Evaluative Study of River Birim in Denkyembuor, Ghana, Using Water Quality Indices

Abstract

Aim: To evaluate water quality of the river Birim after a two-year ban as a result of illegal mining activities in the catchment areas of the river. Methodology: Samples were taken during wet and dry seasons in acid-washed plastic containers. Two water quality indices were adapted for the river under study and used in the evaluation. These were Water Quality Index (WQI) and Heavy Metal Pollution Index (HPI). Twelve physicochemical parameters, such as pH, turbidity, conductivity, total suspended solids, total dissolved solids, total hardness, alkalinity, sulphate, phosphate, nitrate, Fluoride, and chloride which were life-threatening and generally acceptable in water quality were used to evaluate the water quality index. The computed WQI was 439.168, which fell within the unfit for drinking category with turbidity and total suspended solids positively influencing the index.  Iron, (Fe), As, Mn, and Hg were used to evaluate HPI, with an index value of 39.49, which was excellent considering a critical value of 100 set, below which the water is fit for good drinking water. Conclusion: Except for heavy metal pollution, the river Birim is unfit for drinking without chemical treatment and that, the two-year ban on artisanal small-scale mining was not enough for the river to recover fully from previous pollution episodes and hence did not have any impact on water quality of the river Birim.