ELECTRICAL RESISTIVITY TOMOGRAPHY

Sampling issues represent a persistent problem in shell matrix research, particularly for large shell deposits. When small samples are taken from large buried deposits it is almost impossible, under current research practices, to understand how representative that sample is of the overall deposit. This case study tests a novel method for creating a better understanding of the buried deposits from which excavated samples are taken, thereby allowing for improved sampling strategies and a better understanding of how representative those samples are of the overall site. The case study employs two geophysical survey methods, ground‐penetrating radar (GPR) and electrical resistivity, to investigate buried shell deposits under experimental conditions. The survey results were used to create volume estimations and three‐dimensional (3D) models of buried shell deposits. This method is novel to shell matrix research and the current case study was designed to test the viability of the method un...

This study investigated the awareness of climate change and adaptation strategies among secondary school students in Ogbaru Local Government Area of Anambra State, Nigeria. Two research questions guided, and two null hypotheses were tested at the 0.05 level of significance. The researchers employed a descriptive survey research design. The population consisted of 8,564 JSS and SS students from the 9 public secondary schools in the area. The sample size consisted of 170 students from the four schools sampled for the study using a simple random sampling technique (balloting). Data was collected using the 40-item climate change awareness and adaptation strategies questionnaire (CCASSQ) developed by the researchers and validated by experts. An estimate of the stability of the instrument yielded a

Direct current Resistivity (DCR) method was carried out to characterize the hydrogeological connection between the Tabular Middle Atlas (TMA) and the Saïs Basin. The TMA is one of the most important aquifers in northern Morocco that supplies the deep aquifer of the Saïs Basin. Electrical resistivity tomography (ERT) survey was focused on the Bittit area that is one of the most important outlet discharges, and it is representative of the relations between the TMA and the Saïs Basin. The high resolution capabilities of the electrical tomography were used to define the geological draining features in the framework of water paths from the TMA to the karstic springs. The synthetic data were calculated for the similar model expected in field data inversion and inversion result of these synthetic data used as a guide for the interpretation of the inverse data resistivity sections. Joint interpretation of geophysical, geological, structural, and synthetic simulation data allowed identifying...

Apart from the fact that groundwater is the most abundant source of water available for human
consumption, it is more advantageous as a source of potable water because it is usually free from
human (Anthropogenic), biological and chemical contaminants. In the quest to search for good and
high quality groundwater, Geophysical investigation involving Electrical Resistivity (Vertical
Electrical Sounding) was employed in Harding model college, Okesa, Ado-Ekiti to delineate
subsurface structures favourable for groundwater occurrence and to depict groundwater flow in the
subsurface. Four Vertical Electrical Sounding was carried out in the study area using schlumberger
electrode array configuration with 100m as the maximum AB/2. The VES data obtained were
interpreted qualitatively and quantitatively by partial curve matching technique and computer
modeling. KHA, AK, KH and A curve types were obtained from the study area. The Geo-electric
section delineated four lithologic units, including topsoil/lateritic layer, weathered layer, fresh
basement rock and fractured basement rock. VES 1 and 3 were observed to have good aquifer
characteristics due to the overburden thickness but cannot yield substantial amount of water supply,
while VES 2 (even though with reduced overburden thickness compared to VES 1 and 3) was
interpreted to have adequate aquifer characteristics that is suitable for development of reliable and
sustainable water supply in Harding model college due to the intensively fractured basement rock
underlying the fresh basement rock.

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The application of multichannel surface wave analysis (MASW) has proven to be an effective method for non-invasive investigation of shallow geological structures, especially under complex conditions with heterogeneous layers and the presence of groundwater. In the technical stone quarry field in Čelina, MASW enabled precise soil characterization, identification of transition zones and anomalies, and determination of seismic resistance of layers based on the Vs30 parameter. The investigations confirmed the presence of a fault structure within the deposit, with the wider fault zone proving to be hydrogeologically significant, potentially acting as an aquifer. The geologicalcomposition of the carbonate terrain, characterized by lateral variability, required a conservative approach to the analysis based on the fundamental dispersion mode. The creation of a three-dimensional model from combined MASW profiles provided accurate spatial insight into the mechanical properties of the soil, facilitating engineering decision-making for future interventions. The results also indicated the need for further investigations, including the potential drilling of an exploration borehole in the fault zone to confirm the presence of an aquifer layer. MASW is confirmed as a reliable, economical, and practically applicable method for a wide range of engineering and hydrogeological studies. Its ability to quickly profile the soil makes it suitable for urban and inaccessible areas, andwhen combined with other geophysical methods, it can contribute to an integrated approach to subsurface analysis.

Archaeo-geophysics currently stands as a powerful discipline in European archaeological research to discover, study and record subsurface archaeological sites. Its importance lies in its capacity to reveal hidden archaeological assets in a non-destructive, rapid and detailed manner in comparison with traditional and more invasive archaeological methods such as excavation or test-trenching. In the last decade, a major technological development in archaeo-geophysics has been the introduction of multi-sensor and motorised instrumentation. This has revolutionised archaeological prospection by allowing extremely fast and high-resolution surveys to explore large areas.Whilst the discipline of archaeo-geophysics is going through an exciting phase of technological development, a major problem concerning researchers and practitioners is that our ability to interpret the full suite of information extractable from geophysical datasets has not kept pace with developments in technology and is st...

