TITLE:
Hydrogeological and Hydrochemical Assessment of Basin Granitoids in Assin and Breman Districts of Ghana
AUTHORS:
Asare Asante- Annor, Joseph Acquah, Ebenezer Ansah
KEYWORDS:
Hydrogeological Assessment, Aquifer Geochemistry, Groundwater Quality, Basin Granitoids, Ghana
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.6 No.9,
September
3,
2018
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/Sw) 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 m2/day with mean of 0.24 m/day and 3.03 m2/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
Ca2+ > Na+ > Mg2+ and Cl− > HCO3− > SO42− respectively. The study area
shows five main water types namely; Ca-HCO3, Na-Mg-HCO3-SO4, Ca-SO4,
Na-Cl and Mg-Na-Cl. Weathering of rock-forming minerals as the mechanism
controlling the groundwater chemistry. Microbiological parameters were above the permissible limits. Groundwater is suitable for drinking after
treatment with chlorination, aeration and slow sand filtration methods.