Geoelectrical Resistivity Research Articles

Wastewater leakage identification in WWTP and concrete pipelines using integrated geophysical imaging methods

Industry and mining activities covers a broad spectrum of processes that dispose an abundant amount of wastewater. Given the vast array of industries, there are equally large number of heavy metals, organic solvents, and hydrocarbons pollutants associated with its wastewater, posing a great threat to aquifers, especially groundwater. Main contributor of this polluting scheme are from the leakage of underground/surface storage tanks, effluent pipework, industrial sewers, and waste injection system. To ascertain the presence of pollution in the subsoil and groundwater resources, an integrated geophysical method can be the alternative of non-invasive methods. The presence of contaminants in subsoil alters the physical properties of rock formations and decrease pore-water resistance, therefore it can be mapped by geoelectrical resistivity. In this paper, study case was conducted in Medan Industrial Estate, Indonesia, to identify potential leakage under the Wastewater Treatment Plant (WWTP) and its pipework, using Geoelectrical Wenner and Magnetotelluric Method with 5 lines in the interval of 40-60 meters and Magnetotelluric Method throughout the 175 meters of pipework in the production area. Based on the Geoelectrical Method, an anomaly with a low resistivity value was detected within 7 meters of the ground depth. Meanwhile, in the Magnetotelluric Method, a moderate permittivity value was detected that is local and located within 2 meters depth which is where the pipe and the bottom of the WWTP storage tank is located. In conclusion, based on the results obtained from the Geoelectrical and Magnetotelluric Methods that have been carried out in the WWTP area and along the wastewater pipeline leading to the WWTP, no anomalies were found that lead to waste water leakage.

Analysis on The Status of Deep-well Geo-electrical Resistivity Observation in China Geoelectric Network

With the deterioration of the observation environment and the increasing interference of surface stray currents, the commonly used surface resistivity observation is facing severe challenges. China began to experiment and develop deep-well geo-electrical resistivity observation. In this paper, the characteristics of the observation system of each resistivity station are counted and analyzed, and the data quality of the deep-well geo-electrical resistivity observation and the ground resistivity observation at the same site is compared in terms of relative standard deviation and annual variation. The results show that the operation of deep-well geo-electrical resistivity observation stations is in good condition, and its data quality and anti-interference ability are superior to ground resistivity observations. The results provide support for the popularization and application of deep-well geo-electrical resistivity observation technology, which can better serve seismic analysis and prediction.

Crustal electrical structure and seismicity of the Weiyuan shale gas block in Sichuan Basin, southwest China

Abstract Hydraulic fracturing, a significant contributor to seismic activity within and around operational fields, has been extensively used in shale gas production. Magnetotelluric (MT) sounding is an effective geophysical tool for identifying high-conductivity fluid-filled and/or molten regions. In this study, we deploy a dense grid of rectangular MT sites to investigate the 3D geoelectrical resistivity structure beneath the Weiyuan shale gas block (WSGB) and subsequently examine the causes of seismic activity. The resistivity data, obtained through 3D inversion accounting for topography using ModEM, reveals a shallow low-resistivity layer (<10 Ω-m) within the WSGB, ranging from ∼2 to 5 km in depth. This layer exhibits multiple isolated areas with very low resistivity (<5 Ω-m), indicative of fluid-filled zones associated with hydraulic fracturing or shale gas-bearing formations. In the northwestern WSGB, the Weiyuan anticline presents a high-resistivity dome extending possibly to depths beyond 20 km, without extending beyond the northern boundary of our study area. Conversely, the sedimentary zone in the southeastern WSGB displays a low-resistivity feature, with an extremely low-resistivity center (<1 Ω-m). Since a consistent high-resistivity zone exists beneath each fault and its top depth is <5 km, so faults might not extend downward below 5 km. Earthquakes with magnitudes (ML) of 3.0 or higher predominantly occur close to the faults, when considering industrial production data, we found a noteworthy correlation between earthquakes with ML < 3.0 and annual shale gas production within the WSGB. Tectonic faulting is not the leading cause for ML < 3.0 earthquakes but likely the primary contributor to seismic events with ML ≥ 3.0.