This paper discusses the occurrence and search for groundwater at school of Agriculture Mgbakwu, in Anambra State, Nigeria as indicated by result of vertical electrical soundings (VES). The project area lies within Longitudes 7°6' E-7° 54'E and Latitudes 5°56'N-6 °52'N, and covers an area spread extent of about hundred plots of land within over seven main geological formations. The thickness, lateral extent and transverse resistance of the aquiferous layers were determined by the geoelectrical survey. Water table information from existing boreholes and hand dug wells records were used to compliment the survey. The data acquired was also used in delineating the geoelectric sections. The study was carried out using the Schlumberger electrode configuration. The interpretation of the resistivity curves over the study area within geologic terrain often referred to as sedimentary environment indicates that the area have groundwater potential. The experiment conducted over the area showed a total depth of 580 and 650 feet respectively which corroborated with ground water data acquired from the existing boreholes and hand dug wells in the study area.

Water saturation in the bedrock or colluvium is highly related to most landslide hazards, and rainfall is likely a crucial factor. The dynamic processes of onsite rock/soil mechanics could be revealed via monitoring using the electrical resistivity tomography (ERT) technique and Archie’s law. This study aims to investigate water saturation changes over time using time-lapse ERT images, providing a powerful method for monitoring landslide events. A fully automatic remote resistivity monitoring system was deployed to acquire hourly electrical resistivity data using a nontraditional hybrid array in the Lantai area of Yilan Taiping Mountain in Northeast Taiwan from 2019 to 2021. Six subzones in borehole ERT images were examined for the temporal and spatial resistivity variations, as well as possible pathways of the groundwater. Two representative cases of inverted electrical resistivity images varying with precipitation may be correlated with water saturation changes in the studied hill...

Construction of landfills and open dumping of solid-waste above fracture-controlled aquifers can increase leachate concentrations, contaminating useable surface and shallow groundwater resources. In such cases, it is essential to define the hydrogeological processes and identify the pathways in the fractured aquifer system for contamination migration near the dumpsite. Abu Zaabal Quarry is a typical example where a solid-waste dumpsite was installed directly on fractured basalt around polluted groundwater ponds. To assess the vulnerability conditions in this complex environment, Seismic Refraction Imaging (SRI) and Electrical Resistivity Tomography (ERT) were integrated with the available geological and hydrogeological information for delineating the effective fractured zones and to refine the site conceptual model of the potential pathways associated with solid waste leachates, The constructed resistivity and seismic images help to identify interflow zones in the basaltic protectiv...

The new urban development is an important priority in Egypt to face a rapid increase in the population during the last few decades. As a case study, the geotechnical assessment of the New Minia City is studied applying direct current (DC) resistivity technique. In the presented study, the DC resistivity data are interpreted to (i) characterize the subsurface layer distributions, (ii) deduce the subsurface structures considering the surface geological and structural setting and borehole information and (iii) predict geotechnical parameters of the bedrock based on empirical relationships. The inversion results of DC resistivity data indicate that a lens of clay is locally capping the fractured limestone in different parts of the area. The constructed geoelectrical cross-sections show that the limestone bedrock is highly fractured regarding many normal faults trending in the NW and NE directions. In an attempt to derive empirical relationships for predicting the geotechnical parameters, the inverted resistivity values of the fractured limestone were correlated with different geotechnical parameters, Rock Quality Designation (RQD) and Unconfined Compressive Strength (UCS). It is noticed that there are good correlations between the limestone resistivity values and geotechnical parameters obtained from borehole data applying linear relations. Accordingly, the results indicate that the DC resistivity method constitutes a valuable technique to introduce a preliminary geotechnical assessment for new urban areas.

The understanding of the site conceptual flow model in fractured-controlled aquifers near landfills and open dumpsites is a challenge for monitoring groundwater pollution as it answers several key issues related to environmental processes. In such hazardous environments, it is essential to define the hydrogeological processes and identify the potential pathways for contamination migration near the dumping sites. Thus, the understanding of fractured basalt characterization with suitable spatial resolution is one of the interesting issues and still open areas of research. This study investigates the potential of combining Electrical Resistivity Tomography (ERT) and Seismic Refraction Imaging (SRI) techniques for understanding a site conceptual flow model in fractured basalt under a hazardous environment. The research was conducted in an area with a history of environmental contamination, where fractured basalt serves as a major pathway for the migration of pollutants. In the considere...

An efficient advanced numerical model for mapping the distribution of the buried tree roots is presented. It not only simplify the complicate root branches to an easy manipulated model, but also grasp the main structure of tree roots ignoring the unnecessary minutiae, and thus provide an intuitive impression of subsurface invisible anomalies. The processing model is combined with an adaptive finite element method, which can automatically generate unstructured triangular meshes during the process of discretization, which also enable user to specifically set the resistivity along each part of tree roots.

