THE EFFECTS OF SITE AND WELL CHARACTERISTICS ON GROUNDWATER QUALITY IN LAGOS, NIGERIA

The paper attempts an examination of the relationship between groundwater quality and some site and well characteristics of 30 hand-dug wells in Lagos, Nigeria. Multivariate procedures of correlation and stepwise regression were used in the study. The results showed that zinc, TDS and EC have the greatest number of correlation with other water parameters while pH and temperature had no significant relationship at all with other parameters. Furthermore, three levels of relationships were identified between water parameters and well/site attributes. a) temperature, pH and chloride were found to be significantly correlated with site/well features namely i) temperature with depth of well, type of well cover and nature of surrounding ground; ii) pH with the nature of surrounding ground and iii) chloride with the age of well. The stepwise regression analysis showed that the well features had significant effects on these parameters. b) Significant relationship was established between the concentration of i) iron and distance to septic tank, ii) manganese and depth of well, iii) e-coli and height of well rim above ground surface, iv) zinc and depth of water in the well, v) magnesium and nature of surrounding ground. However, the stepwise regression indicates that none of the well / site features had significant effect on water parameters. c) No significant relationship was identified between parameters (like nitrate, turbidity, TDS and EC) and well/site features. The paper calls for further research.