Mapping Weak Soil Zones Using Geoelectrical Resistivity for Bridge Construction in Rokan Hulu, Indonesia

Mapping Weak Soil Zones Using Geoelectrical Resistivity for Bridge Construction in Rokan Hulu, Indonesia

Identification of Andesite Rocks Using Dipole-Dipole Geoelectric Method in Batursari Subdistrict, Pekalongan Regency, Central Java

A study has been conducted to identify andesite rocks using the dipole-dipole geoelectric resistivity method in the Batursari Subdistrict, Pekalongan Regency, Central Java Province. Measurements were taken along 12 Lines stretching from northwest to southeast, with a Line length of 280 m and electrode spacing of 10 m. The aim of this research was to model the 2D resistivity value Line of the path, determine the type of andesite rock, and assess the depth of the rock in the study area. Based on data processing results, four lithology units were identified: resistivity values ranging from 0 to 150 Ωm were interpreted as soil, 150 to 250 Ωm as weathered andesite, 250 to 400 Ωm as moderate andesite, and resistivity values from 400 Ωm to 3000 Ωm were interpreted as fresh andesite.

Improved geoelectrical resistivity monitoring for earthquake precursors near the Xinfengjiang reservoir of southern China, with a fixed Wenner array of downhole electrodes in four separated boreholes

Over the past five decades, a geoelectrical resistivity monitoring experiment using fixed electrode arrays has been conducted at Heyuan in the Guangdong Province of China for detecting possible earthquake precursors near the Xinfengjiang reservoir. A pair of surface quasi-Wenner arrays designed to monitor temporal resistivity variations have been used in two oblique directions of N27°E and N80°W with electrode spacings AB/MN of 997 m/315 m and 1032 m/328 m, respectively. To reduce the effects of near-surface environmental changes, an improved experiment has been introduced in August 1992, using a subsurface Wenner array in the direction of N80°W with electrode spacings AB/MN of 54 m/18 m, consisting of downhole electrodes in four horizontally separated boreholes at the same depth of 65 m. During the experimental period of August 1992 to December 1996, a continuously downward trend in apparent resistivity with the improved downhole array and a peculiar annual variation with the conventional surface arrays have been observed. For the same period, no notable earthquakes occur in and around the Xinfengjiang reservoir. The field tests indicate that the downward trend of apparent resistivity was due to the aging of one of the current electrodes. By using simple layered models, we develop a sensitivity analysis to design a monitoring array with minimum environmental effects and to explain the observed resistivity variations, such as a paradoxical resistivity behavior related with negative sensitivity. No significant resistivity variations, which could be attributed to earthquake activity of magnitude 3.4 or less in the study area, are detected. We prove that the two monitoring methods with the modified subsurface Wenner and the conventional surface quasi-Wenner arrangements can complement each other to efficiently estimate a change in the electrical properties of rocks and reduce the ambiguity in the interpretation of apparent resistivity data.

Geo-electrical resistivity–based study to estimate the aquifer parameters—a study in parts of Yamuna Nagar District, Haryana State, North India

Geo-electrical resistivity–based study to estimate the aquifer parameters—a study in parts of Yamuna Nagar District, Haryana State, North India

Subsurface Analysis Using Microtremor and Resistivity to Determine Soil Vulnerability and Discovery of New Local Fault

Microtremor and geoelectrical resistivity surveys have been conducted in areas where the April 10, 2021, earthquake of 6.1 Mw caused the most damage. Wirotaman Village, Malang Regency, was one of the regions with the most extensive damage. This study aims to investigate the seismic vulnerability and subsurface conditions that result in severe damage at the research location. This study's Horizontal to Vertical Spectral Ratio Analysis (HVSR) curve was derived from the recorded microtremor signal in the frequency domain. The frequency parameter and amplification factor obtained from the curve are used to determine the seismic vulnerability index. In addition, a geoelectrical resistivity study with a dipole-dipole configuration was conducted at the site with the most extensive damage. The results of this study show the correlation between the results of the HVSR curve analysis and geoelectrical resistivity in determining the seismic vulnerability of an area. The results indicated that the high seismic vulnerability index value ranged from Kg= 12.0 to 18.0, with the most severe damage concentrated in the Southwest at SA 05 and SA 06. Based on the results of the geoelectrical survey, information was obtained that several points of damage to buildings at SA 05 (red circle) were on the same line, where this condition was associated with the possibility of new faults at that location. This microtremor and geoelectric resistivity investigation reveals thick sedimentary deposits with a high seismic vulnerability index and low resistivity. This study's findings can be utilized as a guide for micro zonation studies in research areas. This research contributes to the surrounding community in the form of disaster mitigation, where construction must avoid local fault positions that have been found to reduce the level of damage when natural geological disasters occur. Doi: 10.28991/CEJ-2023-09-09-014 Full Text: PDF

