Reconnaissance visit to assess the hydrogeology of the Oku area, Sekyere West District, Ashanti Region, Ghana

The Oku area of central Ghana experiences severe water shortages during the October to March dry season. Surface water in the form of rivers and ponds is widely available in the wet season, but tends to dry up during the remainder of the year. Diseases associated with contaminated drinking water are prevalent. A large proportion of boreholes drilled into the well-lithified low permeability sandstones fail after two or three years, because despite the high seasonal rainfall, rates of recharge to the aquifer are very low. Boreholes typically yield only a few basins of water a day, and need to be left overnight to recharge. This leads to long queues, and forces some people to turn to potentially contaminated surface water sources. Successful boreholes have been sited along shallow river valleys and on structural lineations, but these boreholes are often not near settlements. Several options exist for improving the water supply in the Oku area, including the following: 1. Small dams or bunded ponds. 2. Large diameter shallow wells constructed in alluvium. 3. Further boreholes. 4. Rainwater harvesting. 5. The artificial recharge of existing boreholes using rainwater or filtered surface water. The last option would allow existing water points to be used, and would contribute towards avoiding the problems of contaminated surface water. However, the permeability of the aquifer may be so low that recharge rates would not be able to meet the water needs of the community. It is likely that a system of seasonal conjunctive use involving some or all of the above options will prove to be most effective