Soil Electrical Resistivity Research Articles

Polyethylene microplastic pollution changes the electrical resistance and thermal conductivity of loess soil.

While plastics provide convenience, they also endanger the safety of the natural environment. Microplastic pollution caused by plastic aging has become an urgent concern in public places. In order to study the effects of microplastics on soil physical properties, the electrical resistance and thermal conductivity of soils containing different polyethylene and moisture content were tested. The results show that polyethylene have two effects on soil electrical resistance: one is that the plastic particles increase electrical resistance, and the other is that the electrostatic field carried by the plastic particles reduces electrical resistance. The effect of the two factors is balanced by the content of polyethylene at 6-8%. When the polyethylene content of the soil was 6% and 10%, the coefficients of electrical resistance variation were 0.89, 0.67, 0.85, 0.96, 0.97, 0.99 and 0.95, 0.68, 0.71, 0.93, 0.95, 0.96, respectively. Polyethylene alters soil properties by affecting water distribution through hydrophobicity. The water content gradually increases to 10%, the liquid conduction area inside the soil increases, and the higher the soil's ability to conduct electricity and heat. The results can provide theoretical reference for evaluating and controlling soil microplastic pollution.

Comprehensive analysis of correlations between soil electrical resistivity and index geotechnical properties

This study investigates the relationships between soil electrical resistivity and key geotechnical properties to develop predictive models for designing grounding systems in electrical substations. Conducted on 30 soil samples from various different regions of Thailand, the research evaluates resistivity in relation to soil water content, plasticity index, and dry density. Using a comprehensive laboratory setup, the soil samples were evaluated under controlled conditions, including temperature, humidity, and salt content of the soil samples, to establish robust correlations between the measured resistivity and the index geotechnical parameters. The results reveal a significant inverse relationship between soil resistivity and water content, confirming that water content is a dominant factor influencing resistivity. Further analysis using multiple non-linear regression demonstrated strong correlations, indicating that a combination of water content, soil dry density, and plasticity index can predict soil resistivity with high reliability. This approach enables optimization of substation grounding designs to ensure operational safety and regulatory compliance. The study suggests that integrating these geotechnical assessments into standard grounding system design procedures can significantly improve the effectiveness and safety of electrical infrastructure. Recommendations for future research include expanding the dataset to encompass a broader range of soil types and investigating the effects of particle size and electrolyte content on soil resistivity. These enhancements aim to refine the predictive models and address the broader applicability of the results in diverse geological settings.

Predicting soil parameters in Maroua 1st, Cameroon, using correlations of geophysical and geotechnical data

This study aims to predict specific soil parameters based on quantitative and qualitative correlations between electrical and geotechnical data. A total of 21 geotechnical boreholes followed by sampling, 21 light dynamic penetrometer tests, and 76 vertical electrical sounding surveys were carried out in Maroua 1st. The electrical resistivity data of the soil layers were obtained through 1D and 2D inversions of the ERT surveys. The geotechnical data were obtained from field tests and laboratory experiments. The statistical analysis of the entire dataset indicates that most of the samples are clay formations, as demonstrated by the means of variables and low variance coefficients, enabling qualitative identification. The distribution analysis of the parameters confirms the complexity of the physical characteristics of soils and the measurement procedures for each parameter. The Spearman's rank correlation matrix indicates that these observations can be used to propose predictive models for free swelling, allowable stress, natural water content, and electrical resistivity. Correlations between free swelling (εg) and other variables are not significant, as the degree of significance is lower than the fixed limit, except for models εg - W (R2 = 0.94), εg - ρ (Ώ.m) (R2 = 0.803), and εg - σ adm (R2 = 0.757). Grouping variables in multiple linear regression enables the development of a mathematical model. The predicted values of εg from this model demonstrate good agreement with the measured values for a validity domain of 0–16 %. The soil's natural water content has a strong correlation (R2 = 0.80 and rs = – 0.87) with electrical resistivity, meaning that an increase in water content results in a decrease in electrical resistivity. The permissible stress σadm has a strong correlation (R2 = 0.89 and rs = 0.85) with electrical resistivity. This indicates that changes in soil electrical resistivity are associated with soil stiffness.

