Recent Investigation on Hydrogeology of the Basin Granitoids in the Sekyere South District of Ashanti Region, Ghana

Communities in the Sekyere South District of the Ashanti Region of Ghana experience water
shortages because majority of the existing water supply systems are primarily based on ephemeral
surface water sources that are fed by rainfall but not evenly distributed all-year round. The
hydrogeology of the Basin Granitoids in the Sekyere South District of Ashanti Region of Ghana has
been evaluated applying the electrical resistivity imaging (ERI) geophysical technique and pumping
test analysis. The ERI was conducted to obtain information on resistivity distribution for groundwater
accumulation and pumping test was used to obtain transmissivity and sustainable yields of boreholes.
Results from the ERI technique show that the general resistivity distribution in the area is between (20
- 4000) Ω-m and the resistivity range that is related to groundwater occurrence is between (50 - 300)
Ω-m for the weathered and (100 - 600) Ω-m for the fractured granitic rocks. The aquifers are generally
shallow to medium depth and where resistivities of the aquifer zones are less than 400 Ω-m in the
fresh granites, high yields are likely to be attained. Pumping test also revealed that transmissivity
values range between (5.89 - 43) m2/day, with sustainable yields ranging between 50 - 380 m3/day.
These results suggest that boreholes in the area will be sustainable for domestic supplies.
Transmissivity values obtained show that the boreholes in the area can be used for domestic
purposes for individual homes and small town water supply schemes.
The results from this study could serve as a guide to groundwater exploration in the Granitoids in the
area and similar geology.