Geo-Electrical and Borehole Investigation of Groundwater in Some Basalts on the South-Eastern Flank of Mount Cameroon, West Africa

摘要

The study area, located on the southwestern flank of Mt. Cameroon, is under-lain by basalts. The occurrence of groundwater in these rocks has been evaluated in order to determine their potentials as a source of water for a water bottling and soft drink plant. To achieve this, the constant separation traversing (CST) was used and the data qualitatively analyzed to determine the occurrence of fractures as most probable borehole sites. From this analysis, three sites were selected, sites at which a vertical electrical sounding (VES) was done and interpreted. Results obtained show a four layered earth profile model type KHKH, corresponding to a typical weathered/fractured confined aquifer type curve. This profile was later confirmed from borehole information after drilling at three of the selected sites. The comparison of VES data with geological sections is corroborative. A constant rate pumping test was done at rates as well as the investigation of other hydraulic properties. The results obtained for hydraulic properties investigated for all three boreholes reveal that productivity is very good and these results also reveal that at maximum exploitation rates, lowest tolerable drawdown for all three boreholes may not be reached after ten years. Chemical analysis done in-situ and on samples at the laboratory reveal that this water has a better mineralisation compared to other bottled water brands sold on the Cameroon market.