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The Magnetotelluric (MT) geophysical method has successfully been applied in groundwater exploration within the Birimian rocks of Mankessim. The technique has provided information on the rocks and structural relationships within the investigative depth of up to 300 m for hydrogeological purposes. The method provides information on the aquiferous zone and the general depth of burial. The study revealed that the resistivity of the subsurface materials within the study area ranges from 0.1 Ωm to 4.0 Ωm. The study shows that the groundwater occurrence in the area is mainly controlled by fractured and weathered zones. It is highly possible to encounter groundwater at the saprock zone. This zone is fractured and weathered zones sandwiched by the overburden and the bedrock. The static water level of the study area is about 25 m. This shallow depth makes the groundwater resource prone to contamination through anthropogenic activities such as the application of agrochemicals and the use of pit latrine which are common practices in the study area. The MT method is effective in the exploration of groundwater within the sedimentary environment.

Hydrogeological investigations to delineate zones of high groundwater potential in five selected communities in the Agona East District of Ghana have been successfully carried out using the magnetotelluric geophysical technique. The technique has successfully been applied to delineate potential zones of high groundwater potential in terms of location and depth-to-aquifer zones. The study has revealed that the apparent electrical resistivity of the subsurface of the study area to a depth of 300 m displays the stratigraphic layers of different resistivities. Eburnean Plutonic suite and the Tamnean Plutonic Suite were the two major geologic materials encountered in the study area. The Eburnean Plutonic suite shows relatively low resistivity rang of 0-480 Ωm at a depth of 0-300 m which indicates the presence of weathered zones capable of holding water. However, the Tamnean Plutonic Suites shows a resistivity range of 200-2800 Ωm which shows that it is a consolidated rock with no developed primary and/or secondary hydrogeological properties such as porosity and permeability. Therefore, the exploration of groundwater in the Tamnean Plutonic Suite depends strictly on the fracture zones which may contain water. Again, the study revealed that the prevailing aquifer systems of the study area are not regional but are controlled by fractures and weathered zones. Therefore, it is highly envisaged that groundwater would be intersected at the saprock region which is the fractured and weathered zone between fresh bedrock and the regolith at the depth of 80-100 m. Also, the study has shown the capability of the magnetotelluric geophysical technique to delineate zones of high groundwater potentials for borehole drilling purpose.

Hydrogeophysical assessment of aquifers in the Upper Denkyira East and West Districts of Ghana has been carried out for groundwater potential and protective capacity of the overburden rocks determination. The data for the study were obtained from the Regional office of Community Water and Sanitation Agency (CWSA), Cape Coast. A total of thirty-seven VES probed using a Schlumberger array with maximum current electrode spacing (AB/2) of 100 m at each point using the Abeam Terameter was used. The data were interpreted using the partial curve matching and WINRESIST computer iteration program techniques. The thickness and resistivities of the various overburden layers, basement resistivity, reflection coefficient and longitudinal conductance were used for the assessment of the groundwater potential and the protective capability of the overburden layers. The study revealed three-to-six layers with an average of four (4) layers including laterite (0.34–3.57 m); clay (0.64–8.84 m); sandy-clay (0.67–27.09 m) and slightly-to-highly weathered bedrock which includes phyllites and granite (3.09–86.89 m) that show high level of heterogeneity of electrical resistivity of the geologic materials within the study area. The weathered layers serve as the aquiferous zones. About 21.6%, 62.2%, 2.7% and 13.5% showed high, medium, low and very low potential for groundwater, respectively, with higher groundwater potentials at the western and south-eastern corner of the study area underlain by the Birimian and Tarkwaian formations, respectively, indicating that the two formations have similar groundwater potentials in the study area. The lowest groundwater potential was observed at the point underlain by the granitic intrusion. The assessment of the protective capacity of the aquifer showed very good (5%), good (27%), moderate (19%), weak (22%) and poor (27%) indicating that the study area is overlain mostly by materials of different protective capacities. This study presents information on the aquifer protective capacity evaluation by using geophysical technique and it has revealed that the Birimian formation has a good aquifer protective capacity than the Tarkwaian formation and has also confirmed the effectiveness of using geophysical techniques in ground investigation.

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