Science.gov

Sample records for 3-d ground-penetrating radar

  1. 3-D representation of aquitard topography using ground-penetrating radar

    SciTech Connect

    Young, R.A.; Sun, Jingsheng

    1995-12-31

    The topography of a clay aquitard is defined by 3D Ground Penetrating Radar (GPR) data at Hill Air Force Base, Utah. Conventional processing augmented by multichannel domain filtering shows a strong reflection from a depth of 20-30 ft despite attenuation by an artificial clay cap approximately 2 ft thick. This reflection correlates very closely with the top of the aquitard as seen in lithology logs at 3 wells crossed by common offset radar profiles from the 3D dataset. Lateral and vertical resolution along the boundary are approximately 2 ft and 1 ft, respectively. The boundary shows abrupt topographic variation of 5 ft over horizontal distances of 20 ft or less and is probably due to vigorous erosion by streams during lowstands of ancient Lake Bonneville. This irregular topography may provide depressions for accumulation of hydrocarbons and chlorinated organic pollutants. A ridge running the length of the survey area may channel movement of ground water and of hydrocarbons trapped at the surface of the water table. Depth slices through a 3D volume, and picked points along the aquitard displayed in depth and relative elevation perspectives provide much more useful visualization than several 2D lines by themselves. The three-dimensional CPR image provides far more detailed definition of geologic boundaries than does projection of soil boring logs into two-dimensional profiles.

  2. 3D Monitoring under the Keciova Mosque (Casbah-Algier, Algeria) with Ground Penetrating Radar Method

    NASA Astrophysics Data System (ADS)

    Kadioglu, Selma; Kagan Kadioglu, Yusuf; Deniz, Kiymet; Akin Akyol, Ali

    2014-05-01

    Keciova (Ketchaoua) Mosque, in Casbah-Algiers, the capital of Algeria, is a UNESCO World Heritage Site. Keciova Mosque was originally built in 1612 by the Ottoman Empire. A RAMAC CU II GPR system and a 250 MHz shielded antenna have been employed inside of the Mosque including the Cathedral and inside of the burial chambers under the Cathedral Site on parallel profiles spaced approximately 0.30 m apart to measure data. After applying standard two-dimensional (2D) and three dimensional (3D) imaging techniques, transparent 3D imaging techniques have been used to photograph the foundational infrastructures, buried remains and safety problems of the Mosque. The results showed that we obtained 3D GPR visualization until 12.0 m in depth. Firstly we imaged the base floor including corridors. Then we monitored buried remains under the first ground level between 5.0-7.0 m in depths. Finally we indicated 3D GPR photographs a spectacular protected buried old mosque structures under the second ground level between 9.0-12.0 m in depths. This project has been supported by Republic of Turkey Prime Ministry Turkish Cooperation and Coordination Agency (TIKA). This study is a contribution to the EU funded COST action TU1208, "Civil Engineering Applications of Ground penetrating Radar".

  3. Time-lapse 3D ground-penetrating radar during plot-scale infiltration experiments

    NASA Astrophysics Data System (ADS)

    Allroggen, Niklas; Jackisch, Conrad; Tronicke, Jens

    2016-04-01

    In electrical resistive soils, surface-based ground-penetrating radar (GPR) is known as the geophysical tool providing the highest spatial resolution. Thus, 2D and 3D GPR surveys are commonly used for imaging subsurface structures or estimating soil moisture content. Due to its sensitivity to soil moisture and its non-invasive character, GPR provides a large potential to monitor soil moisture variation at high temporal and spatial resolution. As shown in previous experiments, the acquisition of time-lapse GPR data under field conditions requires a high data quality in terms of repeatability as well as spatial and temporal resolution. We present hydrogeophysical field experiments at the plot scale (1m x 1m), during which we record time-lapse 3D GPR. For GPR data acquisition, we use a pulseEKKO PRO GPR system equipped with a pair of 500 MHz antennas in combination with a specially designed metal-free measuring platform. Additionally, we collect tracer and soil moisture data, which are used to improve the interpretation of the GPR data with special focus on preferential flow paths and their structured advective flow field. After an accurate time-lapse GPR data processing, we compare 3D reflection events before and after infiltration and quantitatively interpret their relative time-shift in terms of soil moisture variations. Thereby, we are able to account for basically all of the infiltrated water. The first experiments demonstrate the general applicability of our experimental approach but are limited by the number of acquired time steps and measurement during the sprinkling period (the time of the highest temporal dynamics) are not possible at all. Based on this experience we redesign our experimental setup to continuously collect GPR data during irrigation and infiltration. Thereby, we strongly increase the temporal resolution of our measurements, improve the interpretability of the GPR data, and monitor the temporal and spatial dynamics of shallow subsurface

  4. Detection of 3D tree root systems using high resolution ground penetration radar

    NASA Astrophysics Data System (ADS)

    Altdorff, D.; Honds, M.; Botschek, J.; Van Der Kruk, J.

    2014-12-01

    Knowledge of root systems and its distribution are important for biomass estimation as well as for the prevention of subsurface distribution network damages. Ground penetration radar (GPR) is a promising technique that enables a non-invasive imaging of tree roots. Due to the polarisation-dependent reflection coefficients and complicated three-dimensional root structure, accurate measurements with perpendicularly polarized antennas are needed. In this study, we show GPR data from two planes and one chestnut at two locations with different soil conditions. Perpendicular 10 x 10 cm grid measurements were made with a shielded 250 MHz antenna in combination with a high precision self-tracking laser theodolite that provides geo-referenced traces with a spatial resolution of ~ 2 cm. After selecting potential root hyperbolas within the perpendicular GPR profiles, the corresponding three-dimensional coordinates were extracted and visualized in planar view to reveal any linear structure that indicates a possible tree root. The coordinates of the selected linear structures were projected back to the surface by means of the laser-theodolite to indicate the locations for groundtruthing. Additionally, we interpolated the measured data into a 3D cube where time slices confirmed the locations of linear reflection events. We validated the indicated predictions by excavation of the soil with a suction dredge. Subsequent georeferencing of the true root distribution and comparison with the selected linear events showed that the approach was able to identify the precise position of roots with a diameter between 3 and 10 cm and a depth of up to 70 cm. However, not all linear events were roots; also mouse channels were found in these depths, since they also generate GPR hyperbolas aligned in linear structures. Roots at a second location at depths of 1 to 1.20 m did not generate identifiable hyperboles, which was probably due to an increased electrical conductivity below 86 cm depth. The

  5. Ground-penetrating radar methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ground-penetrating radar geophysical methods are finding greater and greater use in agriculture. With the ground-penetrating radar (GPR) method, an electromagnetic radio energy (radar) pulse is directed into the subsurface, followed by measurement of the elapsed time taken by the radar signal as it ...

  6. Estimating 3D variation in active-layer thickness beneath arctic streams using ground-penetrating radar

    USGS Publications Warehouse

    Brosten, T.R.; Bradford, J.H.; McNamara, J.P.; Gooseff, M.N.; Zarnetske, J.P.; Bowden, W.B.; Johnston, M.E.

    2009-01-01

    We acquired three-dimensional (3D) ground-penetrating radar (GPR) data across three stream sites on the North Slope, AK, in August 2005, to investigate the dependence of thaw depth on channel morphology. Data were migrated with mean velocities derived from multi-offset GPR profiles collected across a stream section within each of the 3D survey areas. GPR data interpretations from the alluvial-lined stream site illustrate greater thaw depths beneath riffle and gravel bar features relative to neighboring pool features. The peat-lined stream sites indicate the opposite; greater thaw depths beneath pools and shallower thaw beneath the connecting runs. Results provide detailed 3D geometry of active-layer thaw depths that can support hydrological studies seeking to quantify transport and biogeochemical processes that occur within the hyporheic zone.

  7. Estimating porosity with ground-penetrating radar reflection tomography: A controlled 3-D experiment at the Boise Hydrogeophysical Research Site

    NASA Astrophysics Data System (ADS)

    Bradford, John H.; Clement, William P.; Barrash, Warren

    2009-04-01

    To evaluate the uncertainty of water-saturated sediment velocity and porosity estimates derived from surface-based, ground-penetrating radar reflection tomography, we conducted a controlled field experiment at the Boise Hydrogeophysical Research Site (BHRS). The BHRS is an experimental well field located near Boise, Idaho. The experimental data set consisted of 3-D multioffset radar acquired on an orthogonal 20 × 30 m surface grid that encompassed a set of 13 boreholes. Experimental control included (1) 1-D vertical velocity functions determined from traveltime inversion of vertical radar profiles (VRP) and (2) neutron porosity logs. We estimated the porosity distribution in the saturated zone using both the Topp and Complex Refractive Index Method (CRIM) equations and found the CRIM estimates in better agreement with the neutron logs. We found that when averaged over the length of the borehole, surface-derived velocity measurements were within 5% of the VRP velocities and that the porosity differed from the neutron log by less than 0.05. The uncertainty, however, is scale dependent. We found that the standard deviation of differences between ground-penetrating-radar-derived and neutron-log-derived porosity values was as high as 0.06 at an averaging length of 0.25 m but decreased to less than 0.02 at length scale of 11 m. Additionally, we used the 3-D porosity distribution to identify a relatively high-porosity anomaly (i.e., local sedimentary body) within a lower-porosity unit and verified the presence of the anomaly using the neutron porosity logs. Since the reflection tomography approach requires only surface data, it can provide rapid assessment of bulk hydrologic properties, identify meter-scale anomalies of hydrologic significance, and may provide input for other higher-resolution measurement methods.

  8. Ground Penetrating Radar, Barrow, Alaska

    SciTech Connect

    John Peterson

    2015-03-06

    This is 500 MHz Ground Penetrating Radar collected along the AB Line in Intensive Site 1 beginning in October 2012 and collected along L2 in Intensive Site 0 beginning in September 2011. Both continue to the present.

  9. Integrated 3-D Ground-Penetrating Radar, Outcrop, and Borehole Data Applied to Reservoir Characterization and Flow Simulation

    SciTech Connect

    George McMechan; Rucsandra Corbeanu; Craig Forster; Kristian Soegaard; Xiaoxian Zeng; Carlos Aiken; Robert Szerbiak; Janok Bhattacharya; Michael Wizevich; Xueming Xu; Stephen Snelgrove; Karen Roche; Siang Joo Lim; Djuro Navakovic; Christopher White; Laura Crossey; Deming Wang; John Thurmond; William Hammon III; Mamadou BAlde; Ari Menitove

    2001-08-31

    OAK-B135 (IPLD Cleared) Existing reservoir models are based on 2-D outcrop studies; 3-D aspects are inferred from correlation between wells, and so are inadequately constrained for reservoir simulations. To overcome these deficiencies, we initiated a multidimensional characterization of reservoir analogs in the Cretaceous Ferron Sandstone in Utah. The study was conducted at two sites (Corbula Gulch and Coyote Basin); results from both sites are contained in this report. Detailed sedimentary facies maps of cliff faces define the geometry and distribution of potential reservoir flow units, barriers and baffles at the outcrop. High resolution 2-D and 3-D ground-penetrating radar (GPR) images extend these reservoir characteristics into 3-D, to allow development of realistic 3-D reservoir models. Models use geometric information from the mapping and the GPR data, petrophysical data from surface and cliff-face outcrops, lab analyses of outcrop and core samples, and petrography. The measurements are all integrated into a single coordinate system using GPS and laser mapping of the main sedimentological features and boundaries.The final step is analysis of results of 3-D fluid flow modeling to demonstrate applicability of our reservoir analog studies to well siting and reservoir engineering for maximization of hydrocarbon production. The main goals of the project are achieved. These are the construction of a deterministic 3-D reservoir analog model from a variety of geophysical and geologic measurements at the field sites, integrating these into comprehensive petrophysical models, and flow simulations through these models. This unique approach represents a significant advance in characterization and use of reservoir analogs.

  10. Intergrated 3-D Ground-Penetrating Radar,Outcrop,and Boreholoe Data Applied to Reservoir Characterization and Flow Simulation.

    SciTech Connect

    McMechan et al.

    2001-08-31

    Existing reservoir models are based on 2-D outcrop;3-D aspects are inferred from correlation between wells,and so are inadequately constrained for reservoir simulations. To overcome these deficiencies, we initiated a multidimensional characterization of reservoir analogs in the Cretaceous Ferron Sandstone in Utah.The study was conducted at two sites(Corbula Gulch Coyote Basin); results from both sites are contained in this report. Detailed sedimentary facies maps of cliff faces define the geometry and distribution of potential reservoir flow units, barriers and baffles at the outcrop. High resolution 2-D and 3-D ground penetrating radar(GPR) images extend these reservoir characteristics into 3-D to allow development of realistic 3-D reservoir models. Models use geometric information from the mapping and the GPR data, petrophysical data from surface and cliff-face outcrops, lab analyses of outcrop and core samples, and petrography. The measurements are all integrated into a single coordinate system using GPS and laser mapping of the main sedimentologic features and boundaries. The final step is analysis of results of 3-D fluid flow modeling to demonstrate applicability of our reservoir analog studies to well siting and reservoir engineering for maximization of hydrocarbon production. The main goals of this project are achieved. These are the construction of a deterministic 3-D reservoir analog model from a variety of geophysical and geologic measurements at the field sites, integrating these into comprehensive petrophysical models, and flow simulation through these models. This unique approach represents a significant advance in characterization and use of reservoir analogs. To data,the team has presented five papers at GSA and AAPG meetings produced a technical manual, and completed 15 technical papers. The latter are the main content of this final report. In addition,the project became part of 5 PhD dissertations, 3 MS theses,and two senior undergraduate research

  11. Transparent 3D Visualization of Archaeological Remains in Roman Site in Ankara-Turkey with Ground Penetrating Radar Method

    NASA Astrophysics Data System (ADS)

    Kadioglu, S.

    2009-04-01

    Transparent 3D Visualization of Archaeological Remains in Roman Site in Ankara-Turkey with Ground Penetrating Radar Method Selma KADIOGLU Ankara University, Faculty of Engineering, Department of Geophysical Engineering, 06100 Tandogan/ANKARA-TURKEY kadioglu@eng.ankara.edu.tr Anatolia has always been more the point of transit, a bridge between West and East. Anatolia has been a home for ideas moving from all directions. So it is that in the Roman and post-Roman periods the role of Anatolia in general and of Ancyra (the Roman name of Ankara) in particular was of the greatest importance. Now, the visible archaeological remains of Roman period in Ankara are Roman Bath, Gymnasium, the Temple of Augustus of Rome, Street, Theatre, City Defence-Wall. The Caesar Augustus, the first Roman Emperor, conquered Asia Minor in 25 BC. Then a marble temple was built in Ancyra, the administrative capital of province, today the capital of Turkish Republic, Ankara. This monument was consecrated to the Empreror and to the Goddess Rome. This temple is supposed to have built over an earlier temple dedicated to Kybele and Men between 25 -20 BC. After the death of the Augustus in 14AD, a copy of the text of "Res Gestae Divi Augusti" was inscribed on the interior of the pronaos in Latin, whereas a Greek translation is also present on an exterior wall of the cella. In the 5th century, it was converted in to a church by the Byzantines. The aim of this study is to determine old buried archaeological remains in the Augustus temple, Roman Bath and in the governorship agora in Ulus district. These remains were imaged with transparent three dimensional (3D) visualization of the ground penetrating radar (GPR) data. Parallel two dimensional (2D) GPR profile data were acquired in the study areas, and then a 3D data volume were built using parallel 2D GPR data. A simplified amplitude-colour range and appropriate opacity function were constructed and transparent 3D image were obtained to activate buried

  12. A parallel 3-D staggered grid pseudospectral time domain method for ground-penetrating radar wave simulation

    NASA Astrophysics Data System (ADS)

    Huang, Qinghua; Li, Zhanhui; Wang, Yanbin

    2010-12-01

    We presented a parallel 3-D staggered grid pseudospectral time domain (PSTD) method for simulating ground-penetrating radar (GPR) wave propagation. We took the staggered grid method to weaken the global effect in PSTD and developed a modified fast Fourier transform (FFT) spatial derivative operator to eliminate the wraparound effect due to the implicit periodical boundary condition in FFT operator. After the above improvements, we achieved the parallel PSTD computation based on an overlap domain decomposition method without any absorbing condition for each subdomain, which can significantly reduce the required grids in each overlap subdomain comparing with other proposed algorithms. We test our parallel technique for some numerical models and obtained consistent results with the analytical ones and/or those of the nonparallel PSTD method. The above numerical tests showed that our parallel PSTD algorithm is effective in simulating 3-D GPR wave propagation, with merits of saving computation time, as well as more flexibility in dealing with complicated models without losing the accuracy. The application of our parallel PSTD method in applied geophysics and paleoseismology based on GPR data confirmed the efficiency of our algorithm and its potential applications in various subdisciplines of solid earth geophysics. This study would also provide a useful parallel PSTD approach to the simulation of other geophysical problems on distributed memory PC cluster.

  13. Ground penetrating radar and microwave tomography 3D applications for the deck evaluation of the Musmeci bridge in Potenza, Italy

    NASA Astrophysics Data System (ADS)

    Bavusi, Massimo; Soldovieri, Francesco; Di Napoli, Rosario; Loperte, Antonio; Di Cesare, Antonio; Carlo Ponzo, Felice; Lapenna, Vincenzo

    2011-09-01

    An extensive experimental and numerical investigation has been carried out to assess the status of the 'Ponte sul Basento' (1967-1976), in the town of Potenza (Basilicata region, southern Italy), better known as the Musmeci bridge. Architecturally, the bridge is a considerable reinforced 20th century concrete structure that was designed and built by the Italian architect Sergio Musmeci (1926-1981). Moreover, the bridge represents an important element of the infrastructural network, linking the city centre to the Potenza-Sicignano highway, crossing the Basento river and the railway close to the main train station of the city. Recently, due to ageing and continuous and significant traffic, the bridge started to be affected by several problems such as water infiltration. Within the presented study, a widespread ground penetrating radar (GPR) survey has been designed to investigate the geometrical characteristics of the bridge deck (Gerber saddles, internal stiffening walls, pillar supports) and detect the presence of defects or damage due to water infiltration and traffic fatigue. Concerning this, a 900 MHz 3D GPR survey has been performed along a zone of one of the lanes on the road surface. Moreover, a second 1500 MHz 3D survey has been carried out at the bottom of the bridge deck in order to gain detailed information about an important structural element of the bridge, the Gerber saddle. Both results have been processed following two approaches: the first a classical time-domain processing session based on commercial software and the use of migration; the second in microwave tomography, an advanced frequency domain automatic PC-based inversion algorithm. In this paper, we present a comparative interpretation of both kinds of processed results, and provide considerations about the investigated structures.

