GPR survey for the reconstruction of the canalization system beneath the orchestra level of the Ancient Theatre of Catania (Italy)

Characterization of inland water is a topic of great interest due to the broad spectrum of potential applications. Applied geophysic boasts different techniques adapted to retrieve useful information about these kinds of environments. Certainly, the most common geophysical techniques used in shallow waters are the seismic methods. However, there are some situations in which seismic methods could fail. Although nowadays it does not exist a method able to solve completely this task, electromagnetic techniques are a cost efficient tool to provide useful information. Thanks to their versatility, we concentrated our attention on the possibility of the Ground Penetrating Radar (GPR) and of the low induction number electromagnetic multi-frequency soundings measurements, carried from the water surface. We started from acquisitions performed in controlled settings. We described how we reproduced the field condition of a riverine GPR survey in laboratory experimentation. We selected a 1500 MHz GPR antenna, and we studied five types of riverine bottom sediments. We developed two different approaches to interpret the GPR responses of the sediments: the velocity and the amplitude analysis. The amplitude analysis developed is particularly innovative and fit very well the field requirements. We tried to estimate the sediments porosities by some mixing rules by the electromagnetic properties founded with both the analysis performed. The comparison among the porosities provided by the GPR measurements and the porosities measured by direct methods confirm the accuracy of the velocity analysis and it highlights the poor reliability of the amplitude analysis. Successively, we tested our methodology in survey condition. We conducted an integrated geophysical campaign on a stretch of the river Po in order to check the GPR ability to discriminate the variability of riverbed sediments through an analysis of the bottom reflection amplitudes. We conducted continuous profiles with a 200MHz GPR system and a handheld broadband electromagnetic sensor. A conductivity meter and a TDR provided punctual measurements of the water conductivity, permittivity and temperature. The processing and the interpretation of both the GEM-2 and GPR data were enhanced by the reciprocal results and by integration with the punctual measurements of the electromagnetic properties of the water. The GPR measurements provided maps of the bathymetry and of the bottom reflection amplitude. The high reflectivity of the riverbed, derived from the GPR interpretation, agreed with the results of the direct sampling campaign that followed the geophysical survey. The variability of the bottom reflection amplitudes map, which was not confirmed by the direct sampling, could also have been caused by scattering phenomena due to the riverbed clasts which are dimensionally comparable to the wavelength of the radar pulse. About the multi-frequency electromagnetic sensor, we analyzed the induction number, the depth of investigation (DOI) and the sensitivity of our experimental setup by forward modeling varying the water depth, the frequency and the bottom sediment resistivity. The simulations led to an optimization of the choice of the frequencies that could be reliably used for the interpretation. The 3406 Hz signal had a DOI in the PO water (27 Ωm) of 2.5m and provided sediment resistivities higher than 100 Ωm. We applied a bathymetric correction to the conductivity data using the water depths obtained from the GPR data. We plotted a map of the river bottom resistivity and compared this map to the results of a direct sediment sampling campaign. The resistivity values (from 120 to 240Ωm) were compatible with the saturated gravel with pebbles in a sandy matrix that resulted from the direct sampling, and with the known geology

In May of 1997, the Department of Geology and Geophysics at the University of Missouri-Rolla conducted a reflection seismic survey and a ground penetrating radar (GPR) survey for the Missouri Department of Transportation (MoDOT) along and adjacent to a 300 meter section of Interstate 44 in Springfield, Missouri. In October of 1997, a second GPR survey was conducted along the same section of interstate. The site was located approximately 1.5 kilometers west of Missouri Highway 266. The section of interstate studied overlies an active sinkhole and has experienced continued, localized subsidence. Seven 12-fold reflection seismic profiles were acquired along or near Interstate 44, using a Bison 24- channel seismograph and an EWG weight drop source. Forty-live GPR profiles were acquired along paved sections of Interstate 44 during the first survey. During the second GPR survey, the survey area was expanded to include a total of seventy ground penetrating radar profiles. A GSSI SIR-S GPR unit equipped with a 500 MHZ (megahertz) monostatic antenna/receiver was used to acquire the data. The geophysical surveys were successful. The reflection seismic data established that sinkholes, both active and nonactive are prevalent in the area. The seismic data also supports the interpretation that a sinkhole lies immediately beneath the interstate. The ground-penetrating radar data also proved to be of significant utility. Anomalous areas interpreted as voids on the GPR data were drilled and significant volumes of grout were injected. The second GPR survey established the success of the grouting program.