Hydrochemical analysis of water samples from Yenagoa in the Niger Delta shows widespread occurrence of iron (Fe) in the groundwater. The Fe concentration is more than 0.3 mg/L at many places, and the distribution is heterogeneous both vertically and horizontally. In order to identify the cause of the high heterogeneity, we carried out an integrated study consisting of hydrogeochemical, electrical resistivity sounding and induced polarization (IP) chargeability measurements at eleven sites and 2-D electrical resistivity profiling (at 2 sites). Data processing using inversion techniques resulted in 4-layered resistivity and chargeability-depth models. The results show that clean sand and gravel exhibit high resistivity but low chargeability and normalized chargeability values, whereas clay and sandy clay exhibit relatively low resistivity but high chargeability and normalized chargeability values. In sites where the aquifer is overlain by a thick clay layer, Fe concentration is high (Fe > 0.3 mg/L) in the groundwater and redox potential values range between 118 and 133 mV. We interpret that the low-permeability clay layer creates a relatively atmosphere-isolated state in the underlying aquifer, which is responsible for the reductive ambient subsurface groundwater environment. In sites where the aquifer is capped by silt, Fe concentration is low (< 0.3 mg/L) in the groundwater and redox potential values range between 115 and 164 mv indicating a mild oxidation environment. We interpret that the clay acts as a controlling factor to the Fe enrichment in the groundwater regime. Knowledge of the clay layer, which is identified in the present study, will be helpful in selecting suitable sites for boreholes.

Siliyin spring is one of the many natural fresh water springs in the Western Desert of Egypt. It is located at the central part of El-Fayoum Delta, which is a potential place for urban developments and touristic activities. Integrated geoelectrical survey was conducted to facilitate mapping the groundwater resources and the shallow subsurface structures in the area. Twenty-eight transient electromagnetic (TEM) soundings, three vertical electrical soundings (VES) and three electrical resistivity tomography (ERT) profiles were carried out around the Siliyin spring location. The dense cultivation, the rugged topography and the existence of infra structure in the area hindered acquiring more data. The TEM data were inverted jointly with the VES and ERT, and constrained by available geological information. Based on the inversion results, a set of geoelectrical cross-sections have been constructed. The shallow sand to sandy clay layer that forms the shallow aquifer has been completely mapped underneath and around the spring area. Flowing of water from the Siliyin spring is interconnected with the lateral lithological changes from clay to sand soil. Exploration of the extension of Siliyin spring zone is recommended. The interpretation emphasizes the importance of integrating the geoelectrical survey with the available geological information to obtain useful, cheap and fast lithological and structural subsurface information.

Electrical impedance tomography (EIT), as a monitoring tool of regional lung ventilation, is radiation-free imaging with high temporal resolution. The most important purpose of EIT is to visualize the distribution of tidal volume in different lung regions especially between dependent (dorsal in supine patients) and non-dependent (ventral in supine patients) regions. Many clinical studies evaluated the applicability of PulmoVista® 500 (Dräger Medical GmbH, Lübeck, Germany) and similar EIT devices in estimating optimal PEEP after recruitment maneuvers (RM) in lung healthy patients and acute respiratory distress syndrome (ARDS), ventilation distribution in cystic fibrosis, COPB, pneumonia and respiratory diseases syndrome in infants.

This paper presents how near surface soil characteristics are obtained through soil electric resistivity ratio from soil apparent resistivity profile. In recent advances of electrical sensors, soil apparent resistivity is implemented as nondestructive method for obtaining near surface soil profile. Although geo-electric techniques offer an improvement to traditional soil sampling methods, the resulting data are still often misinterpreted for obtaining soil characteristics through apparent electrical resistivity in the field. Because, soil resistivity as before rain and after rain are changeable due to the presence of more moisture contents in field investigations. In this study, the parameter of soil electric resistivity ratio is incorporated to obtain reliable near surface soil profiles from apparent resistivity of adjacent two layers in soil. The variations of potential differences are taken into account for using four probes method to get the soil apparent resistivity profile. The research is significant for simpler and faster soil characterizations using resistivity ratio of apparent resistivity in soil investigations.

The seismic refraction method belongs to the group of non-destructive testing techniques and represents an efficient geophysical approach for determining the propagation velocity of seismic waves through different geological environments. This allows for the assessment of key geomechanical parameters of the terrain. In this study, measurements were conducted along three profiles in the excavation zone of the Vranduk tunnel, located on the Corridor Vc route, with the aim of characterizing the rock mass and determining its condition before the commencement of construction work. Analysis of the obtained data defined the velocities of seismic waves, which were used to assess rock mass quality, classify materials, and identify potential discontinuities and weakened zones. The results indicated that in the upper zone, at a depth of 6-8 meters, the rock mass is weathered, whereas in deeper layers, the rock mass is more intact and only slightly fragmented. Since this method is entirely non-destructive, it enables rapid and reliable terrain investigation without disturbing its structure. The results were compared with in-situ geotechnical investigations, confirming the method's reliability in determining the mechanical properties of rocks. The obtained data served as a foundation for optimizing design solutions, adjusting excavation techniques, and improving the stability of the tunnel structure.

