Hydrogeological Characteristics Of Aquifers In The Greater Accra Region

The economic importance of groundwater in the Greater Accra Region cannot be overemphasized, since supply from boreholes and wells continues to be the most dependable alternative sources of water for most rural and urban communities in the region. Three different consolidated hard rocks underlie the region making it difficult to produce volumes of groundwater for supplies. Demand for portable water has led to the drilling of large numbers of boreholes. This study statistically assesses the general conditions of groundwater resources for successful exploitation, classify areas for prolific groundwater exploration and assess the quality of water in the region to be used for domestic purposes. Statistical approach was adopted to compare the variability and distribution of specific capacity and transmissivity values of existing boreholes in the various hydrogeological units. Hydrogeological units were classified using Krasny’s transmissivity classification in order to delineate prospective zones for groundwater exploration. The results from the Krasny’s transmissivity classification showed Transmissivity coefficient of 197m 2 /day, 197.3m 2 /day and 211.3m2 /day for Dahomeyan, Granitoids and Togo hydrogeological units respectively. All the hydrogeological units belonged to the class of transmissivity magnitude class II which depict high transmissivity coefficient that suggests abstraction potential suitable for regional supply. The transmissivity indices are 6.04, 6.23 and 6.24 for Birimian Granitoids, Dahomeyan formation and Togo formation respectively. These categorised all the three hydrogeological units into moderate variation in a heterogeneous environment but the Togo formation being the most prolific. Based on WQI most of samples are suitable for domestic purpose except for few locations, which show values beyond the permissible limits that cannot be used without treatment.