| Abstrakt: |
The Adamawa region of Cameroon is facing the problem of setting up and mobilizing groundwater, in line with the quantity and quality of water. In fact, we have many borehole failures in this part of country due to the lack of knowledge about the influence of lithology and their structures on the productivity of aquifers. In addition, we noted waterborne diseases due to the lack of knowledge about water quality and hydrogeochemical processes. This study was carried out in order to provide a solution to this problem, by combination of geological and geophysical prospecting on ten sites and then followed by the completion of 7 boreholes with six samples of groundwater analysis (R023, R480, R481, R569, R570, and R571), before the commissioning of the works. Geological study with completion of boreholes showed that the aquifers exploited consisted of fractured granites, weathered and fissured basalts, and sometimes phonolites. The ten vertical electrical soundings (VES) modeled showed seven models of curves (AKH, H, HKH, K, KH, KQ, and QH) that allow to distinguish resistive to conductive layers which in main case constitute fractured aquifers (between 20 and 65 m depth) and whose resistivity ranged from 8.247 to 916.7 Ω.m. The boreholes have yields varying between 0.8 and 4.5 m3/h. The permeability varies from 10−7 to 10−5 m/s, and the transmissivity varies from 10−6 to 10−4 m2/s. Based on order of borehole yields and VES shape, HKH, AKH, KH, QH, and K curve models are more favorable to drill a positive borehole in this area and other part around the world where we have same geological conditions. The hydrogeochemical study shows that groundwaters are weakly mineralized (34.11 to 354.23 mg/l) and meet the WHO standards for drinking, coming from recent infiltration of rain and influenced mainly by water–rock interaction process. These groundwaters have low time residence and have a dominant calcium and magnesium bicarbonate facies. [ABSTRACT FROM AUTHOR] |
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