In this paper we present a combination of several near surface geophysical investigation techniques with high resolution remote sensing image interpretations, in order to define the groundwater flow paths and whether they can be affected by future seismic events. A seasonal spring (Amvrakia) located at the foot of Meteora pillars near the village of Kastraki (Greece) was chosen as a test site. The Meteora conglomeratic formations crop out throughout the study area and are characterized by large discontinuities caused by post Miocene till present tectonic deformation [Ferriere et al. 2011, Royden and Papanikolaou 2011]. A network of groundwater pathways has been developed above the impermeable marls underlying the conglomeratic strata. Our research aims to define these water pathways in order to investigate and understand the exact mechanism of the spring by mapping the exposed discontinuity network with classic field mapping and remote sensing image interpretation and define their u...

The Amvrakia spring is located at the bottom of Meteora pillars and more specifically near the village of Kastraki (Kalambaka municipality). It is a seasonal spring since it functions only during the wet period. The Meteora conglomerates which dominate the area are characterized by large discontinuities creating a network of groundwater pathways above the impermeable strata of the underlying marls. The research targets was to define these water pathways in order to understand the mechanism of Amvrakia spring, by mapping the exposed discontinuity network and define their underground extension with the contribution of geophysical techniques. Electrical Resistivity Tomography (ERT) and Very Low Frequency (VLF) methodologies were applied. The VLF method is indicated for the detection of water-bearing fracture zones, but before the application of their filters they had to be processed for topographic corrections, as the area had not smooth relief. Five (5) VLF profiles were conducted with different directions around the spring's area, in order to detect possible conductive zones in the conglomerates surrounding the study area. Moreover, two (2) ERT sections of a total length of 140m were carried out, parallel to existent VLF sections, for crosschecking the geophysical information. Both techniques revealed important conductive zones (<200 Ohm.m) from the south-eastern Meteora conglomerate pillars, possibly interpreted as discontinuities filled with water feeding the spring.

Accurate subsurface assessment is critical for ensuring the integrity and longevity of engineered structures, especially in weathered terrains characterized by highly variable soil and rock properties. This challenge is particularly evident in the complex granitic terrain of Ipoh, Perak, Malaysia, where differential weathering and fracturing introduce substantial uncertainty into foundation design. Despite increasing demands for resilient infrastructure, conventional site investigation methods often fall short in capturing the spatial and lithological heterogeneity required for informed decision-making. This study addresses these limitations by integrating electrical resistivity tomography (ERT), induced polarization (IP), standard penetration testing (SPT), and supervised machine learning (ML) algorithms to enhance subsurface characterization and predictive modeling of chargeability. The combined ERT–IP inversion results, supported by borehole logs and SPT data, delineated four distinct lithological units across the study area. Four ML algorithms—SLR, KNN, SVM, and CatBoost—were trained to model relationships between geophysical and geotechnical parameters, with all achieving strong performance (training R² > 0.90; error metrics <10%). Among all the evaluated models, CatBoost exhibited the strongest overall performance, achieving high predictive accuracy and maintaining consistent generalization across validation and test sets, although with mild overfitting observed. Among all the evaluated models, CatBoost exhibited the strongest overall performance, achieving high predictive accuracy and maintaining consistent generalization across validation and test sets, although with mild overfitting observed. From a geotechnical perspective, the topsoil/residual and highly weathered/fractured units were deemed unsuitable for heavy structural loads due to poor consolidation and water retention. In contrast, the relatively weathered bedrock unit, defined by resistivity values of 800 to >1000 Ωm and chargeability >18 msec, was identified as a suitable foundation material after appropriate soil and rock modifications. This research introduces a novel, noninvasive geophysical–geotechnical framework enhanced by ML, offering a cost-effective and scalable approach for subsurface evaluation. The methodology significantly reduces uncertainty in engineering assessments and supports safer, data-driven construction decisions, with potential applicability to other complex weathered terrains, subject to site-specific calibration.

Leachate plume emanating from an old unlined municipal landfill site near the city of Norman, Oklahoma, is discharging into the underlying alluvial aquifer. Subsurface imaging techniques, electrical resistivity tomography and electrical conductivity (EC) logging, were used on the site to detect and map the position of the leachate plume. Anomalous EC zones, delineated with the two methods, correlated with the occurrence of the plume detected by water chemistry analyses from multilevel monitoring wells. Specific conductance, a potential indicator of leachate contamination, ranged from 1861 to 7710 μS/cm in contaminated zones and from 465 to 2180 μS/cm in uncontaminated ground water. Results are in agreement with those from earlier studies that the leachate plume emerges from the landfill along preferential pathways. Additionally, there are indications that the leading edge of the plume has migrated, at least, 200 m away from the landfill in the direction of ground water flow.

This presents study assessed some physicochemical parameters (temperature, pH, conductivity, turbidity and dissolved oxygen) in hand dug well water from ten (10) locations within Wannune in Tarka LGA of Benue State, Nigeria. Ten (10) heavy metals concentration zinc (Zn), mercury (Hg), Arsenic (As), chromium (Cr), copper (Cu), nickel (Ni), iron (Fe), cadmium (Cd) and lead (Pb) were also determined using atomic absorption spectrophotometry (AAS). The results revealed the mean values for temperature, pH, conductivity, turbidity and dissolved oxygen to be 2.79±0.876 o C, 6.35±0.313, 153.4±99.633 µs/cm, 3.85±1.556 NTU, and 5.70±0.666 mg/L respectively. The results also revealed very low concentrations of heavy metals (within WHO and NSDWQ standard for portable water) except for Fe (0.51 mg/L) from W4 which is slightly above the prescribed limit (0.3 mg/L) prescribed by WHO and NSDWQ and is attributed to mechanical repairs of vehicles, use of engine oils on daily basis and rusting from iron buckets used for abstracting water from the well. Hg, As, Cu and Mn were not detected in any of the well water samples. The authors therefore recommend that the water is safe for drinking and domestic use but members of the community should construct wells away from dumpsites or sites where mechanical activities occur also adopt a better practice of abstracting well water than the use of iron buckets.

