Groundwater evolution in the Voltaian Basin, Ghana-an application of multivariate statistical analyses to hydrochemical data

Multivariate statistical methods were applied to hydrochemical data obtained from various field sampling campaigns in order to highlight the major groundwater types and the evolution of groundwater from recharge areas to discharge areas in the groundwater flow regime. Four factors were distinguished: dissolution of chlorides of the major ions, silicate mineral weathering and organic matter oxidation, dissolution of kieserite group of minerals, and anthropogenic conta mination. Of all these factors, silicate mineral weathering is the most pervasive throughout the study area. This is apparently due to the presence of silicate minerals almost everywhere in the terrain. This analysis was determined by means of factor scores computed from the factor loadings and the standardized dataset through regression. The resulting refined factor scores were then interpolated by ordinary kriging. The dissolution of the chlorides and kieserite group of minerals are limited to locations where such minerals are present in the lithology. Anthropogenic contamination of the aquifers occurs almost everywhere within the basin but the effects are generally low.