  14. 2D and 3D Ground Penetrating Radar monitoring of a reinforced concrete asphalt plate affected by mechanical deformation.

    NASA Astrophysics Data System (ADS)

    Bavusi, M.; Dumoulin, J.; Loperte, A.; Rizzo, E.; Soldovieri, F.

    2012-04-01

    , a zero setting acquisition was carried out before perturbing the plate. Described experience demonstrates the GPR is a reliable technique for the: • foundation soil characterization and monitoring • Reinforced structural elements monitoring • asphalt/reinforced concrete characterization and monitoring • detection of water infiltration, structural elements, defects • evaluation of restoration intervention. In fact, the GPR technique was able to investigate the layers beyond the asphalt and provides a spatial resolution complying with the needs of the technical problem at hand by use of different antennas. Moreover noticeable performances of this technique can be further improved by implementing 3D processing and MT inversion procedures in order to increase the amount of information by the survey [2]. Acknowledgements. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement n. 225663 Joint Call FP7-ICT-SEC-2007-1 [1] Lapenna, V.; Cuomo, V.; Rizzo, E.; Fiore, S.; Troisi, S.; Straface, S. (2006). A new Large Lab-scale Facility for Hydro-Geophysical Experiments: Hydrogeosite. American Geophysical Union, Fall Meeting 2006, abstract #H31B-1422 [2] Bavusi M., Soldovieri F., Di Napoli R., Loperte A., Di Cesare A., Ponzo F.C and Lapenna V. (2011). Ground penetrating radar and microwave tomography 3D applications for the deck evaluation of the Musmeci bridge in Potenza, Italy. J. Geophys. Eng. 8 S33 doi:10.1088/1742-2132/8/3/S04

  15. Ground penetrating radar: 2-D and 3-D subsurface imaging of a coastal barrier spit, Long Beach, WA, USA

    NASA Astrophysics Data System (ADS)

    Jol, Harry M.; Lawton, Don C.; Smith, Derald G.

    2003-07-01

    The ability to effectively interpret and reconstruct geomorphic environments has been significantly aided by the subsurface imaging capabilities of ground penetrating radar (GPR). The GPR method, which is based on the propagation and reflection of pulsed high frequency electromagnetic energy, provides high resolution (cm to m scale) and shallow subsurface (0-60 m), near continuous profiles of many coarser-grained deposits (sediments of low electrical conductivity). This paper presents 2-D and 3-D GPR results from an experiment on a regressive modern barrier spit at Willapa Bay, WA, USA. The medium-grained sand spit is 38 km long, up to 2-3.5 km wide, and is influenced by a 3.7-m tidal range (spring) as well as high energy longshore transport and high wave energy depositional processes. The spit has a freshwater aquifer recharged by rainfall. The GPR acquisition system used for the test was a portable, digital pulseEKKO™ system with antennae frequency ranging from 25 to 200 MHz and transmitter voltages ranging from 400 to 1000 V. Step sizes and antennae separation varied depending on the test requirements. In addition, 100-MHz antennae were used for conducting antennae orientation tests and collecting a detailed grid of data (50×50 m sampled every meter). The 2-D digital profiles were processed and plotted using pulseEKKO™ software. The 3-D datasets, after initial processing, were entered into a LANDMARK™ workstation that allowed for unique 3-D perspectives of the subsurface. To provide depth, near-surface velocity measurements were calculated from common midpoint (CMP) surveys. Results from the present study demonstrate higher resolution from the 200-MHz antennae for the top 5-6 m, whereas the 25- and 50-MHz antennae show deeper penetration to >10 m. For the study site, 100-MHz antennae provided acceptable resolution, continuity of reflections, and penetration. The dip profiles show a shingle-like accretionary depositional pattern, whereas strike profiles

  16. Advances in 3D soil mapping and water content estimation using multi-channel ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Moysey, S. M.

    2011-12-01

    Multi-channel ground-penetrating radar systems have recently become widely available, thereby opening new possibilities for shallow imaging of the subsurface. One advantage of these systems is that they can significantly reduce survey times by simultaneously collecting multiple lines of GPR reflection data. As a result, it is becoming more practical to complete 3D surveys - particularly in situations where the subsurface undergoes rapid changes, e.g., when monitoring infiltration and redistribution of water in soils. While 3D and 4D surveys can provide a degree of clarity that significantly improves interpretation of the subsurface, an even more powerful feature of the new multi-channel systems for hydrologists is their ability to collect data using multiple antenna offsets. Central mid-point (CMP) surveys have been widely used to estimate radar wave velocities, which can be related to water contents, by sequentially increasing the distance, i.e., offset, between the source and receiver antennas. This process is highly labor intensive using single-channel systems and therefore such surveys are often only performed at a few locations at any given site. In contrast, with multi-channel GPR systems it is possible to physically arrange an array of antennas at different offsets, such that a CMP-style survey is performed at every point along a radar transect. It is then possible to process this data to obtain detailed maps of wave velocity with a horizontal resolution on the order of centimeters. In this talk I review concepts underlying multi-channel GPR imaging with an emphasis on multi-offset profiling for water content estimation. Numerical simulations are used to provide examples that illustrate situations where multi-offset GPR profiling is likely to be successful, with an emphasis on considering how issues like noise, soil heterogeneity, vertical variations in water content and weak reflection returns affect algorithms for automated analysis of the data. Overall

  17. A lightweight ground penetrating radar

    SciTech Connect

    Koppenjan, S.K.; Allen, C.M.; Gardner, D.; Wong, H.R.

    1998-12-31

    The detection of buried objects, particularly unexploded ordnance (UXO), has gained significant interest in the US in the late 1990s. The desire to remediate the thousands of sites worldwide has become an increasing humanitarian concern. The application of radar to this problem has received renewed attention. Bechtel Nevada, Special Technologies Laboratory (STL) has developed several frequency modulated, continuous wave (FM-CW) ground penetrating radar (GPR) units for the US Department of Energy since 1984. To meet these new technical requirements for high resolution data and UXO detection, STL is moving forward with advances to GPR technology, signal processing, and imaging with the development of an innovative system. The goal is to design and fabricate a lightweight, battery operated unit that does not require surface contact and can be operated by a novice user.

  18. Delineate subsurface structures with ground penetrating radar

    SciTech Connect

    Wyatt, D.E.; Hu, L.Z.; Ramaswamy, M.; Sexton, B.G.

    1992-10-01

    High resolution ground penetrating radar (GPR) surveys were conducted at the Savannah River Site in South Carolina in late 1991 to demonstrate the radar techniques in imaging shallow utility and soil structures. Targets of interest at two selected sites, designated as H- and D-areas, were a buried backfilled trench, buried drums, geologic stratas, and water table. Multiple offset 2-D and single offset 3-D survey methods were used to acquire high resolution radar data. This digital data was processed using standard seismic processing software to enhance signal quality and improve resolution. Finally, using a graphics workstation, the 3D data was interpreted. In addition, a small 3D survey was acquired in The Woodlands, Texas, with very dense spatial sampling. This data set adequately demonstrated the potential of this technology in imaging subsurface features.

  19. Delineate subsurface structures with ground penetrating radar

    SciTech Connect

    Wyatt, D.E. ); Hu, L.Z. ); Ramaswamy, M. ); Sexton, B.G. )

    1992-01-01

    High resolution ground penetrating radar (GPR) surveys were conducted at the Savannah River Site in South Carolina in late 1991 to demonstrate the radar techniques in imaging shallow utility and soil structures. Targets of interest at two selected sites, designated as H- and D-areas, were a buried backfilled trench, buried drums, geologic stratas, and water table. Multiple offset 2-D and single offset 3-D survey methods were used to acquire high resolution radar data. This digital data was processed using standard seismic processing software to enhance signal quality and improve resolution. Finally, using a graphics workstation, the 3D data was interpreted. In addition, a small 3D survey was acquired in The Woodlands, Texas, with very dense spatial sampling. This data set adequately demonstrated the potential of this technology in imaging subsurface features.

  20. 3D imaging of the internal structure of a rock-cored drumlin using ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    King, Edward; Spagnolo, Matteo; Rea, Brice; Ely, Jeremy; Lee, Joshua

    2016-04-01

    One key question linking subglacial bedform analyses to ice dynamics relates to the flux of sediment at the bed. It is relatively easy to measure the upper surface of subglacial sediments either in active contemporary systems (using ice-penetrating radar surveys) or in relict subglacial terrain (using high-resolution digital elevation models). However, constraining the lower surface of subglacial sediments, i.e. the contact between the bedform sediment and a lower sediment unit or bedrock, is much more difficult, yet it is crucial to any determination of sediment volume and hence flux. Without observations, we are reliant on assumptions about the nature of the lower sediment surface. For example, we might assume that all the drumlins in a particular drumlin field are deposited on a planar surface, or that all comprise a carapace of till over a rock core. A calculation of sediment volume will give very different results leading to very different interpretations of sediment flux. We have been conducting experiments in the use of ground-penetrating radar to find the lower sedimentary surface beneath drumlins near Kirkby Stephen (Northern England), part of the extensive Eden Valley drumlin field. The drumlins comprise diamict overlying a bedrock surface of Carboniferous limestone which outcrops frequently between the drumlins. Here we present the results of a grid survey over one of the drumlins that clearly demonstrate this drumlin comprises a thin carapace of till overlying a stepped limestone bedrock surface. We provide details on the field data acquisition parameters and discuss the implications for further geophysical studies of drumlin fields.

  1. Ground Penetrating Radar in Hydrogeophysics

    SciTech Connect

    Hubbard, Susan; Lambot, S.; Binley, A.; Slob, E.; Hubbard, S.

    2008-01-15

    To meet the needs of a growing population and to provide us with a higher quality of life, increasing pressures are being placed on our environment through the development of agriculture, industry, and infrastructures. Soil erosion, groundwater depletion, salinization, and pollution have been recognized for decades as major threats to ecosystems and human health. More recently, the progressive substitution of fossil fuels by biofuels for energy production and climate change have been recognized as potential threats to our water resources and sustained agricultural productivity. The vadose zone mediates many of the processes that govern water resources and quality, such as the partition of precipitation into infiltration and runoff , groundwater recharge, contaminant transport, plant growth, evaporation, and energy exchanges between the Earth's surface and its atmosphere. It also determines soil organic carbon sequestration and carbon-cycle feedbacks, which could substantially impact climate change. The vadose zone's inherent spatial variability and inaccessibility precludes direct observation of the important subsurface processes. In a societal context where the development of sustainable and optimal environmental management strategies has become a priority, there is a strong prerequisite for the development of noninvasive characterization and monitoring techniques of the vadose zone. In particular, hydrogeophysical approaches applied at relevant scales are required to appraise dynamic subsurface phenomena and to develop optimal sustainability, exploitation, and remediation strategies. Among existing geophysical techniques, ground penetrating radar (GPR) technology is of particular interest for providing high-resolution subsurface images and specifically addressing water-related questions. Ground penetrating radar is based on the transmission and reception of VHF-UHF (30-3000 MHz) electromagnetic waves into the ground, whose propagation is determined by the soil

  2. Stepped frequency ground penetrating radar

    DOEpatents

    Vadnais, Kenneth G.; Bashforth, Michael B.; Lewallen, Tricia S.; Nammath, Sharyn R.

    1994-01-01

    A stepped frequency ground penetrating radar system is described comprising an RF signal generating section capable of producing stepped frequency signals in spaced and equal increments of time and frequency over a preselected bandwidth which serves as a common RF signal source for both a transmit portion and a receive portion of the system. In the transmit portion of the system the signal is processed into in-phase and quadrature signals which are then amplified and then transmitted toward a target. The reflected signals from the target are then received by a receive antenna and mixed with a reference signal from the common RF signal source in a mixer whose output is then fed through a low pass filter. The DC output, after amplification and demodulation, is digitized and converted into a frequency domain signal by a Fast Fourier Transform. A plot of the frequency domain signals from all of the stepped frequencies broadcast toward and received from the target yields information concerning the range (distance) and cross section (size) of the target.

  3. Ground Penetrating Radar (GPR) Imaging to Distinguish Active from Inactive Sinkholes in Covered Karst Terrain: Results from Field Data and 3D FDTD Modeling

    NASA Astrophysics Data System (ADS)

    Gooch, B. T.; Kruse, S. E.

    2009-12-01

    Ground penetrating radar (GPR) is widely used to identify locations of sinkholes in covered karst terrain in Florida. Some sinkholes serve as hydraulic conduits between the surficial and underlying aquifers. Their role is critical in determining the surficial aquifer response to pumping in deeper aquifers. Improved methods for discriminating between hydraulically active sinkholes and plugged sinkholes could help regional water management. In the covered karst of west-central Florida a clay-rich weathering horizon forms over the limestone. The clay-rich layer is in turn overlain by surficial sands. Ground penetrating radar profiles typically show a strong reflector from the top of clay-rich horizon as well as internal layering within sands. Active sinkholes are expected to have sandy conduits that broach the clay layer, and perhaps layering in the overlying sand indicative of ongoing subsidence. Three dimensional simulations of GPR profiles over sinkhole with and without conduits were run with the finite-difference time-domain (FDTD) program GprMax. Results from the synthetic surveys were then processed with standard techniques, including migration. The modeling confirms that conduits appear in GPR records primarily as gaps in the return from the clay layer. The modeling also shows that non-traditional survey geometries (varying antenna spacing and orientation) are unlikely to recover more information than traditional proximal transmitter-receiver separation. We also examine GPR profiles and 3D grids over a set of active and inactive sinkholes in Tampa, Florida. Preliminary analysis suggests that active sinks may present more identifiable gaps in the overlying clay layer, but consistent differences in structure of active and inactive sinkholes are not easily discerned. Other geophysical methods may prove to be more helpful in discerning the presence or absence of active conduits in these situations.

  4. Subsurface investigation with ground penetrating radar

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ground penetrating radar (GPR) data was collected on a small test plot at the OTF/OSU Turfgrass Research & Education Facility in Columbus, Ohio. This test plot was built to USGA standards for a golf course green, with a constructed sand layer just beneath the surface overlying a gravel layer, that i...

  5. Ground penetrating radar for asparagus detection

    NASA Astrophysics Data System (ADS)

    Seyfried, Daniel; Schoebel, Joerg

    2016-03-01

    Ground penetrating radar is a promising technique for detection of buried objects. Recently, radar has more and more been identified to provide benefits for a plurality of applications, where it can increase efficiency of operation. One of these fields is the industrial automatic harvesting process of asparagus, which is performed so far by cutting the soil ridge at a certain height including all the asparagus spears and subsequently sieving the latter out of the soil. However, the height where the soil is cut is a critical parameter, since a wrong value leads to either damage of the roots of the asparagus plants or to a reduced crop yield as a consequence of too much biomass remaining in the soil. In this paper we present a new approach which utilizes ground penetrating radar for non-invasive sensing in order to obtain information on the optimal height for cutting the soil. Hence, asparagus spears of maximal length can be obtained, while keeping the roots at the same time undamaged. We describe our radar system as well as the subsequent digital signal processing steps utilized for extracting the information required from the recorded radar data, which then can be fed into some harvesting unit for setting up the optimal cutting height.

  6. Wide band stepped frequency ground penetrating radar

    DOEpatents

    Bashforth, Michael B.; Gardner, Duane; Patrick, Douglas; Lewallen, Tricia A.; Nammath, Sharyn R.; Painter, Kelly D.; Vadnais, Kenneth G.

    1996-01-01

    A wide band ground penetrating radar system (10) embodying a method wherein a series of radio frequency signals (60) is produced by a single radio frequency source (16) and provided to a transmit antenna (26) for transmission to a target (54) and reflection therefrom to a receive antenna (28). A phase modulator (18) modulates those portion of the radio frequency signals (62) to be transmitted and the reflected modulated signal (62) is combined in a mixer (34) with the original radio frequency signal (60) to produce a resultant signal (53) which is demodulated to produce a series of direct current voltage signals (66) the envelope of which forms a cosine wave shaped plot (68) which is processed by a Fast Fourier Transform unit 44 into frequency domain data (70) wherein the position of a preponderant frequency is indicative of distance to the target (54) and magnitude is indicative of the signature of the target (54).

  7. Wide band stepped frequency ground penetrating radar

    DOEpatents

    Bashforth, M.B.; Gardner, D.; Patrick, D.; Lewallen, T.A.; Nammath, S.R.; Painter, K.D.; Vadnais, K.G.

    1996-03-12

    A wide band ground penetrating radar system is described embodying a method wherein a series of radio frequency signals is produced by a single radio frequency source and provided to a transmit antenna for transmission to a target and reflection therefrom to a receive antenna. A phase modulator modulates those portions of the radio frequency signals to be transmitted and the reflected modulated signal is combined in a mixer with the original radio frequency signal to produce a resultant signal which is demodulated to produce a series of direct current voltage signals, the envelope of which forms a cosine wave shaped plot which is processed by a Fast Fourier Transform Unit 44 into frequency domain data wherein the position of a preponderant frequency is indicative of distance to the target and magnitude is indicative of the signature of the target. 6 figs.

  8. Ground Penetrating Radar Technologies in Ukraine

    NASA Astrophysics Data System (ADS)

    Pochanin, Gennadiy P.; Masalov, Sergey A.

