Electrical Resistivity Tomography Technique Research Articles

Combined Electrical Resistivity Imaging and Electromagnetic Survey for Groundwater Studies in the Tarkwa Mining Area, Ghana

The major source of potable water in Tarkwa is the Bonsa Treatment Plant sourced from the Bonsa River. The activities of illegal miners along the banks of the Bonsa River has resulted in pollution of the river. This has resulted in high treatment cost and irregular supply of water to the Tarkwa Township and surrounding communities that are fed by the Bonsa Treatment Plant. In view of the difficulty in getting frequent and regular potable supply of water, people have resorted to construction of boreholes and hand-dug wells. However, the success rates and borehole yields are low especially in the hydrogeologically difficult terrains in the Tarkwa area. The aim of this paper is to investigate the hydrogeological conditions of the Tarkwa area using both the Electrical Resistivity Imaging (ERI) and Electromagnetic (EM) geophysical techniques to determine the electrical resistivity and conductivity values that are related to groundwater accumulation, so that potential water-bearing zones can be identified. Results from electrical resistivity show that the general resistivity distribution in the Tarkwa area is between 32 Ωm and 100 000 Ωm. Water-bearing zones in the Huni Sandstone occur to a depth of 35 m with an average resistivity value of 400 Ωm, at a depth of 60 m and a resistivity of 600 Ωm in the Tarkwa Phyllite, at a depth of 55 m and a resistivity of 600 Ωm in the Banket Series and 50 m depth with resistivity value of 500 Ωm in the Kawere Conglomerate respectively. The electromagnetic conductivity values also show that the general conductivity distribution in the Tarkwa area is 3 – 32 S/m. The application of electrical resistivity and electromagnetic techniques separately gives success rate of 80 % and 65 % respectively. An improved success rate of 86 % is achieved combining the two techniques. Keywords: Electrical Resistivity Imaging, Electromagnetic Method, Groundwater

The Estimation of Hydraulic Properties from Geophysical Measurement of Subsoil Depend on Regression Equation

This paper illustrated an establishment relationship between electrical resistivity by using electrical resistivity imaging (ERI) technique and hydraulic conductivity. The test conducted in two locations (Kampung Semerbok, Rembau and Felda Bukit Rokan Utara, Gemencheh) in Malaysia. Schlumberger array configuration was adopted by using ABEM SAS 4000 with eighty-one (81) electrodes for first site and forty-one (14) electrodes for second site. The total length of resistivity survey line was 400 m and 200 m for site one and two respectively. Statistical analysis based on regression equation was involved to find the relationship between hydraulic conductivity and resistivity. This result was compared with the hydraulic conductivity obtained from pumping tests for the well which is located within the resistivity survey line range. This study showed a good relationship between resistivity and hydraulic conductivity and can be used as preliminary tool to assess subsurface zone with non- invasive non-destructive for the soil with reducing time and cost.

Foundation Evaluation of a Repeater Installation Building using Electrical Resistivity Tomography and Seismic Refraction Tomography

Geophysical investigations were carried out for evaluation of damage and to assess the possible causes for repeated occurrence of damage at one of the buildings constructed for oil pumping in the northern part of India. Electrical Resistivity Tomography (ERT) and Seismic Refraction Tomography (SRT) techniques were adopted for studying the subsurface of the area around the building with an objective of ascertaining the cause of damage. High resolution imaging was done using both the techniques in this investigation. ERT delineated the presence of low resistivity (2 ohm-m) water filled voids below the structures and mapped different subsurface layers such as sandy soil, clay and sandstone in the study area. SRT revealed P-wave velocity ( VP) of the subsurface medium in the range of 400–3,400 m/s. Corresponding densities and S-wave velocities ( VS) were determined based on Gardner's and Castagna's relationships. Subsequently, the VP, VS and the modulus values were used in estimating compressibility of soil and rock strata. Results showed near surface layers were characterized by high compressibility (26.673 × 10−5 Pa−1), decreases with depth. This paper presents the details of the site, techniques used in the investigation and correlation of geophysical results with lithological information, and the subsequent analysis for understanding the distress in the subsurface of the study area.

