Assessment of surface water quality in mining area: A case study of the southwest region of Burkina Faso

Mining activities, whether industrial or artisanal, are often responsible for the pollution of water resources, leading to significant degradation of water quality. This study aims to assess the quality of surface waters in three out of the four provinces of the South-Western region of Burkina Faso, an area known for its numerous mining sites. To evaluate the water quality in the study area and to assess the importance of each parameter in influencing this quality, we applied Weighted Arithmetic Water Quality Indices (WAWQI) and Hierarchical Cluster Analysis. These analyses were based on data obtained from the measurement of various physicochemical parameters (pH, electrical conductivity, total hardness, calcium, magnesium, sodium, potassium, bicarbonate, chloride, sulphate, nitrate, phosphate) and heavy metals (total iron, manganese, lead, cadmium, chromium, copper, zinc, arsenic) collected at the end of 2020. Samples were taken from a variety of sources: four rivers and five reservoirs. This approach provided a comprehensive assessment of the surface water quality in the study area.

The results indicated that, of the twenty parameters analysed, only total iron consistently exceeded the World Health Organization (WHO) standards across all samples, while bicarbonate exceeded the standard in three instances and calcium-phosphate in one. The water quality index values ranged from 8.18 to 165.85, with an average of 46.84. Only one river sampling point, situated at the Poni province (SW4 at Poniro River), exhibited "poor" water quality, while all other water bodies exhibited water quality ranging from "good" to "excellent." The dendrogram analysis confirmed this finding by showing that total iron is separated from the other parameters, highlighting its negative role in the deterioration of water quality, whereas the other parameters play a positive role.