The regular application of geophysical survey techniques to evaluate archaeological sites is well established as a method for locating, defining, and mapping buried archaeological materials. However, it is not always feasible to apply a range of different methods over a particular site or landscape due to constraints in time or funding. This paper addresses the integrated application of three geophysical survey methods over an important archaeological site located in south Italy. In particular, it is focused on the results achieved from a past geophysical survey and the ongoing excavations performed by archaeologists in the site of Muro Leccese. Muro Leccese (Lecce) is one of the most important Messapian archaeological sites in southern Italy. The archaeological interest of the site was generated since the discovery of the remains of Messapian walls (late 4th–3rd centuries BC). With the aim of widening the archaeological knowledge of the Messapian settlement, several integrated methods, including magnetometry, ground-penetrating radar, and electrical resistivity tomography were used on site to fulfill a number of different research objectives. Since the most important targets were expected to be located at shallow soil depth, a three-dimensional (3D) ground-penetrating radar (GPR) survey was carried out in two zones, which were labeled respectively as zone 1 and zone 2, and were both quite close to the archaeological excavations. The GPR investigations were integrated with a 3D electrical resistivity tomography (ERT) survey in zone 1 and with a magnetometric, in gradiometry configuration survey in zone 2. The integration of several techniques allowed mapping the structural remains of this area and leading the excavation project. The geophysical results show a good correspondence with the archaeological features that were found after the excavation. Current work on the geophysical survey data using different codes for the processing of the data and merging different datasets using a Geographic Information System allowed achieving a user-friendly visualization that was presented to the archaeologists.

Beginning in December 2002 GeoPotential Philippines, Inc. (GPI) in conjunction with the International Recovery Group Philippines, Inc. (IRGPI) conducted a series of geophysical surveys over several potential treasure sites in the Philippines. The purpose of the geophysical surveys was to locate massive gold deposits that had been buried by the Japanese military during the occupation of the Philippines in World War II. This paper discusses the geophysical surveys conducted at one of the treasure sites (Figure 1 INDEX MAP) called the “Waterfall Site”.<br>At the Waterfall site Gravity, Magnetic and Ground Penetrating Radar (GPR) Surveys were conducted to search for 250 metric tons of Gold buried at a depth of 10 to 15 meters. An initial Gravity Profile indicated a possible massive Gold deposit. The GPR Survey produced an anomaly indicative of a buried chamber. However subsequent excavation of the feature indicated a hoax. The follow up Gravity Survey produced a Gravity Anomaly consistent with a massive deposit of gold. Excavation at the Site is currently suspended due to environmental and political concerns.