Electrical Resistivity Behavior of Saline Soil under Low-Temperature Conditions

Freeze-thaw cycling of frozen soils is known to be the cause of various engineering failures of infrastructure in cold regions. Researchers found that electrical resistivity methods outperform traditional ground surveying methods in frozen soils for their greater convenience and cost-effectiveness. However, detailed investigation into the relationship between the electrical resistivity of soil and a variety of soil properties is still needed. In this study, a series of laboratory experiments using the Wenner method were conducted to determine the relationship between soil electrical resistivity and soil geotechnical properties such as initial water content and pore fluid concentration under freeze-thaw conditions. Cylindrical soil samples undergo artificial freeze-thaw cycles to a temperature as low as −70°C, and electrical resistivity and temperature values are recorded simultaneously. Measurement results are summarized for curve fitting, and a statistical model showing relationship between electrical resistivity and temperature during freezing and thawing was given. Above freezing point, the log of electrical resistivity had a linear relationship with temperature. Below freezing point and above −15°C, the log of electrical resistivity had a square root relationship with temperature. Different trends in electrical resistivity change in extremely low-temperature regions (from −15°C to −70°C) are also discussed. In extremely low-temperature regions, the electrical resistivity of frozen soils did not monotonously increase with lower temperature, which may be because of increasing salt concentration in the unfrozen water phase. The findings of this study are expected to bring more insights to frozen soil structure, and assist in geophysical surveying in cold regions and construction methods utilizing ground freezing.

Naive Bayesian classifier and random forest approaches for modeling the electrical resistivity of soils in tropical zones by meteorological variables: case of nine sites in Lomé, Togo

The work combined in this article presents the results of modeling the electrical resistivity of soils based on meteorological data such as geo-referenced coordinates (A), the state of nature the day before (B), the state of nature of the day (C), the ambient temperature (D). A total of 9815 data were sampled over three consecutive years in Lomé, Togo. As methods, we carried out the characterization of the electrical resistivities of the soils measured by Wenner – Schlumberger techniques on nine sites selected in Lomé. Random forests and Naive Bayesian Classifiers are the algorithms used. Certain performance evaluation criteria most commonly encountered in the bibliography are taken into account to evaluate the models. The best result is obtained with random forests and gives MAPE = 17.372%, RMSE = 22.419%, RRMSE = 15.185% and R2 = 70.4%. The result obtained with the naive Bayesian classifier is: MAPE = 24.01%, RMSE = 49.79%, RRMSE = 33.63% and R2 = 37.34%. We deduce from these results that random forests are well suited to predicting the electrical resistivity of soils in tropical areas using meteorological variables. However, it would be good to explore other algorithms to check if the performance will not be better.

Imaging of the electrical activity in the root zone under limited-water-availability stress: a laboratory study for Vitis vinifera

Abstract. Understanding root signals and their consequences for the whole plant physiology is one of the keys to tackling the water-saving challenge in agriculture. The implementation of water-saving irrigation strategies, such as the partial root zone drying (PRD) method, is part of a comprehensive approach to enhance water use efficiency. To reach this goal tools are needed for the evaluation of the root's and soil water dynamics in time and space. In controlled laboratory conditions, using a rhizotron built for geoelectrical tomography imaging, we monitored the spatio-temporal changes in soil electrical resistivity (ER) for more than a month corresponding to eight alternating water inputs cycles. Electrical resistivity tomography (ERT) was complemented with electrical current imaging (ECI) using plant-stem-induced electrical stimulation. To estimate soil water content in the rhizotron during the experiment, we incorporated Archie's law as a constitutive model. We demonstrated that under mild water stress conditions, it is practically impossible to spatially distinguish the limited-water-availability effects using ECI. We evidenced that the current source density spatial distribution varied during the course of the experiment with the transpiration demand but without any significant relationship to the soil water content changes. On the other hand, ERT showed spatial patterns associated with irrigation and, to a lesser degree, to RWU (root water uptake) and hydraulic redistribution. The interpretation of the geoelectrical imaging with respect to root activity was strengthened and correlated with indirect observations of the plant transpiration using a weight monitoring lysimeter and direct observation of the plant leaf gas exchanges.