Identification of gypsum karstification using an electrical resistivity tomography technique: The case-study of the Sivas gypsum karst area (Turkey)

The Sivas district is the most important gypsum karstified area in Turkey. The oldest evaporites in the region were formed during the sedimentation process of the Oligocene period. Generally, these units extend along the southern part of the Sivas basin. After the Early Miocene Sea drained from this region, extensive evaporite deposition developed. An electrical resistivity tomography (ERT) study was carried out between the Hafik and İmranlı districts of the Sivas gypsum karstified area. In this research, the prior aim was to determine the general characterization, geometry, sedimentary cover and resistivity properties of gypsums. In addition, the study includes the synthetic modelling of different gypsum karstification types. The evaluation and interpretation were based on ERT data that was collected from the Hafik-İmranlı region. First, the different karstifications were identified, together with the characteristic features of gypsum in the area. The ERT studies showed that there are large and old karst structures between the Hafik and Zara district. However, the karst structures that are located between the Zara and İmranlı regions were interpreted as smaller and younger. The characteristics of both of the regions are different in terms of the morphometric properties. It is certain that the Kızılırmak River has an important impact on the formation of these structures. ERT studies have shown that the cover- and bedrock-type collapse sinkholes are very spread out across the area, and their geometries are different. Throughout time, the suffosion type of cavities formed inside the cover-type sinkholes as a consequence of geological and geomorphological events. The ERT sections showed that certain parts of these structures collapsed, and then alluvial materials filled in. The shallow groundwater level in the drilling results and the conductive zone in the ERT results are compatible with each other. ERT studies clearly determined the various karstification typologies of gypsums in the region, which also contributed to the creation of a detailed conceptual geological model.

Combining Electrical Resistivity Tomography and Satellite Images for Improving Evapotranspiration Estimates of Citrus Orchards

An adjusted satellite-based model was proposed with the aim of improving spatially distributed evapotranspiration (ET) estimates under plant water stress conditions. Remote sensing data and near surface geophysics information, using electrical resistivity tomography (ERT), were used in a revised version of the original dual crop coefficient (Kc) FAO-56 approach. Sentinel 2-A imagery were used to compute vegetation indices (VIs) required for spatially estimating ET. The potentiality of the ERT technique was exploited for tracking the soil wetting distribution patterns during and after irrigation phases. The ERT-derived information helped to accurately estimate the wet exposed fraction (few) and therefore the water evaporated from the soil surface into the dual Kc FAO-56 approach. Results, validated by site-specific ET measurements (ETEC) obtained using the eddy covariance (EC) technique, showed that ERT-adjusted ET estimates (ETERT) were considerably reduced (15%) when compared with the original dual Kc FAO-56 approach (ETFAO), soil evaporation overestimation being the main reason for these discrepancies. Nevertheless, ETFAO and ETERT showed overestimations of 64% and 40% compared to ETEC. This is because both approaches determine ET under standard conditions without water limitation, whereas EC is able to determine ET even under soil water deficit conditions. From the comparison between ETEC and ETERT, the water stress coefficient was experimentally derived, reaching a mean value for the irrigation season of 0.74. The obtained results highlight how new technologies for soil water status monitoring can be incorporated for improving ET estimations, particularly under drip irrigation conditions.

INSIGHT INTO SEISMIC REFRACTION AND ELECTRICAL RESISTIVITY TOMOGRAPHY TECHNIQUES IN SUBSURFACE INVESTIGATIONS

Geophysical subsurface investigations use the principles of physics to unravel intrinsic Earth’s subsurface features and nature of the underlying geology. Over the past two decades, the use of Seismic Refraction Tomography (SRT) and Electrical Resistivity Tomography (ERT) for subsurface investigations has greatly improved the quality of acquired data for two- and three-dimensional (2D and 3D) surveys. SRT employs more shotpoints and receivers than the conventional seismic refraction for its imaging technique. ERT uses automated multi-electrode array systems to improve the confidence of large and dense data collection. SRT and ERT techniques use powerful inversion algorithms to achieve high resolution subsurface inversion models for resolving subsurface characteristics and geological conditions over a complex and larger area that may be difficult with the use of their conventional methods. The 2D and 3D inversion models (tomograms) generated from the field data sets of these techniques efficiently ameliorate inaccurate subsurface boundaries and structural delineation with higher depth resolution, especially the 3D inversion models for areas of complex geology. These state-of-the-art techniques have extensively been used for groundwater, environmental, engineering and mining investigations among others. This study provides insight from theories to data inversion techniques for the known tomography techniques (SRT and ERT) in use for subsurface investigations.

