Assessment of Hydrogeoelectrical Characteristics of Crystalline Aquifers and Groundwaters Quality in Adamawa Plateau: Case of Mbakaou (Adamawa - Cameroon)

Abstract

Population in Adamawa Plateau faced to borehole failure and return to alternative water supply structures (wells and catchments) with a doubtful quality. This study was carried out to highlight the location of aquifers, their hydrodynamics characteristics and groundwaters quality in Mbakaou locality, which belong to the Adamawa Region. Combination of geological and geoelectrical surveys at 10 stations, with hydrodynamic study of 4 boreholes were carried out to characterize aquifers. Hydrochemical analysis of 10 waters samples has been done to determine physico-chemical water quality and origin of waters mineralization. Geological studies show that basement rocks, which constitute fractured aquifers, consists of a large assemblage of granitoid. Geophysics and drilling data highlight superficial aquifers located between 2 and 17 m and fractured aquifers located between 11 and 74 m, with resistivity ranging from 50 to 671 Ω.m. The borehole have yield varying between 2.80 and 5.14 m3/h. Transmissivity and permeability ranging from 10-6 to 10-5 m2/s and 10-7 to 10-6 m/s respectively, indicating that aquifers are semi-permeable. Waters are of good quality compared to WHO norms and weakly mineralized (35 to 247.9 mg/l). Piper diagram show that calcium and magnesium bicarbonate facies is dominant. Mineralisation of water is mainly influenced by water-rock interaction through silicate weathering.