    2014-05-01

    Transient electromagnetic fields are of great interest in Ukraine. The following topics are studied by research teams, with high-level achievements all over the world: (i) Ultra-Wide Band/Short-pulse radar techniques (IRE and LLC "Transient Technologies", for more information please visit http://applied.ire.kharkov.ua/radar%20systems_their%20components%20and%20relevant%20technologies_e.html and http://viy.ua); (ii) Ground Penetrating Radar (GPR) with stepped frequency sounding signals (IRE); (iii) Continuous-Wave (CW) radar with phase-shift keying signals (IRE); and (iv) Radio-wave interference investigation (Scientific and Technical Centre of The Subsurface Investigation, http://geophysics.ua). GPR applications are mainly in search works, for example GPR is often used to search for treasures. It is also used to identify leaks and diffusion of petroleum in soil, in storage areas, as well as for fault location of pipelines. Furthermore, GPR is used for the localization of underground utilities and for diagnostics of the technical state of hydro dams. Deeper GPR probing was performed to identify landslides in Crimea. Rescue radar with CW signal was designed in IRE to search for living people trapped under the rubble of collapsed buildings. The fourth version of this radar has been recently created, showing higher stability and noise immunity. Radio-wave interference investigation allows studying the soil down to tens of meters. It is possible to identify areas with increased conductivity (moisture) of the soil. LLC "Transient Technologies" is currently working with Shevchenko Kyiv University on a cooperation program in which the construction of a test site is one of the planned tasks. In the framework of this program, a GPR with a 300 MHz antenna was handed to the geological Faculty of the University. Employees of "Transient Technologies" held introductory lectures with a practical demonstration for students majoring in geophysics. The authors participated to GPR

  9. Ground-penetrating radar: use and misuse

    NASA Astrophysics Data System (ADS)

    Olhoeft, Gary R.

    1999-10-01

    Ground penetrating radar (GPR) has been used to explore the subsurface of the earth since 1929. Over the past 70 years, it has been widely used, misused and abused. Use includes agriculture, archaeology, environmental and geotechnical site characterization, minerals, groundwater and permafrost exploration, tunnel, utility, and unexploded ordnance location, dam inspection, and much more. Misuse includes mistaking above ground reflections for subsurface events or mapping things from off to the side as if they were directly below, synthetic aperture processing of dispersive data, minimum phase deconvolution, locating objects smaller than resolution limits of the wavelength in the ground, ignoring Fresnel zone limitations in mapping subsurface structure, processing radar data through seismic software packages without allowing for the differences, mapping the bottom of metal pipes from the top, claiming to see through thousands of feet of sediments, and more. GPR is also being abused as the regulatory environment changes and the radiofrequency spectrum is becoming more crowded by cellular phones, pagers, garage door openers, wireless computer networks, and the like. It is often thought to be a source of interference (though it never is) and it is increasingly interfered with by other radiofrequency transmitters.

  10. Ground penetrating radar characterization of a landfill

    NASA Astrophysics Data System (ADS)

    Yochim, April Theresa

    Ground penetrating radar was investigated in an active landfill to determine if the in-situ water content could be measured. Water content is an important parameter in predicting the generation of landfill gas (LFG), an important renewable energy source. Unfortunately, predicting the quantity of LFG is difficult due to the heterogeneities present in a landfill and the lack of in-situ input parameters. GPR is a non-invasive, near-surface geophysical technique that provides high resolution images of dielectric properties in the earth's subsurface. A transmitter emits high frequency (10 - 1000 MHz) electromagnetic pulses through the subsurface, with the receiver recording the echo. Specialized software is then used to create images of the subsurface. The challenge with using GPR in landfills is the heterogeneity of the subsurface and the clay cap linear covering landfills, both affecting the transmission of the electromagnetic pulses. The use of GPR in a landfill was evaluated at the Region of Waterloo's Waste Management Centre. Measurements were completed using both the surface and the borehole approach. The results indicated that a borehole GPR can be used, with successful measurement of water content a function of borehole separation distance and frequency of the electromagnetic pulses. The developed approach was confirmed at the City of Hamilton's Glanbrook Landfill. The successful comparison of in-situ water content values to laboratory determined values at both landfills shows that GPR can be used to measure in-situ water content.

  11. Pavement thickness evaluation using ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Harris, Dwayne Arthur

    Accurate knowledge of pavement thickness is important information to have both at a network and project level. This information aids in pavement management and design. Much of the time this information is missing, out of date, or unknown for highway sections. Current technologies for determining pavement thickness are core drilling, falling weight deflectometer (FWD), and ground penetrating radar (GPR). Core drilling provides very accurate pin point pavement thickness information; however, it is also time consuming, labor intensive, intrusive to traffic, destructive, and limited in coverage. FWD provides nondestructive estimates of both a surface thickness and total pavement structure thickness, including pavement, base and sub-base. On the other hand, FWD is intrusive to traffic and affected by the limitations and assumptions the method used to estimate thickness. GPR provides pavement surface course thickness estimates with excellent data coverage at highway speed. Yet, disadvantages include the pavement thickness estimation being affected by the electrical properties of the pavement, limitations of the system utilized, and heavy post processing of the data. Nevertheless, GPR has been successfully utilized by a number of departments of transportation (DOTs) for pavement thickness evaluation. This research presents the GPR thickness evaluation methods, develops GPRPAVZ the software used to implement the methodologies, and addresses the quality of GPR pavement thickness evaluation.

  12. Ground penetrating radar investigations in Upper Kama potash mines

    NASA Astrophysics Data System (ADS)

    Kovin, Oleg Nikolaievich

    An understanding of the structure and state of the rock mass surrounding underground openings in the potash mines is critically important for safe mining, planning the methods of extraction of an orebody, and preventing the influx of ground water. Continuous common offset ground penetrating radar (GPR) data were acquired in the potash mine operated by the Joint Stock Company (JSC) "Silvinit" (Russia) as part of an investigation of both pre-existing fractures exposed by mine workings and other anomalous geological structures. During the course of GPR investigation, the electrical properties of salt-bearing units were determined, site-specific data acquisition techniques and object-oriented data processing schemes adapted to the geological and geotechnical environment of the Upper Kama potash deposit were developed, and the methodology of 2-D and 3-D GPR data interpretation using interactive modeling was worked out. Open fractures and fault and fold features were successfully mapped using 2-D and 3-D GPR techniques. FK filtering significantly improved the reliability of fracture detection. Spatial models of mapped fractures were created using 3-D GPR imaging technique. Migration of the georadar data was required to obtain the true geometry of folded salt beds. The results of this GPR-based investigation demonstrate that the ground penetrating radar georadar method is capable of providing valuable information about deformation structures within the evaporite units of the Upper Kama potash deposit.

  13. Ground penetrating radar field evaluation in Angola

    NASA Astrophysics Data System (ADS)

    Walls, Richard; Brown, Todd; Clodfelter, Fred; Coors, Jeff; Laudato, Stephen; Lauziere, Steve; Patrikar, Ajay; Poole, Michael; Price, Mike

    2006-05-01

    Deminers around the globe are still using handheld metal detectors that lack the capability to distinguish mines from clutter, detect mines containing very little metal, or find mines buried at deeper depths. In the southern African country of Angola, many areas and roads are impassable due to the threat of anti-tank landmines. Some of these mines are undetectable using current metal detector technology. The US Army has funded the development of the NIITEK ground penetrating radar (GPR) for detection of anti-tank (AT) landmines. This radar detects metal and plastic mines as well as mines that are buried too deep for handheld metal detectors to find. The US Department of Defense Humanitarian Demining (HD) Research & Development Program focuses on developing, testing, demonstrating, and validating new technology for immediate use in humanitarian demining operations around the globe. The HD team provided funding and guidance to NIITEK Incorporated for development of a prototype system called Mine Stalker - a relatively light-weight, remote-controlled vehicle outfitted with the NIITEK GPR, detection algorithms, and a marking system. Individuals from the HD team, NIITEK Inc, and the non-governmental organization Meschen Gegen Minen (MgM) participated in a field evaluation of the Mine Stalker in Angola. The primary aim was to evaluate the effectiveness and reliability of the NIITEK GPR under field conditions. The Mine Stalker was extremely reliable during the evaluation with no significant maintenance issues. All AT mines used to verify GPR performance were detected, even when buried to depths as deep as 25-33cm.

  14. Numerical Modelling of Ground Penetrating Radar Antennas

    NASA Astrophysics Data System (ADS)

    Giannakis, Iraklis; Giannopoulos, Antonios; Pajewski, Lara

    2014-05-01

    Numerical methods are needed in order to solve Maxwell's equations in complicated and realistic problems. Over the years a number of numerical methods have been developed to do so. Amongst them the most popular are the finite element, finite difference implicit techniques, frequency domain solution of Helmontz equation, the method of moments, transmission line matrix method. However, the finite-difference time-domain method (FDTD) is considered to be one of the most attractive choice basically because of its simplicity, speed and accuracy. FDTD first introduced in 1966 by Kane Yee. Since then, FDTD has been established and developed to be a very rigorous and well defined numerical method for solving Maxwell's equations. The order characteristics, accuracy and limitations are rigorously and mathematically defined. This makes FDTD reliable and easy to use. Numerical modelling of Ground Penetrating Radar (GPR) is a very useful tool which can be used in order to give us insight into the scattering mechanisms and can also be used as an alternative approach to aid data interpretation. Numerical modelling has been used in a wide range of GPR applications including archeology, geophysics, forensic, landmine detection etc. In engineering, some applications of numerical modelling include the estimation of the effectiveness of GPR to detect voids in bridges, to detect metal bars in concrete, to estimate shielding effectiveness etc. The main challenges in numerical modelling of GPR for engineering applications are A) the implementation of the dielectric properties of the media (soils, concrete etc.) in a realistic way, B) the implementation of the geometry of the media (soils inhomogeneities, rough surface, vegetation, concrete features like fractures and rock fragments etc.) and C) the detailed modelling of the antenna units. The main focus of this work (which is part of the COST Action TU1208) is the accurate and realistic implementation of GPR antenna units into the FDTD

  15. GSTAMIDS ground-penetrating radar: hardware description

    NASA Astrophysics Data System (ADS)

    Sower, Gary D.; Eberly, John; Christy, Ed

    2001-10-01

    The Ground Standoff Mine Detection System (GSTAMIDS) is now in the Engineering, Manufacturing and Development (EMD) Block 0 phase for USA CECOM. The Mine Detection Subsystem (MDS) presently utilizes three different sensor technologies to detect buried anti-tank (AT) land mines; Ground Penetrating Radar (GPR), Pulsed Magnetic Induction (PMI), and passive infrared (IR). The GSTAMIDS hardware and software architectures are designed so that other technologies can readily be incorporated when and if they prove viable. Each sensor suite is designed to detect the buried mines and to discriminate against various clutter and background objects. Sensor data fusion of the outputs of the individual sensor suites then enhances the detection probability while reducing the false alarm rate from clutter objects. The metal detector is an essential tool for buried mine detection, as metal land mines still account for a large percentage of land mines. Technologies such as nuclear quadrupole resonance (NQR or QR) are presently being developed to detect or confirm the presence of explosive material in buried land mines, particularly the so-called plastic mines; unfortunately, the radio frequency signals required cannot penetrate into a metal land mine. The limitation of the metal detector is not in detection of the metal mines, but in the additional detection of metal clutter. A metal detector has been developed using singular value decomposition (SVD) extraction techniques to discriminate the mines from the clutter, thereby greatly reducing false alarm rates. This mine detector is designed to characterize the impulse response function of the metal objects, based on a parametric three-pole model of the response, and to use pattern recognition to determine the match of the responses to known mines. In addition to discrimination against clutter, the system can also generally tell one mine type from another. This paper describes the PMI sensor suite hardware and its physical incorporation

  16. Use of ground-penetrating radar techniques in archaeological investigations

    NASA Technical Reports Server (NTRS)

    Doolittle, James A.; Miller, W. Frank

    1991-01-01

    Ground-penetrating radar (GPR) techniques are increasingly being used to aid reconnaissance and pre-excavation surveys at many archaeological sites. As a 'remote sensing' tool, GPR provides a high resolution graphic profile of the subsurface. Radar profiles are used to detect, identify, and locate buried artifacts. Ground-penetrating radar provides a rapid, cost effective, and nondestructive method for identification and location analyses. The GPR can be used to facilitate excavation strategies, provide greater areal coverage per unit time and cost, minimize the number of unsuccessful exploratory excavations, and reduce unnecessary or unproductive expenditures of time and effort.

  17. 3D mapping of reinforcement and tendon ducts on pre-stressed concrete bridges by means of Ground Penetrating Radar (GPR)

    NASA Astrophysics Data System (ADS)

    Cheilakou, E.; Theodorakeas, P.; Koui, M.; Zeris, C.

    2014-03-01

    The present study evaluates the potential of GPR for the inspection of pre-stressed concrete bridges and its usefulness to provide non visible information of the interior structural geometry and condition, required for strengthening and rehabilitation purposes. For that purpose, different concrete blocks of varying dimensions with embedded steel reinforcement bars, tendon ducts and fabricated voids, were prepared and tested by means of GPR in a controlled laboratory environment. 2D data acquisition was carried out in reflection mode along single profile lines of the samples in order to locate the internal structural elements. 3D surveys were also performed in a grid format both along horizontal and vertical lines, and the individual profiles collected were interpolated and further processed using a 3D reconstruction software, in order to provide a detailed insight into the concrete structure. The obtained 2D profiles provided the accurate depth and position of the embedded rebars and tendon ducts, verifying the original drawings. 3D data cubes were created enabling the presentation of depth slices and providing additional information such as shape and localization of the internal elements. The results obtained from this work showed the effectiveness and reliability of the GPR technique for pre-stressed concrete bridge investigations.

  18. Drainage Pipe Detection and Assessment Using Ground Penetrating Radar

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The research conducted to date clearly shows that ground penetrating radar (GPR) is feasible for use locating buried drainage pipes in both farm and golf course settings. Within farm settings, GPR seems to work quite well locating drainage pipes buried within one meter of the surface, and the succes...

  19. A Rover Deployed Ground Penetrating Radar on Mars

    NASA Technical Reports Server (NTRS)

    Grant, J. A.; Campbell, B. A.; Schutz, A. E.

    2001-01-01

    Radar is a fundamental tool capable of addressing a variety of geological problems on Mars via collection of data suitable for interpreting variations in surface morphology and reflectivity. Surface-deployed ground penetrating radar (GPR) can help further constrain the geology and structure of the near surface of Mars by directly measuring the range and character of in situ radar properties. In recognition of this potential, a miniaturized, easily modified GPR is being developed for possible deployment on a future Mars rover and will enable definition of radar stratigraphy at high spatial resolution to depths of 10-20 meters. Ongoing development of a Mars impulse GPR with industry partners at Geophysical Survey Systems, Inc., focuses on design and testing of a prototype transducer array (with both high frequency bistatic and low frequency monostatic components) in parallel with fabrication of a low power, mass, and volume control unit. The operational depth of 10-20 meters is geared towards definition of stratigraphy, subsurface blocks, and structure at the decimeter to meter scale that is critical for establishing the geologic setting of the rover. GPR data can also be used to infer the degree of any post-depositional pedogenic alteration or weathering that has subsequently taken place, thereby enabling assessment of pristine versus secondary morphology at the landing site. As is the case for most remote sensing instruments, a GPR may not detect water unambiguously. Nevertheless, any local, near-surface occurrence of liquid water will lead to large, easily detected dielectric contrasts. Moreover, definition of stratigraphy and setting will help in evaluating the history of aqueous activity and where any water might occur and be accessible. Most importantly perhaps, GPR can provide critical context for other rover and orbital instruments/data sets. Hence, GPR deployment along well positioned transects in the vicinity of a lander should enable 3-D mapping of

  20. Ground Penetrating Radar for SMART CITIES

    NASA Astrophysics Data System (ADS)

    Soldovieri, Francesco; Catapano, Ilaria; Gennarelli, Gianluca

    2016-04-01

    The use of monitoring and surveillance technologies is now recognized as a reliable option of the overall smart cities management cycle, for the advantages that they offer in terms of: economically sustainable planning of the ordinary and extraordinary maintenance interventions; situational awareness of possible risks factors in view of a reliable early warning; improvement of the security of the communities especially in public environments. In this frame, the abstract will deal with the recent advances in the development and deployment of radar systems for the urban surveillance, exploitation of the subsurface resources and civil engineering structures. In particular, we will present the recent scientific developments and several examples of use of these systems in operational conditions.

  1. Application of ground-penetrating-radar methods in hydrogeologic studies

    USGS Publications Warehouse

    Beres, Milan, Jr.; Haeni, F.P.

    1991-01-01

    A ground-penetrating-radar system was used to study selected stratified-drift deposits in Connecticut. Ground-penetrating radar is a surface-geophysical method that depends on the emission, transmission, reflection, and reception of an electromagnetic pulse and can produce continuous high-resolution profiles of the subsurface rapidly and efficiently. Traverse locations on land included a well field in the town of Mansfield, a sand and gravel pit and a farm overlying a potential aquifer in the town of Coventry, and Haddam Meadows State Park in the town of Haddam. Traverse locations on water included the Willimantic River in Coventry and Mansfield Hollow Lake in Mansfield. The penetration depth of the radar signal ranged from about 20 feet in fine-grained glaciolacustrine sediments to about 70 feet in coarse sand and gravel. Some land records in coarse-grained sediments show a distinct, continuous reflection from the water table about 5 to 11 feet below land surface. Parallel reflectors on the records are interpreted as fine-grained sediments. Hummocky or chaotic reflectors are interpreted as cross-bedded or coarse-grained sediments. Other features observed on some of the radar records include the till and bedrock surface. Records collected on water had distinct water-bottom multiples (more than one reflection) and diffraction patterns from boulders. The interpretation of the radar records, which required little or no processing, was verified by using lithologic logs from test holes located along some of the land traverses and near the water traverses.

  2. Use of ground-penetrating radar for asphalt thickness determination

    NASA Astrophysics Data System (ADS)

    Choubane, Bouzid; Fernando, Emmanuel; Ross, Stephen C.; Dietrich, Bruce T.

    2003-07-01

    A computer program, called TERRA (Thickness Evaluation of Roads by RAdar) was recently developed for estimating pavement layer thicknesses from ground penetrating radar (GPR) data. This program incorporates decision criteria for automated detection of layer interfaces, computation of layer thicknesses and a segmentation algorithm for delineating segments based on layer thicknesses. The Florida Department of Transportation (FDOT) initiated the present field study for an initial assessment of TERRA. Radar and core data were collected from several flexible pavement sections of Florida's roadway system. These sites were selected to represent the present Florida in-place mixes (Superpave and Marshall mixtures) and different asphalt layer thicknesses, which varied from approximately 50 to 300 mm (2 to 12 in). Radar data were collected at both highway speeds and in stationary mode. This paper presents a description of the data collection effort as well as the subsequent analysis and findings.