Conclusions of the field and interpretation work led to the definition of areas of specific archaeological potential-six on site 1 (none irrelevant) and three on site 2 (one less relevant)-and to the suggestion for excavation locations. Overall archaeological potential is higher on site 1. In the aftermath of the prospection, Site 2 was selected for construction, though subject to archaeological monitoring. Construction excavation as shown close accordance to the results; a shallow graveyard, with no sarcophagus or slabs, was discovered in the limits of the prospected area. Building at Site 1 was deferred for the time being.

This study was conducted in the Mersa-Girana sub basin in north wollo zone, Ethiopia. It aims to map the groundwater
potential zones in the area. VES and magnetic geophysical methods were employed to achieve this objective. As part of
the geophysical survey, 293 magnetic data were collected at 100 meter intervals along east-west profiles and 10 VES
points were acquired along four east-west profiles with an interval of 500 meter between the VES points. In addition
to the primary VES data, ten (10) VES data were collected from secondary sources. The VES data were acquired using
a Schlumberger array and a maximum current electrode spacing of 1000m. The results reveal the main aquifer depth
is between 43 and 351 meters in the area. Furthermore, the analysis of Dar-Zarrouk parameters in the research area
shows that 35% of the aquifers exhibit high productivity, while 65% of the aquifers demonstrate moderate productivity.
The estimated hydraulic conductivity and transmissivity values are high in the central and eastern region of the research
area. The results of electrical resistivity and magnetic measurements also demonstrate the region is strongly affected by
faulting, which is believed to regulate the groundwater movement in the underlying volcanic series

Electric resistivity tomography (ER T), self-potential (SP), soil Celi flux and temperature are used to study the inner structure of La Fossa cone (Vulcano, Aeolian Islands). Nine . profiles were performed across the cone with a measurement spacing of 20 m. The crater rims of La Fossa cone are underlined by sharp horizontal resistivity contrasts. SP, Celi flux. and temperature anomalies underline these boundaries which we interpret as structural limits associated to preferential circulation of fluids. The Pietre Cotte crater and Gran Cratere crater enclose the main hydro thermal system, identified at the centre of the edifice on the base of low electrical resistivity values ( <20 n m) and strong Celi degassing, SP, and temperature anomalies. In the periphery, the hydrothermal activity is also visible along structural boundaries such as the Punte Nere, Forgia Vecchia. and Palizzi crater rims and at the base of the cone, on the southern side of the edifice, along a fault attributed to the NW main tectonic trend of the island. Inside the Punte Nere crater, the ER Tsections show an electrical resistive body that we interpret as an intrusion or a dome. This magmatic body is reconstructed in 30 using the available ER T profiles. Its shape and position, with respect to the Pietre Cotte crater fault, allows replacing this structure in the chronology of the development of the volcano. It corresponds to a late phase of activity of the Punte Nere edifice. Considering the position of the SP, soil Celi flux. and temperature maxima and the repartition of conductive zones related to hydrothermal circulation with respect to the main structural features, La Fossa cone could be considered as a relevant example of the strong influence of preexi sting structures on hydrothermal fluid circulation at the scale of a volcanic edifice.

Groundwater resources in Morocco are increasingly scarce. The study area which is Central Haouz belonging to the Marrakech plain is not immune to this phenomenon. This is due to the semi-arid climate on the one hand, and on the other hand, due to accelerated population growth and the economic development implications. The Plio-Quaternary aquifer of the Central Haouz has been the subject of several studies, but its Hydrogeological characterization has been classically carried out using geological and pumping test studies. Our study is in this sense to show the importance of the contribution of GIS and Electrical Resistivity Tomography (ERT). The first GIS approach determined the Runoff coefficient, which helps to locate low runoff areas corresponding to recharge zones of the water table. These areas are chosen as the site for geophysical surveys. The second method consists to detect the effect of the recharge to increase the water table in the study area and the characterization of the aquifer. Four ERT surveys were performed showed on the aquifer the positive effect of the recharge dike recently built at the Wadi and dismantle the reliability of the GIS results concerning the infiltration zones founded.

BALLIET J.M. - Neuf-Brisach, emblématique et méconnue ; Les saisons d'Alsace, 2018, No. 76, p. 46-51.
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Archétype de la fortification bastionnée, la place forte de Neuf-Brisach, ville-forteresse créée ex nihilo à partir de 1698, occupe une place de choix dans l'œuvre de Vauban. Mais ses caractéristiques architecturales restent paradoxalement méconnues : trop souvent, le mythe a pris le pas sur l'étude factuelle.

