Journal of Earth Sciences and Geotechnical Engineering
Ground Water Exploration using Geoelectrical investigation in Bafia Area, Cameroon
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Abstract
Fifty Schlumberger electrical soundings were carried out in the centre region of Cameroon in Bafia subdivision. These were done using a maximum current electrode spacing AB/2 of 83 m in order to show the vertical distribution of structures directly below measurement stations. The field data were smoothened and interpreted using IP2WIN computer software. This software converts the apparent resistivity (as a function of electrode spacing) to the true resistivity as a function of depth. The depth and resistivity of the subsurface layers were determined. Also, the isoapparent resistivity maps for two depth levels (according to AB/2 range of about 4.4m and 58m), discharge map, hydraulic conductivity and transmissivity maps are drawn. The results from the interpretation of VES data reveal the presence of following terrains models’ types: three layers (Q, A, H and K), four layers (KH, QH, AK and KQ) and five layers (KHK, HKH, KQH, and KHA) models. The following geoelectrical layers are: (1) the top layer with resistivity ranging from 6.5 to 301.3 Ù.m and thickness ranging from 0.1 to 6.6 m. (2). The second layer has resistivity varying from 0.1 to 4100 Ù.m while the thickness varies from 0.2 to 63.8 m. It is composed of cracked granites and gneiss, or clay sandy or clayey soil which contributes to the development of groundwater.(3) The third layer, characterized by electrical resistivity value ranging from 0.2 to 2965 Ù.m in most parts of the area and with depth ranging between 0.6 and 41.4m. This layer corresponds probably to shaly layer or confined aquifer. (4) The forth geoelectrical layer, which may constitute the bedrock, has resistivity values ranging from 14.16 to 11189 Ù.m and depth ranging from 17 to 79.4m. The high resistivity is probably caused by existing gneisses and granites. In addition, the relationship between discharge, hydraulic conductivity and transmissivity is used to determine zones with high yield potential for groundwater exploitation in the area.
