A comparative aquifer vulnerability study of the Quaternary Sombreiro – Warri Deltaic plain deposits, Western Niger Delta, Nigeria

This paper investigates the effect of two parameters, resistivity and hydraulic conductivity of the vadose zone, and their reliability in assessing aquifer vulnerability. Hence, the vulnerability of the aquifers within the Quaternary – Sombreiro Deltaic deposits to contamination was assessed using two models: longitudinal conductance and hydraulic resistance. The results from the simulation of the models show four vulnerability zones indicated by the longitudinal conductance model, while the hydraulic resistance model revealed five zones. Two-way analysis of variance (ANOVA) reveals that thickness, lithology, and the interactions of the two variables have a significant effect on the two models. The longitudinal conductance and hydraulic resistance models show a closer coincidence of vulnerability in 72% of the study area. The differences in results and delimitations of varying vulnerability zones by the two models depend primarily on the two parameters employed in estimating the vulnerability, with the vadose layer's hydraulic conductivity imposing remarkable influence on the general vulnerability of the study area.