Spatial correlation of groundwater pollutants with the vulnerability index in Kano Metropolis, North-western Nigeria

This study performed a correlation analysis between groundwater quality parameters with organic and inorganic pollutantsusing the area under the curve (AUC) of receiver operating characteristics (ROC) map in Kano Metropolis, North-western Nigeria.The aim is to present the spatial relationship between groundwater pollutants and the existing vulnerability condition of thegroundwater resources with a view to developing a vulnerability risk map. Eight water quality parameters (Ca, Al, Cl, NO3,TH, Mg, TDS which include potassium and sodium) and pH were used to develop the water quality index to represent the gen-eral overview of the groundwater pollutants. Vulnerability parameters (depth of water, net recharge, aquifer media andgroundwater conferment on sensitivity analysis) were used as reference points for preparing ROC. Inorganic pollutants andhydrocarbons representing organic pollutants were integrated into the analysis process with a view to identifying their influ-ence on the groundwater pollution level in the area. The measured AUC under ROC revealed a positive correlation betweengroundwater vulnerability with organic (63.7%) and inorganic pollutants (65.6%). Vulnerability risk mapping based on hydro-carbon concentration revealed a high level of pollution risk, especially in the core centre of the metropolitan Kano.