confer particularly bad chemical qualities water, even though groundwater main source drinking for local population. For reason, aimed at understanding mechanisms govern functioning aquifer Bahar-El-Ghazal been carried out. with mind piezometric being out first instance. This reveals presence hydrodynamic anomalies. Thus, shallow depth body observed Harr and sandy extreme West. However, underground flows oriented these two zones towards central characterize deepening level. Subsequently, hydro-chemical was undertaken. As regards facies, they also show evolutionary character. They pass calcium magnesian bicarbonate facies chloride or sodium potassium sulphate depression. The values isotopic composition studied vary -4.86 4.04‰ -35.60 14.50‰ delta 2H respectively.