  3. Advanced Signal Analysis for Forensic Applications of Ground Penetrating Radar

    SciTech Connect

    Steven Koppenjan; Matthew Streeton; Hua Lee; Michael Lee; Sashi Ono

    2004-06-01

    Ground penetrating radar (GPR) systems have traditionally been used to image subsurface objects. The main focus of this paper is to evaluate an advanced signal analysis technique. Instead of compiling spatial data for the analysis, this technique conducts object recognition procedures based on spectral statistics. The identification feature of an object type is formed from the training vectors by a singular-value decomposition procedure. To illustrate its capability, this procedure is applied to experimental data and compared to the performance of the neural-network approach.

  4. Locating a subsurface oil leak using ground penetrating radar

    NASA Astrophysics Data System (ADS)

    King, Martin L.

    2000-04-01

    An underground high voltage cable, in which pressurized mineral oil is used as an insulating medium, was known to be leaking oil at one or more locations along its 2.5 kilometer length. It was impractical and even dangerous for the most part to dig along the cable route in an attempt to find the location of this leak or leaks. It was known that a significant quantity of mineral insulating oil had left the cable and entered the soil at the site of the leak. It was decided to trial ground penetrating radar by scanning along and over the buried cable to attempt to pinpoint the site of the oil leak. Soil dielectric properties are largely determined by the moisture content so that where moisture is displaced by oil the soil dielectric properties will change. Soil stratigraphy seen using radar is due to a large extent to the variable moisture content in the layering of the soil. Where oil is dispersed through the soil, it will tend to displace moisture. This dielectric property change makes the area sufficiently anomalous so that it can be detected utilizing ground penetrating radar. This principle has now been successfully used on a number of occasions in New Zealand.

  5. Modeling and imaging of ground-penetrating radar data

    NASA Astrophysics Data System (ADS)

    Sena D'Anna, Armando Ruggiero

    Ground Penetrating Radar (GPR) is an active and non-invasive exploration technique based on the propagation of electromagnetic waves in the subsurface. Modeling of GPR data is important because it helps us with data interpretation and forms the basis (solution to the forward problem) for most iterative inversion techniques. Conversely, migration (or imaging) is a type of inversion technique (backward propagation) that creates an image related to the subsurface reflectivity and can be used to estimate the model parameters of the media that affect the propagation of the waves. However, for practical applications, modeling and migration techniques must be fast, accurate and efficient. I have developed a fast, efficient and accurate GPR modeling technique for stratified media (isotropic and laterally homogeneous layers) based on the invariant imbedding or reflectivity technique. To test the results obtained with this technique, and have a general tool for modeling of GPR data in heterogeneous, dispersive and isotropic media, I have implemented a 3D explicit Finite Difference Time Domain (FDTD) technique. The FDTD formalism is presented in conjunction with a discussion of the electromagnetic dispersion mechanisms that affect the GPR signal in most geologic media. I show that the results obtained with the reflectivity and FDTD techniques are nearly identical for laterally homogeneous media. Real GPR data is used to study the capabilities and practical aspects that affect the accuracy of the reflectivity technique. I have developed a new technique for migration of GPR data in heterogeneous and lossy media. I have implemented the technique in 2D media and presented the formalism for its extension to 3D media. The new technique, based on the Split Step Fourier migration technique, allows us to efficiently include the dispersion and attenuation effects in the media. An approximation of homogeneous plane waves, which do not add new restrictions to the Split Step Fourier

  6. A review of ground penetrating radar research and practice in the United Kingdom

    NASA Astrophysics Data System (ADS)

    Giannopoulos, Antonios; Alani, Amir

    2014-05-01

    Ground penetrating radar has been playing an important role for many years in assisting in the non-destructive evaluation of UK's built environment as well as being employed in more general shallow depth geophysical investigations. Ground penetrating radar, in the United Kingdom, has a long history of original work both in developing original research ideas on fundamental aspects of the technique, both in hardware and in software, and in exploring innovative ideas relating to the practical implementation of ground penetrating radar in a number of interesting projects. For example, the base of one of the biggest organisations that connects ground penetrating radar practitioners is in the United Kingdom. This paper will endeavour to review the current status of ground penetrating radar research - primarily carried out in UK Universities - and present some key areas and work that is carried out at a practical level - primarily by private enterprises. Although, the main effort is to concentrate on ground penetrating radar applications relating to civil engineering problems other related areas of ground penetrating radar application will also be reviewed. The aim is to create a current picture of ground penetrating radar use with a view to inform and potentially enhance the possibility of new developments and collaborations that could lead to the advancement of ground penetrating radar as a geophysical investigative method. This work is a contribution to COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar.

  7. The RIMFAX Ground Penetrating Radar on the Mars 2020 Rover.

    NASA Astrophysics Data System (ADS)

    Hamran, S. E.; Amundsen, H. E. F.; Carter, L. M.; Ghent, R. R.; Kohler, J.; Mellon, M. T.; Paige, D. A.

    2014-12-01

    The Radar Imager for Mars' Subsurface Exploration - RIMFAX is a Ground Penetrating Radar selected for NASA's Mars 2020 rover mission. RIMFAX will add a new dimension to the rover's toolset by providing the capability to image the shallow subsurface beneath the rover. The principal goals of the RIMFAX investigation are to image subsurface layering and structure, and to provide information regarding subsurface composition. Depending on materials, RIMFAX will image the subsurface stratigraphy to maximum depths of 10 to 500 meters, with vertical resolutions of 5 to 20 cm, with a horizontal sampling distance of 2 to 20 cm along the rover track. The resulting radar cross sections will provide important information on the geological context of surface outcrops as well as the geological and environmental history of the field area. The radar uses a Gated FMCW waveform and a single ultra wideband antenna that is used both for transmitting and receiving. The presentation will give an overview of the RIMFAX investigation, the radar system and show experimental results from a prototype radar.

  8. Using Ground Penetrating Radar to Investigate Cavities below Spillway

    NASA Astrophysics Data System (ADS)

    Lin, Y.-F.; Hsu, H.-H.; Hsu, K.-T.; Wang, J.-Y.

    2012-04-01

    The Pai-Ho Reservoir, which is located in the south of Taiwan, was completed in 1965 and operated for over 45 years. It is an embankment dam with 112.5 meters high, and the crest width is 12 meters. To evaluate the safety of reservoir, it is necessary to inspect the hydraulic structures through non-destructive testing methods. The scour at spillway causes cavities below its surface. These cavities are hard to be detected their locations under the spillway. This study intended to detect the distribution of cavities below spillway by ground penetrating radar (GPR). The output images were identified and compiled to estimate the damage of spillway. Research results show clear images of cavities distributed below spillway. These cavities locate at the shallow layer near its surface, repair positions of concrete, and ground water line of dam crest. This paper demonstrates the operation method of GPR at testing site, displays output images, and evaluates performance of spillway.

  9. Signal processing software for ground penetrating radar, user's manual

    NASA Astrophysics Data System (ADS)

    Liem, Ronnie; Davis, Thomas J.

    1988-03-01

    This is the user's manual for the signal processing software for reducing ground penetrating radar (GPR) data. The manual provides background information and instructions for operating the computer program. The developed program is based on the synthetic aperture focusing technique. Input data to the program consists of digitized sequential GPR scans from a linear survey. The format for the input data is specified in Appendix C. The output of the program are two-dimensional plots of the ground profile showing the stations and depth of the objects identified by the program. Features of the program include utilities to determine the velocity of propagation of the GPR signal and the location of the ground surface as well as semi-automatic and automatic processing of the data. The program is designed to operate on an IBM PC or compatible computer. Other hardware and supporting software requirements for operating the program are specified in Appendix B.

  10. Defect Detection in Wooden Logs Using Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Halabe, Udaya B.; Agrawal, Sachin; Gopalakrishnan, Bhaskaran; Grushecky, Shawn

    2007-03-01

    Presently there are no suitable non-invasive methods for precisely detecting the subsurface defects in logs in real time. Internal defects such as knots, decays, and embedded metals are of greatest concern for lumber production. Nondestructive scanning of logs using Ground Penetrating Radar (GPR) to detect defects in logs prior to sawing can greatly increase the productivity and yield of high value lumber, and prevent damage to saw blade from embedded metals. In this research, the GPR scanned data has been analyzed to detect subsurface defects such as metals, decays, and knots. Also, GPR offers high speed scanning capability which is needed for future on-line implementation in saw mills. This paper explains the advantages of the GPR technique, experimental setup and parameters used, and data processing for detection of subsurface defects in logs. The results show that GPR can be a very promising technique for future on-line implementation in saw mills.

  11. Removal of surface returns in ground-penetrating radar data

    NASA Astrophysics Data System (ADS)

    Larsson, Erik G.; Li, Jian; Habersat, James D.; Maksymonko, George B.; Bradley, Marshall R.

    2001-10-01

    Techniques using ground-penetrating radar (GPR) for the detection of targets such as abandoned landmines or unexploded ordnance (UXO) buried under the ground surface continue to receive considerable attention especially in the area of signal processing. In this paper we consider the problem of eliminating the so-called ground-bounce effect, which is due to the specular ground surface reflections of the radar signal. The ground-bounce returns are often significantly stronger than the reflection from a target and pose a challenging problem. Existing techniques commonly assume that the ground response is constant as the radar equipment moves along a track. By using measured data, we show that this is, for several reasons, an unrealistic assumption. Instead, we consider a semi-parametric model for the ground-bounce that is in better agreement with observed data. Furthermore, we show how this model can be used to derive an accurate and robust but yet conceptually simple algorithm for the removal of the ground return. We demonstrate our technique using data recorded by an ultra-wideband GPR on a U.S. Army test range.

  12. Integrated, Dual Orthogonal Antennas for Polarimetric Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Pauli, Mario; Wiesbeck, Werner

    2015-04-01

    Ground penetrating radar systems are mostly equipped with single polarized antennas, for example with single linear polarization or with circular polarization. The radiated waves are partly reflected at the ground surface and very often the penetrating waves are distorted in their polarization. The distortion depends on the ground homogeneity and the orientation of the antennas relative to the ground structure. The received signals from the reflecting objects may most times only be classified according to their coverage and intensity. This makes the recognition of the objects difficult or impossible. In airborne and spaceborne Remote Sensing the systems are meanwhile mostly equipped with front ends with dual orthogonal polarized antennas for a full polarimetric operation. The received signals, registered in 2x2 scattering matrices according to co- and cross polarization, are processed for the evaluation of all features of the targets. Ground penetrating radars could also profit from the scientific results of Remote Sensing. The classification of detected objects for their structure and orientation requires more information in the reflected signal than can be measured with a single polarization [1, 2]. In this paper dual linear, orthogonal polarized antennas with a common single, frequency independent phase center, are presented [3]. The relative bandwidth of these antennas can be 1:3, up to 1:4. The antenna is designed to work in the frequency range between 3 GHz and 11 GHz, but can be easily adapted to the GPR frequency range by scaling. The size of the antenna scaled for operation in typical GPR frequencies would approximately be 20 by 20 cm2. By the implementation in a dielectric carrier it could be reduced in size if required. The major problem for ultra wide band, dual polarized antennas is the frequency independent feed network, realizing the required phase shifts. For these antennas a network, which is frequency independent over a wide range, has been

  13. Civil Engineering Applications of Ground Penetrating Radar in Finland

    NASA Astrophysics Data System (ADS)

    Pellinen, Terhi; Huuskonen-Snicker, Eeva; Olkkonen, Martta-Kaisa; Eskelinen, Pekka

    2014-05-01

    Ground penetrating radar (GPR) has been used in Finland since 1980's for civil engineering applications. First applications in this field were road surveys and dam inspections. Common GPR applications in road surveys include the thickness evaluation of the pavement, subgrade soil evaluation and evaluation of the soil moisture and frost susceptibility. Since the 1990's, GPR has been used in combination with other non-destructive testing (NDT) methods in road surveys. Recently, more GPR applications have been adopted, such as evaluating bridges, tunnels, railways and concrete elements. Nowadays, compared with other countries GPR is relatively widely used in Finland for road surveys. Quite many companies, universities and research centers in Finland have their own GPR equipment and are involved in the teaching and research of the GPR method. However, further research and promotion of the GPR techniques are still needed since GPR could be used more routinely. GPR has been used to evaluate the air void content of asphalt pavements for years. Air void content is an important quality measure of pavement condition for both the new and old asphalt pavements. The first Finnish guideline was released in 1999 for the method. Air void content is obtained from the GPR data by measuring the dielectric value as continuous record. To obtain air void content data, few pavement cores must be taken for calibration. Accuracy of the method is however questioned because there are other factors that affect the dielectric value of the asphalt layer, in addition to the air void content. Therefore, a research project is currently carried out at Aalto University in Finland. The overall objective is to investigate if the existing GPR technique used in Finland is accurate enough to be used as QC/QA tool in assessing the compaction of asphalt pavements. The project is funded by the Finnish Transport Agency. Further research interests at Aalto University include developing new microwave asphalt

  14. Developments in ground-penetrating radar at LLNL

    SciTech Connect

    Sargis, P.D.

    1994-05-01

    Lawrence Livermore National Laboratory (LLNL) is developing a side-looking, ground-penetrating impulse radar system that will eventually be mounted on an airborne platform to locate buried minefields. Presently, the radar system is mounted on top of a 60-foot adjustable boom. Several unique as well as commercial antennas having bandwidths in the 200 to 2000 MHz range are being experimented with. Also, LLNL-developed monocycle pulse generators are tailored to be most efficient over this frequency range. A technical description of the system will be presented with details about the video pulser, the wideband antennas, the receiver hardware, and the data acquisition system. The receiver and data acquisition hardware consist of off-the-shelf components. Testing of this system is conducted on a minefield located at the Nevada Test Site (NTS). The minefield contains real and surrogate mines of various sizes placed in natural vegetation. Some areas of the minefield have been cleared for non-cluttered studies. In addition, both metal and plastic mines are buried in the minefield. There is room in the NTS minefield for burying additional objects, such as unexploded ordnance, and this is expected to be done in the future. Recent results indicate success in imaging the NTS minefield using the GPR system. The data has been processed using in-house image reconstruction software, and has been registered with the ground truth data. Images showing clearly visible mines, surface reference markers, and ground clutter will be presented.

  15. Advanced ground-penetrating radar for digital soil mapping

    NASA Astrophysics Data System (ADS)

    Lambot, S.; Minet, J.; Jadoon, K. Z.; Slob, E.; Vereecken, H.

    2009-04-01

    Sustainable and optimal agricultural and environmental management of water and land resources particularly relies on the description and understanding of soil water distribution and dynamics at different scales. We present an advanced ground penetrating radar (GPR) method for mapping the shallow soil water content and unsaturated hydraulic properties at the field scale. The radar system is based on vector network analyzer technology, for which calibration is simple and constitutes an international standard. A directive horn antenna is used as both transmitter and receiver and operates off the ground. A full-waveform model describes accurately the radar signal, and is based on a linear system of complex transfer functions for efficiently describing electromagnetic phenomena within the antenna and its interaction with soil, and a specific solution of the three-dimensional Maxwell's equations for wave propagation in multilayered media. The soil electromagnetic properties and their vertical distribution are estimated by resorting to full-waveform inverse modeling using iterative global optimization methods. The proposed methodology has been validated for a series of model configurations of increasing complexity. The method is now routinely used for real-time mapping of soil surface water content and reconstruct a few number of shallow soil layers. For more complex configurations, it is necessary to regularize the inverse problem. We have shown that constraining radar data inversion using soil hydrodynamic modeling has the potential to reconstruct time-lapse, continuously variable, vertical soil water content profiles and identify the shallow unsaturated hydraulic properties. The proposed approach shows great promise for quantitative imaging of the soil properties at the field scale. The technique will be combined with electromagnetic induction in a mechanistic data fusion framework to further extend its capabilities in a digital soil mapping context.

  16. 47 CFR 15.509 - Technical requirements for ground penetrating radars and wall imaging systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Technical requirements for ground penetrating radars and wall imaging systems. 15.509 Section 15.509 Telecommunication FEDERAL COMMUNICATIONS... ground penetrating radars and wall imaging systems. (a) The UWB bandwidth of an imaging system...

  17. 47 CFR 15.509 - Technical requirements for ground penetrating radars and wall imaging systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Technical requirements for ground penetrating radars and wall imaging systems. 15.509 Section 15.509 Telecommunication FEDERAL COMMUNICATIONS... ground penetrating radars and wall imaging systems. (a) The UWB bandwidth of an imaging system...

  18. 47 CFR 15.509 - Technical requirements for ground penetrating radars and wall imaging systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Technical requirements for ground penetrating radars and wall imaging systems. 15.509 Section 15.509 Telecommunication FEDERAL COMMUNICATIONS... ground penetrating radars and wall imaging systems. (a) The UWB bandwidth of an imaging system...

  19. 47 CFR 15.509 - Technical requirements for ground penetrating radars and wall imaging systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Technical requirements for ground penetrating radars and wall imaging systems. 15.509 Section 15.509 Telecommunication FEDERAL COMMUNICATIONS... ground penetrating radars and wall imaging systems. (a) The UWB bandwidth of an imaging system...

  20. 47 CFR 15.509 - Technical requirements for ground penetrating radars and wall imaging systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Technical requirements for ground penetrating radars and wall imaging systems. 15.509 Section 15.509 Telecommunication FEDERAL COMMUNICATIONS... ground penetrating radars and wall imaging systems. (a) The UWB bandwidth of an imaging system...

  1. Ground-penetrating radar: A tool for monitoring bridge scour

    USGS Publications Warehouse

    Anderson, N.L.; Ismael, A.M.; Thitimakorn, T.

    2007-01-01

    Ground-penetrating radar (GPR) data were acquired across shallow streams and/or drainage ditches at 10 bridge sites in Missouri by maneuvering the antennae across the surface of the water and riverbank from the bridge deck, manually or by boat. The acquired two-dimensional and three-dimensional data sets accurately image the channel bottom, demonstrating that the GPR tool can be used to estimate and/or monitor water depths in shallow fluvial environments. The study results demonstrate that the GPR tool is a safe and effective tool for measuring and/or monitoring scour in proximity to bridges. The technique can be used to safely monitor scour at assigned time intervals during peak flood stages, thereby enabling owners to take preventative action prior to potential failure. The GPR tool can also be used to investigate depositional and erosional patterns over time, thereby elucidating these processes on a local scale. In certain instances, in-filled scour features can also be imaged and mapped. This information may be critically important to those engaged in bridge design. GPR has advantages over other tools commonly employed for monitoring bridge scour (reflection seismic profiling, echo sounding, and electrical conductivity probing). The tool doesn't need to be coupled to the water, can be moved rapidly across (or above) the surface of a stream, and provides an accurate depth-structure model of the channel bottom and subchannel bottom sediments. The GPR profiles can be extended across emerged sand bars or onto the shore.

