Integrated Hydrogeophysical Model for Identifying and Preventing Hydrocarbon Pollution in the Oil Terminal Constanța Area in the Context of Neptun Deep development

Locating unmarked graves is frequently necessary in older cemeteries that have poor or no records. Such is the case for a cemetery located on the fort Hood Army Base. the base is located in central Texas and is home to more than 2,000 archeological sites of varying ages. the goal of our Investigation was to determine if unmarked graves were present at a particular site. the Tools utilized to reach this goal were a soil resistivity meter and a Ground Penetrating Radar (GPR) system. the existing headstones indicate the cemetery was active at least from 1871 through 1964. However, it is suspected that the cemetery was used prior to 1871. Soils at the site consist of thin loam overlying limey clay. the Walnut formation (Cretaceous) crops out at the site and consists of lime marl with layers of fossiliferous limestone. the survey area was approximately sixty meters by fifty meters. Resistivity measurements were made using the Wenner array with an A-spacing of one meter and a transect spacing of two meters. the GPR system utilized a 270 MHz antenna with half meter transect spacing. Resistivity data indentified areas believed to be disturbed, but not at a scale useful for locating specific graves. GPR successfully located eighty-four percent of the marked graves. GPR also identified nine anomalies consistent with graves that were not marked. Data indicates that specific graves are not identifiable in a lime marl environment using soil resistivity alone. the use of GPR greatly enhanced the ability to identify individual graves, both marked and unmarked.

6. Resistivity and Induced Polarization Methods

Current uses of ground penetrating radar in groundwater-dependent ecosystems research

The effectiveness of electromagnetic (EM), ground penetrating radar (GPR) and seismic refraction (SR) were evaluated by surveying a shallow trench in which a number of objects of varying composition and size were buried. The trench was excavated in granular calcareous fill material. An experienced geophysical contractor was asked to provide blind predictions of object locations using each of the techniques in turn. GPR with a 400 MHz antenna was the most successful, followed by SR and EM surveying. GPR and SR were also carried out at the port of Hilo to investigate complex subsurface conditions.

Subsurface cavity detection: field evaluation of radar, gravity and earth resistivity methods : Fountain, L S Transp Res Rec, n612, 1976, p38–46

Macrofossil and microfossil remains from Quaternary sediments are important archives of palaeoenvironmental and palaeoecological information. Remains in anoxic swamp and lacustrine environments are often well preserved. Several fossil deposits have been located in wetlands in the North Canterbury fold and fault zone, but the fossil remains are often damaged or destroyed by development when their presence is unsuspected. Near-surface geophysical imaging provides, however, a means of investigating potential sites and mapping deposits. As part of ongoing palaeobiological investigations, the lacustrine deposit at Pyramid Valley was imaged by ground penetrating radar (GPR). Because of an unusually dry summer, the lake bed was dry and the water table low, and the high ionic content typical of the waters of the Pyramid Valley lake and lake bed did not interfere unduly with the GPR response. Two sets of GPR data were acquired for 3D analysis. Near the western shore, Site 1 included areas of previous excavations that had yielded macrofossil remains of vegetation and vertebrates, along the lake edge. The GPR survey showed some clearly anomalous responses, one of which was found on excavation to be associated with a buried matai tree (Prumnopitys taxifolia). The radar images also showed undulating layers which can be correlated with continuous stratigraphie features disrupted by dehydration cracks developed in a previously unrecognised desiccation surface. At Site 2, in the middle of the southern basin of the lake bed, some small anomalous responses were obtained, but the major feature recorded was associated with a previous attempt at piston coring the sediments. As is clear from the GPR 3D image, the piston had simply pushed sediments out, causing updoming of the surrounding material.

Many subsurface investigations are requested in areas unsuitable for most geophysical methods. In some instances, difficult terrain prevents surface coupling with transmitters, receivers, or other instrumental components. In other instances, such as in urban areas, spatial restrictions prohibit the use of seismic methods. Ground penetrating radar (GPR) is one method that can be used to attempt data collection in these difficult areas. In this paper, we will demonstrate the application of low frequency GPR to map a sloping bedrock surface configuration in an urban setting with the aforementioned site limitations. The sloping bedrock surface with a relief of approximately 21.5 meters underlies a stabilized slide area resulting from a failed retaining wall. 40-MHz and 100-MHz antenna systems were employed on boulder rip-rap (used to stabilize the slide area) and within an apartment house complex. Seismic refraction and surface wave investigations were performed to help constrain the GPR data interpretation and to provide bedrock integrity information.

