The Hydrochemistry of Groundwater in Some Communities in the Ayensu River Basin in the Central Region of Ghana

Abstract

Hydrochemical analysis of groundwater samples in some communities in the Ayensu river basin of the central Region of Ghana was used to establish the hydrochemistry of the study area. The methodology consisted of physicochemical sampling and laboratory analysis of groundwater resources in the Basin and basic statistical analysis of the laboratory results. Generally, the groundwater is weakly acidic with a mean pH value of 6.32, had high electrical conductivity and TDS values in the range, 256.4 µS cm^-1 to 2313.3 µS cm^-1 and 101.7 mg/L to 1247.0 mg/L respectively. The groundwater in the area is undersaturated with respect to carbonate phases and is fresh except for one borehole at Gyangyanadze which has TDS value of 1247.0 mg/L considered as saline water.  The dominant water types in the study area are Na- Cl, Ca- Mg - Cl and Ca - Mg - SO₄. The groundwater is to a large extent potable. However, approximately 13% of the groundwater samples had chloride concentrations slightly exceeding the respective WHO maximum acceptable limits for drinking water. Approximately 43%, 16% and 10% respectively of the water samples had Al³⁺, Fe²⁺ and Cd²⁺ concentrations above the respective WHO maximum acceptable limit for drinking water.  Silicate mineral weathering is probably the main process through which major ions enter the groundwater.

Keywords:Groundwater quality  hydrochemistry  silicate weathering  Central Region  Ghana