Investigation of leachate infiltration on groundwater using georesistivity and natural electric field method around Ojoou-Olayanju’s dumpsite, Ada, southwestern Nigeria

Abstract

The investigation of groundwater within the dumpsite environment is highly important in geophysical study. This is because the extent of  interaction between the aquiferous medium and the contaminated zone could pose a serious threat to the end users especially  humans when consumed. This research aimed at investigating leachate infiltration and its potential influence on groundwater at Ojoou  Olayanju's Dumpsite using combining geo-resistivity and natural electric field (NEF) methods. In this study, five dipole-dipole and five  NEF measurements were obtained using the Omega resistivity meters and PQWT-150 equipment respectively. The dipole-dipole method  was deployed to obtain a 2D near-surface pseudo-section, and the NEF method was used to obtain the frequency curve and profile maps  of electric potential difference. The dipoledipole results revealed the lateral variation in the resistivity along the traverses, suggesting that  the materials within this near-surface are heterogeneous, and the closely spaced contours' varying gradients indicate fracture,  which would facilitate potential leachate filtration. The NEF results revealed curves, and a subsurface image with respect to depth and  profile distance. The points of convergence signals on the frequency model correspond to a medium with low resistivity on the profile  map. The conductive medium is seen as being saturated with leachate, which suggests that very large portion of the study area around the dumpsite has been contaminated by leachate. Conclusively, it was revealed that leachate filtration is evidence especially at the topsoil  and due to the presence of fractured zones, the groundwater quality is at risk of contamination by continuous filtration of  leachate