Hydrogeological And Hydrochemical Characterization Of Aquifers In The Akatsi Area, Ghana

Abstract

Groundwater remains the most significant source of water supply in the Akatsi area for multiple purposes. The demand for clean water supply is increasing year after year because of the growth of population and urbanisation in the district. However, without proper monitoring, the quality of groundwater is easily compromised by either natural processes or anthropogenic activities. Some of these activities comprise agriculture, improper disposal of domestic waste, and rock water interaction as found in the area. In addition, there is very little existing research work on the sustainability and quality of water resources in the study area. This study aimed to assess the hydrogeological and hydrochemical properties of aquifers underlying the Akatsi and surrounding areas. Then identify the major processes that influence groundwater hydro-chemistry and its suitability for diverse purposes in the study area. Hence, a thorough quality assessment of groundwater resources and characterization of aquifers of the Akatsi area was carried out by employing conventional graphical methods, and multivariate statistical methods, as well as the Cooper Jacob method using pumping test data. Conventional graphical techniques, R-mode Hierarchical Cluster Analysis (HCA), and Principal Component Analysis (PCA) revealed carbonate and silicate minerals weathering coupled with reverse ion exchange as well as the impact of domestic waste and agrochemicals as the key factors that control groundwater chemistry in the Akatsi area. Q-mode HCA combined with Stiff diagrams indicated that recharge zones are characterized by Ca-HCO3 low salinity waters, which evolve through rock-water interactions to Na-K-HCO3 high salinity waters in the discharge zones. Groundwater quality for domestic purposes was assessed using the weighted arithmetic index technique. The calculated values of water quality indices from the data suggest that over 91% of groundwater samples fall within "excellent" and "good" water categories, whereas 8.1% of the samples fall within the "poor" water category. Groundwater quality assessment for irrigation purposes based on the classification of United State Salinity Laboratory (USSL, 1964), Wilcox and Doneen's diagrams suggest groundwater from the study area is of suitable quality for irrigation purposes, but the levels of salinity increase towards the discharge zones, such that some of the boreholes in the discharge zones may not be acceptable for irrigation purposes on the soils of high salinities, which might affect the osmotic potentials of crops.