Experimental Study on Interaction between Slurry and Soil on Excavation Face of Shield in Sand Stratum

In sandy soil, the timely and effective formation of a filter cake is crucial for maintaining the stability of the excavated face during slurry shield tunnelling. Obtaining real-time information on slurry infiltration and particle migration is challenging, which greatly impacts the formation of the filter cake. Real-time monitoring of slurry infiltration and particle deposition is achieved through the use of electrical resistivity and pore water pressure measurements of the soil. It has been discovered that the primary pathway for slurry infiltration is inevitable in sandy soil, and it is crucial to take note of the persistent slurry leakage resulting from this situation in the shield excavation face. The distribution of slurry particle deposition is highly non-uniform in the penetration direction, with the maximum particle deposition occurring at the slurry-soil interface. However, this deposition is susceptible to disturbance from shield cutting tools, which can compromise the safety of the excavation face. Even if the particle size of the slurry is smaller than the pore size of the sand stratum, the slurry with higher viscosity can still form an internal filter cake. Furthermore, the research indicates that slurry infiltration can induce regular changes in soil electrical resistivity.

Impacts of Land Use Changes on Soil Functions and Water Security: Insights from a Three-Year-Long Study in the Cantareira System, Southeast of Brazil

Maintaining soil functions is crucial for human well-being, but there is a lack of integration between soil, water security, ecosystem services, and climate change. To bridge this knowledge gap and address erosion-induced soil and water losses and considering intrinsic impacts of soil structure, a three-year-long study was conducted focused on three dominant soil types (Typic Hapludult, Typic Dystrudept, and Typic Usthortent) combined with different land uses (native forest, eucalyptus plantation, rotational grazing, and extensive grazing) in a critical water supply region for the São Paulo metropolitan area in Southeastern Brazil. Surface runoff, evaluated for erosion resistance, was measured using the Cornell infiltrometer, and soil electrical resistivity tomography estimated soil water content to a depth of 1.5 m for groundwater recharge analysis. Soil hydraulic properties were also measured. The results revealed that native forest soils had higher hydraulic conductivity, particularly in the surface layer, compared to eucalyptus and pastures. Native forests in Typic Hapludult showed a higher runoff rate (200 to 250 mm h−1) due to a naturally dense subsoil layer that negatively impacted water infiltration and recharge with a high erosion potential, therefore reducing the amount of water stored. Typic Usthortent maintained a higher soil water content in pastures than in other land uses and also showed a low rate of water infiltration, resulting in perched water in the surface layer. In Typic Dystrudept, the native forest presented higher hydraulic conductivity (0–5 cm: 115.9 cm h−1) than eucalyptus (0–5 cm: 36.4 cm h−1), rotational grazing (0–5 cm: 19.4 cm h−1), and extensive grazing (0–5 cm: 2.6 cm h−1), but there were no significant differences in soil water content among land uses. This work illustrates the crucial role of native forests in affecting deep water recharge, reducing the soil surface erosion, mainly in soils without naturally subsoil layer, maintaining recharge potential. For Ultisols, pastures preserved soil structure and are therefore less impacted by soil management. With these results, a contribution is made to soil and water conservation, providing support for sustainable management practices in erosion-prone areas.

Method for characterization of soil electrical resistivity based on Wenner measurements by means of Nelder–Mead algorithm and FEM calculations

Method for characterization of soil electrical resistivity based on Wenner measurements by means of Nelder–Mead algorithm and FEM calculations

Quantification of freeze–thaw hysteresis of unfrozen water content and electrical resistivity from time lapse measurements in the active layer and permafrost

AbstractWe quantified seasonal, in‐situ variation in ground electrical resistivity, unfrozen water content, and ground temperature using daily and sub‐daily measurements in active layer and in permafrost on a high‐latitude monitoring site in West Greenland. The in‐situ unfrozen water content in a clayey soil undergoing phase change was 10% higher during freezing than during thawing at the same ground temperature, thus shifting the freezing curve parameterization seasonally. The freeze–thaw unfrozen water content hysteresis was a measurable part of the energy balance of the active layer and corresponds to 12.1% of the total yearly enthalpy change for our field site. We also observed and quantified hysteresis in the relationships between ground electrical resistivity and unfrozen water content, where the inverted resistivities during freezing in the temperature range from 0°C to approximately −4°C were up to one order of magnitude higher than during thawing at the same unfrozen water content. As a result, the petro‐physical models that uniquely derive soil unfrozen water content from bulk soil electrical resistivity measured from ground surface do not fully capture the complexity of the in‐situ processes. The hysteresis should therefore be considered in quantitative interpretation of ground resistivity changes in terms of ground temperature and ice content changes.

