Comparative analyzes among electrical resistivity tomography arrays in the characterization of flow structure in free aquifer

Abstract

This paper makes a comparative analysis between the Dipole-dipole, Wenner and Schlumberger arrays through electric resistivity tomography (ERT), about the sensitivity and resolution in the spatial characterization of infiltrating pollutants in septic tank and cone of depression in supply well, both contained in unconfined aquifer. Data acquisition consisted of electrical resistivity rea-dings using five parallel lines with 105m long, electrode spacing and lines of 5m. The data from each line were subjected to 2D inversion and then interpolated to generate 3D blocks, which were extracted from a fixed resistivity isosurface (620 W.m), which enabled the modeling of volumes related to the flow structures. The results for the Dipole-dipole array allowed the modeling of the cylindrical structure associated to the supply well, and an isosurface deformation associated to the septic tank, but did not allow the modeling of the plume. The data for the Schlumberger array cannot allow for the cone recognition, but resulted in a drop shape model, associated to the septic tank and similar to a contamination plume. The Wenner array resulted in a model with structu-re in elongated keel format associated to the cone of depression, and another that is similar to the drop shape model, also associated to the septic tank. The comparative analysis shows that the Dipole-dipole array is recommended in works of modeling vertically integrated three-dimensional structures of high resistivity in the saturated zone. The Wenner and Schlumberger arrays are recommended for modeling vertically integrated three-dimensional structures of low resistivity in unsaturated zone, with emphasis on the Schlumberger array.

Gold ore identification in Santa Catarina Gabbro using electrical resistivity tomography (ERT) and visualization of mineralization in three dimensions, São Sepé, Rio Grande do Sul, Brazil

“…The presence of gold in the Santa Catarina Gabbro was indicated geochemical exploration in current sediments in recent fluvial sedimentary deposits conducted in previous geological and metalogenetic surveys (CPRM, 1995). Similar DC (> 5,000 Ω.m) and IP (> 10mV/V) values for this type of mineralization have been described in geophysical surveys carried out in the region by some authors and served as a basis for correlation in this work, and this shows that, in fact, the use of electrical methods are reliable for metals prospecting (Côrtes et al, 2016;Moreira et al, 2012Moreira et al, , 2016Moreira & Ilha, 2011).…”

“…Data was obtained by using the dipole-dipole arrangement and the methods of Electroresistivity and Induced Polarization (Dentith & Mudge, 2014). The dipole-dipole array presents good lateral resolution and good results in the identification of vertical structures, as it is the geological context of the study area (Moreira et al, 2016;2018;2020;Cortês et al, 2019). For the studied targets the dipole-dipole arrangement, associated with the geological and structural surveys carried out in the field, returned promising results with the geological reality of the mineralized bodies.…”

Slope Stabilization of Twin-Tubes Tunnel Portal by Anchor Bolts Support System

“…It also allows, by measurements between galleries, the obtaining of valuable information on the mechanical properties of land in mining and civil engineering. Seismic tomography exploits the propagation of elastic waves to characterize the medium by parameters related to the theory of OF TRANSPORT INFRASTRUCTURE Houssam Khelalfa, U. Sakalli, E. B. Aygar, O.Şimşek, Bünyamin Aykan, H. Boulmaali Slope stabilization of twin-tubes tunnel portal by anchor bolts support system elasticity such as the propagation speed of seismic waves [55][56][57]. The measurement of the travel times of the seismic rays crossing the medium gives the possibility of obtaining the distribution of the velocity parameter in the portion of the prospected subsoil [58][59][60][61][62].…”

Groundwater identification using geophysical tools and its implications for the stability of slopes in an open pit mine

“…Geophysical methods, such as DC (Direct Current) resistivity, have been widely used to map fractured aquifers on rock mass (Porsani et al, 2005; Gomes de Oliveira et al 2014;Hamdan et al 2014;Moreira et al 2016;Pádua and Campos 2020;Whiteley et al 2021;Yan et al 2022). Frequent events of intense precipitation, as recorded in tropical climate countries, can aggravate the risk of rupture from the elevation of pore pressure in the rock mass (Corrêa et al 2021;Sun et al 2021;Wyllie and Mah 2004).…”