A Quantitative interpretation of salt water mixture in the shallow aquifer through the geoelectrical resistivity data

The main problem of groundwater in coastal areas is the intrusion of saltwater into freshwater aquifers. This study aims to predict the amount of saltwater content in aquifers polluted by intro-sea saltwater. In this study, an attempt is made to provide a direct correlation approach for resistivity measurements with the physical characteristics of groundwater. A 2D resistivity survey with the Wenner configuration have been carried out in the coastal area. The geoelectrical resistivity survey is about 3 km from the shoreline. The chemical measurement was done on freshwater, seawater and fresh-seawater mixture, which the mixture was consisted of 25%, 50% and 75% of seawater content. The results showed that the resistivity below 5 ohm.m indicated the presence of seawater with a concentration of more than 50% mixed with fresh water. In general, it can be seen that the decrease in resistivity appears to decrease exponentially with increasing seawater content in the aquifer.

A preliminary groundwater investigation using geoelectrical resistivity survey in the Bengkalis Island, Indonesia

Groundwater resources are one of the natural resources that need to be preserved. The main problem of groundwater in coastal areas is the intrusion of seawater into the groundwater aquifer. The problem will be even more complex when the land is covered by peat soil. The purpose of this study was to investigate the potential of groundwater in the western part of Bengkalis Island. Geoelectrical resistivity data was taken with the Schumberger configuration with the increase in the electrode distance being varied to obtain accurate measurements. Groundwater samples were measured to obtain the physical character of the groundwater. The results show that groundwater close to the shoreline has been contaminated by the presence of seawater intrusion. However, in areas that are a bit far from the shoreline, the shallow aquifer groundwater conditions are still not contaminated by seawater. It can be concluded that the presence of seawater in the aquifer is caused by the trapping of seawater in the aquifer during sediment deposition in the past.

Eksplorasi Batuan Andesit Berdasarkan Interpretasi Data Resistivitas Di Desa Petangis, Kecamatan Batu Engau, Kabupaten Paser

Exploration activities are very important before mining andesite rocks. This research was conducted in Petangis Village, Batu Engau District, Paser Regency using the Wenner-Schlumberger geoelectric resistivity method with 10 tracks, where 7 tracks have a length of 705 meters in an East-West direction and 3 tracks have a length of 235 meters in a North-South direction. The purpose of this study is to identify the resistivity value of andesite rocks and determine the 2D and 3D distribution of andesite rocks based on the obtained resistivity values. Based on the 2D resistivity section results, it was found that in the study area, andesite rocks have resistivity values ranging from 212-460 Ωm with varying depths of 1-52 meters and the 3D modeling results indicate that andesite rocks are predominantly distributed on the East side with an estimated volume of 1.34588e+007 m3.
 Keywords: Andesite, Exploration, Resistivity, Wenner-Schlumberger.

Recent developments in the use of geoelectric resistivity for landslide surveys: an overview

Recent developments in the use of geoelectric resistivity for landslide surveys: an overview

Analisis Struktur Lapisan Tanah Menggunakan Metode Geolistrik Resistivitas Konfigurasi Schlumberger Vertikal di Kompleks Perumahan Dosen Uncen Kali Acai, Kulurahan VIM, Distrik Abepura, Kota Jayapura

Research on the analysis of the structure of the soil layer using the Vertical Schlumberger Geoelectric method in the Lecturer Housing Complex of Uncen Kali Acai, VIM Village, Abepura District, Jayapura City. This study aims to determine the soil layer, determine the location and depth of the soft soil layer, determine the soft and hard soil. Data retrieval using geoelectric resistivity method with vertical Schlumberger configuration. The instrument used for subsurface surveys is the HV 500 AK resistivity meter. Field measurements obtained electric current and voltage values and then calculated the apparent resistivity values obtained from analysis using IP2win software to see the distribution profile, depth, and thickness of the soil layer.After doing research in the field, it can be seen that the subsurface structure at the research site is dominated by soft clay material with a resistivity value of 0.24 -692.00 Ωm. . In addition, there is a layer of hard rock in the form of a mixture of limestone with a resistivity value of 1181.00 - 8319.00 Ωm.. And the types of subsurface rocks found at the research site are clay, sandstone and limestone.

