Application of Water Quality Index (WQI) and Multivariate Analysis for Groundwater Quality Assessment of the Birimian and Cape Coast Granitoid Complex: Densu River Basin of Ghana

• Published in: Exposure and health 2011-10, Vol.3 (2), p.63-78
• Main Authors: Gibrilla, A., Bam, E. K. P., Adomako, D., Ganyaglo, S., Osae, S., Akiti, T. T., Kebede, S., Achoribo, E., Ahialey, E., Ayanu, G., Agyeman, E. K.
• Format: Article
• Language: English
• Subjects: Anthropogenic factors; Aquatic Pollution; Capes (landforms); Chemical analysis; Earth and Environmental Science; Eigenvalues; Environment; Environmental Health; Geology; Groundwater; Groundwater quality; Ions; Irrigation; Multivariate analysis; Permeability; Point source pollution; Pollution; Pollution sources; Principal components analysis; Quality assessment; Quality control; River basins; Rivers; Sodium; Sodium carbonate; Statistical analysis; Surface water; Waste Water Technology; Water and Health; Water Management; Water Pollution Control; Water quality; Water Quality/Water Pollution
• ISSN: 1876-1658; 2451-9766; 1876-1666; 2451-9685
• DOI: 10.1007/s12403-011-0044-9

Groundwater quality study of the Birimian, Cape Coast granitoid and the Densu River have been carried out using Water Quality Index (WQI) and multivariate statistics with the aim of determining their suitability for drinking and irrigation. The results showed that the Cape Coast granitoid generally had elevated values of dissolved ions as compared to the Birimian and surface waters. The WQI values were found ranging from 0 to 50 belonging to “excellent” and “good” water quality. The visualization of the WQI distributions using GIS software suggests point source pollution to areas of deteriorating water quality. Chemical indices like percentage of sodium (Na%), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), and permeability index (PI) indicate that the groundwater in the study area are suitable for irrigation. Cluster and Principal Component Analysis with varimax rotation were also used as a complementary tool to help organize and interpret the chemical analysis. Four principal components with eigen-values greater than unity accounting for 73.16% of the variability in the data were delineated. The factor score plot also separated the polluted areas and identified areas with potential deteriorating water quality. Even though the geology is the main factor controlling the presence of the dissolved ions, the study shows an increase in anthropogenic contributions in some areas.