  2. Mapping peat morphology in sag pond with ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Iryanti, Mimin; Nugraha, Harya Dwi; Setiawan, Tedy; Bijaksana, Satria

    2013-09-01

    In the tropics peat is commonly found in low-land areas. In certain condition, however, peat could also be found in high elevation, such as in sag ponds near fault zones. Information regarding thickness and morphology of peat in Sag Pond can be used to infer fault activities in the past. In this study, we attempt to identify the thickness and morphology of peat in a sag pond at Karyawangi Village near the Lembang fault, to the north of Bandung, West Java, Indonesia. We use ground penetrating radar (GPR) method with 250 Mhz antennae in several lines. The data were them processes using Reflexw software. The results show that in each survey line, peat layer is clearly identifiable. In some lines, the peat layer is continous while in some other, the peat layer is undulated. The peat layer in general in about 0.5 to 2 m thick. In conclusion, the GPR method with 250 Mhz antennae is suitable for mapping peat thickness and morphology in Sag Pond.

  3. Electromagnetic modelling of Ground Penetrating Radar responses to complex targets

    NASA Astrophysics Data System (ADS)

    Pajewski, Lara; Giannopoulos, Antonis

    2014-05-01

    This work deals with the electromagnetic modelling of composite structures for Ground Penetrating Radar (GPR) applications. It was developed within the Short-Term Scientific Mission ECOST-STSM-TU1208-211013-035660, funded by COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar". The Authors define a set of test concrete structures, hereinafter called cells. The size of each cell is 60 x 100 x 18 cm and the content varies with growing complexity, from a simple cell with few rebars of different diameters embedded in concrete at increasing depths, to a final cell with a quite complicated pattern, including a layer of tendons between two overlying meshes of rebars. Other cells, of intermediate complexity, contain pvc ducts (air filled or hosting rebars), steel objects commonly used in civil engineering (as a pipe, an angle bar, a box section and an u-channel), as well as void and honeycombing defects. One of the cells has a steel mesh embedded in it, overlying two rebars placed diagonally across the comers of the structure. Two cells include a couple of rebars bent into a right angle and placed on top of each other, with a square/round circle lying at the base of the concrete slab. Inspiration for some of these cells is taken from the very interesting experimental work presented in Ref. [1]. For each cell, a subset of models with growing complexity is defined, starting from a simple representation of the cell and ending with a more realistic one. In particular, the model's complexity increases from the geometrical point of view, as well as in terms of how the constitutive parameters of involved media and GPR antennas are described. Some cells can be simulated in both two and three dimensions; the concrete slab can be approximated as a finite-thickness layer having infinite extension on the transverse plane, thus neglecting how edges affect radargrams, or else its finite size can be fully taken into account. The permittivity of concrete can be

  4. Audit of a road bridge superstructure using ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Yelf, Richard; Carse, Alan

    2000-04-01

    This paper describes a new application of Ground Penetrating Radar (GPR) in non-destructively assessing the delivered quality of bridge superstructure beams. A case history is described where GPR was used to assess the quality of 180 prestressed concrete beams in relation to the requirements specified in the engineering design. The beams analyzed in this project represent a standard design used in Queensland where several large polystyrene blocks (called 'voids') are cast internally within the deck beams to reduce the mass of the beams. GPR was used effectively to determine the finished location of these voids within the beams and identify any defects associated with the movement of the voids during manufacture of the beams. It was concluded that at least 90% of the beams were out of tolerance due to significant void movement in a vertical direction and there were significant associated defects of air cavities within the concrete, thin top and bottom flanges and longitudinal soffit cracking. Predominantly the voids had moved downwards during the concrete placement process. The accuracy of the GPR survey was determined to be +/- 5 mm where good calibration was obtained and +/- 10 mm for the global set of results of 4860 measurement points.

  5. Visual Inspection of Water Leakage from Ground Penetrating Radar Radargram

    NASA Astrophysics Data System (ADS)

    Halimshah, N. N.; Yusup, A.; Mat Amin, Z.; Ghazalli, M. D.

    2015-10-01

    Water loss in town and suburban is currently a significant issue which reflect the performance of water supply management in Malaysia. Consequently, water supply distribution system has to be maintained in order to prevent shortage of water supply in an area. Various techniques for detecting a mains water leaks are available but mostly are time-consuming, disruptive and expensive. In this paper, the potential of Ground Penetrating Radar (GPR) as a non-destructive method to correctly and efficiently detect mains water leaks has been examined. Several experiments were designed and conducted to prove that GPR can be used as tool for water leakage detection. These include instrument validation test and soil compaction test to clarify the maximum dry density (MDD) of soil and simulation studies on water leakage at a test bed consisting of PVC pipe burying in sand to a depth of 40 cm. Data from GPR detection are processed using the Reflex 2D software. Identification of water leakage was visually inspected from the anomalies in the radargram based on GPR reflection coefficients. The results have ascertained the capability and effectiveness of the GPR in detecting water leakage which could help avoiding difficulties with other leak detection methods.

  6. Using ground-penetrating radar for assessing highway pavement thickness

    NASA Astrophysics Data System (ADS)

    Lenngren, Carl A.; Bergstrom, Joergen; Ersson, Benny M.

    2000-07-01

    Surface distress is a fairly good indicator of rehabilitation needs but it does not directly relate to remaining life estimates. Mechanistic pavement design requires that strains be calculated utilizing more or less complex modeling. Over the years many devices measuring surface deflections under a given load have been developed. The device by choice for assessing strains due to load is the falling weight deflectometer (FWD). It creates an impulse load on the pavement surface. The data are commonly used in models for backcalculation of elastic moduli and strains. More complex modeling would involve finite element or dynamic element methods. The FWD method has proven to be an excellent tool for overlay design. For this purpose its simplicity and straightforwardness are well documented. However, to successfully backcalculate layer stiffness adequate layer thickness is needed. Thus there is a strong need for assessing layer data at testing points. Using Ground Penetrating Radar (GPR) it is possible to achieve data without coring. The present paper is a part of an ongoing bearing capacity study carried out by a regional road administration in central Sweden. Its objective is to optimize testing for equipment and methods used and presently available. In addition to evaluate the results from the study, the present paper discusses some other applications for GPR that may evolve from it.

  7. Ground penetrating radar mini-CRADA final report

    SciTech Connect

    Swanson, R.; Stump, G.; Weil, G.

    1996-09-01

    The purpose of this project was to determine the feasibility of using ground penetrating radar (GPR) to assess the ease of excavability prior to and during trenching operations. The project partners were EnTech Engineering Inc., Vermeer Manufacturing Co., and AlliedSignal Federal Manufacturing & Technology (FM&T)/Kansas City Plant (KCP). Commercial GPRs were field tested as well as a system developed at AlliedSignal FM&T. The AlliedSignal GPR was centered around a HP8753 Network Analyzer instrument. Commercial GPR antennas were connected to the analyzer and data was collected under control of software written for a notebook PC. Images of sub-surface features were generated for varied system parameters including: frequency, bandwidth, FFT windowing, gain, antenna orientation, and surface roughness conditions. Depths to 10 feet were of primary interest in this project. Although further development is required, this project has demonstrated that GPR can be used to identify transitions between different sub-surface conditions, as in going from one rock type to another. Additionally, the average relative dielectric constant of the material can be estimated which can be used to help identify the material. This information can be used to characterize an excavation site for use in budgeting a job. A real-time GPR would provide the operator with sub-surface images that could help with setting the optimum feed and speed rates of the trenching machine.

  8. Forward-Looking IED Detector Ground Penetrating Radar

    NASA Technical Reports Server (NTRS)

    Kim, Soon Sam; Carnes, Steven R.; Ulmer, Christopher T.

    2013-01-01

    There have been many developments of mine or metal detectors based on ground penetrating radar techniques, usually in hand-held or rover-mounted devices. In most mine or metal detector applications, conditions are in a stationary mode and detection speed is not an important factor. A novel, forward-looking, stepped-frequency ground penetrating radar (GPR) has been developed with a capability to detect improvised explosive devices (IEDs) at vehicular speeds of 15 to 20 mph (24 to 32 km/h), 10 to 20 m ahead of the vehicle, to ensure adequate time for response. The GPR system employs two horn antennas (1.7 to 2.6 GHz, 20 dBi) as transmit and receive. The detector system features a user-friendly instantaneous display on a laptop PC and is a low-power-consumption (3 W) compact system with minimal impact on vehicle operations. In practice, the whole GPR system and a laptop PC can be powered by plugging into a cigarette lighter of a vehicle. The stepped-frequency continuous-wave (CW) radar scans frequency from 1.7 to 2.6 GHz in 1,000 steps of 0.9 MHz, with the full frequency scan in 60 ms. The GPR uses a bi-static configuration with one horn antenna used as a transmitter and the other used as a receiver so that isolation between transmitter and receiver is improved. Since the horn antennas (20 dBi) are mounted on the roof of a vehicle at a shallow inclination angle (15 to 25 with respect to horizontal), there is a first-order reduction in ground reflection so that a significant amount of the total reflected power received by the GPR comes from the scattering of RF energy off of buried objects. The stepped-frequency technique works by transmitting a tone at a particular frequency, while the received signal is mixed with the transmitted tone. As a result, the output of the mixer produces a signal that indicates the strength of the received signal and the extent to which it is in phase or out of phase with the transmitted tone. By taking measurements of the phase

  9. Automated Ground Penetrating Radar hyperbola detection in complex environment

    NASA Astrophysics Data System (ADS)

    Mertens, Laurence; Lambot, Sébastien

    2015-04-01

    Ground Penetrating Radar (GPR) systems are commonly used in many applications to detect, amongst others, buried targets (various types of pipes, landmines, tree roots ...), which, in a cross-section, present theoretically a particular hyperbolic-shaped signature resulting from the antenna radiation pattern. Considering the large quantity of information we can acquire during a field campaign, a manual detection of these hyperbolas is barely possible, therefore we have a real need to have at our disposal a quick and automated detection of these hyperbolas. However, this task may reveal itself laborious in real field data because these hyperbolas are often ill-shaped due to the heterogeneity of the medium and to instrumentation clutter. We propose a new detection algorithm for well- and ill-shaped GPR reflection hyperbolas especially developed for complex field data. This algorithm is based on human recognition pattern to emulate human expertise to identify the hyperbolas apexes. The main principle relies in a fitting process of the GPR image edge dots detected with Canny filter to analytical hyperbolas, considering the object as a punctual disturbance with a physical constraint of the parameters. A long phase of observation of a large number of ill-shaped hyperbolas in various complex media led to the definition of smart criteria characterizing the hyperbolic shape and to the choice of accepted value ranges acceptable for an edge dot to correspond to the apex of a specific hyperbola. These values were defined to fit the ambiguity zone for the human brain and present the particularity of being functional in most heterogeneous media. Furthermore, the irregularity is particularly taken into account by defining a buffer zone around the theoretical hyperbola in which the edge dots need to be encountered to belong to this specific hyperbola. First, the method was tested in laboratory conditions over tree roots and over PVC pipes with both time- and frequency-domain radars

  10. Searching for facies indicators in ground penetrating radar data

    NASA Astrophysics Data System (ADS)

    Moysey, S.; Knight, R.; Brunner, D.; Endres, T.

    2004-05-01

    Developing an accurate conceptual model of subsurface spatial heterogeneity is a critical step in producing reliable predictions of hydrogeologic processes. One approach to this problem is to divide the subsurface into distinct geologic units or facies. Obtaining a realistic facies model in complex geologic environments, however, can be impossible using well-based data alone. Therefore, alternative data that have the potential to sample large volumes of the subsurface, such as ground penetrating radar (GPR) reflection images, can be valuable tools to aid in facies characterization. GPR images provide a record of the interactions between an electromagnetic wave and subsurface heterogeneity. Due to the complexity of the processes encoded in this image, it cannot be considered a direct `image' of the subsurface. As a result, building a facies model from GPR data typically requires expert interpretation. Manual interpretations have the disadvantages of being highly labor intensive, subjective, and qualitative. Unsupervised classification techniques, such as clustering algorithms and neural networks, have the potential to overcome these disadvantages. It is currently unclear, however, whether these automated approaches can be used to obtain facies classifications that are consistent with expert interpretations or geologic reality. In particular, it is uncertain whether there are key elements, or attributes, of a radar image that can be used as primary indicators for different facies. To address these questions, we compare the facies classifications obtained by expert interpretation to those obtained using K-means clustering for GPR data obtained from the Whiteman's Creek watershed in southern Ontario, Canada. The automated classification was performed once using instantaneous attributes, such as envelope, phase, and frequency, and again using structural attributes, which are related to the geometric arrangement of reflectors in the subsurface. In this example, the

  11. Characterisation and optimisation of Ground Penetrating Radar antennas

    NASA Astrophysics Data System (ADS)

    Warren, Craig; Giannopoulos, Antonios

    2014-05-01

    Research on the characterisation and optimisation of Ground Penetrating Radar (GPR) antennas will be presented as part of COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar". This work falls within the remit of Working Group 1 - "Novel GPR instrumentation" which focuses on the design of innovative GPR equipment for Civil Engineering (CE) applications, on the building of prototypes and on the testing and optimisation of new systems. The diversity of applications of GPR has meant there are a number of different GPR antenna designs available to the end-user as well as those being used in the research community. The type and size of a GPR antenna is usually dependent on the application, e.g. low frequency antennas, which are physically larger, are used where significant depth of penetration is important, whereas high frequency antennas, which are physically smaller, are used where less penetration and better resolution are required. Understanding how energy is transmitted and received by a particular GPR antenna has many benefits: it could lead to more informed usage of the antenna in GPR surveys; improvements in antenna design; and better interpretation of GPR signal returns from the ground/structure. The radiation characteristics of a particular antenna are usually investigated by studying the radiation patterns and directivity. For GPR antennas it is also important to study these characteristics when the antenna is in different environments that would typically be encountered in GPR surveys. In this work Finite-Difference Time-Domain (FDTD) numerical models of GPR antennas have been developed. These antenna models replicate all the detailed geometry and main components of the real antennas. The models are representative of typical high-frequency, high-resolution GPR antennas primarily used in CE for the evaluation of structural features in concrete: the location of rebar, conduits, and post-tensioned cables, as well as the estimation of

  12. Multiple instance learning for landmine detection using ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Manandhar, Achut; Morton, Kenneth D., Jr.; Collins, Leslie M.; Torrione, Peter A.

    2012-06-01

    Ground Penetrating Radar (GPR) has been extensively employed as a technology for the detection of subsurface buried threats. Although vehicular mounted GPRs generate data in three dimensions, alarm declarations are usually only available in the form of 2-D spatial coordinates. The uncertainty in the depth of the target in the three dimensional volume of data, and the difficulties associated with automatically localizing objects in depth, can adversely impact feature extraction and training in some detection algorithms. In order to mitigate the negative impact of uncertainty in target depth, several algorithms have been developed that extract features from multiple depth regions and utilize these feature vectors in classification algorithms to perform final mine/nonmine decisions. However, the uncertainty in object depth significantly complicates learning since features at the correct target depth are often significantly different from features at other depths but in the same volume. Multiple Instance Learning (MIL) is a type of supervised learning approach in which labels are available for a collection of feature vectors but not for individual samples, or in this application, depths. The goal of MIL is to classify new collections of vectors as they become available. This set-based learning method is applicable in the landmine detection problem because features that are extracted independently from several depth bins can be viewed as a set of unlabeled feature vectors, where the entire set either corresponds to a buried threat or a false alarm. In this work, a novel generative Dirichlet Process Gaussian mixture model for MIL is developed that automatically infers the number of mixture components required to model the underlying distributions of mine/non-mine signatures and performs classification using a likelihood ratio test. In this work, we show that the performance of the proposed approach for discriminating targets from non-targets in GPR data is promising.

  13. O' Connell bridge inspection by means of Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Santos Assuncao, Sonia, ,, Dr

    2016-04-01

    Ground Penetrating Radar (GPR) is a well-known technique successfully applied in different areas. In structural inspection the methodology may expose information about structural arrangement and pathologies. GPR emits high frequency electromagnetic impulses allowing to detect changes on the electromagnetic properties: electrical conductivity, dielectric constant and magnetic permeability. The central frequency of the each antenna is characterized by a specific resolution and penetration depth. Therefore, different scales of structures can be analysed. High frequency antennas output high resolution images/signals about the shallowest elements such as rebar and the thickness of the first layer. On the other hand, intermediate or lower frequency antennas locate deeper structures, such as the thickness of the arch. The compilation of distinct frequencies gives a better understanding and a more accurate detection of elements in the inner structure. O'Connell Bridge (1877) is one of 24 bridges along River Liffey and one the most famous historical structures in Dublin. It is composed by sandstones and granite and covered by asphalt which represents a suitable structure to evaluate by means of GPR. The lack of inner structural information, especially the thickness of the layer, presence of reinforcement or other metallic elements of support required, at least, a dual frequency analysis of the bridge. In this case, it was applied the (200 MHz and 600 MHz) Multi-Channel Stream EM combined with 1.6 GHz GSSI high frequency antenna. The inspection of bridges by means of GPR may provide not exclusively interesting structural data but historical information and the state of conservation.

  14. Ground penetrating radar estimates of permafrost ice wedge depth

    NASA Astrophysics Data System (ADS)

    Parsekian, A.; Slater, L. D.; Nolan, J. T.; Grosse, G.; Walter Anthony, K. M.