Experimental Evaluation of Stiffness Properties of a Quicklime-Stabilized Clay Subgrade Using a Resistivity Plate Loading Testing Device

Quicklime-mixing in soil stabilization applications for subgrade construction is crucial to its engineering performance and controlling quicklime and water content. Modern construction quality control devices and methods have improved construction quality control substantially. Certain devices, meanwhile, still need to be studied more thoroughly. This study used the resistivity plate loading device to assess the physical and stiffness properties of compacted quicklime-stabilized subgrade instantaneously and simultaneously for compaction quality control. The Taguchi L9 orthogonal array was used to design the experiment considering the dry density, test time, quicklime, and water content at various input factor levels. The pH, cation exchange capacity, conductivity, X-ray diffraction analysis (XRD), and scanning electron microscope (SEM) tests were further conducted. Analysis of the Taguchi experiment shows that the average soil electrical resistivity responses increased with dry density, test time, and quicklime content, and were highest at low water content. Whether the dry density, quicklime content, and test time are positively or negatively related to the average subgrade reaction modulus depends on the level of the water content. Regression equations are proposed to predict the average subgrade reaction modulus and soil electrical resistivity. The tested soils’ pH, conductivity, and cation ion exchange capacity properties were directly related to the test time, water, and quicklime content. The XRD showed nearly similar X-ray diffraction peaks. The SEM analysis confirmed marked changes in the microstructure of the samples that explained the changes in electrical resistivity and subgrade reaction modulus responses. The test results show that the resistivity plate loading device efficiently assesses compacted quicklime’s stiffness and physical properties at ease and instantaneously.

Soil resistivity measurements to evaluate subsoil salinity in rice production systems in the Vietnam Mekong Delta

AbstractRice is a staple crop in the Vietnam Mekong Delta (VMD) in which more than half of Vietnam's rice is produced. However, rice production in the VMD is threatened by increasing saltwater intrusion due to land subsidence and climate change induced sea level rise. Saltwater intrusion into lowland areas through the canal system or capillary rise of saline water from near surface saline water tables may result in salt accumulation in the topsoil. Therefore, it is important to disentangle the two effects and their relative importance to implement appropriate strategies for water and salinity management for adapting rice production systems of the VMD to climate change. Here, we report on the possibility of using geoelectrical methods to evaluate the potential threat of subsoil salinity to rice production. To evaluate the level of subsoil salinity, we measured soil electrical resistivity using an ARES II to a depth of 40 m in a case study comprising five locations in the VMD. Electrical resistivity measurements were calibrated to soil types, which were identified through evaluating 1 m core sections obtained by drilling down to 40 m depth. The relationship between drilling data and soil resistivity was determined by applying clustering and principal component analysis. Resistivity values smaller than 3 Ω m were clearly identified as indicative for a saline water table. The results show a direct link between the depth of the saline water table and the proximity to the sea, but not to the rice production system (single, double, or triple cropping). This study proved for the first time the applicability of the electrical resistivity tomography method for identifying groundwater tables and evaluating subsoil salinity on an agricultural field scale in the VMD.

Pit-mound microrelief on a forested slope drives infiltration and preferential flow after heavy rainfall – experiments with soil resistance monitoring and dye tracing

With the changing climate, short heavy rainfalls (SHRs) are becoming more frequent and intensive. The distribution of rainwater and subsurface runoff formation in forest soils can be strongly affected by soil disturbances and surface microrelief. Rainwater redistribution and the formation of preferential flow in response to natural and simulated SHRs were investigated in soil profiles on slopes forested by Norway spruce with a pit-mound microrelief formed by historical tree uprooting using two independent methods; soil electrical resistance monitoring and the application of dye tracer. In the deepest soil layers, resistance decreased in responses to natural SHRs on average by 46% in pits and by 11% on ‘smooth slope’ controls, reflecting the deeper redistribution of infiltrated water in pits. Dye tracing in the simulated rainfall revealed the formation of shallow biomat flow at the control plot. In contrast, the shallow lateral flow was focused by the pit and redirected into funnel flow underneath the pit bottom. The sum of medium and high dye concentration classes obtained with the support vector machine classification of profile photographs indicated a higher water entry into topsoil and subsoil layers in pit (44% and 31% of area, respectively) as compared to the control profile (16% and 8% of area, respectively). Leaving pit-mound microrelief as the natural legacy in forest soils can mitigate some of the negative hydrological effects of intensive forest management and may improve the water yields on forested slopes by redirecting shallow subsurface runoff and facilitating deep distribution of infiltrated water. Such beneficial effects of pit-mounds on the hydrology of forested slopes should be considered in future hydrological modelling and land management.

