2D inversion of electrical resistivity investigation of contaminant plume around a dumpsite near Onitsha expressway in southeastern Nigeria

Abstract

The study tries to utilize vertical electrical sounding (VES) and 2D resistivity tomography to evaluate the region of influence of the leachate plume on the groundwater around a dumpsite at Onitsha expressway, southeastern Nigeria. The borehole log data were acquired and their respective geoposition logged with Garmin GPS device. In addition, four 1D (VES) soundings and 2D electrical profile data were acquired in the field utilizing the Schlumberger and Wenner profiles respectively. Petrozenith PZ-03 Resistivity meter was used to acquire the electrical data, while RES2DINV and WinResist software were used to interpret the 2D and 1D data respectively. The resulting geoelectic layers were correlated with the borehole logs and were interpreted according to their resistivity distribution. Results of the 2D inversion at profiles 1 and 3 showed low resistivity zones indicating influence from the leachate plume. Profiles 2 and 4 gave low resistivity zone within 14.6 and 44.3 Ωm from surface to between 0.375 and 3.60 m depths indicating influence from leachate plume. Likewise, profiles 1 and 3, which penetrated groundwater, also showed very low resistivity with resistivity ranging from 3.12 to 8.7 Ωm, from surface to few meters depths. This indicates that it has been polluted by the leachate. In contrast, Profiles 2 and 4, from the 2D inversion, has no leachate influence on the groundwater. The VES result showed that the depth to the water table at location 1, 2, 3 and 4 are 21.7 m, 17.9 m, 15.9 m and 12.2 m respectively, with the leachate plume flowing in the southeast direction in line with the groundwater flow direction.

Interpretation of large‐scale, long‐term electrical geophysical monitoring guided by a process simulation

“…The geophysical method of electrical resistivity tomography (ERT) is a demonstrated technology that is sensitive to porosity, pore fluid/moisture content, and lithology (Archie, 1942), which are important for characterizing the vadose zone. ERT has been used at waste sites to characterize plume extents (Bichet et al., 2016; Chambers et al., 2006; Liao et al., 2018; Maurya et al., 2017; Ugbor et al., 2021) in conjunction with tracer tests (Cassiani et al., 2006; Wilkinson et al., 2010) and pumping tests (Vogelgesang et al., 2020) for hydrologic characterization. ERT monitoring has also been used to image contaminant migration and solute transport (Casado et al., 2015; Kemna et al., 2002; Kuras et al., 2016), infer the distribution of vadose zone contaminants (Benecke et al., 2006; T. C. Johnson & Wellman, 2013; Rucker & Fink, 2007), and identify the preferential flow paths of surface water intruding into groundwater (T. C. Johnson et al., 2012, 2015; Robinson et al., 2023; Wallin et al., 2013).…”

Identifying the origin of springs in weathered-fractured crystalline aquifers using a hydrogeophysical approach

“…However, these researches never addressed the issue of spring characterization. Electrical resistivity tomography (ERT) methods are widely used in this type of context, as they provide 2D information, or even quasi 3D in the case of serial profiles, and as there is a good correlation between geophysical facies and those of the weathering profile 35 – 38 . The complexity of crystalline environments gives rise to biases that severely limit the validity of 1D methods 28 , 37 , 39 , 40 which, for technical and low-cost reasons, are unfortunately still often used.…”

Physics-informed W-Net GAN for the direct stochastic inversion of fullstack seismic data into facies models

“…The accurate prediction of the spatial distribution of facies at targeted depths is required in many fields related to geo-energy and environmental applications. These types of models are key pieces of information, for example, to characterize groundwater systems, geothermal or hydrocarbon reservoirs, or to assess the capacity storage of captured carbon dioxide [2][3][4][5] .…”