Assessing water quality using water quality index and multivariate analysis

Groundwater is increasingly gaining significance as the main solution to the water supply problems in Ghana, especially in the rural areas. This study was conducted to determine which factors play significant roles in the hydrochemistry of groundwater from the southern Voltaian formation. Conventional graphical and multivariate statistical methods were used. The study reveals three main factors controlling the hydrochemistry. Silicate mineral weathering and reverse cation exchange are the most important processes affecting the hydrochemistry of groundwater at this part of the formation. Interpolation maps created from factor scores suggest that these processes are the most pervasive, recording high scores almost everywhere in the study area. Carbonate mineral weathering is the second most important process in the hydrochemistry. This study finds that carbonate mineral weathering in the area is probably facilitated by carbonic acid rather than sulfuric acid. Chemicals from agricultural activities constitute the third most important process influencing groundwater quality in the area. Eighty samples were used to calculate water quality indices, WQI, which were in turn used to classify groundwater from the study area. Over 98% of the samples fall within the “Excellent” and “Good” categories, suggesting that groundwater from the southern Voltaian formation is generally acceptable for drinking purposes.