Integrated Geophysical and Geotechnical Methods for Pre-Foundation Investigations

An integrated geophysical and geotechnical investigation for a proposed building foundation of an industrial plant layout was carried out to determine the competency of the subsoil as foundation materials. Electrical Resistivity Imaging (ERI) and soil analyses techniques were adopted. Two traverses of four Vertical Electrical Sounding (VES) points were carried out and 8 Boreholes for Standard Penetration Test (SPT) were drilled. In addition soil samples were taken at 1.5 m and 10 m depths and subjected to various laboratory analyses. Three geoelectric layers were delineated from VES including topsoil, saturated sandy clay soil and limestone. The SPT N value indicates that the relative density of the soils is medium dense to very dense while the result of the geotechnical analyses shows that maximum dry density of the soils range from 1680-1900 kg/m3 and 1600-1850 kg/m3 respectively at 1.5 m and 10 m while the optimum moisture content range from 14-19% and 13-19% respectively at 1.5 m and 10 m. The soils are silty sand with low plasticity depiting low to medium swelling potential. Conclusively, the subsurface on which the foundation of the industrial structures will be located within the study area is safe and fairly competent for any engineering work. Owning to the water lodge nature of the area it is advice that the building should rest on pill between 5 m and 10 m depth.

Contribution of Electrical Resistivity Tomography and Boring Technique in the Realization of Ten (10) Large Boreholes in a Crystalline Basement Rocks in the Centre-West of Benin

In order to ensure access to drinking water for Benin populations by 2021, the Emergency Measure program for the reinforcement of the drinking water supply system of Savalou city was initiated in 2018. This program focuses on densification and extension of hydraulic infrastructures. Therefore, it is prominent to use rigorous approach for implementation and execution of drilling activities. The present work has the advantage of combining the use of electrical resistivity tomography and borehole technique to locate ten high flow drilling in Savalou city. The electrical resistivity tomography (ERT) panels were made based on the dipole-dipole arrays with 48 electrodes with 5 m inter-electrode spacing. The drilling was carried out over ten selected points and in two stages: confirmation test using piezometer and borehole diameter enlargement. Moreover, only piezometers with flow rate greater than 10 m3/h were enlarged. The tomography processing has identified 10 fractured zones that are defined by 250 - 1000 ohm.m resistivity values and a width between 15 - 55 m. The confirmation test carried out over ten piezometers exhibits high flow rates ranging from 9 to 35 m3/h with depths of 30 to 68 m. Nine over the ten boreholes with a flow rate equal or greater than 10 m3/h, have improved their flow rates by 50% to 100% after the boring technique. Thus, the cumulative flow rate has reached 252. 7 m3/h for Savalou city and his surrounding areas.

Electrical resistivity mapping as a tool for post-reclamation assessment of subsurface condition at a sand-filled site in Lagos, southwest Nigeria

The occurrence of collapsible and unstable subsurface materials (clay, silt, peats etc.) in alluvial deposits and other soil deposits throughout the world and the difficulties with building on them have long been recognized. Accordingly inclusive site investigation of subsurface condition is important for construction of engineering structures and buildings on land reclaimed from wetland such as marsh or swamp with soft compressible clays and peat materials. Peatlands common in most coastal areas of Lagos, Nigeria are characteristic waterlogged locations. These areas characterized by low human and economic activities in the past are now considered for building residential houses due to the surging population of the metropolis. Problem usually arises when there is uneven soil settlement which might results in disastrous collapse of structures. This study presents a subsurface geophysical mapping of a site reclaimed by sand filling in Victoria Island, Lagos, using integrated electrical resistivity techniques. The geoelectric data acquired through vertical electrical sounding (VES) and electrical resistivity imaging (ERI) techniques were processed and interpreted to provide a detailed characterization of the subsoil profile and soil parameters of the study area. VES technique employed Schlumberger configuration because of its obvious deeper current penetration, while for ERI, a combination of Werner, dipole–dipole and pole–dipole were utilized. Results from the two procedures show a maximum of four geoelectric strata, with the second and third layers consisting either sandy clay (50 Ωm 140 Ωm). Due to the lateral discontinuous and inhomogeneous nature of these sandwiched layers of high compressibility and low shear strength, the possibility of occurrence of subsidence and differential settlement is high. This might result in minor or major failure in building and engineering structures built on such soils. Sand medium encountered at shallow depth of about 0.6–0.9 m, beneath VES 7, 8, 14 and 19, could have been a suitable layer for foundation of buildings and structures except that it is directly underlain by peat/clay. Other locations with competent sand layers for which deep foundation might be required lie at depth within 9.5–30.8 m. Thus, this study has revealed both the lateral and vertical variation with depth of the subsurface strata within the study area. This would assist local structural engineers and builders in designing appropriate and adequate foundation of structures in this area.