    2013-12-01

    Vertical ground ice wedges associated with polygonal patterning in permafrost environments form due to frost cracking of soils under harsh winter conditions and subsequent infilling of cracks with snow melt water. Ice wedge polygon patterns have implications for lowland geomorphology, hydrology, and vulnerability of permafrost to thaw. Ice wedge dimensions may exceed two meters width at the surface and several meters depth, however few studies have addressed the question of ice wedge depth due to challenges related to measuring the vertical dimension below the ground. Vertical exposures where ice wedges maybe observed are limited to rapidly retreating lake, river, and coastal bluffs. Coring though the ice wedges to determine vertical extent is possible, however that approach is time consuming and labor intensive. Many geophysical investigations have noted signal anomalies related to the presence of ice wedges, but no reliable method for extracting wedge dimensions from geophysical data has been yet proposed. Here we present new evidence that ground penetrating radar (GPR) may be a viable method for estimating ice wedge depth. We present three new perspectives on processing GPR data collected over ice wedges that show considerable promise for use as a fast, cost effective method for evaluating ice wedge depth. Our novel approaches include 1) a simple frequency-domain analysis, 2) an S-transform frequency domain analysis and 3) an analysis of the returned signal power as a radar cross section (RCS) treating subsurface ice wedges as dihedral corner retro-reflectors. Our methods are demonstrated and validated using finite-difference time domain FDTD) GPR forward models of synthetic idealized ice wedges and field data from permafrost sites in Alaska. Our results indicate that frequency domain and signal power data provide information that is easier to extract from raw GPR data than similar information in the time domain. We also show that we can simplify the problem by

  15. Analysis of landslide mitigation effects using Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Ristic, Aleksandar; Govedarica, Miro; Vrtunski, Milan; Petrovacki, Dusan

    2013-04-01

    Area of Ground Penetrating Radar (GPR) technology applications becomes wider nowadays. It includes utility mapping as important part of civil engineering applications, geological structure and soil analyses, applications in agriculture, etc. Characteristics of the technology make it suitable for structure analysis of shallow landslides, whose number and impact on environment is dominant in the region. Especially when shallow landslide endangers some man-made structures such as buildings, roads or bridges, analysis of GPR data can yield very useful results. The results of GPR data analysis of the shallow landslide are represented here. It is situated on the mountain Fruska Gora in Serbia. Despite its dimensions (50x20m) this landslide was interesting for analysis for two reasons: - The landslide occurred at the part of the single road between the cement factory and the marl mine. The cement factory "Lafarge" in Beocin (Fruska Gora) is the largest cement manufacturer in the country. One of major priorities of the factory management is to keep the function of this road. The road is heavily exploited and over the years it led to landslide movements and damaging of the road itself. - The landslide dates back to earlier period and the mitigation measures were performed twice. Laying the foundation of the retaining wall was not performed during the first mitigation measures. The second mitigation measures were performed in 2010 and included detailed geotechnical analysis of the location with the appropriate foundation laying. Since the GPR technology can produce high resolution images of subsurface it provides clear insight into the current state of surveyed location. That kind of analysis is necessary to maintain permanent functionality of the road and to check the status of mitigation measures. Furthermore, the location characteristics do not allow easy access so the possibilities of other analysis technologies application are limited. In order to assess the effects of

  16. NAPL detection with ground-penetrating radar (Invited)

    NASA Astrophysics Data System (ADS)

    Bradford, J. H.

    2013-12-01

    Non-polar organic compounds are common contaminants and are collectively referred to as nonaqueous-phase liquids (NAPLs). NAPL contamination problems occur in virtually every environment on or near the earth's surface and therefore a robust suite of geophysical tools is required to accurately characterize NAPL spills and monitor their remediation. NAPLs typically have low dielectric permittivity and low electric conductivity relative to water. Thus a zone of anomalous electrical properties often occurs when NAPL displaces water in the subsurface pore space. Such electric property anomalies make it possible to detect NAPL in the subsurface using electrical or electromagnetic geophysical methods including ground-penetrating radar (GPR). The GPR signature associated with the presence of NAPL is manifest in essentially three ways. First, the decrease in dielectric permittivity results in increased EM propagation velocity. Second, the decrease in permittivity can significantly change reflectivity. Finally, electric conductivity anomalies lead to anomalous GPR signal attenuation. The conductivity anomaly may be either high or low depending on the state of NAPL degradation, but with either high or low conductivity, GPR attenuation analysis can be a useful tool for identifying contaminated-zones. Over the past 15 years I have conducted numerous modeling, laboratory, and field tests to investigate the ability to use GPR to measure NAPL induced anomalies. The emphasis of this work has been on quantitative analysis to characterize critical source zone parameters such as NAPL concentration. Often, the contaminated zones are below the conventional resolution of the GPR signal and require thin layer analysis. Through a series of field examples, I demonstrate 5 key GPR analysis tools that can help identify and quantify NAPL contaminants. These tools include 1) GPR velocity inversion from multi-fold data, 2) amplitude vs offset analysis, 3) spectral decomposition, 4) frequency

  17. Ground Penetrating Radar technique for railway track characterization in Portugal

    NASA Astrophysics Data System (ADS)

    De Chiara, Francesca; Fontul, Simona; Fortunato, Eduardo; D'Andrea, Antonio

    2013-04-01

    Maintenance actions are significant for transport infrastructures but, today, costs have to be necessary limited. A proper quality control since the construction phase is a key factor for a long life cycle and for a good economy policy. For this reason, suitable techniques have to be chosen and non-destructive tests represent an efficient solution, as they allow to evaluate infrastructure characteristics in a continuous or quasi-continuous way, saving time and costs, enabling to make changes if tests results do not comply with the project requirements. Ground Penetrating Radar (GPR) is a quick and effective technique to evaluate infrastructure condition in a continuous manner, replacing or reducing the use of traditional drilling method. GPR application to railways infrastructures, during construction and monitoring phase, is relatively recent. It is based on the measuring of layers thicknesses and detection of structural changes. It also enables the assessment of materials properties that constitute the infrastructure and the evaluation of the different types of defects such as ballast pockets, fouled ballast, poor drainage, subgrade settlement and transitions problems. These deteriorations are generally the causes of vertical deviations in track geometry and they cannot be detected by the common monitoring procedures, namely the measurements of track geometry. Moreover, the development of new GPR systems with higher antenna frequencies, better data acquisition systems, more user friendly software and new algorithms for calculation of materials properties can lead to a regular use of GPR. Therefore, it represents a reliable technique to assess track geometry problems and consequently to improve maintenance planning. In Portugal, rail inspection is performed with Plasser & Theurer EM120 equipment and recently 400 MHz IDS antennas were installed on it. GPR tests were performed on the Portuguese rail network and, as case study in this paper, a renewed track was

  18. DRAINAGE PIPE DETECTOR: GROUND PENETRATING RADAR SHOWS PROMISE IN LOCATING BURIED SYSTEMS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One of the more frustrating problems confronting farmers and land improvement contractors in the Midwestern United States involves locating buried agricultural drainage pipes. Conventional geophysical methods, particularly ground penetrating radar (GPR), presently being used for environmental and co...

  19. Design of spectrally versatile forward-looking ground-penetrating radar for detection of concealed targets

    NASA Astrophysics Data System (ADS)

    Phelan, Brian R.; Ressler, Marc A.; Mazzaro, Gregory J.; Sherbondy, Kelly D.; Narayanan, Ram M.

    2013-05-01

    The design of high-resolution radars which can operate in theater involves a careful consideration of the radar's radiated spectrum. While a wide bandwidth yields better target detectability and classification, it can also interfere with other devices and/or violate federal and international communication laws. Under the Army Research Laboratory (ARL) Partnerships in Research Transition (PIRT) program, we are developing a Stepped-Frequency Radar (SFR) which allows for manipulation of the radiated spectrum, while still maintaining an effective ultra-wide bandwidth for achieving good range resolution. The SFR is a forward-looking, ultra-wideband (UWB) imaging radar capable of detecting concealed targets. This paper presents the research and analysis undertaken during the design of the SFR which will eventually complement an existing ARL system, the Synchronous Impulse REconstruction (SIRE) radar. The SFR is capable of excising prohibited frequency bands, while maintaining the down-range resolution capability of the original SIRE radar. The SFR has two transmit antennas and a 16-element receive antenna array, and this configuration achieves suitable cross-range resolution for target detection. The SFR, like the SIRE radar, is a vehicle mounted, forward-looking, ground penetrating radar (GPR) capable of using synthetic aperture radar (SAR) technology for the detection of subsurface targets via 3D imaging. Many contradicting design considerations are analyzed in this paper. The selection of system bandwidth, antenna types, number of antennas, frequency synthesizers, digitizers, receive amplifiers, wideband splitters, and many other components are critical to the design of the SFR. Leveraging commercial components and SIRE sub-systems were design factors offering an expedited time to the initial implementation of the radar while reducing overall costs. This SFR design will result in an ARL asset to support obscured target detection such as improvised explosive devices

  20. Ground Penetrating Radar Technique to Locate Coal Mine Subsidence Features at Malakoff, Texas

    NASA Astrophysics Data System (ADS)

    Save, N.; Everett, M. E.; Brandt, J.; Reimer, W.

    2003-12-01

    Coal mine subsidence features around Malakoff, Texas, are being studied with ground penetrating radar (using a pulseEKKO system from Sensors & Software Inc.). This work is being done in collaboration with the Railroad Commission of Texas (RRC). RRC has been carrying out reclamation of abandoned underground coal mines near this location since early 1990s. The history of the specific mining operations that took place in the 1920s and 1930s has been difficult to ascertain; therefore, the use of a geophysical techniques, like ground penetrating radar (GPR) to identify hidden voids and potential subsidence features, are vital to the reclamation process. The landscape at the field site in Malakoff is rolling with a moderate-relief, sandy mud substrate. Some of the mine workings have collapsed over time and, in some cases, have affected the surface structures by creating sinkholes. GPR data, employing 25 MHz and 100 MHz frequency, have been collected over a 3D grid pattern and azimuthal pattern in the vicinity of these sinkholes. The penetration depth of the radar signal was approximately 20 meters from the surface. GPR data represent the mine drifts/void spaces with hyperbolae that bound the top and bottom of the mine workings. Diffractions against possible boulders and variation in the stratigraphy are also seen. Post-processing of the acquired data, using software developed by Sensors & Software Inc., provided a 3D representation of the voids and subsidence features. The goal of this research was to identify the efficacy of GPR in locating the subsidence features. Azimuthal surveys provide information regarding the connectivity between existing sinkholes. RRC ground-truthed the data during its reclamation process (in turn, the acquired geophysical data were used to guide the reclamation). Mine drift openings observed during ground-truthing from some of the sinkholes matched the orientation of the void space observed in the GPR data lines. The GPR data is helpful in

  1. Ultra wideband ground penetrating radar imaging of heterogeneous solids

    DOEpatents

    Warhus, J.P.; Mast, J.E.

    1998-11-10

    A non-invasive imaging system for analyzing engineered structures comprises pairs of ultra wideband radar transmitters and receivers in a linear array that are connected to a timing mechanism that allows a radar echo sample to be taken at a variety of delay times for each radar pulse transmission. The radar transmitters and receivers are coupled to a position determining system that provides the x,y position on a surface for each group of samples measured for a volume from the surface. The radar transmitter and receivers are moved about the surface, e.g., attached to the bumper of a truck, to collect such groups of measurements from a variety of x,y positions. Return signal amplitudes represent the relative reflectivity of objects within the volume and the delay in receiving each signal echo represents the depth at which the object lays in the volume and the propagation speeds of the intervening material layers. Successively deeper z-planes are backward propagated from one layer to the next with an adjustment for variations in the expected propagation velocities of the material layers that lie between adjacent z-planes. 11 figs.

  2. Ultra wideband ground penetrating radar imaging of heterogeneous solids

    DOEpatents

    Warhus, John P.; Mast, Jeffrey E.

    1998-01-01

    A non-invasive imaging system for analyzing engineered structures comprises pairs of ultra wideband radar transmitters and receivers in a linear array that are connected to a timing mechanism that allows a radar echo sample to be taken at a variety of delay times for each radar pulse transmission. The radar transmitters and receivers are coupled to a position determining system that provides the x,y position on a surface for each group of samples measured for a volume from the surface. The radar transmitter and receivers are moved about the surface, e.g., attached to the bumper of a truck, to collect such groups of measurements from a variety of x,y positions. Return signal amplitudes represent the relative reflectivity of objects within the volume and the delay in receiving each signal echo represents the depth at which the object lays in the volume and the propagation speeds of the intervening material layers. Successively deeper z-planes are backward propagated from one layer to the next with an adjustment for variations in the expected propagation velocities of the material layers that lie between adjacent z-planes.

  3. Recursive impedance inversion of ground-penetrating radar data in stochastic media

    NASA Astrophysics Data System (ADS)

    Zeng, Zhao-Fa; Chen, Xiong; Li, Jing; Chen, Ling-Na; Lu, Qi; Liu, Feng-Shan

    2015-12-01

    The travel time and amplitude of ground-penetrating radar (GPR) waves are closely related to medium parameters such as water content, porosity, and dielectric permittivity. However, conventional estimation methods, which are mostly based on wave velocity, are not suitable for real complex media because of limited resolution. Impedance inversion uses the reflection coefficient of radar waves to directly calculate GPR impedance and other parameters of subsurface media. We construct a 3D multiscale stochastic medium model and use the mixed Gaussian and exponential autocorrelation function to describe the distribution of parameters in real subsurface media. We introduce an elliptical Gaussian function to describe local random anomalies. The tapering function is also introduced to reduce calculation errors caused by the numerical simulation of discrete grids. We derive the impedance inversion workflow and test the calculation precision in complex media. Finally, we use impedance inversion to process GPR field data in a polluted site in Mongolia. The inversion results were constrained using borehole data and validated by resistivity data.

  4. Subsurface polarimetric migration imaging for full polarimetric ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Feng, Xuan; Yu, Yue; Liu, Cai; Fehler, Michael

    2015-08-01

    Polarization is a property of electromagnetic wave that generally refers to the locus of the electric field vector, which can be used to characterize surface properties by polarimetric radar. However, its use has been less common in the ground-penetrating radar (GPR) community. Full polarimetric GPR data include scattering matrices, by which the polarization properties can be extracted, at each survey point. Different components of the measured scattering matrix are sensitive to different types of subsurface objects, which offers a potential improvement in the detection ability of GPR. This paper develops a polarimetric migration imaging method. By merging the Pauli polarimetric decomposition technique with the Krichhoff migration equation, we develop a polarimetric migration algorithm, which can extract three migrated coefficients that are sensitive to different types of objects. Then fusing the three migrated coefficients, we can obtain subsurface colour-coded reconstructed object images, which can be employed to interpret both the geometrical information and the scattering mechanism of the subsurface objects. A 3-D full polarimetric GPR data set was acquired in a laboratory experiment and was used to test the method. In the laboratory experiment, four objects-a scatterer, a ball, a plate and a dihedral target-were buried in homogeneous dry sand under a flat ground surface. By merging the reconstructed image with polarization properties, we enhanced the subsurface image and improved the classification ability of GPR.

  5. Investigations of the Subsurface by Ground Penetrating Radar (GPR); Examples From Spitsbergen.

    NASA Astrophysics Data System (ADS)

    Baelum, K.

    2007-12-01

    With the IPY scientific investigations in arctic regions are more relevant then ever and electromagnetic waves are favorable for geological mapping in Polar Regions for several reasons: They have high penetration in many materials, especially dry and frozen ones, and they give good structural resolution. Ground Penetrating Radar (GPR) is a fast and versatile investigation method, in addition to being cost efficient once the initial equipment cost has been laid down. The equipment can be towed, hauled, driven or carried across virtually any terrain and can in most situations be operated by 2 people. The main problem with the method is its need for a power source and a lack of durability in harsh environments such as the Arctic. Traditionally the main use of GPR in Polar Regions have been mapping of ice thickness but the method has many other applications, the aim of this presentation is to give some examples of GPR use in the high arctic. In the spring of 2004 and 2005 some 117 km of radar line was collected on Tellbreen, a medium size valley glacier located near Longyearbyen, Spitsbergen of which 37,5 km were used for this presentation. The objective of the investigations was to make a simple 3D model of the glacier to gain more knowledge about the internal structures and drainage system. This summer 3 km of radar line was collected on what is presumed to be a cast surface. The data is still not thoroughly processed and further investigations are needed but it indicates that there has been extensive cast activity in the area and the plan is to make a high resolution 3D study of the area.

  6. Location of Agricultural Drainage Pipes and Assessment of Agricultural Drainage Pipe Conditions Using Ground Penetrating Radar

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methods are needed to not only locate buried agricultural drainage pipe, but to also determine if the pipes are functioning properly with respect to water delivery. The primary focus of this research project was to confirm the ability of ground penetrating radar (GPR) to locate buried drainage pipe ...

  7. QUANTIFYING SUBSURFACE HYDROLOGY WITH GROUND PENETRATING RADAR AND AGRICULTURAL MONITORING DATA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hydrology, especially subsurface-water flow can influence crop growth patterns within a production field as well as the fate of surface-applied fertilizers and pesticides migrating thru agricultural land. Ground-penetrating radar (GPR) and digital elevation maps (DEM) were used to locate and quanti...

  8. Location of agricultural drainage pipes and assessment of agricultural drainage pipe conditions using ground penetrating radar

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methods are needed to not only locate buried agricultural drainage pipe, but to also determine if the pipes are functioning properly with respect to water delivery. The primary focus of this research project was to confirm the ability of ground penetrating radar (GPR) to locate buried drainage pipe ...

  9. SEISMIC-REFLECTION AND GROUND PENETRATING RADAR FOR ENVIRONMENTAL SITE CHARACTERIZATION

    EPA Science Inventory

    This research seeks to show how shallow, high-resolution, three-component seismic reflection techniques, in concert with ground-penetrating radar (GPR), might assist in characterizing hydrologic-transport parameters at environmentally sensitive sites. The high dynamic range and m...