Shell middens are a significant component of the Australian coastal archaeological record, however, they are notoriously difficult to research. Shell matrix sites are often large and structurally heterogeneous with complex formation histories. For large stratified shell matrix sites, the majority of the deposits are buried making the design of appropriate and representative sampling regimes challenging, as short of total excavation the population from which the sample was taken will never be fully understood. This study aims to address these sampling issues through the application of geophysical survey techniques to shell matrix sites, and by developing novel methods for creating three-dimensional models and volume estimates of buried shell deposits from these survey results. An extensive literature review found only 22 published papers (representing 15 archaeological case studies) have applied geophysical surveys to shell matrix sites. Not one of these studies used geophysical methods to calculate volume estimates of the buried matrices or to create three-dimensional models of the deposits. Outside of archaeology, there have been studies (typically in glacial load research) which have attempted to create volume estimations from geophysical survey results. These studies have, however, typically not included ground truthing of results or calculated error values for the volume estimates. This research has three primary aims: (1) to delineate and map buried shell matrix deposits in tropical Australian contexts; (2) to establish methods for transforming these survey results into volume estimates and three-dimensional models of the deposits; and (3) is to test the accuracy of these models and estimates. To achieve these aims two geophysical methods were chosen and compared; ground-penetrating radar (GPR) and electrical resistivity. These two geophysical methods were chosen, on the basis of the literature review, as being the most appropriate methods to meet the research aims. Both survey methods were employed under field and experimental conditions. Survey results were processed and then exported to Esri's ArcGIS suite of software for further processing, to create the three-dimensional models and volume estimates. Results from this modelling were then compared to the in-ground deposits to test their accuracy. Survey and modelling results for the buried shell matrix deposits varied between geophysical method, and were dependent on the environmental conditions present on site. The electrical resistivity could not differentiate shell material from sand, but could differentiate shell from an organic-rich sediment. The GPR produced clearer, easier to interpret results under drier conditions, while the electrical resistivity produced them under wetter conditions. The modelled results showed more accurate three-dimensional representations of buried shell matrices could be created from the GPR, rather than the electrical resistivity surveys. Similarly, the volume calculations were highly accurate when based on GPR survey data, with an error margin on the estimates of 16%±11%, though it was found that small misinterpretations of the results can easily produce errors in excess of 50%. Volume calculations based on the electrical resistivity data were less accurate than the GPR and varied significantly depending on how the results were interpreted, meaning their overall error margin was significantly higher at 50%±29%. The geophysical survey results for this research also provided a greater understanding of the palaeolandscape on which the shell matrix at the field site was deposited. In order to create accurate accounts of the archaeological record of coastal Australia it is vital that improved methods for characterising the variability of shell matrix sites are explored. The current research addressed this issue by evaluating the capabilities of two geophysical survey techniques in investigating buried shell matrices, and by developing methods for transforming the survey results into three-dimensional models and volume estimates. These methods provide a way to greatly improve sampling regimes in shell matrix research by providing an understanding of the buried deposits before excavation takes place. The methods also provide information in their own right, allowing for a better understanding of the size and shape of buried matrices, and the palaeolandscapes on which they were deposited.

Twelve kilometers of ground penetrating radar (GPR) data have been collected over the Brookswood aquifer in southwestern British Columbia. The data have been analyzed to assess how GPR can be used to characterize the distribution and connectivity of hydraulic units. We have used GPR to locate the aquifer/aquitard boundary at several locations in the study area. The electrical contrast between these two materials makes the aquifer/aquitard boundary an excellent target for GPR surveys. GPR was also used to reconstruct the paleo-environment of one area of the Brookswood aquifer. This was accomplished by using a modification of the concept of architectural element analysis. Radar elements were identified in the survey and were assigned sedimentary parameters using data from trenching and drilling in the area. These elements were used to develop an interpretation of the paleo-environment that provides information about the spatial distribution of hydraulic units. INTRODUCTION Hydrogeologists require quantitative data to produce a realistic model of the spatial variabilities in hydraulic properties of an aquifer. Such data can be difficult and expensive to obtain. A possible solution is to develop geophysical techniques as a means of aquifer characterization. Ground penetrating radar (GPR), a shallow geophysical technique, is well suited for this purpose as it can be used to image to a depth of up to 30m in sand and gravel environments. However, the image produced by a GPR survey does not supply hydrogeologic parameters directly. The focus of this paper is to investigate how GPR can be used for aquifer characterization. At an aquifer scale of lo’s to 100’s of meters, the most fundamental aspect of aquifer characterization is the determination of the aquifer’s hydraulic connectivity through mapping of aquifer/aquitard interfaces. GPR can be used for this purpose due to the large contrast in electrical conductivity between the sand and gravel material of an aquifer, and the clay rich material of an aquitard. The electrical conductivity of a material affects the penetration depth of radar waves, such that radar waves penetrate well through resistive material, but poorly through conductive material. Aquifers, composed of sands and gravels, are resistive, while aquitards, composed of clay rich materials, are electrically conductive. Therefore a radar survey will show good penetration in aquifer materials and very poor penetration in aquitards. By exploiting this difference in radar response, the aquifer boundaries can be mapped. At a smaller scale of centimeters to meters, the determination of the internal structure of an aquifer is also important for aquifer characterization. For example, anisotropy within the aquifer can cause significant differences in hydraulic properties and so must be identified where present. In addition, identification of sedimentary features aids in the determination of the paleo-environment that can provide important insight into the probable arcal extent and orientation of geological units. GPR can be used to image these features because of changes in their electrical properties. GPR and Sedimentology GPR has received considerable attention as a means of imaging sedimentary stratigraphy (Jo1 and Smith, 1992; Smith and Jol, 1992; Pratt and Miall, 1993; Greenhouse et al, 1987; Rea et al, 1991; Huggenberger et al, 1994). The key question that needs addressing is exactly which sedimentary aspects of the subsurface are imaged with GPR. A GPR survey, conducted by transmitting radar waves into the subsurface and recording the reflected energy, will image changes in the subsurface dielectric constant and conductivity. If these electrical properties correspond to changes in sedimentary parameters, then a GPR survey can be said to image sedimentary features. The dielectric constant and conductivity of earth materials are dependent upon composition and geometry of the solid and liquid components. Sedimentological classification is based upon five fundamental properties from which all others can be derived: grain composition, size, shapes, orientation and packing (Blatt et al, 1980). These five properties clearly are related to the composition and geometry of the solid component of a system. It is therefore reasonable to assume that a change in sedimentological properties at some boundary will cause a change in electrical properties. If the resulting change in electrical properties is large enough, then the sedimentary boundary will be imaged in a radar survey. The complicating issue is the liquid, usually water, component which does not play a role in sedimentary

