The use of very low-frequency electromagnetic survey in the mapping of groundwater condition in oporoza-gbamaratu area of the Niger Delta

Abstract

The use of VLF-EM in sedimentary basins has not been fully understood and has not attracted substantial usage in groundwater exploration, specifically in coastal Niger Delta. In the present study, VLF and 2D electrical resistivity imaging (ERI) surveys were combined with hydrogeochemical data to examine groundwater quality. Both interpretations of VLF and 2D ERI uncovered subsurface conductive geologic materials. Eight groundwater and one river water samples as well as static water level were analyzed to complement geophysical data (VLF-EM and ERI). The results suggested that conductive materials detected in the subsurface are unconnected with intrusion of sea water but depicted clay material typical of tidal flat deposits. Furthermore, hydraulic heads estimated from water level and land elevation measurements did suggest that groundwater flows into the Escravos River. Also, the stage of the Escravos River is above water levels in boreholes and hand-dug wells, which is not an indicative of the incursion of salt water into aquifer from the river. The slight level of nitrate loading in groundwater probably suggests contamination emanating from anthropogenic sources such as septic tanks and leachates from diffuse refuse dumps. The study has validated the effectiveness of VLF technique usage in sedimentary basins for the delineation of groundwater quality, but not without important hydrogeochemical data.

Hydrochemical-geophysical study of saline paleo-water contamination in alluvial aquifers

“…VLF-EM has been typically used to prospect for conductive mineral deposits (Paal 1965) and for the identification of fracture zones for groundwater exploration (Jamal and Singh 2018), detection of fractures in the bedrock (Adepelumi et al 2006), geological boundaries and shear zones/faults (Gnaneshwar et al 2011;Parker 1980;Phillips and Richards 1975;Saydam 1981, Ramesh Babu et al 2007Sundararajan et al 2006), but it has been also applied to map groundwater conditions in sedimentary basins (Ohwoghere-Asuma et al 2020) and to detect leachate plumes and groundwater pollution (Al-Tarazi et al 2008).…”

Investigation of the Source of Groundwater Contamination Near a Farmland Using the VLF-EM and Magnetic Methods

“…VLF instruments can be used to study large areas very quickly because of its lightweight and portability. Thus, VLF method has been applied in the exploration of fractured zones, groundwater exploration and groundwater contamination (e.g., Adelusi et al, 2014;Al-Tarazi et al, 2008;Jamal & Singh, 2018;Ohwoghere-Asuma et al, 2020;Sharma & Baranwal, 2005;Sundararajan et al, 2007). A special quality that makes the VLF-EM very useful is that it is very sensitive to ground water quality and can detect conductive geological materials easily as it is able to determine the electrical characteristics of rocks in the shallow zone (Sharma & Baranwal, 2005;Sundararajan et al, 2007).…”