Combined Electrical Resistivity Imaging and Electromagnetic Survey for Groundwater Studies in the Tarkwa Mining Area, Ghana

  • Jamel Seidu University of Mines and Technology
  • Anthony Ewusi University of Mines and Technology
  • Jerry S. Y. Kuma University of Mines and Technology

Abstract

The major source of potable water in Tarkwa is the Bonsa Treatment Plant sourced from the Bonsa River. The activities of illegal miners along the banks of the Bonsa River has resulted in pollution of the river. This has resulted in high treatment cost and irregular supply of water to the Tarkwa Township and surrounding communities that are fed by the Bonsa Treatment Plant. In view of the difficulty in getting frequent and regular potable supply of water, people have resorted to construction of boreholes and hand-dug wells. However, the success rates and borehole yields are low especially in the hydrogeologically difficult terrains in the Tarkwa area. The aim of this paper is to investigate the hydrogeological conditions of the Tarkwa area using both the Electrical Resistivity Imaging (ERI) and Electromagnetic (EM) geophysical techniques to determine the electrical resistivity and conductivity values that are related to groundwater accumulation, so that potential water-bearing zones can be identified. Results from electrical resistivity show that the general resistivity distribution in the Tarkwa area is between 32 Ωm and 100 000 Ωm. Water-bearing zones in the Huni Sandstone occur to a depth of 35 m with an average resistivity value of 400 Ωm, at a depth of 60 m and a resistivity of 600 Ωm in the Tarkwa Phyllite, at a depth of 55 m and a resistivity of 600 Ωm in the Banket Series and 50 m depth with resistivity value of 500 Ωm in the Kawere Conglomerate respectively. The electromagnetic conductivity values also show that the general conductivity distribution in the Tarkwa area is 3 – 32 S/m. The application of electrical resistivity and electromagnetic techniques separately gives success rate of 80 % and 65 % respectively. An improved success rate of 86 % is achieved combining the two techniques.

Author Biographies

Jamel Seidu, University of Mines and Technology
Assistant Lecturer
Anthony Ewusi, University of Mines and Technology

A. Ewusi holds a PhD Hydrogeophysics and an MSc in Environmental Hydrogeology from the Brandenburg University of Technology, Germany. He obtained a BSc (Hons) Geological Engineering from the Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana. His research interests are in groundwater management and geophysics. He is currently a Senior Lecturer in the Geological Engineering Department, UMaT.

Jerry S. Y. Kuma, University of Mines and Technology

J. S. Y. Kuma is a Professor in Environmental Hydrogeology and Geophysics at the University of Mines and Technology (UMaT), Tarkwa. He was awarded a BSc (Hons) in Geology and Physics at the University of Ghana, Legon. He received the Pg Dip and MSc degrees in Geophysics at Delft, The Netherlands. Professor Kuma received a PhD in Water Resources Engineering from the University of Newcastle upon Tyne, England. He is currently actively involved in mine water hydrogeological research and water management issues.

Published
2019-06-29
Section
Geological Eng. Article