High‐resolution ground penetrating radar (GPR) surveys were carried out to image any archaeological features that may be located beneath the present floor of the Cactus House and several adjacent sites, Nazareth, Israel. The Cactus House occupies a portion of a much larger structure located in close proximity to Mary's Well and the Greek Orthodox Church of the Annunciation. Excavations in the basement of Cactus revealed a portion of a hypocaust and furnace of a bath house. Radiocarbon results date the present bath house (in the basement of the store), excavated by the owners, to the Crusader period. The lower yet‐to‐be excavated archaeological site is hypothesized to be a Roman bath house which would have been where Jesus and his family would have bathed. The objective of the geophysical surveys was to gather, in a non‐intrusive and non‐destructive manner, as much information as possible about underlying features of the excavated portion of the bath house as well as surrounding locations. GPR data was collected in 3 localities within the Cactus House and 3 sites adjacent and behind the House. The data was collected using a pulseEKKO 1000 GPR system (225 & 450 MHz antennae; 200 V transmitter). Step sizes ranged from 0.05 m to 0.1 m. To aid in interpretation, three dimensional (3D) cubes were assembled from a series of identical length 20D GPR profiles running parallel to each other along an x‐y grid system. The 3D cubes provide a unique perspective of the subsurface layers that will aid in locating sites for excavation. The application of radar stratigraphic analysis on the collected data provided the framework from which to investigate both lateral and vertical geometry of any potentially buried archaeological features. The resulting images from these geophysical surveys show that various anomalies exist in the subsurface and may indicate archaeological features exist below the present floors. For example, the upper bath house may have been built upon an earlier bath house that more closely aligns with the water system located and excavated at the adjacent Mary's Well site. Several test probes and samples for radiocarbon dating are planned to be undertaken based upon the results from these geophysical surveys.

High-resolution ground penetrating radar (GPR) surveys were carried out to image any archaeological features that may be located beneath the present floor of the Cactus House and several<br>adjacent sites, Nazareth, Israel. The Cactus House occupies a portion of a much larger structure located in close proximity to Mary’s Well and the Greek Orthodox Church of the Annunciation. Excavations in the basement of Cactus revealed a portion of a hypocaust and furnace of a bath house. Radiocarbon results date the present bath house (in the basement of the store), excavated by the owners, to the Crusader period. The lower yet-to-be excavated archaeological site is hypothesized to be a Roman bath house which would have been where Jesus and his family would have bathed. The objective of the geophysical surveys was to gather, in a non-intrusive and non-destructive manner, as much information as possible about underlying features of the excavated portion of the bath house as well as surrounding locations. GPR data was collected in 3 localities within the Cactus House and 3 sites adjacent and behind the House. The data was collected using a pulseEKKO 1000 GPR system (225 & 450 MHz antennae; 200 V transmitter). Step sizes ranged from 0.05 m to 0.1 m. To aid in interpretation, three dimensional (3D) cubes were assembled from a series of identical length 2D GPR profiles running parallel to each other along an x-y grid system. The 3D cubes provide a unique perspective of the subsurface layers that will aid in locating sites for excavation. The application of radar stratigraphic analysis on the collected data provided the framework from which to investigate both lateral and vertical geometry of any potentially buried archaeological features. The resulting images from these geophysical surveys show that various anomalies exist in the subsurface and may indicate archaeological features exist below the present floors. For example, the upper bath house may have been built upon an earlier bath house that more closely aligns with the water system located and excavated at the adjacent Mary's Well site. Several test probes and samples for radiocarbon dating are planned to be undertaken based upon the results from these geophysical surveys.

