HYDROGEOLOGICAL CHARACTERIZATION OF THE SOUTHERN VOLTAIAN SYSTEM: A SIMULATION/OPTIMIZATION APPROACH

In the southern Voltaian sedimentary basin, aquifer hydraulic conductivity and transmissivity respectively range from 0.07 m/d to 3.78 m/d, and 0.5 m2/d to 197.7 m2/d. Aquifer transmissivity is based on the intensity of rock fracturing and weathering. The hydrogeology of the southern Voltaian sedimentary aquifers in the Afram Plains area, Ghana was studied using a ten layer groundwater flow simulation model. Both steady and transient state simulations were performed from available data on the geology and hydrogeology of the area. The flow simulation model suggests that groundwater in the area flows from the central areas, where recharge appears to take place, to the outer regions, discharging into the Lake Volta. Hydraulic heads range from 50 m in some of the discharge areas, to 200 m in the recharge areas. An optimization model, summing up the various water needs, economic and environmental constraints, was linked up with the transient flow model to simulate the effects of various scenarios of extraction on the hydrogeological system. The results of the simulation/optimization model suggest that there is promise for the extraction of groundwater in the aquifers of the southern Voltaian aquifers for various purposes. Wells and boreholes drilled in the outer recharge areas appear to hold much promise for use in commercial irrigation purposes compared to those in the central recharge areas.