Abstract:
This paper surveys the aquifers and the groundwater resources landscape in Ghana to identify the critical resource issues constraining the development and management of groundwater throughout the country. The research is based on a collation of the recent data on the hydrogeological properties of the different geological terrains in the country. This study finds that there are five main hydrogeological provinces distinguished by their well yields, lithology, and groundwater quality. This latest hydrogeological zonation, which is an improvement over previous works consists of the Birimian Province, the Crystalline Basement Granitoid Complex Province, the Voltaian Province, the Pan African Province, and Coastal Sedimentary Province. The hydrogeological properties of each province are discussed. The most prolific aquifers in the country have been identified among the fractured and weathered zones within the Togo Series, Buem Formation, Birimian and Tarkwaian System rocks. Aquifers of these rock formations also offer groundwater of the best quality for most uses in the country. Hydrochemical data gathered from wells drilled through all the hydrogeological terrains in the country for this study suggest that groundwater hydrochemistry is controlled principally by the weathering of silicate minerals and cation exchange activity. These processes are pervasive throughout the country. In isolated areas, groundwater contamination due to domestic waste discharge and agricultural activities has been noted. Four groundwater types have been identified based on Q-mode hierarchical cluster analysis and conventional graphical methods. In the coastal areas such as the Keta basin, seawater intrusion has been identified as one of the major influences on hydrochemistry of groundwater in the shallow unconfined aquifers. On the basis of the hydrochemistry, groundwater suitability for irrigation purposes is copiously discussed. The aquifer management problems can be posed as follows. There is inadequate knowledge base of the aquifer geometry and safe yield characteristics of most of the aquifers in the country. There is also inadequate information to address the status and trends in groundwater quality for most areas of the country. The following emerging issues have been identified: anthropogenic effects on groundwater quality; salt-water intrusion in coastal aquifers, groundwater depletion or inadequate supplies from groundwater to meet human needs; uncertainties about recharge and sustainability due to increased abstraction; as well as lack of institutional capacity to respond adequately to sustainable groundwater use. Recommendations to ameliorate these problems include the strengthening of institutional capacity for comprehensive national evaluation of groundwater resources, including aquifer delineation and pro-active strategies to reduce groundwater abstraction to safe yield levels and adoption of aquifer protection strategies for overall protection of groundwater quality. © 2011 by Nova Science Publishers, Inc. All rights reserved.