Development and construction over karst often leads to unintended results. In this case study, a retention pond was built in a new subdivision to capture surface runoff and add appeal for potential homeowners. However, water never rose to the proposed level and has drained suddenly and frequently since construction in the year 2000. The failure of the retention pond to perform as designed is due to the presence of carbonate bedrock beneath the site. The bedrock, the Prairie du Chien dolomite, is highly weathered and prone to many relatively small sinkholes. Geophysical surveys were proposed to evaluate the subsurface conditions and to determine the extent of sinkholes below the pond shorelines in an attempt to propose engineering solutions to the problem. Four geophysical surveys were performed: ground penetrating radar (GPR), seismic reflection and refraction, electromagnetics (EM), and subbottom profiling. Although all methods provided subsurface information, the GPR surveys were most useful to site characterization. The GPR surveys show evidence of severely disturbed soil in the subsurface that is associated with sinkhole formation. These surveys help delineate the areas around the retention pond that may produce additional sinkholes and failure and will help to focus remediation efforts.

There are many studies referring to the analysis of floodplain architecture using GPR (ground-penetrating radar). However, the geophysical surveys are usually conducted at a single set of land surface and groundwater level conditions. The main question is whether an optimal set of such conditions resulting in optimal (highest possible) resolution and depth range can be determined? A field experiment, based on the GPR surveys conducted at various groundwater levels and parameter settings, was carried out to study their influence on depth range and resolution of the GPR surveys. The test was conducted in the lower course of the Obra River (western Poland). Three sets of the GPR measurement were done: at low groundwater level, at the groundwater level situated close to the land surface and when the surface of the floodplain was inundated and frozen. The results indicated significant differences in the depth range and resolution of particular surveys. The GPR images from the survey conducted on the frozen floodplain were featured with a low depth range in comparison with the remaining experimental measurement. Despite the smooth surface of the frozen floodplain that seemed suitable for the geophysical surveys, the images were obscured by numerous diffractions originating from a layer of water underlying the ice cover. The presented results are the first step to create an atlas of georadar images illustrating various depositional environments. The research showed that such database should consist of GPR images illustrating given sedimentary environment by at least three different sets of hydrogeologic conditions and parameter settings.

