Delineating Zones of Groundwater Recharging Potential using Geospatial Techniques Integrated with GRA-TOPSIS - A Case Study of Wassa West District of the Republic of Ghana
Identifying and analyzing environmental parameters for assessing groundwater existence and recharge potential using geospatial techniques is crucial and cost effective, particularly for areas where surface water is contamination due to illegal mining activities. In this study, GIS and Multi-criteria decision analysis tool, GRA-TOPSIS, were used to identify groundwater recharge zones in the Wassa West District of Ghana. The study considered geo-environmental factors such as slope, soil types and lithology, land use and land cover types, drainage, and lineament density to map the groundwater recharge zones. Overlay analysis tools in ArcGIS and GRA-TOPSIS were used to select suitable areas, rank and assign weights to the contributing factors to produce the final map. The recharge zones were classified into four categories based on their potential: extremely high, high, moderate, and low. Results showed that 1% of the study area had an extremely high recharge potential, 25% had a high recharge potential, while the majority of the district (73%) had moderate recharge potential. Areas with low recharge potential constituted only 1% of the total area. The results were validated by location data of drilled boreholes using handheld GPS. Depths of boreholes ranged from 35 m to 62 m with yields ranging from 8.1 m3/h - 14.3 m3/h. The study has revealed that lineament density could be used as a proxy for groundwater recharge potential for the study area. The study demonstrated that GIS integrated with GRA-TOPSIS model provides an effective and fast method for identifying the distribution of groundwater yield potential zones in the study area. The findings can support water resource managers in promoting sustainable groundwater management in the Wassa West District of Ghana.
