Application of electromagnetic and electrical resistivity methods in investigating groundwater resources of the Sunyani Municipality in the Brong-Ahafo Region of Ghana

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Date
2014
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Abstract
Two geophysical techniques, the Electromagnetic (EM) and Vertical Electrical Soundings (VES) were employed to explore for groundwater in thirteen communities in the Sunyani Municipality. The Geonics EM 34-3 was used for the electromagnetic profiling which employed both the horizontal and vertical dipole modes of recording conductivity values. Vertical Electrical Soundings were also conducted with the ABEM Terrameter SAS 1000C using the Schlumberger protocol. The collected data was analyzed using the Grapher 8 and RES1D softwares. A total of 18 EM profiles of length 2.8 km were traversed and 40 vertical electrical soundings established. The interpretation of the 40 VES points suggested that 13 points were suitable for borehole drilling. From the VES curve analyses, it was also revealed that the subsurface structure of 27 out of the 40 VES points were underlain by three lithological layers while the remaining 13 are of four layer types of varying resistivities. The results are indicated slight to moderate fracture development in the bedrock. Results from the interpretation of the data collected led to the inference of low groundwater potential at Antwikrom, low to moderate groundwater potential at Domsesre and relatively moderate to high groundwater potential in the rest of the eleven (11) communities. The use of the integrated geophysical technique employed for this study shows how the two methods can be applied complimentarily to groundwater exploration. Whereas the Electromagnetic (EM) was used as a reconnaissance tool in determining areas of increasing conductivity with depth, the Vertical Electrical Sounding (VES) technique was used in delineating the sequence of subsurface lithologies in order to identify potential aquifers.
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A thesis submitted to the Department of Physics, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the degree of Master of Science (Geophysics)
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