Detection of subsurface cracking depth using electrical resistivity tomography: A case study in Masjed-Soleiman, Iran

Soil cracks affect the engineered earth structures, being known to contribute to failures in road surfacing. Electrical resistivity imaging technique is a generally appealing method to investigate such phenomena. Cracks deviate the resistivity distribution of the soil, since resistivity of the air-filled cracks is significantly higher than the intact soil. In this study, the non-invasive 2D electrical resistivity imaging survey was conducted along two parallel lines using a Wenner-Schlumberger configuration to investigate vertical and horizontal extension of the existing cracks in the structure of a road covered by asphaltic sandstone near Masjed-Soleiman city. From the inverted results, 17 different cracks were detected, which their depths ranged from 0.5 to 5.5 m. However, there is not any considerable crack progressing toward the axis of the road. Borehole drilling confirmed the results of electrical resistivity sections to detect the cracks. The results show that the 2D electrical resistivity imaging survey using the Wenner-Schlumberger array in combination with an appropriate 2D inversion method can be highly useful to delineate vertical extension of the existing cracks in road structures.

Surface variations effect on electrical resistivity measurement: Aroughness based approach

Electrical Resistivity Imaging technique requires accurately taking surface geometry into account during the inversion process to avoid artefacts. Some terrains (for example volcanology) or materials (at low scale) present important high frequency topography variations that common inversion software cannot take into account. Recent Digital Elevation Model (DEM) tools offer a high resolution that permit to image some characteristics of these rough surfaces. The aim of this paper is to examine the effect on the electrical measurement of different surface topography features at different DEM resolutions. For this purpose, we evaluate the effects on a micro and macro scale. We define mathematical criteria (based on geometrical roughness parameters) to analyse and generate surfaces and we simulate electrical measurements with a Finite Element Analysis code. An initial numerical study shows that roughness parameters play a key role in resistivity measurement. A second study performed on 30 limestone samples shows that a DEM resolution trade-off can be found based on geometrical roughness parameters. This study gives a rule of thumb to determine a resolution threshold for real survey data.

Optimized electrical resistivity tomography investigation established in identifying pit tombs of Mogareb, a cemetery area in a Pre-Aksumite archaeological site of Seglamen, northern Ethiopia

The larger area of Aksum is known as the most important archaeological areas in northern Ethiopia. It is included in the UNESCO World Heritage List as from about the IV century BC, it developed as one of several polities on the Tigrean plateau and emerged as the capital city of a powerful kingdom roughly between the II and the VIII centuries AD. The Mogareb is a cemetery in a Pre-Aksumite archaeological site of Seglamen located about 12 km South-West of Aksum.The geophysical survey was deployed to investigate the cemetery with the objective of finding and locating unmarked tombs. This work was also intended to test potential of the technique for the wider archaeological area of Aksum, in similar context to Mogareb, where application of geophysical techniques in multidisciplinary archaeological researches, in general, is not common.The approach in this work established an optimized use of the electrical resistivity tomography technique in understanding the archaeological context of the Pre-Aksumite site of Seglamen. The electrical resistivity tomography investigation of large cemetery sites as Mogareb requires a methodological approach designed to define areas of maximum interest where data collection should be planned. Thus, the ERT method suited the Mogareb cemetery area due to the large amount of apriory information from previous archaeological expeditions involving surface collections and excavations that identified and limit extent of the cemetery and were used in the calibration of geophysical survey results.The electrical resistivity tomography survey was conducted on a rectangular grid of 19.5 m by 44.25 m with 0.75 m unit electrode spacing and line spacing in a Dipole-Dipole configuration resulting in high resolvable 2D and 3D electrical resistivity model sections. The models were successful to show interpreted pit tombs anomalies some of which were verified in an excavation of a 10 m by 10 m grid that had an overlap of 6 m by 10 m area to the Northern edge of the electrical resistivity tomography grid.