Reliable characterization of subsurface conditions, such as depth to bedrock, lithological variability, and the presence of fractures or faults, is critical for designing safe and durable foundations. However, geophysical methods remain underutilized in geotechnical design due to limited interdisciplinary collaboration, a general lack of awareness among engineers, and the absence of standardized integration frameworks. Hence, this study addresses these gaps by integrating geophysical and geotechnical data with machine learning (ML) techniques to enhance subsurface integrity modeling for foundation designs. Conducted in a granitic terrain in Minden, Pulau Penang, Malaysia, the research utilized electrical resistivity tomography, induced polarization, seismic refraction tomography, and standard penetration test (SPT-N) data acquired along two transects. The findings revealed critical subsurface anomalies-such as fractures, weathered zones, and lithological transitions-that pose potential risks to structural stability. Three major lithological layers were delineated: saturated clayey/silty topsoil extending to the residual profile; a transitional zone comprising weathered (clayey/silty) and fractured rock; and partially weathered to hard bedrock. ML algorithms applied included K-nearest neighbors (R² = 0.930 training, 0.905 testing), simple linear regression (R² = 0.898 training, 0.905 testing), principal component analysis, and K-means clustering (Silhouette score = 0.6688, residual sum of squares of 30.87 at K m = 3), all demonstrating strong predictive performance. The integrated framework proved effective for delineating subsurface lithology and assessing geomechanical properties, offering a scalable, data-driven strategy for cost-effective, high-resolution foundation design. This approach supports improved engineering decisions, reduces reliance on extensive invasive testing, and highlights the transformative potential of ML-assisted geophysical-geotechnical investigations in infrastructure development.

The present investigation was focused on the variations in rainwater infiltration experienced by soils of Gamboa zone (Panama Canal Watershed) during various seasons of the year, employing a time-lapse analysis of electrical resistivity tomography (ERT). In 2009, a total of 3 geoelectrical tests were undertaken during the dry, transition and rainy seasons across a profile 47 m in length, strategically distributed on site. The results obtained in this study showed strong variations in calculated resistivity between these seasons, taking the dry season as a reference with decreases and increases of percent difference of resistivity between -20% and -100%, and between 50% and 100%, respectively. These decreases, when displayed through a sequence of time-lapse images, reveal a superficial extension of the water content variations along the entire profile, as well as strong inversion artifacts showing false increases of calculated electrical resistivity. Decreases are the product of the ...

Two ERT (Electrical Resistivity Tomography) profiles were conducted at the eastern head of Lago Fagnano within the main deformation zone of the Magallanes-Fagnano Transform fault system (MFS) which represents the onland boundary between the South America and Scotia plates. Results from the inversion models have provided new evidence of the presence and location, at shallow depths, of some strands of the MFS. Tomographic models showed significant resistivity contrasts across the inferred fault zones in the subsurface. The combination of ERT, geomorphic and outcrop structural data allowed us to interpret the stepped, southward subsidence of Tertiary and Quaternary units within the studied area. The Holocene development and evolution of a shallow deltaic basin at the mouth of Río Turbio, the eastern tributary of Lago Fagnano, was also interpreted from electrical imaging.

This presents study assessed some physicochemical parameters (temperature, pH, conductivity, turbidity and dissolved oxygen) in hand dug well water from ten (10) locations within Wannune in Tarka LGA of Benue State, Nigeria. Ten (10) heavy metals concentration zinc (Zn), mercury (Hg), Arsenic (As), chromium (Cr), copper (Cu), nickel (Ni), iron (Fe), cadmium (Cd) and lead (Pb) were also determined using atomic absorption spectrophotometry (AAS). The results revealed the mean values for temperature, pH, conductivity, turbidity and dissolved oxygen to be 2.79±0.876 o C, 6.35±0.313, 153.4±99.633 µs/cm, 3.85±1.556 NTU, and 5.70±0.666 mg/L respectively. The results also revealed very low concentrations of heavy metals (within WHO and NSDWQ standard for portable water) except for Fe (0.51 mg/L) from W4 which is slightly above the prescribed limit (0.3 mg/L) prescribed by WHO and NSDWQ and is attributed to mechanical repairs of vehicles, use of engine oils on daily basis and rusting from iron buckets used for abstracting water from the well. Hg, As, Cu and Mn were not detected in any of the well water samples. The authors therefore recommend that the water is safe for drinking and domestic use but members of the community should construct wells away from dumpsites or sites where mechanical activities occur also adopt a better practice of abstracting well water than the use of iron buckets.

The present survey aimed to image the subsurface structure, including karstic voids, and to evaluate the extent of the heterogeneities that can result in potentially dangerous collapse of road segments overlying these features. A multidisciplinary geophysical approach (seismic refraction, frequency domain electromagnetic and ground penetrating radar) in combination with a detailed geological survey indicated the presence of tectonic faults as well as velocity and conductivity anomalies along an old road within the area of Akrotiri at Chania (Crete). Due to the presence of subsurface fuel pipes, perpendicular to the direction of the road, 2D resistivity imaging was excluded from the applied geophysical methods.Interpretation of the geophysical data revealed that the section of the road investigated overlies prominent voids attributed mostly to karst features. The conductivity and velocity anomalies are interpreted to indicate an area where the host limestone rock has been downthrown ...

