Hydrogeological Properties of the Rocks in Adansi Mining Area, Ghana

Abstract

Groundwater is an important resource in the Adansi mining area as certain communities are not connected to the Ghana national water network. These communities therefore utilise groundwater for their potable water supply. The hydrogeological properties of an aquifer coupled with climatic conditions and geomorphology will determine how much groundwater exists in that location. The properties of groundwater which influence its spatial availability include the transmissivity, hydraulic conductivity, specific capacity, yield, drawdown, storativity and porosity. A hydrogeological study of the rocks in the Adansi area has been carried out to obtain the aquifer hydraulic parameters of the area. Drilling and pumping test analysis were used to assess these parameters. The average borehole depth for the study area was 44.3 m whilst the average static water is 10.75 m. There is a general decrease in maximum yield with an increase in borehole total depth. There is no strong correlation between aquifer saturated thickness and maximum yield and drawdown. The transmissivity decreases from the phyllite, argillitc sediments, granites to sandstone. Three hydrogeological regimes (> 0.9 m/day, 0.9 – 0.09 m/day and 0.09 m/day) were realised based on the hydraulic conductivity. The spatial distribution of the hydraulic properties suggest the influence of geological structures on the occurrence of groundwater.