Ground‐penetrating radar and electrical resistivity tomography studies in the biblical Pisidian Antioch city, southwest Anatolia

AbstractPisidian Antioch was founded as a military base in the Hellenistic period around 300 bc. A consecutive archaeological structure, extending 55 m long, mainly includes two adjacent abscissas and a wall remain thought to be a watchtower. An integrated geophysical survey including ground‐penetrating radar (GPR) and electrical resistivity tomography (ERT) techniques was conducted to determine the existence of counterparts of this structure in a small‐scale area. GPR scans acquired via zigzag mode using 500 MHz antenna along 45 parallel lines were evaluated by a series of basic data processing steps. Considering the results obtained, two‐dimensional (2D) ERT data collected in a restricted area using Wenner‐alpha array along 41 parallel lines were inverted using 2D and three‐dimensional (3D) tomographic inversion schemes. On the basis of the findings obtained from various GPR and ERT imaging techniques, the existence of one of the abscissa, displaying dimensional parameters being in good accordance with those of ones still standing on the west side of the survey area was clearly revealed. Moreover, some regular anomalies, which can be attributed to the remains of the watchtower in question and various wall ruins, were successfully traced from the GPR depth slices. The existence of an antisymmetric geometry for the consecutive archaeological structure under investigation was also determined in the survey area. Combining all of that information, a possible 3D virtual image of the military headquarters was then created, and this pointed out a small square quadriburgia characteristic of the structure investigated. Thus, we can conclude that the integration of GPR and ERT and imaging techniques used in the evaluation were quite effective to provide useful prior information for the subterranean targets in the non‐excavated parts of the ancient city. An archaeological evaluation by trial trenching is therefore required to confirm the results of the archaeo‐geophysical survey in the investigation area.

Case study of electrical resistivity tomography measurements used in landslides investigation, Southern Poland

AbstractMass movements are an ever present threat to building construction, water management, vegetation formation and biodiversity. This paper presents an approach to landslides research based on non-invasive geoelectrical method - Electrical Resistivity Tomography (ERT). Mapping and displacement monitoring of unstable slopes is crucial for the hazards prevention and assessment. The ERT technique is an effective tool to obtain structural differentiation of geological medium through interpretation of 2D electrical resistivity models. The main advantage of the method is a wide range of applicability what makes its useful during field works on a landslide. It is commonly used for measurements of slope instability, determination of shear surface, landslide susceptibility, depth of bedrock, slip plane geometry. The aim of the work is to identify the geological structures underneath three selected landslides in south Poland: in Racibórz, Milówka and Porąbka. Attempts have been focused on determination of the usefulness of the proposed ERT methodology for evaluation of possible further development of mass movements. On two investigation sites two different arrays have been used: Wenner-Schlumberger and dipole-dipole which allowed to prepare combined data set and resistivity models based on them. Forward modelling of synthetic models based on a priori information allowed to understand anomalies present on resistivity models. Applied approach ensured quality increase of final interpretation of resistivity models.

Delineation of groundwater resources using electrical resistivity tomography

Chandrabhaga basin of the Nagpur district is a part of the drought prone Vidarbha region of Maharashtra, India. This region is facing acute shortage of water for drinking and irrigation purposes. The basin is located at the eastern fringe of the Deccan traps consisting of volcanic rocks. Presently, dug wells penetrating composite layers of the weathered mantle and highly fractured rocks overlying stratified basaltic lava flows are the main source of water supply. However, water available in the dug wells is inadequate to meet the ever increasing demand for water causing considerable economic losses to the farming community. In this work, we present the results of an electrical resistivity tomography (ERT) survey carried out in the basin for the delineation of groundwater potential zones. Validity of the hydrogeological setup obtained from the ERT results has been confirmed by bore well drillings at two investigated sites. The study demonstrates the efficacy of the ERT technique in delineation of groundwater potential zones in the hydrogeologically complex basaltic terrain of the Deccan traps.

A comprehensive study for moisture control in cultural heritage using non-destructive techniques

This article describes the use of non- or minimally destructive methods to study damp in San Juan Bautista Church at Talamanca de Jarama in the Spanish province of Madrid. The combination of Electrical Conductivity Meter (EC), Infrared Thermography (IR), RH/T monitoring by means of Data Loggers (DL) and Wireless Sensor Networks (WSN), Electrical Resistivity Tomography (ERT) and Ground-Penetrating Radar (GPR) techniques provided sub-surface and surface information. The respective findings and ranges of observation were inter-related to identify the decay associated with the damp and determine the advantages and drawbacks of each instrumental method. Electrical conductivity meters and infrared thermography deliver rough estimates of the extent of damp on wall surfaces, furnishing qualitative information on the areas where depth studies should be undertaken using techniques such as ERT or GPR or where long-term WSN monitoring sensors should be positioned to determine variability in a given number of points. When the purpose is to distinguish between areas with widely varying moisture contents, ERT is more precise. However, GPR proved to be the most accessible and efficient technique for studying the under-floor profiles.

