Physico-Chemical Analysis of Surface and Groundwater in the Ayensu River Basin in the Central Region of Ghana

Abstract

The hydrochemistry of the Ayensu river basin in the central Region of Ghana has been established. The methodology consisted of physicochemical sampling and laboratory analysis of both groundwater and surface water resources in the Basin and basic statistical analysis of the laboratory results.. Generally, the groundwater is weakly acidic with a mean pH value of 6.33±0.01, had high electrical conductivity and TDS values in the range, 297.65 to 6011.0 and 100.85 to 2746.0 respectively. Three main hydrochemical facies have been identified in the basin. These are Na- Cl, Ca- Mg - Cl and Ca - Mg - SO₄ water types. Groundwater is to a large extent potable. However, approximately 24% and 22% respectively of groundwater samples had chloride and sulphate concentrations slightly exceeding the respective WHO maximum acceptable limits for drinking water. The concentrations of aluminium, iron and manganese were the only minor ions that significantly exceeded their respective detection limits. Nearly 43% of the groundwater samples had the Al³⁺ concentrations exceeding the WHO acceptable limit of 0.2 mg/l for drinking water, which reflects the acidic nature of the groundwater. The main geochemical process influencing the hydrochemistry of the Ayensu river basin is mineral dissolution.

Keywords Groundwater quality, hydrochemistry, Mineral dissolution, Central Region Ghana.