Several geophysical techniques are available for the investigation and characterization of shallow subsurface. Most commonly used are electrical methods, seismic refraction and reflection methods, multichannel analysis of surface waves, gravity, magnetic, electromagnetic induction and ground penetrating radar. Mars is the one of the terrestrial planet, under discussion from several years due to interesting facts obtained from surface features including the evidences for the presence of water. Surface features on Mars include plans, mountains, impact crater, lava flows and dust cover. The possibility of life on the Mars is a question mark which is yet to be defined. In this article GPR technique is proposed for planetary missions to explore the subsurface of Mars. Ground Penetrating Radar (GPR) is a recent technology which provides high resolution picture for near surface structures. Due to the small size, light weight, high resolution, and simple operational system the GPR is supposed to be a best tool for the exploration of near surface features and hydrology of Mars. Launching a planetary mission at Mars with GPR could provide the information about the subsurface structures. This information could be used to define many question marks about red planet.

The Seismic refraction technique (SRT) and Electrical resistivity technique (ERT) have long been in use in geotechnical exploration. A relatively recent technique is Ground penetrating radar (GPR). The study presented in this paper is on GPR-aided geotechnical subsurface exploration. The usual method of exploration is drilling, which gives much-needed site-specific information, but is expensive and restricted to a few point locations. The possibilities of non-invasive investigation offered by GPR make it useful for supplementing geotechnical investigations. The present work describes GPR survey at a construction site in Mumbai. The objective was to derive subsurface logs from GPR signals. Conventionally, subsurface logging is done using boreholes. First, the extracted soil and rock samples are examined visually. Second, additional information such as Core recovery ratios (CRR), Rock quality designation (RQD) and Standard penetration test (SPT) N values are collected and strata are demarcated. In comparison, the amplitude variations of GPR signals may not correspond directly to variations of these physical properties with depth. However, the study shows that fairly good correlations do exist with the subsurface stratification and transformed signals. Method and materials The geology of the study area is composed of Mesozoic rocks of volcanic origin. Known as the Deccan trap, the main rock type is basalt (Geocon, 2011). The rock exhibits weathering of varying degrees and the overlying soil is known locally as murrum. The GPR study area is covered by survey grids that are 7 m x 26 m in size. The subsurface conditions, particularly, depth to rock, varied significantly between boreholes, raising possibility of a sloping bedrock surface and arousing stability concerns for the proposed tall building. Six boreholes were drilled at site and borehole logs were available. GPR has been used to obtain supplementary information particularly between the boreholes. Two GPR frequencies (40MHz and 20 MHz), were employed. A typical survey grid is presented in Figure 1. GPR data using a 40 MHz antenna was collected in 2D point mode scanning from left to right, bottom to top, with Scans/m = 5. In L1, 9 X lines of 7m length & 3 Y lines of 26 m length each were traversed The 20 MHz survey was conducted close to and parallel toY2. The initial GPR data gathering settings are given in Figure 2.

Various techniques have been designed to maximize the use of ground penetrating radar (GPR) as an exploration tool. Improvements in signal processing are expected to further facilitate the accuracy of parameters derived from using GPR in certain geologic environments. Common-offset GPR data were collected at the Marine Corps Air Station (MCAS) in Beaufort, South Carolina, and dielectric constants were calculated following the application of the empirical mode decomposition (EMD) for dewowing GPR traces. Conventional signal processing is applied to the GPR traces to provide hydrogeophysical parameter estimates such as volumetric water content, porosity, and hydraulic conductivity. The results are validated using a coincident vertical radar profile, existing hydraulic data from direct measurements, and comparing EMD derived parameters with those non-EMD derived. The results of the comparison between the EMD and non-EMD methods show improved hydrogeophysical estimations from the EMD processed data. Dielectric constant [Formula: see text] values from the non-EMD method are outside the range of the values for all geologic materials [Formula: see text]. The subsequent parameter estimates using dielectric constants derived from non-EMD processed data yield erroneous results therefore justifying the use of EMD as a method in dewowing GPR data for quantitative analyses.

This study examines the application of Ground Penetrating Radar (GPR) to the detection of severe caverns and sinkholes in non-clastic rock formations. Due to the presence of vertically sloping bedrock, cavities, and sinkholes, geotechnical engineers face significant challenges when designing and constructing foundations in karstic formations such as limestone. The territory under investigation is located close to the Giza limestone plateau, the northern side of which has experienced severe stability issues. The ground-penetrating radar (GPR) method was used to identify the presence and extent of exposed caves and caverns in the studied region. The research area’s geological and geomorphological background is explored, including the creation of primary and secondary caves, as well as solution caves generated by the breakdown of soluble rocks like limestone. Data collecting, processing, and interpretation procedures used in the GPR survey are described. GPR survey findings revealed the existence of a severe cave and many minor sinkholes in the studied region. GPR has shown to be a useful and efficient tool for determining geometric karst features in the subsurface, helping to a better evaluation of the dangers associated with this geological environment.

