Prospecting for groundwater using the electromagnetic method in the Voltaian Sedimentary Basin in the Northern region of Ghana – a case study of the Gushiegu-Karaga district

Abstract

The Gushiegu-Karaga District is one of the most deprived areas in the Northern Region of Ghana in terms of water supply. Only about 15% of the population have access to potable water, and has a chronic water supply problem. In an attempt to improve the water supply situation the Ghana Rural Water Project (GRWP) of the World Vision initiated Conrad-Hilton Funded Borehole Water Project in Gushiegu-Karaga district, with the objective of drilling 100 wet boreholes. In this study a ground geophysical technique, the Electromagnetic (EM) method using the GEONICS EM 34-3 equipment has been used to delineate and locate water-bearing zones. The EM profiles of interest were analysed and interpreted qualitatively to locate suitable and potential sites to drill boreholes for groundwater abstraction. Drilling results and findings from drill logs show that the mean depths of productive and unproductive boreholes were 41.0 and 64.0 m respectively. The groundwater producing zones were found to be between 30.0 m and 60.0 m depths. A minimum yield of 10 litres per minute has been used as the basis for a borehole to be successful. However, 60% success rate was achieved out of 100 boreholes drilled. When compared with the success rate of drilling productive boreholes, the 60% success achieved was higher. It is recommended that the EM method, which is fast, efficient, less laborious and cost effective, be used to locate suitable borehole sites in programmes aimed at accelerated rural water supply to the rural communities in the district. Journal of Science and Technology Vol. 25(2) 2005: 53-65