Combined application of GPR and ERT for the assessment of a wall structure at the Heptapyrgion fortress (Thessaloniki, Greece)

Non-destructive investigation of monuments can be an extremely valuable tool to evaluate potential structural defects and assist in developing any restoration plans. In this work, both Ground Penetrating Radar (GPR) and Electrical Resistivity Tomography (ERT) techniques were applied to a tower wall of the Heptapyrgion fortress located in Thessaloniki, Greece, which was facing significant moisture problems. GPR cross sections, mainly obtained with a 500 MHz centre frequency antenna, and ERT profiles were collected along the same survey grid on the tower wall. The gprMax numerical solver was used for the GPR forward modelling. In addition, an auxiliary program was used to design and import into gprMax complicated structures and this allowed to simulate more realistically the wall defects and moisture. The GPR simulator was used to assess and optimize the field data acquisition and processing parameters, and to assist in interpreting the GPR cross sections. The ERT sections were inverted as individual 2D lines and also, as a full 3D dataset. The final GPR and ERT data were jointly interpreted in view of the studied problem as results of both methods are highly correlated. A high moisture content area at the eastern part of the wall was identified in both GPR and ERT data, along with the interface between different phases of construction. Through the GPR data we were also able to delineate possible structural defects (cracks, small voids) which was not possible with just using the ERT data. Furthermore, a very good matching was evident between the simulated GPR modelling results incorporating field-interpreted features, and the actual field GPR results, thereby validating the proposed data interpretation. The overall survey and modelling approach produces results that are in a very good agreement between them and proved very useful in accessing the wall structure.

Application of electrical resistivity tomography technique for delineation of gold mineralization in Bugai town, Birnin Gwari, Kaduna, North Western Nigeria

Application of electrical resistivity tomography technique for delineation of gold mineralization in Bugai town, Birnin Gwari, Kaduna, North Western Nigeria

Electrical Resistivity Tomography with Angular Separation for Characterization of Burial Mounds in Southern China

The study aims at providing the spatial distribution and potential structure of the burial mounds at the Sifangling site, Hepu Han Tombs, in southern China. We implemented an electrical resistivity tomography (ERT) technique to obtain high‐resolution imaging of archaeological targets, considering the challenging environment and the depth of the burials. Three ERT profiles were tested above a small ancient mound previously detected by exhaustive archaeological drillings, following which 18 ERT profiles with angular separation were performed on the largest mound at the test site, without any a priori archaeological evidence below the surface. Then, a series of two‐dimensional (2D) profiles were combined as a ‘pseudo‐3D’ volume, which allowed a detailed characterization of the burial mound, and iso‐resistivity surfaces were also calculated to emphasize the location and spatial extent of the target. The results gave an effective identification of the funeral chamber and its structural details, and allowed detailed pre‐excavation planning.

ERT, GPR, InSAR, and tracer tests to characterize karst aquifer systems under urban areas: The case of Quebec City

Urban infrastructures built over karst settings may be at risk of collapse due to hydro-chemical erosion of underlying rock structures. In such settings, mapping cave networks and monitoring ground stability is important to assure civil safety and guide future infrastructure development decisions. However, no technique can directly and comprehensively map these hydrogeological features and monitor their stability. The most reliable method to map a cave network is through speleological exploration, which is not always possible due to restrictions, narrow corridors/passages, or high water levels. Borehole drilling is expensive and is often only performed where the presence of karsts is suggested by other techniques. Numerous indirect and cost-effective methods exist to map a karst flow system, such as geophysics, geodesy, and tracer tests. This paper presents the outcomes from a challenging application in Quebec City, Canada, where a multidisciplinary approach was designed to better understand the groundwater dynamics and cave paths.Two tracer tests in groundwater flowing through the cave system indicated that water flows along an approximately straight path from the sinking stream to the spring. It also suggests the presence of a parallel flow path close to the one already partially mapped. This observation was confirmed by combining Ground Penetrating Radar (GPR) and Electrical Resistivity Tomography (ERT) techniques, and ultimately by observing voids in several boreholes drilled close to the main cave path. Lowering the water levels at the suspected infiltration zone and inside the karst, the infiltration cracks were identified and the hydraulic link between them was confirmed. In fact, almost no infiltration occurs into the karst system when the water level at the sinking stream drops below a threshold level. Finally, SAR interferometry (InSAR) using RADARSAT-2 images detected movements on few buildings located over a backfilled sinkhole intercepted by the karst system and confirmed the stability of the rest of the karst area. The knowledge of the flow system described in this paper is used by policy makers to assure civil security of this densely populated area.