Hydrogeophysical Investigation in Parts of the Eastern Dahomey Basin, Southwestern Nigeria: Implications for Sustainable Groundwater Resources Development and Management

Geoelectrical resistivity measurements were conducted in five locations within the eastern portion of the Dahomey basin for the purpose of subsurface evaluation and detecting saturated zones. The locations are Covenant University (L1), Bells University (L2), Oju-Ore-Ilogbo Road (L3), Obasanjo-Ijagba Road (L4), and Iyana Iyesi (L5). The study was carried out to avert the common challenges of drilling low-yield groundwater boreholes in the area. A total of 30 Vertical Electrical Soundings (VES) and five two-dimensional Electrical Resistivity Tomography (ERT) data sets have been acquired along the study areas. The geoelectrical resistivity results were integrated with the borehole logs to generate the spatial distribution of the subsurface lithologies in the area. The delineated subsurface lithologies include the topsoil (lateritic clay), clayey sand, sandy clay, fine silty sand, coarse sand, and shale/clay units. The fine silty sand and coarse sand units were identified as the two main aquifer units within the area. The depths to the upper aquifer unit in the area include 31.7–96.7 m, 38.5–94.0 m, 30.7–57.5 m, 39.1–63.4 m, and 46.9–57.5 m for locations L1, L2, L3, L4, and L5, respectively. At the same time, the depths to the lower aquifer unit in the area include 43.4–112.7 m, 52.2–108.0 m, 44.2–72.5 m, 53.7–78.5 m, and 63.5–72.9 m for locations L1, L2, L3, L4, and L5, respectively. The estimated hydraulic parameters for both aquifers show they are highly productive with mean porosity, mean hydraulic conductivity, and mean transmissivity of 20–22%, 12.4–17.0 × 10−2 m/s, 1.56–2.18 m2/s for the upper aquifer, and 48–50%, 371–478 × 10−2 m/s, 50.00–62.14 m2/s for the lower aquifer. By focusing on these aquifer systems during exploration, sustainable groundwater resources can be secured, providing relief to homeowners within the study area who might otherwise face the frustration of drilling unproductive and low-yield boreholes. However, it is crucial to consider the presence of sub-vertical faults in the study area, as these faults can significantly impact groundwater development and management. These sub-vertical structural faults may lead to changes in the permeability, hydraulic conductivity, and transmissivity of the delineated aquifers, affecting their productivity across the divide and ultimately influencing the overall water availability in the area. Careful consideration of these geological factors is essential for effective aquifer management and sustainable groundwater utilisation.

Simulation of Biophysicochemical Characteristics of the Soils Using Geoelectrical Measurements near the Sewage Station, Assiut City, Egypt

Numerous farmers regularly irrigate their farms with inadequately treated sewage water pumped from the sewage system in the Arab El-Madabegh district of Assiut City, Egypt. According to previous studies, long-term irrigation with partially treated sewage water resulted in significant changes in the physicochemical properties of soil. The principal goals of this study are (1) to infer empirical equations between geoelectrical resistivity measurements and certain biophysicochemical parameters of some soil samples, and (2) to use these empirical equations to calculate the biophysicochemical parameters of the unknown samples for the same location. For this purpose, 27 soil samples at different depth levels (0 to 25, 25 to 60, and 60 to 90 cm) were collected from eleven locations at the sewage station. Physical properties including water content and particle size distribution, chemical properties including soil pH, electrical conductivity (EC), and the heavy metals concentrations, biological properties including total coliform counts, and geoelectrical resistivity measurements were estimated and analyzed for these samples. Electrical resistivity measurements and biophysicochemical properties were cross-correlated using the exponential trend line to fit the cross-correlated data, and the empirical relationships were obtained. These empirical relationships in conjunction with the measured electrical resistivity measurements were used to calculate the biophysicochemical values of the other three random soil samples. The biophysicochemical values of the former three samples were measured by the same normal procedures as 27 samples. Then, the calculated values were correlated with the measured ones. Good correlations between the estimated and the measured values for biophysicochemical features were obtained. Therefore, this method can be employed to calculate the biophysicochemical parameters for any unknown samples that have the same geological conditions for estimating and monitoring soil contamination.

