Groundwater potential mapping of the Central Region using integrated geological and geophysical methods

Surface waters across Ghana are deteriorating due mainly to poor farming practices, illegal mining activities and also climate change. In the Central region this has led to a rise in the dependence on groundwater as potable water supply. However, the Central Region is known to be characterized by high unsuccessful rates of borehole drilling for groundwater, which usually results in waste of time and resources. The need to delineate groundwater potential areas in the region has long been felt. This study sought to map and delineate the groundwater potential zones of the Central Region by integrating input variables such as lineaments map deduced from magnetic survey data, digital elevation model, geology, soil type, land use/land cover, drainage density, slope and flow accumulation maps using Fuzzy Logic in a GIS software. The final groundwater potential map of the area was validated using borehole yield data and the reliability testing executed using the area under curve operation technique. Results of the study revealed that the region is characterized by very low to high groundwater potential zones. High groundwater potential zones cover the least of about 1083.7 km2, representing 11.17% and moderate groundwater potential zones cover about 1978 km2 constituting 20.4%. About 3461.16 km2 of the region representing 35.68% and 3176.88 km2 (32.74%) were found to have low and very low groundwater potential respectively. The final output revealed that the high potential areas are mainly located in the central part of the region which is mainly occupied by fractured granitoids. The low groundwater potential areas are mostly encountered in the southeastern but are found also in the northern and central part of the region and fall mainly on non-porous metavolcanics rocks. It is anticipated that the groundwater prospectivity map could be used as a valuable source for sustainable water resource management and development in the Central Region and also serve as guide for drilling campaigns in the region.