  10. Detectability of underground electrical cables junction with a ground penetrating radar: electromagnetic simulation and experimental measurements

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; serhir, mohammed; kameni, abelin; lambert, marc; pichon, lionel

    2016-04-01

    For a company like Electricity De France (EDF), being able to detect accurately using non-destructive methods the position of the buried junction between two underground cables is a crucial issue. The junction is the linking part where most maintenance operations are carried out. The challenge of this work is to conduct a feasibility study to confirm or deny the relevance of Ground Penetrating Radar (GPR) to detect these buried junctions in their actual environment against clutter. Indeed, the cables are buried in inhomogeneous medium at around 80cm deep. To do this, the study is conducted in a numerical environment. We use the 3D simulation software CST MWS to model a GPR scenario. In this simulation, we place the already optimized bowtie antennas operating in the frequency band [0.5 GHz - 3 GHz] in front of wet soil (dispersive) and dry soil where the underground cable is placed at 80cm deep. We collect the amplitude and phase of the reflected waves in order to detect the contrast provoked by the geometric dimensions variation of the cable [1] (diameter of the cable is 48mm and the diameter of the junction 74mm). The use of an ultra-wideband antenna is necessary to reconcile resolution and penetration of electromagnetic waves in the medium to be characterized. We focus on the performance of the GPR method according to the characteristics of the surrounding medium in which the electric cables are buried, the polarization of the Tx and Rx antennas. The experimental measurement collected in the EDF site will be presented. The measured data are processed using the clutter reduction method based on digital filtering [2]. We aim at showing that using the developed bowtie antennas that the GPR technique is well adapted for the cable junction localization even in cluttered environment. References [1] D. J. Daniels, "Surface-Penetrating Radar", London, IEE 1996. [2] Potin, D.; Duflos, E.; Vanheeghe, P., "Landmines Ground-Penetrating Radar Signal Enhancement by Digital

  11. Ground-penetrating radar and electromagnetic surveys at the Monroe Crossroads battlefield site, Fort Bragg, North Carolina

    USGS Publications Warehouse

    Kessler, Richard; Strain, R.E.; Marlowe, J. I., II; Currin, K.B.

    1996-01-01

    A ground-penetrating radar survey was conducted at the Monroe Crossroads Battlefield site at Fort Bragg, North Carolina, to determine possible locations of subsurface archaeological features. An electromagnetic survey also was conducted at the site to verify and augment the ground-penetrating radar data. The surveys were conducted over a 67,200-square-foot grid with a grid point spacing of 20 feet. During the ground-penetrating radar survey, 87 subsurface anomalies were detected based on visual inspection of the field records. These anomalies were flagged in the field as they appeared on the ground-penetrating radar records and were located by a land survey. The electromagnetic survey produced two significant readings at ground-penetrating radar anomaly locations. The National Park Service excavated 44 of the 87 anomaly locations at the Civil War battlefield site. Four of these excavations produced significant archaeological features, including one at an abandoned well.

  12. Analysis of Jaycor's forward-looking ground-penetrating radar data

    NASA Astrophysics Data System (ADS)

    Rosen, Erik M.; Ayers, Elizabeth; Bonn, Darrell; Sherbondy, Kelly D.; Amazeen, Charles A.

    2000-08-01

    To date, most of the vehicular-mounted mine detection systems employing ground-penetrating radar are down looking in the sense that the array of radar antennas is approximately 1-m forward of the vehicle and pointed straight down. Advantages of systems that are able to look forward of the vehicle by more than 10 m include the ability to make detections at greater stand-off distances and to use mulitpe looks at targets to discriminate mines from clutter. Data collected by Jaycor's forward-looking ground- penetrating radar (FLGPR) system provides a means by which these advantages can be assessed. In February 1999, Jaycor took, its FLGPR to the antitank (AT) mine lanes at Socorro, New Mexico. Jaycor made several excursions over simulated roads that contained a mix of metal- and plastic-cased AT mines on the surface and buried up to 4 in.

  13. Fast Numerically Based Modeling for Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Sassen, D. S.; Everett, M. E.

    2007-05-01

    There is a need for computationally fast GPR numerical modeling. This includes circumstances where real time performance is needed, for example discrimination of landmines or UXO's, and in circumstances that require a high number of successive forward problems, for example inversion or imaging. Traditional numerical techniques such as finite difference or finite element are too slow for these applications, but they provide results from general scenarios such as scattering from very complicated shapes with high contrast. Neural networks may fit in the niche between analytical techniques and traditional numerical techniques. Our concept is training a neural network to associate the model inputs of electromagnetic properties of the background and targets, and the size and shape of the targets, with the output generated by a 3-D finite difference model. Successive examples from various electromagnetic properties and targets are displayed to the neural network, until the neural network has adapted itself though optimization. The trained neural network is now used as the forward model by displaying new input parameters and the neural network then generates the appropriate output. The results from the neural network are then compared to results from finite difference models to see how well the neural networks is performing and at what point it breaks down. Areas of poor fit can be addressed through further training. The neural network GPR model can be adapted by displaying additional finite difference results to the neural network, and can also be adapted to a specific field area by actual field data examples. Because of this adaptation ability the neural network GPR model can be optimized for specific environments and applications.

  14. 4D ground-penetrating radar during a plot scale dye tracer experiment

    NASA Astrophysics Data System (ADS)

    Allroggen, Niklas; van Schaik, N. Loes M. B.; Tronicke, Jens

    2015-07-01

    Flow phenomena in the unsaturated zone are highly variable in time and space. Thus, it is challenging to measure and monitor such processes under field conditions. Here, we present a new setup and interpretation approach for combining a dye tracer experiment with a 4D ground-penetrating radar (GPR) survey. Therefore, we designed a rainfall experiment during which we measured three surface-based 3D GPR surveys using a pair of 500 MHz antennas. Such a survey setup requires accurate acquisition and processing techniques to extract time-lapse information supporting the interpretation of selected cross-sections photographed after excavating the site. Our results reveal patterns of traveltime changes in the measured GPR data, which are associated with soil moisture changes. As distinct horizons are present at our site, such changes can be quantified and transferred into changes in total soil moisture content. Our soil moisture estimates are similar to the amount of infiltrated water, which confirms our experimental approach and makes us confident for further developing this strategy, especially, with respect to improving the temporal and spatial resolution.

  15. Work flow of signal processing data of ground penetrating radar case of rigid pavement measurements

    SciTech Connect

    Handayani, Gunawan

    2015-04-16

    The signal processing of Ground Penetrating Radar (GPR) requires a certain work flow to obtain good results. Even though the Ground Penetrating Radar data looks similar with seismic reflection data, but the GPR data has particular signatures that the seismic reflection data does not have. This is something to do with coupling between antennae and the ground surface. Because of this, the GPR data should be treated differently from the seismic signal data processing work flow. Even though most of the processing steps still follow the same work flow of seismic reflection data such as: filtering, predictive deconvolution etc. This paper presents the work flow of GPR processing data on rigid pavement measurements. The processing steps start from raw data, de-Wow process, remove DC and continue with the standard process to get rid of noises i.e. filtering process. Some radargram particular features of rigid pavement along with pile foundations are presented.

  16. Ground-penetrating imaging radar development for bridge deck and road bed inspection

    SciTech Connect

    Warhus, J.P.; Mast, J.E.; Nelson, S.D.; Johansson, E.M.

    1993-05-01

    Ground-penetrating imaging radar (GPIR) is proposed for large-area inspection of concrete and concrete/asphalt composite bridge decks and roadways. This technique combines ground-penetrating radar (GPR) with unique image reconstruction algorithms developed for identification and characterization of subsurface flaws and structural features. New data acquisition hardware and image reconstruction techniques, under development at LLNL, offer the possibility for reliable and efficient, high-resolution subsurface imaging through the use of improved ultra-wideband transmitters, antennas, and arrays, and enhanced image- and signal-processing software. A field test of a limited-capability prototype system is planned for FY-93, as is completion of a conceptual design for a practical inspection system. A follow-on program for FY-94 would focus on development and demonstration of an advanced bridge inspection system prototype based on the conceptual design completed during FY-93.

  17. Use of Ground Penetrating Radar at the FAA's National Airport Pavement Test Facility

    NASA Astrophysics Data System (ADS)

    Injun, Song

    2015-04-01

    The Federal Aviation Administration (FAA) in the United States has used a ground-coupled Ground Penetrating Radar (GPR) at the National Airport Pavement Test Facility (NAPTF) since 2005. One of the primary objectives of the testing at the facility is to provide full-scale pavement response and failure information for use in airplane landing gear design and configuration studies. During the traffic testing at the facility, a GSSI GPR system was used to develop new procedures for monitoring Hot Mix Asphalt (HMA) pavement density changes that is directly related to pavement failure. After reviewing current setups for data acquisition software and procedures for identifying different pavement layers, dielectric constant and pavement thickness were selected as dominant parameters controlling HMA properties provided by GPR. A new methodology showing HMA density changes in terms of dielectric constant variations, called dielectric sweep test, was developed and applied in full-scale pavement test. The dielectric constant changes were successfully monitored with increasing airplane traffic numbers. The changes were compared to pavement performance data (permanent deformation). The measured dielectric constants based on the known HMA thicknesses were also compared with computed dielectric constants using an equation from ASTM D4748-98 Standard Test Method for Determining the Thickness of Bound Pavement Layers Using Short-Pulse Radar. Six inches diameter cylindrical cores were taken after construction and traffic testing for the HMA layer bulk specific gravity. The measured bulk specific gravity was also compared to monitor HMA density changes caused by aircraft traffic conditions. Additionally this presentation will review the applications of the FAA's ground-coupled GPR on embedded rebar identification in concrete pavement, sewer pipes in soil, and gage identifications in 3D plots.

  18. Peat analyses in the Hudson Bay Lowlands using ground penetrating radar

    NASA Technical Reports Server (NTRS)

    Pelletier, R. E.; Davis, J. L.; Rossiter, J. R.

    1991-01-01

    The use of ground penetrating radar (GPR) as a means to determine peak thickness and estimate peat volume in the Hudson Bay Lowlands of Canada is examined. Ground-based and airborne GPR data were acquired so as to extrapolate measurements to larger scales. While the ground-based measurements did an excellent job in determining peat depth, the airborne techniques did a fair job a low altitudes and demonstrated great promise with additional system engineering changes.

  19. Imaging Structure, Stratigraphy and Groundwater with Ground-Penetrating Radar on the Big Island, Hawaii

    NASA Astrophysics Data System (ADS)

    Shapiro, S. R.; Tchakirides, T. F.; Brown, L. D.

    2004-12-01

    A series of exploratory ground-penetrating radar (GPR) surveys were carried out on the Big Island, Hawaii in March of 2004 to evaluate the efficacy of using GPR to address hydrological, volcanological, and tectonic issues in extrusive basaltic materials. Target sites included beach sands, nearshore lava flows, well-developed soil covers, lava tubes, and major fault zones. Surveys were carried out with a Sensors and Software T Pulse Ekko 100, which was equipped with 50, 100, and 200 MHz antennae. Both reflection profiles and CMP expanding spreads were collected at most sites to provide both structural detail and in situ velocity estimation. In general, the volcanic rocks exhibited propagation velocities of ca 0.09-0.10 m/ns, a value which we interpret to reflect the large air-filled porosity of the media. Penetration in the nearshore area was expectedly small (less than 1 m), which we attribute to seawater infiltration. However, surveys in the volcanics away from the coast routinely probed to depths of 10 m or greater, even at 100 MHz. While internal layering and lava tubes could be identified from individual profiles, the complexity of returns suggests that 3D imaging is required before detailed stratigraphy can be usefully interpreted. A pilot 3D survey over a lava tube complex supports this conclusion, although it was prematurely terminated by bad weather. Although analysis of the CMP data does not show a clear systematic variation in radar velocity with age of flow, the dataset is too limited to support any firm conclusions on this point. Unusually distinct, subhorizontal reflectors on several profiles seem to mark groundwater. In one case, the water seems to lie within a lava tube with an air-filled roof zone. Surveys over part of the controversial Hilana fault zone clearly image the fault as a steeply dipping feature in the subsurface, albeit only to depths of a few meters. The results suggest, however, that deeper extensions of the faults could be mapped by

  20. A review of selected ground penetrating radar applications to mineral resource evaluations

    NASA Astrophysics Data System (ADS)

    Francke, Jan

    2012-06-01

    Since the commercialisation of ground penetrating radar (GPR) in the 1970s, the technology has been relegated to niche applications in the mining industry. Advances in radar technology, such as flexible collinear antennas and the integration of live differential GPS positioning, have spurred GPR's acceptance in recent years as a standard exploration method for a number of deposit types. Provided herein is an overview of commercialised GPR applications for surface mineral resource evaluations, covering examples of alluvial channels, nickel and bauxitic laterites, iron ore deposits, mineral sands, coal and kimberlites.

  1. Multi-band sensor-fused explosive hazards detection in forward-looking ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Havens, Timothy C.; Becker, John; Pinar, Anthony; Schulz, Timothy J.

    2014-05-01

    Explosive hazard detection and remediation is a pertinent area of interest for the U.S. Army. There are many types of detection methods that the Army has or is currently investigating, including ground-penetrating radar, thermal and visible spectrum cameras, acoustic arrays, laser vibrometers, etc. Since standoff range is an important characteristic for sensor performance, forward-looking ground-penetrating radar has been investigated for some time. Recently, the Army has begun testing a forward-looking system that combines L-band and X-band radar arrays. Our work focuses on developing imaging and detection methods for this sensor-fused system. In this paper, we investigate approaches that fuse L-band radar and X-band radar for explosive hazard detection and false alarm rejection. We use multiple kernel learning with support vector machines as the classification method and histogram of gradients (HOG) and local statistics as the main feature descriptors. We also perform preliminary testing on a context aware approach for detection. Results on government furnished data show that our false alarm rejection method improves area-under-ROC by up to 158%.

  2. Combining ground penetrating radar and electromagnetic induction for industrial site characterization

    NASA Astrophysics Data System (ADS)

    Van De Vijver, Ellen; Van Meirvenne, Marc; Saey, Timothy; De Smedt, Philippe; Delefortrie, Samuël; Seuntjens, Piet

    2014-05-01

    soil electrical conductivity (ECa) and magnetic susceptibility (MSa). For both methods one of the latest-generation instruments was used. GPR data were collected using a 3d-Radar stepped-frequency system with multi-channel antenna design. For EMI, this was the multi-receiver DUALEM-21S sensor. This sensor contains four different transmitter-receiver coil pair configurations, which allows to record the ECa and MSa for four different soil volumes at the same time, thereby providing information about the vertical variation of these soil properties. Both the EMI and GPR survey were performed in a mobile set-up with real-time georeferencing to obtain a high-resolution coverage of the area. The results of both surveys were validated with conventional site characterization that was conducted for a soil contamination investigation, and ancillary information such as aerial photographs and utility maps. Both methods were compared on their performance in detecting different types of anomalies. We report on the successes and failures with this multi-sensor approach. The authors acknowledge funding by COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar"

  3. Improving Ground Penetrating Radar Imaging in High Loss Environments by Coordinated System Development, Data Processing, Numerical Modeling, & Visualization

    SciTech Connect

    Wright, David L.

    2004-12-01

    Improving Ground Penetrating Radar Imaging in High Loss Environments by Coordinated System Development, Data Processing, Numerical Modeling, and Visualization Methods with Applications to Site Characterization EMSP Project 86992 Progress Report as of 9/2004.

  4. Remote-Controlled Electrical Resistivity Tomography and Concurrent Ground-Penetrating Radar Laboratory

    NASA Astrophysics Data System (ADS)

    Kruger, A.; Daniels, J. J.; Yeh, T. J.; Zhu, J.; Niemeier, J. J.; Mansheim, T. J.; Hart, T. R.; Shaelek, K. S.; Illman, W. A.; Craig, A. J.

    2008-12-01

    A team of researchers at The University of Iowa, Ohio State University, and the University of Arizona have developed an over-the-internet experimental setup that enables researchers and educators at remote locations to make concurrent electrical resistivity tomography (ERT) and ground penetrating radar (GPR) measurements. The setup is comprised of a carefully constructed sandbox with known layers of sand with embedded wells and ERT electrodes. A GPR transmitter and receiver are mounted on an xy-traverse scanner. Computers control all the components. Computer software and communications interfaces allow remote users to perform concurrent ERT and GPR measurements and retrieve the measured results in real- time over the internet. A camera enables each internet user to view the active experiment. The users can then apply various inversion- and post-processing algorithms to the data, fuse their results, interpret the data, and adjust the data collection for additional data runs. The system allows for flexible and rapid ERT measurements by researchers developing inversion algorithms, and near real-time 3D images of dielectric constant variations (moisture and water concentrations) in the model. It also has utility in geophysics education, enabling real-time demonstration of ERT and GPR measurements. The distributed arrangement allows institutions at different locations to collaborate and leverage their individual strengths: experimental and cyberinfrastructure knowledge, ERT expertise, and GPR expertise. Large subsystems in the laboratory were designed as stand-alone equipment without any network capability, and this posed major technical obstacles. Our plans include extending the system to interface with pumps and pressure transducers to facilitate hydrologic tomography experiments and possibly offer the research setup to other investigators who do not have access to a laboratory system.

  5. Ground-penetrating radar methods used in surface-water discharge measurements

    USGS Publications Warehouse

    Haeni, F.P.; Buursink, Marc L.; Costa, John E.; Melcher, Nick B.; Cheng, Ralph T.; Plant, William J.

    2000-01-01

    In 1999, an experiment was conducted to see if a combination of complementary radar methods could be used to calculate the discharge of a river without having any of the measuring equipment in the water. The cross-sectional area of the 183-meter wide Skagit River in Washington State was measured using a ground-penetrating radar (GPR) system with a single 100-MHz antenna. A van-mounted, side-looking pulsed-Doppler radar system was used to collect water-surface velocity data across the same section of the river. The combined radar data sets were used to calculate the river discharge and the results compared closely to the discharge measurement made by using the standard in-water measurement techniques.

  6. Mapping the course of an englacial channel using ground-penetrating radar at Hansbreen, Svalbard

    NASA Astrophysics Data System (ADS)

    Murray, T.; Benn, D.; Maghami-Nick, F.; Adamek, A.

    2007-12-01

    A series of surface ground-penetrating radar profiles at 100 MHz have been collected over an englacial channel system 'Crystal Cave' on the tidewater glacier, Hansbreen, Svalbard. The aim of the surveys was assess radar as a method for determining the size and shape of the channel system and its fill, and to map inaccessible parts of the channel system. It is possible to descend into the main channels of the system from moulins along its course and a detailed map of the accessible regions has been made. This mapping allows ground-truthing of the radar interpretation. The channel system consists of multiple channels at different elevations. The channels generally have low gradient sections linked by near vertical shafts. In common with other channels in Svalbard glaciers, the channels probably initiated as a supraglacial features progressively downcutting into the ice and filling with compressed snow from above. We show that ground-penetrating radar can be successfully used to determine the depth, shape, and water content of englacial channels because of the strong contrast in electrical properties between water, ice, and air. This technique has exciting possibilities for the remote monitoring of inaccessible englacial channels. Members of the Polish Station at Hornsund are thanked for their hospitality and logistic support.