In this study, geological researches carried out before the construction of underground rail systems and geotechnical application methods preferred during the construction were examined within the scope of Halkalı-İstanbul Airport metro project. The metro line consists of a total of 66.2 km long underground tunnels, 31.3×2 km main line and 1.8×2 km repertorium connection line. 1006 soil and 1230 rock samples were collected for the main line whose geological research was carried out with 198 core drillings with a total length of 9588.5 m. The results of the laboratory tests on the samples and the field tests carried out in the boreholes were obtained. In addition, a total of four two-dimensional inverted solution resistor underground sections were obtained by using the Multiple Electrode Electrical Resistance Tomography measurement method in the middle of two lines (Line-1 Km. 61+440 – 61 +660 /Line-2 Km: 61 +400 - 61+620), in the Olympic Stadium station (Km: 62+215 – 62 +490) and in...

Nuraghe S&#39;Urachi is a monumental architectural complex in West Central Sardinia that was probably first built in the Bronze Age and remained occupied continuously into the early Roman Imperial period. It has been the object of systematic and large‐scale archaeological investigations in three different phases since 1948 when the first excavations revealed a complex building within a massive defensive wall and multiple towers. Intermittent fieldwork between the 1980s and 2005 subsequently showed that the central nuraghe might comprise up to five principal towers. In 2013, a new collaborative research project, sponsored by Brown University and the Municipality of San Vero Milis, brought together a multidisciplinary research project to investigate this important archaeological site. In this framework, multi‐frequency and multi‐coil electromagnetic measurements (FDEM) and Electrical resistivity tomography (ERT) were carried out in 2018, 2019, and 2020, over and close to the nuraghe t...

Among all geophysical techniques, electrical resistivity and magnetic surveying as an integrative approach has been used widely for archaeological prospection at different scales of investigations. In this study, DC resistivity (1D vertical sounding and/2D/3D ERT) and magnetic surveys (total and gradient) as a multi-scale approach was applied in a highly terraneous archaeological site (Tell) with a case study to characterize and image the various archaeological assets at different depths with different spatial resolutions. Four critical zones of great interest within the considered Tell were surveyed. At the heart of the study area, three layers were depicted clearly from 1D resistivity sounding. A thick conductive zone of mostly clay is sandwiched between two resistive layers. The topmost layer contains construction debris (dated back to the Islamic Era), whereas the deeper layer could be related to Gezira sand on which the probable Pharaonic temple was constructed. A long 2D ERT p...

Tolnaku, a village situated in the Kupang Regency, East Nusa Tenggara, Indonesia, is an area susceptible to landslides. An investigation into the likelihood of slope failures in this locality is imperative for landslide mitigation. This study endeavors to elucidate the subsurface conditions and evaluate the physical parameters and contributing factors that could precipitate landslides in this territory. The method of geoelectric resistivity, employing the Schlumberger configuration, has been applied to discern the varieties of rocks and cavities present in this area. The data amassed through the resistivity survey has been processed and analyzed to delineate the subsurface strata and assess their stability. The findings indicate that clay and limestone are the predominant materials in this area, and are deemed unstable. Furthermore, cavities and voids were identified in this area, amplifying the probability of landslide occurrences therein. Ultimately, the Safety Factor (SF) was ascertained to be less than 1, robustly suggesting that the slopes are perilous and vulnerable to landslides. To alleviate landslide risks in Tolnaku, Continuous Monitoring, Infrastructure Strengthening, Community Education, Coordination with Local and National Authorities, and the Development of Spatial Regulations are advocated for the future.

This study aims to assess water erosion across five watersheds in western Karbala toward Arar using the RUSLE model supported by GIS, remote sensing data, and artificial intelligence tools. The five RUSLE factors (R, K, LS, C, P) were calculated using digital analysis, and Sentinel-2 imagery was used to extract NDVI. The Random Forest algorithm was applied to improve the estimation of the cover factor (C) and to develop a predictive model for erosion density. Results showed that Wadi Hamir is the most erosion-prone basin (333.69 tons/km²/year), while Wadi Abu Ghar recorded the lowest density. The predictive modeling experiment demonstrated that RUSLE accuracy improves significantly with the use of synthetically generated data and machine learning algorithms, reaching an R² value of 0.63. The study recommends implementing effective soil conservation practices in high-risk watersheds and adopting routine NDVI monitoring via Sentinel-2 and Google Earth Engine. The findings confirm that integrating deterministic models with artificial intelligence enhances erosion assessment accuracy and supports environmental resource management planning.

Seawater intrusion is a major problem in urbanized coastal regions of India which is due to over exploitation of groundwater for various purposes. This study was carried out with the objective of assessing the zone of mixing between seawater and groundwater in the coastal aquifer in south of Chennai, Tamil Nadu, India using high resolution electrical resistivity tomography. High resolution electrical resistivity tomography was carried out in five profiles perpendicular to the sea using IRIS make SYSCAL Pro-96 system with 2.5 m or 5 m inter-electrode separation. The maximum length of the profile was 170 m which resulted in a depth of investigation of 28.7 m. The apparent resistivity measured in this area varies from 0.3 ohm-m to 30,000 ohm-m. The apparent resistivity of saturated zone decreases towards the sea, indicating the influence of seawater. This was also confirmed by measuring the electrical conductivity of groundwater, which gradually increases from 156 µS/cm to 3430 µS/cm towards the sea. Further, the concentration profiles of electrical conductivity, sodium, chloride and chloride / bicarbonate ratio are compared with the high resolution electrical resistivity tomography profile. The distance of influence of seawater is comparatively high in northern part than in southern part of the area. The high resolution electrical resistivity tomography was effectively used to determine the effect of seawater mixing with groundwater.

