Hydrogeologic framework and borehole yields in Ghana

In Ghana, 68% of the population live in rural communities, which are scatte red and remote. Groundwater is the most feasible source of potable water su pply for most of these dispersed and remote settlements. To meet the presen t and future challenges of population expansion vis-a-vis the observed decl ining rainfall in most parts of Africa including Ghana, it is necessary to assess, efficiently manage, and utilize the groundwater resources. The obje ctive of this paper is therefore to describe the hydrogeologic framework an d analyze borehole yields as part of the groundwater-resources assessment o f Ghana. The hydrogeologic units are broadly categorized as: (1) the Baseme nt Complex (crystalline rocks), which underlies about 54% of the country; ( 2) the Voltaian System, which underlies about 45%; and (3) the Cenozoic, Me sozoic, and Paleozoic sedimentary strata (Coastal Provinces), which underli e the remaining 1% of the country. The Basement Complex and the Coastal Pro vinces have higher groundwater potential than the Voltaian System. This is particularly significant, because the Basement Complex and the Coastal Prov inces underlie the most densely populated areas of the country and can henc e be tapped for human use. The average bore hole yields of the Basement Com plex, the Coastal Provinces and the Voltaian System range from 2.7-12.7, 3. 9-15.6, and 6.2-8.5 m(3)/h, respectively.