The Ground Penetrating Radar (GPR) method potentially offers many possibilities for fast and reliable lithostratigraphic sediment models to be developed. From a cognitive point of view, this represents a major simplification and shortening of procedures with which information about sediments can be obtained. And from the point of view of the economy of operations, there can be a significant reduction in costs and time of research in shallow geology and the stratigraphy of areas where unconsolidated clastic sediments are of superficial occurrence. Also noteworthy is the possibility for the results of GPR surveys to be deployed in support of geological mapping, as well as in the shallow exploration of resources and hydrogeological studies.The most major advantage of the GPR method related to the possibility of the structure of forms being observed in full shape. In the absence of large outcrops, geophysical prospection of geomorphological forms is helpful, insofar as we are able to translate the results of geophysical surveys into the actual lithostratigraphic system of sediments building a specific form.Against that background, the research presented in this article forms part of the work to develop radar stratigraphy, as an important support for direct geological research (Huggenberger et al., 1994; Van Overmeeren, 1998; Beres et al., 1999, Overgaard and Jakobsen, 2001; Jakobsen and Overgaard, 2002; Neal, 2004; Lejzerowicz et al., 2014; Żuk and Sambrook Smith, 2015; Lejzerowicz et al., 2018). It also points to the research potential of the GPR method in determining the genesis of form. The discussion on the way kames form has been going on in the literature for years (Niewiarowski, 1959; 1961; Karczewski, 1971; Klajnert, 1978; Jaksa, 2003; Terpiłowski, 2008). The studies presented here do not suffice to allow the matter to be determined comprehensively, even though they do provide for verification of the opinions of previous researchers.The area forming the subject of this article is defined by Niewiarowski (1959) as the dead ice zone because of the characteristic set of forms (dead ice moraines, kames and eskers). Like modern researchers (Terpiłowski, 2008), Niewiarowski points to the importance of sub-Quaternary surface elevations in the formation of cracks in the ice sheet, with this leading on to the formation of kame hills above such elevations. This would also seem to have been one of the reasons for the formation in the mass of ice of lakes whose filling with sediment and melting ice walls took the form of kames.The great advantage of the GPR method lies in its ability to recognise macrostructural sediment patterns in glacilimic forms. This diagnosis allows for the high-probability assessment of the genesis of form, especially in the context of its position being determined in the marginal zone of the ice sheet. Also looking extremely promising is the capacity for the thickness of fine clastic sediments lying on till to be determined using GPR. It allows for the determination of the way in which a given form is rooted.Described as they are in brief only, test results for selected sites serve to confirm the great usefulness of the GPR method in the recognition of shallow lithostratigraphy of clastic sediments. Nevertheless, this should not be the only method used to recognise the geological structure of forms and sediments. Significant interpretation ambiguities mean that the GPR method should act in support of direct lithostratigraphic research, not merely serving as an alternative to it. GPR surveys offer a depiction particularly close to the real one – of sediment present in homogeneous sediments in relation to electrical parameters. Sediments ideal for GPR surveys would for example be fine dry sands or silts – and it is precisely these sediments that built most of the investigated kame forms.

Ground penetrating radar (GPR) and electrical resistivity tomography (ERT) surveys have been carried out in the city centre of Thessaloniki (N. Greece), for investigating possible locations of buried building foundations. Geophysical survey has been chosen as a non-destructive investigation method since the area is currently used as a car parking and it is covered by asphalt. The geoelectrical sections derived from ERT data in combination with the GPR profiles provided a broad view of the subsurface. Regarding ERT, high resistivity values can be related to buried building remains, while lower resistivity values are more related to the surrounding geological materials. GPR surveying can also indicate man-made structures buried in the ground. Even though the two geophysical methods are affected in different ways by the subsurface conditions, the processed underground images from both techniques revealed great similarity. High resistivity anomalies and distinct GPR signals were observed in certain locations of the area under investigation, which are attributed to buried building foundations as well as the geological structure of the area.

The United States Department of Energy (US DOE) is developing a Geophysical Performance Evaluation Range (GPER) at Rabbit Valley located 30 miles west of Grand Junction, Colorado. The purpose of the range is to provide a test area for geophysical instruments and survey procedures. Assessment of equipment accuracy and resolution is accomplished through the use of static and dynamic physical models. These models include targets with fixed configurations and targets that can be re-configured to simulate specific specifications. Initial testing (1991) combined with the current tests at the Rabbit Valley GPER will establish baseline data and will provide performance criteria for the development of geophysical technologies and techniques. The US DOE`s Special Technologies Laboratory (STL) staff has conducted a Ground Penetrating Radar (GPR) survey of the site with its stepped FM-CW GPR. Additionally, STL contracted several other geophysical tests. These include an airborne GPR survey incorporating a ``chirped`` FM-CW GPR system and a magnetic survey with a surfaced-towed magnetometer array unit Ground-based and aerial video and still frame pictures were also acquired. STL compiled and analyzed all of the geophysical maps and created a site characterization database. This paper discusses the results of the multi-sensor geophysical studies performed at Rabbitmore » Valley and the future plans for the site.« less