The phosphate series of the basin of Oulad Abdoun begins in Maastrichtian with phosphate deposits relatively very marly. It ends at the Lutetian by a calcareous slab. Derangement is any disruption of the usual succession of the phosphate series and that which disrupts the evolution of the kinematic chain, leading to a decrease in production and profitability. In this case, we have a partially disturbed series and the disturbance consists of all the elements of the series (limestone, flint, marls and phosphate). The present work has been carried out in two ways: The present work has been carried out in two ways: The first one, purely geological, consists of the identification of the different layers of the Ouled Abdoun basin in the El Halassa site and their continuity to the outcrop. At the end of these observations, the basin shows derangement of two kinds: a disturbance on the scale of the whole series known as major disturbance, and a second which affects only part of the series. ...

Geophysical methods are widely used as noninvasive tools for archaeological prospection. In a first step is usually applied basic prospection of vast areas, when data are evaluated only in qualitative way. Sometimes is performed second step, during which take place more detailed multidimensional or combined surveys in order to image archeological monuments complexly, allowing quantitative interpretation. Hence, we used a unique and novel combination of multidimensional electrical resistivity tomography (ERT) on the Early Middle Ages stronghold fortifications at Vinor ˇ(Czechia) to achieve such interpretation. The joint results of 2D/3D/4D (time-lapse) surveys allowed us to precisely characterize individual construction components of the fortifications, including a ditch and rampart enhanced by a front wall with a berm. The ERT results recovered the fortification dimensions and the volume of building material used. The surveyed fortification section was verified by excavations directly after the ERT measurements. A comparison of the excavated section with geophysics proved that ERT was able to infer all the important fortification characteristics. In addition, illustrative picture of the resistivity manifestations of the basic components of this very typical fortification construction were obtained. The results show that multidimensional ERT provide access to quantitative interpretation allowing to explain archaeological structures behind investigated anomalies. In result, sites containing cultural heritage can be leaved intact, excavations can be substituted in surprisingly large extent, while unprecedented amount of archaeological information is still retrieved.

The area south-east of Rome is characterised by the presence of several roman aqueducts which brought water to the eternal city from the Apennine and Alban Hills springs. In the last 40 years, several pieces of evidence about these aqueducts were acquired during the realisation of archaeological test trenches before building activities. In 2019, a small branch of a subterranean aqueduct unknown to the Latin sources was unearthed in Via dei Sette Metri. Here we show that this aqueduct is a lateral branch of the Anio Novus, a major imperial aqueduct built between 38 and 52 CE. To achieve this result, we employed detailed photogrammetric restitution of the new aqueduct and an integrated geophysical survey focused in the area where the Anio Novus was supposed to pass. Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) methods were used to reconstruct aqueduct paths and their relative heights. Different light conditions were tested during the picture acquisition step to determine the best practice in the photogrammetric restitution. The results obtained in this study confirmed the great effectiveness of the integration between geophysical investigation methods and the modern archaeology approach in detecting buried ancient structures.

The Ozark Plateaus region of southern Missouri is underlain by dominantly carbonate marine platform rocks of Paleozoic age. The region has been sub-aerially exposed since the late Paleozoic and is characterized by extensive karst. To better understand the geologic history of this regional karst system, we examined the stratigraphic record preserved in the fill of a large doline near the largest spring in the region. Samples of fill from natural exposures and drill core were analyzed using thermoluminescence (TL) and 10Be cosmogenic techniques, and the physical/chemical characteristics of the fill material were determined by visual inspection, X-ray analyses, and grain-size measurements. Drill-hole data indicate that the allochthonous doline fill is 36.3 m thick and rests on at least 15.6 m of cave breakdown and sediment. The doline fill is divisible into 7 zones. Analysis of 10Be concentrations suggest that the entire doline fill was derived from local residuum during the middle (Illinoian) to late Pleistocene (Wisconsinan). X-ray diffraction analyses of clays throughout the doline fill indicate that they consist of nearly equal amounts of kaolinite and illite, consistent with terrestrial weathering.

Two-dimensional Electrical Resistivity Tomography (2DERT) and Seismic Refraction Tomography (2DSRT) were concurrently applied in assessment of a gully site with the view of assessing its stability and risk level. Eight profile lines oriented parallel and perpendicular to the boundary of the gully were surveyed. As a result, apparent resistivity model tomograms in the range of 1-9,000 and p-wave velocity models in the range of 300-700 were obtained from the two techniques respectively. Interpretation of the models obtained show predominance of unconsolidated clay, shale intercalates, clayey sand, sandy clay and weathered lateritic soil at shallow depths. Low amplitude undulating refracting layers, landslide slip subsurface and lose horizons were also delineated at shallow depths. The predominance of weak, clayey and unconsolidated lithology at the gully site suggests evidence of unstable gravitational equilibrium which imply environmental hazard. The plausible deductions made from th...