Evaluation of groundwater quality using multivariate, parametric and non-parametric statistics, and GWQI in Ibadan, Nigeria

Abstract

ABSTRACTAn attempt was made to assess the properties of groundwater in the Ibadan Metropolitan area, Nigeria by applying multivariate statistical methods on samples collected from various parts of the study area. Out of all the physio-chemical features of groundwater, the quality is a major concern since the long-term progress of groundwater researches in numerous study fields is reliant on the accessibility to high-quality groundwater. Several quantitative methodologies have been successfully used to analyze groundwater hydrochemistry. One other major way to explaining groundwater quality is multivariate statistical analysis, of which hierarchical cluster analysis (HCA) and principal component analysis (PCA) comprise. The Kruskal–Wallis Test, Pearson Correlation, and the Independent Sample Test were employed in assessing water quality. The groundwater quality index was used to examine the suitability of water for ingestion. pH is significantly correlated with Na+ and Ca2+, (0.480 and 0.257), and negatively correlated with Cl− and HCO3_, (−416 and −0.398). TDS levels correlated with K+ concentration levels (0.228). Na+ significantly correlated with Ca2+ and Mg2+ (0.849 and 0.968). pH, EC, magnesium and chloride, were significantly influenced by the lithology (p < 0.05). Furthermore pH, K+, Na+, Mg2+, Ca2+, HCO3−, and NO3−, all differ significantly from the WHO limits (p < 0.05). The water quality index indicates that the water from the different sampling point fall under the good category of the index. Various statistical analysis assists in determining the spatiality of main explanatory variables and in determining the extent to which planning is required.

Keywords

• Groundwater
• hierarchical cluster analysis
• principal component analysis
• multivariate statistics
• GWQI