Delineation of groundwater potential zones using cokriging and weighted overlay techniques in the Assin Municipalities of Ghana

This study has employed cokriging and weighted overlay techniques in a GIS environment to delineate groundwater potential zones from hydrogeological parameters in the Assin Municipalities, Ghana, where groundwater is the main source of potable water but access to it is less predictable since the aquifers are structurally controlled. Data from drilling logs, borehole development and construction, and pumping test on 67 boreholes in the area were utilized to estimate the hydrogeological parameters such as borehole yield, transmissivity, specific capacity, aquifer thickness and water strike elevation. Then, using the cokriging and weighted overlay techniques in ArcGIS, spatial thematic maps were created for all the parameters and integrated to produce the groundwater potential map, which categorized the study area into very low, low, moderate, and high groundwater potential zones. The results revealed that the cokriging technique was better in delineating the groundwater potential zones of the study area with a prediction accuracy of 67%, while the weighted overlay approach had an accuracy of 44%. However, the delineated moderate and high groundwater potential zones in the area for both approaches were largely the same and underlined by granitic rocks. Also, the generated groundwater potential map categorized approximately 0.1% (2.78 km 2 ), 35.2% (850.45 km 2 ), 43.6% (1054.62 km 2 ) and 21.1% (509.15 km 2 ) of the study area as very low, low, moderate and high groundwater potential zones, respectively. Thus, the study provides very useful information on groundwater potential zones delineation, which would aid in effective exploration and development of groundwater resources.