Hydrogeological and Hydrochemical Assessment of Basin Granitoids in Assin and Breman Districts of Ghana

Abstract

Hydrogeological and hydrochemical assessments were carried out in Assin and Breman districts of Ghana. A multi-criteria approach was used in the assessment of the basin granitoids including; electrical resistivity survey, pumping test and water quality analysis. A total of twenty-five (25) representative boreholes were drilled, developed and pumped; obtaining data for aquifer hydraulic parameters estimation. Correlation analysis was used to determine relationships that exist between aquifer hydraulic parameters. Schoeller, Piper, Stiff plot and Gibbs diagrams were used to determine the hydrogeochemical facies, water types and the mechanism that control groundwater quality. The statistical analysis determined that aquifer hydraulic parameters discharge rate (Q), hydraulic conductivity (K) and Transmissivity (T) showed a strong positive correlation with specific capacity (Q/S w) with R value 0.8462, 0.8738 and 0.8332 respectively. The K and T were respectively between 0.02-0.90 m/day and 0.36-13.47 m 2 /day with mean of 0.24 m/day and 3.03 m 2 /day respectively. The K values indicate a hydrogeological condition of aquiclude with relatively low permeability and medium water bearing capacity. The aquifer T magnitude is very low to low, groundwater potential is adequate for local water supply with limited and private consumption. All physicochemical parameters were within the permissible limits of Ghana Standards Authority (GSA) and World Health Organisation (WHO) except for apparent colour, pH, Fe and Mn. Distribution of major ions in groundwater samples was calculated and the general trend among cations and anions was found to be

Water Safety Planning and Implementation in a Ghanaian Small-scale Water Supply System

“…High levels of colour were observed in the raw water. The average colour level for the boreholes for the 3 sampling dates ranged between 64.4 and 131 Pt-Co, as compared to a guideline value of 15 Pt-Co [16], and an average of 7.7 Pt-Co reported for boreholes in the Densu basin of Ghana [34]. Similarly, the levels of turbidity were high, with averages ranging between 11.6 and 22.3 NTU and a maximum of 35.2 NTU being recorded.…”

“…Even though the concentration of iron was not measured in this study due to resource constraints, the more likely cause of high colour and turbidity levels could be the presence of iron since the boreholes were less than five years old. Moreover, Asante-Annor [34] reported high level of colour, turbidity and iron in groundwater from Assin Fosu and attributed the results to the geological formation of the area. The high iron levels in the groundwater may have necessitated the installation of the Aquatec filtration units.…”

“…Similarly, a mean pH of 6.34 has been measured in ten districts/ municipalities/ metropolitan areas (including Assin Fosu) in the Central Region [32]. Generally, the pH of groundwater is influenced by the nature of the geology of the area [33] which is reported to be granitoids in Assin Fosu with an average groundwater pH of 6.04 [34].…”

Investigation of Groundwater Quality with Borehole Depth in the Basin Granitoids of the Ashanti Region of Ghana

“…Groundwater, also a major water supply resource, has been modestly exploited over the last two decades to meet water supply needs in many rural communities in Ghana, where over 95% is used for domestic purposes [8] [15] [16] [17]. Three main factors appear to control the occurrence of groundwater in the basin granitoids: the extent and effect of rock decomposition, the presence of quartz aplite and pegmatite veins, and the presence of fracture openings [18] [19] [20] [21]. According to [20], the most important factor affecting groundwater accumulation in the Birimian Province is rock decomposition.…”

“…In the literature, extensive groundwater quality assessments in Ghana have been carried out by [7] [18] [26]- [35] and several others, but these have mainly emphasized spatial variations in quality and pollution, the determination of chemical constituents of the groundwater, and the constituent's concentration levels in conformity to local and international acceptable limits.…”