Abstract:
Groundwater samples collected from 40 institutions and public boreholes within the Twifo Hemang Lower Denkyira (T), Assin North (AN) and Assin South (AS) districts of the Central Region of Ghana were assessed to determine their suitability for domestic and agricultural purposes, based primarily on recommended permissible limits for parameters stated by World Health Organisation. The area covers an area of about 4,199 km2. The quality assessment was made through the estimation of Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO3-, TH, TDS, EC, and pH. Based on these analyses, parameters like SAR, %Na, RSBC, PI, MAR and KR were calculated. The physicochemical parameters analyzed indicate that the order of abundance of the cations concentration is Ca2+>Na+>Mg2+>K+ while that of the anions is HCO3->Cl->SO42->NO3-. An appraisal of the Piper diagram reveals that the general groundwater type dominating the study area is Ca-HCO3. The scatter diagram of Ca2++Mg2+ vs. HCO3-+SO42 depicts that greater percentage of the samples plot above the equiline illustrating that carbonate weathering is the dominant process producing Ca2+ and Mg2+ in the groundwater. The relationship, Na+K-Cl vs. Ca+Mg-HCO3+SO4 shows that the hydrochemical behavior of the major ions in groundwater is also due to cation exchange processes. The Na+K-Cl ions represent the contribution of sources other than the dissolution of halite to the concentrations of Na+ and K+ in water. As per the Gibb‘s diagram, majority of the samples fall in the rock dominance area indicating that the presence of the major ions is as the result of weathering and dissolution of rocks. The assessment of groundwater in study area reveals that the water is generally suitable for domestic and irrigational purposes.
