Hydrogeochemical characterization of the areas of exploitation of the CBG sites: cas of the plateaus of N'Dangara and Boundou Wandé, Sous-préfecture de Sangarédi, Prefecture of Boké, Republic of Guinea

Abstract This work aims to analyze the quality of groundwater in the riparian areas of the bauxitic plateaus of N'Dangara and Boundou Wandé in operation by the CBG (Compagnie des Bauxites de Guinée). The geology of the study area consists mainly of sedimentary formations of the Devonian faro, Neogene and Quaternary. Three water measurement and sampling campaigns on the two plateaus were carried out with determination of piezometric measurements and physic-chemical parameters. This study showed that the general flow direction of groundwater is dispersed. The flows at Boundou Wandé are from the center of the plateau to the north and that at N'Dangara is from the center to the south and southwest. It can be seen that the direction of groundwater flow reflects overall the relief of the deposit conditioned by its geomorphological framework. It emerges from the analysis of physical and chemical parameters that well water is consumable. However, the water from wells MW15, MW16, MW17, MW18 and MW21 with a low pH (4.84 to 5.13) may present a certain nuisance for its consumption and because it can be corrosive. Analysis of the Piper diagram showed two hydrogeochemical facies (calcium and magnesium bicarbonate facies and sodium and potassium carbonate facies). However, this study strongly suggests continuous monitoring of groundwater in and around the study area in order to meet the demand for water supply to communities without compromising the ability of future generations to meet water quality requirements.