Assessment of Groundwater Mineralization Processes in Mbakaou Area (Adamawa Plateau – Cameroon), by Using Conventional Diagrams and Multivariate Statistical Analysis

Abstract

Management of groundwater require knowing their qualities and hydrogeochemical processes whereby these waters acquire their mineralization. The population of Mbakaou in Adamawa Plateau consumes groundwater from a doubtful quality water supply structures (wells, boreholes and catchments). This study was carried out to highlight groundwater quality and processes that govern water mineralization. So, to achieve this, 11 water samples were analyzed (1 rain water, 1 well, 3 springs and 6 boreholes). After analyzing the samples and comparing the obtained values to World Health Organization (WHO) standards, multivariate statistical analysis including Principal Component Analysis (PCA) were applied. Results show that these waters samples are fresh, generally of good quality compared to WHO standards and weakly mineralized (35 to 247.9 mg/l), due to the short residence time. Calcium and magnesium bicarbonate facies is the main water type. Nitrates are the most common pollutants and reveal high vulnerability of saprolite aquifer than fractured aquifer. The groundwater mineralization is influenced by precipitation, base ion exchange process, anthropogenic activities and water-rock interaction through silicate weathering. The PCA analysis yielded three factors that explained 89.33 % of the total variance. Factor 1 (62.60 %), factor 2 (15.54 %) and factor 3 (11.19 %) made respectively the difference between water samples influenced by precipitation or water rock interaction from those influenced by both water-rock interaction with precipitation or anthropogenic activities and those for water rock interaction with ion exchange process.