Advanced monitoring of soil-vegetation co-dynamics reveals the successive controls of snowmelt on soil moisture and on plant seasonal dynamics in a mountainous watershed

Evaluating the interactions between above- and below-ground processes is important to understand and quantify how ecosystems respond differently to atmospheric forcings and/or perturbations and how this depends on their intrinsic characteristics and heterogeneity. Improving such understanding is particularly needed in snow-impacted mountainous systems where the complexity in water and carbon storage and release arises from strong heterogeneity in meteorological forcing and terrain, vegetation and soil characteristics. This study investigates spatial and temporal interactions between terrain, soil moisture, and plant seasonal dynamics at the intra- and inter-annual scale along a 160 m long mountainous, non-forested hillslope-to-floodplain system in the upper East River Watershed in the upper Colorado River Basin. To this end, repeated UAV-based multi-spectral aerial imaging, ground-based soil electrical resistivity imaging, and soil moisture sensors were used to quantify the interactions between above and below-ground compartments. Results reveal significant soil-plant co-dynamics. The spatial variation and dynamics of soil water content and electrical conductivity, driven by topographic and soil intrinsic characteristics, correspond to distinct plant types, with highest plant productivity in convergent areas. Plant productivity in heavy snow years benefited from more water infiltration as well as a shallow groundwater table depth. In comparison, low snowpack years with an early first bare-ground date, which are linked to an early increase in plant greenness, imply a short period of saturated conditions that leads to lower average and maximum greenness values during the growing season. Overall, these results emphasize the strong impact of snowpack dynamics, and terrain and subsurface characteristics on the heterogeneity in plant type and seasonal dynamics.

Determination of Soil Physical Properties and Pre-Sowing Irrigation Depth from Electrical Resistivity, Moisture, and Salinity Measurements

Seeds require adequate soil moisture prior to planting, and pre-sowing irrigation depth (PSID) represents the optimum seed moisture level. This work proposes a new methodology to obtain soil physical properties and PSID, that includes the application of the electromagnetic profiling method (EMP) as a fast and non-invasive technique. Soil electrical resistivity measurements obtained from an EMP survey are combined with soil moisture and salinity information as experimental input for the PetroWin program. The PetroWin program uses Ryjov’s theoretical model to determine fines content and porosity, and then, PSID values are determined. At the study site, variations in soil resistivity were controlled by variations in fines content and soil moisture, and not by variations in soil salinity. The rooting depth of the crops was limited by a soil thickness of 0.6 m. A PSID between 8 and 9 cm was determined for the site, resulting in a total water volume required of 5313 m3 to ensure that soil moisture reaches the field capacity. The proposed methodology constitutes an effective and efficient tool for the determination of the physical properties and irrigation parameters of agricultural soils and, consequently, for the sustainable use of irrigation water.

STATISTICAL DATA ON GROUNDING DEVICES AND WAYS TO IMPROVE THEIR DURABILITY

Grounding devices of switchgears of substations differ in design, dimensions, operating conditions. Obviously, the damageability of grounding device elements should depend on the length of horizontal and the number of vertical ground electrodes, soil structure, the content of water-soluble salts in the soil, the type of element, etc. Estimates of the frequency of damage to an element of grounding devices reflect the effectiveness of existing methods for monitoring the technical condition of grounding devices. The article examines the presence of a connection between electrical equipment and metal structures of substations with grounding devices and non-exceeding of the ground resistance of standard values when measured by low-current devices, cannot serve as a sufficient sign of a satisfactory state of the elements of grounding devices. Keywords: corrosion failures, soil electrical resistivity, electrical protection of oil and gas pipelines, environment settings.

