Groundwater potential of Basement rocks of parts of the Volta River Basin in Ghana

摘要

The study area is located in a semi-arid region, within the Volta River Basin, covering approximately 30 000 km~2 in the Upper East and Upper West Regions of Ghana. A major drilling campaign took place in the study area between 1973 and 1979 by the Canadian International Development Agency collaborating with the Ghana Water and Sewerage Corporation. To date, these wells have alleviated the paucity of potable water in the study area. The main objective of this study is to investigate the groundwater occurrence and hydrogeological characteristics of the underlying basement rock aquifer within the Volta River Basin. Precambrian granites and migmatites, strewn with quartz-veins, pegmatites and fractures, underlie about 95 percent of the study area. Groundwater occurrence is closely linked to the extent, thickness, depth and degree of interconnection of these fractures. Most of these rocks are highly weathered, facilitating groundwater influx and storage into the fractures and decomposed zones. The average yields of hand pump wells and fuel pump wells are 25.6 m3 clay"' and 130 m~3 day~(-1), respectively. These yields can serve the domestic water needs of 560 and 2,800 people respectively on the basis of water use of 4.6 x 10~(-2) m~3 day~(-1) (10 imperial gallons) per day per person.