A valuable approach in a quantitative seawater intrusion interpretation from the geoelectrical resistivity data for groundwater investigation in Dumai area, Indonesia

An improvement of geoelectrical resistivity interpretation has been done through this research. Up to now, the geoelectrical resistivity data was interpreted qualitatively especially in the case of the aquifer intruded by seawater, and the percentage of seawater mixture content in the aquifer cannot be predicted. In this research, a valuable approach was used in the prediction of percentage seawater mixture in the shallow aquifer that is intruded by seawater. The study was conducted in the coastal area which is mainly covered by peat soil. The research employed the direct soil resistivity measurement and the ground surface resistivity survey. Geoelectrical resistivity with the Wenner configuration was used for both measurements. The soil character and the fluid content in the soil were measured to obtain their correlation to the direct soil resistivity value. The results show that resistivity value is about 2-5 ohm.m for 50% seawater content mixture in aquifer and it increase to be 5-10 ohm.m for 25% seawater mix to freshwater in the aquifer. The increasing seawater content in the pore soil caused the decreases in resistivity value drastically. The percentage of seawater mixture in the fluid pore soil has been successfully predicted through the geoelectrical resistivity measurement on the surface.

Nonlinear inversion of electrical resistivity sounding data for multi-layered 1-D earth model using global particle swarm optimization (GPSO)

Interpreting geophysical data requires solving nonlinear optimization problem(s) in inversion. Analytical methods such as least-square have some intrinsic limitations, which include slow convergence and dimensionality, making heuristic-based swarm intelligence a better alternative. Large-scale nonlinear optimization problems in inversion can be solved effectively using a technique within the swarm intelligence family called Particle Swarm Optimization (PSO). This study evaluates the inversion of geoelectrical resistivity data with global particle swarm optimization (GPSO). We attempted to invert field vertical electrical sounding data for a multi-layered 1-D earth model using the developed particle swarm optimization algorithm. The result of the PSO-interpreted VES data was compared with that of the least square inversion result from Winresist 1.0. According to the PSO-interpreted VES results, satisfactory solutions may be attained with a swarm of 200 or fewer particles, and convergence can be reached in fewer than 100 iterations. The GPSO inversion approach has a maximum capacity of 100 iterations, more than the least square inversion algorithm of the Winresist, which has a maximum capacity of 30 iterations. The misfit error of GPSO inversion is 6.14×10−7, much lower than that of the least square inversion of 4.0. The GPSO inversion model has lower and upper limit values of the geoelectric layer parameters model to fit the true model better. The limitations of the developed PSO inversion scheme include a slower execution time of the inversion procedures than the least-square inversion. There is a need for a priori knowledge of the number of layers from borehole reports in the study area. The PSO inversion scheme, however, estimates inverted models closer to the true solutions with greater accuracy than the least-square inversion scheme.

Characteristic identification of seismogenic electromagnetic anomalies based on station electromagnetic impedance

The main components of seismo-electromagnetic research are the deep underground electromagnetic seismogenic environment, electromagnetic field changes at different stages of the seismogenic process, and the physical mechanism and change rules of electromagnetic properties of the earth’s interior. Traditional electric and magnetic methods mainly analyze the single field change of the geoelectric field, geomagnetic field, or resistivity at frequencies less than 1 Hz. These do not include the extremely low-frequency band that is sensitive to seismic events, so it is difficult to obtain the characteristics of time-spatial variations and propagation characteristics precursors. In comparison, magnetotelluric stations observe magnetotelluric fields containing seismogenic-induced electromagnetic disturbances, and the observation frequency band is wide. In this paper, the three-dimensional numerical simulation method is used to calculate the magnetotelluric apparent resistivity anomaly generated by resistivity changes in the seismogenic zone, and the forward algorithm of arbitrarily orientated dipole source in layered earth is used to simulate the response of low-frequency pre-earthquake electromagnetic radiation. The magnetotelluric response including seismogenic resistivity anomaly and pre-earthquake electromagnetic radiation is obtained using the field component composition method. The frequency characteristics and spatial distribution characteristics of apparent resistivity anomalies are systematically analyzed, and the results are of important significance for the observation, data processing, and identification and analysis of seismic electromagnetic anomalies in different seismogenic processes.