Closely spaced (1 m) ground penetrating radar (GPR) profiles were used for a three-dimensional characterization and comparison of glaciofluvial gravel-bed deposits in palaeodischarge zones of the Würmian Rhine glacier (southwestern Germany). Previous sedimentological outcrop investigations revealed three regionally reoccurring architectural styles of gravel bodies. For each of these styles a three-dimensional GPR dataset has been acquired in active gravel pits in order to calibrate the radar profiles with outcrop walls and to analyse, in three dimensions, the depositional elements and their stacking pattern in the subsurface. The GPR data were interpreted by mapping reflection terminations in order to delineate genetically related units. In particular, radar facies types and radar sequence boundaries were used to define and map depositional elements. Both accretionary and cut-and-fill depositional elements could be identified. Accretionary elements are characterized by horizontally to low-angle inclined (1–3°) and moderately continuous reflections (5–30 m) terminating on flat sequence boundaries; they represent the deposits of gravel sheets and traction carpets. In contrast, cut-and-fill elements are characterized by low to steeply inclined (3–25°), often discontinuous reflections terminating on concave to trough-shaped lower truncation boundaries; these are interpreted as scour-pool fills and small dissection elements (e.g. chutes and lobes). The three basic architectural styles of gravel bodies can be distinguished on the basis of the size and proportion of cut-and-fill elements mapped within the radar images. One type of gravel body is composed of an amalgamation of large cut-and-fill elements whereas the other two types are dominated by accretionary elements and differ by the proportion of smaller cut-and-fill elements. The results show that GPR is an adequate technique to illuminate the sedimentary architecture of the various types of gravel bodies. GPR data allow detailed three-dimensional reconstruction of depositional elements and their stacking pattern in the subsurface.

<p>A 3D geological model was constructed for the Gråbo site to investigate its suitability for artificial groundwater infiltration, to provide drinking water. The modelling work was performed by the Geological Survey of Sweden (SGU) as part of ongoing groundwater investigations. The site is located close to the city of Gothenburg, in western Sweden. A relatively thick succession of coarse-grained glaciofluvial sediment is located at the site, which overlies a typically finer grained and more clay rich sequence. Previously, the site has been the target of several investigations, the most extensive of these was performed in 2006, where a range of geophysical (seismic refraction, ground penetrating radar and resistivity) and borehole measurements were conducted. Based on previous studies the upper course-grained layer has the best potential for infiltration. However, although these investigations improved the understanding of the site, significant uncertainty remained as to the geometry of the upper course grained layer away from borehole locations.</p><p>In order to improve the understanding of the site, additional data was collected in 2018 using a tTEM (towed transient electromagnetic) system developed by Aarhus university. The system is comprised of a transmitter and receiver coil, which are towed behind an ATV (all terrain vehicle). Using the tTEM data a 3D resistivity model of the subsurface was generated down to a depth of between 50 and 70 m at the Gråbo site. On comparison with the available borehole data, it was clear that the course-grained layer could be mapped with relatively high accuracy as a region of high resistivity. The tTEM data was combined with the pre-existing geophysical and borehole data to construct both a voxel and layer-based model of the site. These 3D models have subsequently been used as part of ongoing efforts to evaluate the suitability of the site for infiltration (for example, to decide the location of additional investigation boreholes and to provide input to hydrogeological modelling). In this study we present the tTEM data and the 3D geological model. Finally, we exemplify how the 3D model has been used in subsequent investigations and decision making.</p>

An underground reinforced concrete tank was constructed for a project in the southwest region of India. The tank was 90 m x 35 m in plan and 7.3 m deep resting on partly filled-up and partly native soil. During the peak monsoon, a sudden uplifting of the base slab by about 300 mm and subsequent failure of the foundation raft and a partition wall was observed. Laboratory testing was executed and hydrogeological survey was carried out using ground penetrating radar, seismic refraction and infiltrometer testing, and an analytical study was carried out to identify the root cause of the tank uplifting. Based on this study, it was observed that the uplifting and structural failure was essentially due to the peculiar land terrain and soil properties and the development of excess hydraulic head below the bottom of the tank. After considering different options, the rectification measures were carried out by provision of dewatering wells along the tank periphery to release the excess hydrostatic pressure and stabilize the foundation raft. The structural repair of the top of the foundation raft and partition wall was carried out to strengthen the reinforced concrete members. The rectification measures worked well to increase the structural stability of the tank and to prevent build-up of excess hydrostatic pressure preventing uplift and subsequent damage in the future.

Electrical resistivity imaging (ERI), ground penetrating radar (GPR) and seismic refraction (SRF) profiles were repeated over three lines on a terrace of the Bow River. The site had a resistive gravel layer overlying mudstone bedrock with horizontal transitions to lacustrine and overbank deposits. Electrical resistivity results were best for determining changes in sediment types and detecting boundaries, but the ERI smoothness constraint blurred the location of the boundaries. The GPR gave the most resolution and showed internal structures that the other methods did not image. The GPR signal was severely attenuated in several areas where the surficial sediments became too conductive because of a fine grained component. The seismic refraction inversion provided good reproduction of the bedrock interface, but it did not detect changes in the composition of the surficial sediments. It also required the introduction of a low velocity surficial layer not indicated by the other methods that may be related to the increase in effective stress with depth. Jointly interpreting the three data sets gives a more reliable and less ambiguous interpretation than any single method. The data may be useful to test joint inversion algorithms and are available for download.