Characteristics of a crystalline granitic aquifer in north-western Ghana

2011

english

The groundwater potential of north-western Ghana has been assessed in terms oftransmissivity and specific capacities of the basement aquifers. Data from short-term and constant-discharge pumping tests on 14 boreholes were analysed. The Cooper-Jacob straight line analytical method was used to determine the aquifer characteristics. The computed transmissivity values of the aquifers varied significantly from 0.37 to 44.5m2 d-1 ; with their specific capacity values ranging from 1.04 to 56.7 m3 d-1m-1 • The storage coefficient from four observation boreholes indicated that the aquifers were under confined conditions with values in the order of 10-5• Total head losses of the boreholes anributed to laminar and turbulent flows ranged from 28 per cent to 84 per cent. The aquifer characteristics confirm that groundwater occurrence is localised, confined and controlled by the development of secondary porosity. Therefore, to obtain adequate water for sustainable use, groundwater abstraction in the study area should be preceded by extensive geophysical investigations using integrated methods.

Agyekum, W. A.; Kankam-Yeboah, K.