Detection of groundwater aquifers using geoelectrical resistivity method (case study : Plupuh Sub-district, Sragen District )

An aquifer is a layer below the ground surface that contains groundwater. Inside the earth there are unconfined aquifers and confined aquifers, where unconfined aquifers are located near the surface while confined aquifers are located very deep beneath the earth. This study aims to find the location, depth, and thickness of aquifers that have the potential to contain large amounts of groundwater. The instrument used in this research is a resistivity meter OYO Model 2119C Mc OHM-EL, with a Schlumberger configuration with a current electrode length of AB/2 to 350 meters. Data acquisition were carried out in the Plupuh sub-district, Sragen district as many as 5 sounding points, and data processing using IP2win software. Based on the interpretation of resistivity geoelectrical data, it can be concluded that the area has the potential to have a lot of groundwater content, for unconfined aquifers at the TS1 sounding point with a depth of 7.7 meters to 19.2 meters with a thickness of 11.5 meters. and TS4 with a depth of 15.4 meters to 30 meters with a layer thickness of 14.6 meters. This aquifer layer is dominated by sand layer lithology, while the confined aquifer layer is located around TS1 and TS2. The two sounding points are located in the east and northeast of the research area. TS1 was detected at a depth of 39.9 meters to 110 meters with a layer thickness of 60.1 meters and TS2 was at a depth of 40.2 meters to 66.5 meters and 80.2 meters to 139.7 meters with a thickness of 84.8 meters. This aquifer layer is dominated by the gravel sand layer in TS1 and the sand layer in TS2.

Landslide Soil Failure Parameters Characterization Using Geoelectrical Resistivity Methods in Uruagu, Nnewi, Anambra State, Nigeria

Electrical Resistivity Imaging (ERI) and Vertical Electrical Sounding (VES) were deployed over the Uruagu landslide area. The main purpose of the study was to characterize the landslide failure parameters in to identify the soil failure mechanisms. Ten profiles of 2D ERI measuring 200 m each, and thirty VES, with three VES along each profile, were executed. Nine of the ten profiles were executed within the landslide site while one profile was executed in a residential street as a control profile. Four soil samples were also taken for physical and geotechnical laboratory index analysis. The PASI resistivity meter was used for the geoelectrical resistivity measurements. The Wenner-Schlumberger array was deployed for the ERI with a minimum electrode spacing of 10 m. The Schlumberger array was deployed for the VES with a maximum current spacing of 130 m. ERI resistivity data analysis involved inversion using the RES2DINV software package involving mean model residual and construction of iso-apparent resistivity contour maps. VES resistivity data analysis involved calculated parameters from plotted field data on a log-log graph then used as initial models in an iterative forward modeling WinResist software package. The results of the ERI and VES for the control profile reveal that the subsurface strata are originally composed of silty clay of resistivity values (16.7 – 60.9) Ωm, clayey silty sand having resistivity values (116 – 800) Ωm and sandstone layer with resistivity values (>814 Ωm). The ERI and VES results for the devastated landslide site reveal counteraction material of resistivity values (>814 Ωm), colluvia and regoliths (116 - 300 Ωm), and variably wet weathered sandstones of resistivity values (<60.9 Ωm). The laboratory results revealed the landslide site is majorly composed of silty sandy clay, silty clay, sandy silty clay, and sandstones as the pre-landslide existing lithologies. The natural water content ranges from 10.6% to 14.0%. The liquid limit ranges from 44.0% to 46.0%, the plastic limit ranges from 15.0% to 17.0%, and the plasticity index from 28.0% to 29.1%. The geophysical and laboratory results revealed consistency in the lithological units in agreement with the characteristic geology of the study area. The landslide site has high gully slope gradients and collects a large volume of floods during the intense rainy season. These soils, during the intense rainfall, imbibe more water, following their high plasticity slide along the sandstone to activate the soil failure.