Assessment and Correlation of Saline Soil Characteristics using Electrical Resistivity

Soil salinity is becoming one of the most devastating environmental hazards over the years. Soil investigation involves fast, low cost and non disturbing methods to measure soil characteristics for both construction projects as well as for agricultural use. The electrical resistivity of saline soils is greatly governed by salt concentration and the presence of moisture in soil matrix. Experimental results of this investigation highlight that there is a significant relationship between the electrical resistivity of soil samples mixed with chloride solutions (NaCl, KCl, and MgCl2) at various concentrations, and soil physical properties. Correlations represented by quadratic functions were obtained between electrical resistivity and soil characteristics, namely, water content, degree of saturation and salt concentration. This research reveals that the obtained correlations between electrical resistivity, salt concentration, water content and degree of saturation are effective for predicting the characteristics of salt affected soils in practice, which constitute a governing element in the assessment of saline lands sustaining infrastructure.

Analysis of soil electrical resistivity and hydraulic conductivity relationship for characterisation of lithology inducing slope instability in residual soil

Slope instability occurrences as damaging shallow-landslides in the residual soil around mountains has been widely studied with geophysical, geotechnical and hydrogeological techniques but relating soil electrical resistivity to hydraulic conductivity for characterisation of lithology inducing of these landslides is not common. In this study, we used Electrical Resistivity Tomography (ERT) data and Hydraulic Conductivity (HC) data obtained from soil samples collected within 1–4.5 m depth in the borehole to assess the characteristics of soil that can induce landslide in the study location. The HC data were derived empirically from Beyer, Kozeny-Carman and Slitcher formula which were validated with HC obtained from laboratory experiment. The Empirical Derived Hydraulic Conductivities (EDHC) were correlated with the soil resistivity. The result shows a strong correlation between soil resistivity and HC with regression values of R2 = 0.9702, R2 = 0.9153 and R2 = 0.9232 for Beyer, Kozeny-Carman and Slitcher formula, respectively. The ERT model revealed a possible sliding surface between two contrasting resistive top material and underneath conductive materials at about 4 m depth. The HC assessment result corroborated the ERT model result because high and low-HC values were obtained in the borehole soil samples within 0–4 m and > 4 m depths from EDHC, respectively. The low-HC zone below 4 m depth was responsible for the occurrences of the shallow-landslides in the study.

Ensuring the reliability of energy systems with the application of a new method of decreasing seasonal variations of ground resistance

The possibility of improving the reliability of the grounding system is shown. The analysis of dependence of soil resistivity on humidity was carried out, on the basis of which a composition for normalization (reduction of seasonality) of soil electrical resistivity was proposed. A number of full-scale experiments were carried out to measure the resistance values of the grounding devices of experimental circuits, after backfilling the places of laying the contour elements with various compositions and introducing other types of soils and minerals.

Monitoring assessment of the low-pressure earthen dam of the Varnavinsky reservoir under conditions of an increasing risk of natural and man-made disasters

The need for increased attention to the reliability and safety of hydraulic structures in the water management complex of southern Russia is determined by the scale of the socio-economic consequences of their accidents. During the long-term operation of the low-pressure earthen dam of the Varnavinsky reservoir, various hidden defects and damages were formed. Which in the future can lead to a man-made disaster. The threat of catastrophic floods with the formation of hidden defects and damage will lead to natural disasters, namely the destruction of the dam body. The identification of these hidden defects and damages is a priority task in assessing the technical condition of the body of an earthen dam. The article considers only two methods of non-destructive testing for the detection of hidden defects and damage. Methods of electrocontact dynamic sounding and seismic exploration. They make it possible to obtain the electrical resistivity of soils when subdividing a section according to a lithological feature. As a result of data processing and interpretation, the geoelectric section of the electrical resistivity of soils was obtained. Applied hardware and methodological complex allowed to solve the tasks. The advantage of the complex is its methodological mobility. After a short experimental and methodological work and express processing, it is possible to clearly orient and combine the capabilities of the instrumentation complex and the engineering-geological situation in order to obtain the maximum quality and at the lowest cost of time and money. Studies of low-pressure earth dams should be carried out in the monitoring mode at various water levels in the reservoir. As can be seen from the results of processing, the geophysical complex of non-destructive testing makes it possible to study earth dams with the determination of soil parameters. To determine the physical and mechanical properties of soils, a greater amount of work should be carried out using reference drilling wells and identifying correlation dependencies of parameters.