Geophysical surveys, particularly with ground-penetrating radar (GPR), have been proven useful tools for the detection and mapping of tile drainage in agricultural fields (Wienken & Grenzdorffer, 2024). However, the success of a GPR survey for this purpose depends on both the characteristics of the tile drain pipes, such as their material, diameter, and depth – which are often poorly documented – as well as environmental conditions, such as soil texture and moisture content. Furthermore, these environmental conditions can be highly variable in space and dynamic over time, adding to the challenge of assessing in advance whether a GPR survey will be worth the investment.To assess the likelihood of successfully detecting tile drainage networks before planning a field survey, we developed a synthetic modelling framework using the open-source software gprMax (Warren et al., 2016). The framework evaluates how selected parameters influence the GPR signal, focusing on the reflection contrast expected when the electromagnetic wave interacts with a drainpipe in a simplified one-dimensional (1D) model. Whether detection is possible is determined by comparing the simulated reflection contrast with a general noise threshold typical for a time-domain GPR system with a specified centre frequency. In this study, all synthetic modelling tests were performed for a GPR system with a centre frequency of 300 MHz.We explored the sensitivity of the GPR signal to soil texture, soil moisture content, as well as the radius, depth, and filling of the drainpipe, considering a laterally homogeneous soil profile composed of one or two layers. The validity of the modelling framework was assessed by comparing the predicted detectability with the detection success/failure in two real field cases with sandy and clayey soil types. While the synthetic model predicted feasible detection for the sandy field, no clear contrasts were visible in the radargrams after basic processing. This suggests the need for further refinement of the synthetic model, such as incorporating more complex soil variations and a more detailed representation of the drainpipe structure. Nevertheless, the modelling framework provides useful guidelines for planning and designing GPR field surveys, without requiring extensive prior information on site conditions.Further research is recommended to explore additional centre frequencies, more complex soil structures, and the incorporation of higher-dimensional approaches (2D or even 3D) to extend the current modelling framework. However, it should balance complexity with practical applicability, as real field conditions are never entirely predictable and models must simplify certain aspects due to incomplete knowledge.ReferencesWarren, C., Giannopoulos, A., & Giannakis, I. (2016). gprMax: Open source software to simulate electromagnetic wave propagation for Ground Penetrating Radar. Computer Physics Communications, 209, 163–170. https://doi.org/10.1016/j.cpc.2016.08.020Wienken, J. S., & Grenzdorffer, G. J. (2024). Non-invasive detection methods for subsurface drainage systems: A comparative review. Agricultural Water Management, 304, 109099. https://doi.org/10.1016/j.agwat.2024.109099

This article shows the interesting results of a pioneer effort by IAG/USP researchers to use ground-penetrating radar (GPR) for humanitarian purposes, guiding the rescue of victims in the tragedy of Brumadinho. The tailings Dam I at the Córrego do Feijão iron ore mine, located in the Brumadinho complex, Minas Gerais State, Brazil, collapsed on 25 January 2019. About 11.7 million m3 of mining mud was spilled from the dam, burying bodies, equipment, structural buildings, buses, and cars along a length of 8.5 km up to the Paraopeba River. Additionally, the contaminated mud traveled more than 300 km along the bed of the Paraopeba River toward the São Francisco River. This work shows the results of a geophysical investigation using the GPR method 17 days after the event. To carry out the geophysical survey, an excavator was used for soil compaction. The data acquisition was performed on the tracks left by the excavator chain using SIR-4000 equipment and antennas of 200 and 270 MHz (GSSI). The GPR studies aimed to map bodies, structural buildings, and equipment buried in the mud. The location of the profiles followed preferably the edge of the slope due to the higher probability of finding buried bodies and objects. The GPR results allowed the detection of subsoil structures, such as concentrations of iron ore and accumulations of sand from the dam filter. The GPR was effective because the iron ore sludge in the mixing process became porous and the pores were filled with air, which provided penetration and reflection of the GPR electromagnetic waves up to a depth of 3.5 m. The results were surprising. Although no bodies or underground equipment were found, the results of this research served to eliminate the studied areas from future excavations, thus redirecting the rescue teams and optimizing the search process. These important results can serve as an additional motivation for the use of GPR in future humanitarian work in areas of tragedies.