  7. Detection of Marked and Unmarked Burial Sites in Louisiana Using Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Smith, M.; Nunn, J. A.

    2008-12-01

    Ground penetrating radar has been used in both north and south Louisiana, to locate marked and unmarked graves. Burials in Oak Ridge, Louisiana, which is in the northern part of the state, were in a church cemetery. Dates of burial ranged from the late 1800s to the present. The survey was conducted to determine the location of empty plots within the cemetery that could be used for future burials and to locate any unmarked burials. Burials in St. Gabriel, Louisiana, which is in the southern portion of the state, consisted of three marked graves on private property. Date of burials occurred in the 1970s. This survey was performed to confirm that the headstones were correctly placed over the bodies. A large surface depression was observed near the presumed location of the graves. Information regarding the exact location of the bodies was not known and one or more bodies were possibly buried in the area beneath the observed large surface depression. A Sensors and Software SmartCart bistatic ground penetrating radar unit equipped with 200-megahertz antennas with 0.5 meters of separation was used at both locations. Penetration was to a sufficient depth in order to determine locations of the burials at both sites. Longer wavelength antennas were available but not used because the 200-megahertz antennas adequately characterized the near subsurface. Sediments in the Oak Ridge site consisted of silty loams and a comparatively deeper depth of penetration was achieved. Sediment in the St. Gabriel site consisted of clays with less depth of penetration than in the Oak Ridge site. Previous studies by others in Baton Rouge, Louisiana just to the north of St. Gabriel have had poor results due to limited depth of penetration except in areas where the soil is covered by concrete or asphalt and thus remains dry year round. Both grave sites were surveyed while the soil was dry in order to ensure maximum depth of penetration. Data interpretation was completed on site during each survey

  8. Imaging Buried Culverts Using Ground Penetrating Radar: Comparing 100 MHZ Through 1 GHZ Antennae

    NASA Astrophysics Data System (ADS)

    Abdul Aziz, A.; Stewart, R. R.; Green, S. L.

    2013-12-01

    *Aziz, A A aabdulaziz@uh.edu Allied Geophysical Lab, Department of Earth and Atmospheric Sciences, University of Houston, TX, USA Stewart, R R rrstewart@uh.edu Allied Geophysical Lab, Department of Earth and Atmospheric Sciences, University of Houston, TX, USA *Green, S L slgreen@yahoo.com Allied Geophysical Lab, Department of Earth and Atmospheric Sciences, University of Houston, TX, USA A 3D ground penetrating radar (GPR) survey, using three different frequency antennae, was undertaken to image buried steel culverts at the University of Houston's La Marque Geophysical Observatory 30 miles south of Houston, Texas. The four culverts, under study, support a road crossing one of the area's bayous. A 32 m by 4.5 m survey grid was designed on the road above the culverts and data were collected with 100 MHz, 250 MHz, and 1 GHz antennae. We used an orthogonal acquisition geometry for the three surveys. Inline sampling was from 1.0 cm to 10 cm (from 1 GHz to 100 MHz antenna) with inline and crossline spacings ranging from 0.2 m to 0.5 m. We used an initial velocity of 0.1 m/ns (from previous CMP work at the site) for the display purposes. The main objective of the study was to analyze the effect of different frequency antennae on the resultant GPR images. We are also interested in the accuracy and resolution of the various images, in addition to developing an optimal processing flow.The data were initially processed with standard steps that included gain enhancement, dewow and temporal-filtering, background suppression, and 2D migration. Various radar velocities were used in the 2D migration and ultimately 0.12 m/ns was used. The data are complicated by multipathing from the surface and between culverts (from modeling). Some of this is ameliorated via deconvolution. The top of each of the four culverts was evident in the GPR images acquired with the 250 MHz and 100 MHz antennas. For 1 GHz, the top of the culvert was not clear due to the signal's attenuation. The 250 MHz

  9. A Comprehensive Analysis of Swiss Alpine Glaciers Using Helicopter-Borne Ground-Penetrating-Radar

    NASA Astrophysics Data System (ADS)

    Rabenstein, L.; Maurer, H.; Bauder, A.; Langhammer, L.; Lucas, C.; Rutishauser, A.; Lathion, P.

    2014-12-01

    Detailed information exists on the surface area of glaciers in Switzerland and long-term mass balance observations are available but because glacial thickness remains elusive and so only a rough estimate of the present ice volume is available. After the successful recording of approximately 1000 km of helicopter ground penetrating radar (GPR) profiles on Swiss glaciers during the last three years, the Swiss Competence Center for Energy Research (SCCER) and the Swiss Geophysical Commission (SGPK) began an initiative to obtain for the first time an accurate estimate of the total ice volume located in the Swiss Alps. Steps towards this goal include the delineation of 3D bedrock topography beneath glacerized regions. The final ice volume estimation will comprise an ice flux computation model constrained by a dense network of helicopter-borne GPR profiles. Different systems that have been recently tested for acquiring helicopter GPR data in the Swiss Alps include towed systems (the HERA-G+ and the BGR-P30) and rigidly mounted systems of standard commercial GPR ground units (the GSSI and PulsEkko), all operating in the frequency range of 30 to 70 Mhz. Some measurements were ground-truthed using the same GPR antenna systems. Analyses of these data sets revealed a wealth of useful information on the glacier bed topography and some internal structures. For instance, at depths between 30 and 60 m, we often observe zones of low backscattering followed by a more reflective zone. In the glacial accumulation areas these features are interpreted as firn layers, in which the water percolates down to its base. The same test flights also provided useful technical information on the radar installation. For towed systems it is difficult to maintain a constant orientation of the antennas during the flight. In contrast, the rigidly mounted systems do not suffer from the orientation problem, but ringing effects are pronounced. We applied an SVD-based (singular value decomposition) multi

  10. Detection of Rockfall on a Tunnel Concrete Lining with Ground-Penetrating Radar (GPR)

    NASA Astrophysics Data System (ADS)

    Lalagüe, Anne; Lebens, Matthew A.; Hoff, Inge; Grøv, Eivind

    2016-07-01

    Experiments were conducted using Ground-Penetrating Radar (GPR). The performance of six GPR systems was assessed in terms of: (1) remotely mapping cavities behind concrete linings, (2) detecting rockfall from the tunnel roof onto an inner lining comprising, for example, precast concrete segments. Studies conducted in Norway and the United States demonstrate that the GPR technique is a simple and reliable method that can assist stability inspection in existing Norwegian tunnels. The ground-coupled GPR systems represent a step forward in the remote detection of rockfall on tunnel concrete linings, and are particularly suited to self-standing inner linings. The analysis of the data is relatively straightforward and reasonably accurate.

  11. Radon-transform-based landmine signatures extracted from ground penetrating radar imagery

    NASA Astrophysics Data System (ADS)

    Wilcox, Daren R.; Mersereau, Russell M.

    2003-09-01

    Step-frequency ground penetrating radar (SFGPR) is a prominent sensor in current buried land mine and unexploded ordnance (UXO) detection systems. Often GPR data is presented in its raw form and it is left to the signal processor to condition the signal. Discussed are the basics of SFGPR and how to condition the data with a minimum of a priori information. Qualitative comparison is shown between first order simulations and measured SFGPR data. Upon conclusion, detection and classification features based on the Radon transform are presented.

  12. Ground-penetrating radar for highway and bridge deck condition assessment and inventory

    NASA Astrophysics Data System (ADS)

    Heiler, Michael; McNeil, Sue; Garrett, James H., Jr.

    1995-05-01

    Ground penetrating radar (GPR) has been developed and used successfully for bridge deck and roadway condition assessment. In the past, GPR interpretation has been done manually by trained engineers and technicians with the aid of standard signal processing techniques. This method of collection produced vast quantities of data, and the interpretation required a great amount of time. Recently, parallel processing in the form of artificial neural networks (ANNs) has been applied to the interpretation of GPR condition assessment data from highways. This paper introduces general strategy for using ANNs for the interpretation of GPR data. Results of applying this strategy to bridge deck condition assessment data are also given.

  13. The Ability to Probe the Martian Polar Subsurface Via Ground-penetrating Radar

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.; Mahaffy, P. R.

    2003-01-01

    Ground-penetrating radar (GPR) offers the exciting possibility of remote sensing below the Martian surface for trapped aquifers. A GPR is currently heading to Mars onboard Mars Express (MEX) and a GPR is in consideration to be onboard Mars Reconnaissance Orbiter (MRO) in 2005. While such orbital systems offer great potential for polar stratigraphy studies, their ability to penetrate deep into the Martian polar ice is a function of both the intervening ionospheric density and the overlying ground ice conductivity. The influence of both signal-altering layers will be discussed. Polar Ice and Water: Clifford1,2 has suggested

  14. Ground-penetrating radar signal processing for the detection of buried objects

    NASA Astrophysics Data System (ADS)

    Walters, Mitchell; Garcia, Ephrahim

    2011-06-01

    In this work the singular value decomposition (SVD) is used to analyze matrices of ground penetrating radar (GPR) data. The targets to be detected are Russian PMN antipersonnel landmines and improvised explosive devices constructed from 155mm artillery shells. Target responses are simulated with GPRmax 2D, a simulation package based on the Finite- Difference-Time-Domain method. First, the utility of the SVD for image enhancement and reconstruction is demonstrated. Then the singular values and singular vectors of the decomposed matrices are analyzed with the goal of finding properties that will aid in the development of automated underground detection algorithms.

  15. Metal object detection using a forward-looking polarimetric ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Chun, Ethan H.-Y.; Chun, Cornell S. L.

    2011-06-01

    The usefulness of ground penetrating radar to detect landmines has been limited because of low signal-to-clutter ratios which result in high false alarm rates. We describe a method using polarimetric radar to measure the polarizability angle, the relative phase, and the target magnitude. These three independent quantities are directly related to target shape and dimensions and are invariant with respect to rotation about the sensor-to-target axis. We built a forward-looking polarimetric ground penetrating radar and used it to collect data on an automobile disk brake rotor on the surface of dry sand and buried 1 in under the surface of the sand. Measurements were made over a frequency range of 1.35-2.14 GHz. We also performed a computer simulation using the Method of Moments of a target roughly shaped like the rotor. For the simulation and the measured data, the target magnitude exhibited an interference patterns from scattering centers at the edges. The computer simulation revealed that a target has characteristic frequencies marking transitions from reflection being dominated by one polarization state to reflection being dominated by the orthogonal polarization state. For the rotor in uneven ground the characteristic frequencies were found at the maxima of the polarizability angle. At these particular frequencies, the relative phase changes sign. The characteristic frequencies may be useful as a target signature.

  16. Mapping Fractures in KAERI Underground Research Tunnel using Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Baek, Seung-Ho; Kim, Seung-Sep; Kwon, Jang-Soon

    2016-04-01

    The proportion of nuclear power in the Republic of Korea occupies about 40 percent of the entire electricity production. Processing or disposing nuclear wastes, however, remains one of biggest social issues. Although low- and intermediate-level nuclear wastes are stored temporarily inside nuclear power plants, these temporary storages can last only up to 2020. Among various proposed methods for nuclear waste disposal, a long-term storage using geologic disposal facilities appears to be most highly feasible. Geological disposal of nuclear wastes requires a nuclear waste repository situated deep within a stable geologic environment. However, the presence of small-scale fractures in bedrocks can cause serious damage to durability of such disposal facilities because fractures can become efficient pathways for underground waters and radioactive wastes. Thus, it is important to find and characterize multi-scale fractures in bedrocks hosting geologic disposal facilities. In this study, we aim to map small-scale fractures inside the KAERI Underground Research Tunnel (KURT) using ground penetrating radar (GPR). The KURT is situated in the Korea Atomic Energy Research Institute (KAERI). The survey target is a section of wall cut by a diamond grinder, which preserves diverse geologic features such as dykes. We conducted grid surveys on the wall using 500 MHz and 1000 MHz pulseEKKO PRO sensors. The observed GPR signals in both frequencies show strong reflections, which are consistent to form sloping planes. We interpret such planar features as fractures present in the wall. Such fractures were also mapped visually during the development of the KURT. We confirmed their continuity into the wall from the 3D GPR images. In addition, the spatial distribution and connectivity of these fractures are identified from 3D subsurface images. Thus, we can utilize GPR to detect multi-scale fractures in bedrocks, during and after developing underground disposal facilities. This study was

  17. Ground Penetrating Radar Imaging of the Emigrant Peak Fault Zone and Alluvial Fan

    NASA Astrophysics Data System (ADS)

    Christie, M. W.; Tsoflias, G. P.

    2006-12-01

    Near-surface geophysical studies at the University of Kansas are investigating active faulting in the Eastern California Shear Zone. The Emigrant Peak Fault, in Fish Lake Valley, Nevada, is a normal fault that aids in the transfer of right-lateral deformation associated with the Furnace Creek/Fish Lake/Death Valley fault system of the Walker Lane Belt/Eastern California Shear Zone. During the spring and summer of 2006 we collected ground penetrating radar (GPR) across the deformed alluvial fan associated with the Emigrant Peak Fault. The GPR study is conducted in conjunction with high resolution shallow seismic and geologic investigations underway to more fully characterize the fault zone. The GPR data crosses the surface expression of the Emigrant Peak Fault and it is comprised of a 50 MHz 3-D grid and 25 MHz 2-D lines. The 3-D grid covers an area of 115m X 500m at 1m trace spacing, 5m in-line spacing and intersecting cross-lines at 50, 100, 150, 250, and 450m across the in-lines. 2-D GPR lines were acquired at coincident locations with the shallow seismic data and along a 1500m regional line over the fault and alluvial fan deposits. Depth of imaging ranged between 17m for the 50 MHz data and 25m for the 25 MHz data. GPR imaging aids in the characterization of the fault zone structurally as well as characterizing alluvial fan stratigraphy. Data shows stratigraphic reflectors on a 1m scale. Reflector geometries are quite complex, showing continuous coherent events, as well as areas that are less coherent which appear to signal a change to more boulder/cobble-rich deposition, a common characteristic in debris-flow dominated alluvial fans. The reflectors are also heavily influenced by the structural components that are imaged. The GPR shows a number of west-dipping faults that seem to migrate towards the basin. The faults are not imaged merely as interrupted reflectors, but the fault surfaces are actually imaged. Stratigraphic reflectors truncate at the faults in

  18. Application of the LMC algorithm to anomaly detection using the Wichmann/NIITEK ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Torrione, Peter A.; Collins, Leslie M.; Clodfelter, Fred; Frasier, Shane; Starnes, Ian

    2003-09-01

    This paper describes the application of a 2-dimensional (2-D) lattice LMS algorithm for anomaly detection using the Wichmann/Niitek ground penetrating radar (GPR) system. Sets of 3-dimensional (3-D) data are collected from the GPR system and these are processed in separate 2-D slices. Those 2-D slices that are spatially correlated in depth are combined into separate "depth segments" and these are processed independently. When target/no target declarations need to be made, the individual depth segments are combined to yield a 2-D confidence map. The 2-D confidence map is then thresholded and alarms are placed at the centroids of the remaining 8-connected data points. Calibration lane results are presented for data collected over several soil types under several weather conditions. Results show a false alarm rate improvement of at least an order of magnitude over other GPR systems, as well as significant improvement over other adaptive algorithms operating on the same data.

  19. Characterization of concrete properties from dielectric properties using ground penetrating radar

    SciTech Connect

    Lai, W.L.; Kou, S.C.; Tsang, W.F.; Poon, C.S.

    2009-08-15

    This paper presents the experimental results of a study of the relationships between light-weight (LWAC) and normal aggregate concrete (NAC) properties, as well as radar wave properties that are derived by using ground penetrating radar (GPR). The former (LWAC) refers to compressive strength, apparent porosity and saturated density, while the latter (NAC) refers to real part of dielectric permittivity ({epsilon}' or real permittivity) and wave energy level (E). Throughout the test period of the newly cast concrete cured for 90 days, the above mentioned material properties gradually changed which can be attributed to the effects of cement hydration, different types of aggregates and initial water to binder ratios. A number of plots describing various properties of concrete such as dielectric, strength and porosity perspectives were established. From these plots, we compare the characteristics of how much and how fast free water was turned to absorbed water in LWAC and NAC. The underlying mechanisms and a mechanistic model are then developed.

  20. The Use of Ground Penetrating Radar to Exploring Sedimentary Ore In North-Central Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Almutairi, Yasir; Almutair, Muteb

    2015-04-01

    Ground Penetrating Radar (GPR) is a non-destructive geophysical method that provides a continuous subsurface profile, without drilling. This geophysical technique has great potential in delineating the extension of bauxites ore in north-central Saudi Arabia. Bauxite is from types sedimentary ores. This study aim to evaluate the effectiveness of Ground Penetrating Radar (GPR) to illustrate the subsurface feature of the Bauxite deposits at some selected mining areas north-central Saudi Arabia. Bauxite is a heterogeneous material that consists of complex metals such as alumina and aluminum. An efficient and cost-effect exploration method for bauxite mine in Saudi Arabia is required. Ground penetrating radar (GPR) measurements have been carrying out along outcrop in order to assess the potential of GPR data for imaging and characterising different lithological facies. To do so, we have tested different antenna frequencies to acquire the electromagnetic signals along a 90 m profile using the IDS system. This system equipped with a 25 MHz antenna that allows investigating the Bauxite layer at shallow depths where the clay layers may existed. Therefore, the 25 MHz frequency antenna has been used in this study insure better resolution of the subsurface and to get more penetration to image the Bauxite layer. After the GPR data acquisition, this data must be processed in order to be more easily visualized and interpreted. Data processing was done using Reflex 6.0 software. A series of tests were carried out in frequency filtering on a sample of radar sections, which was considered to better represent the entire set of data. Our results indicated that the GPR profiling has a very good agreement for mapping the bauxite layer depth at range of 7 m to 11 m. This study has emphasized that the high-resolution GPR method is the robust and cost-effect technique to map the Bauxite layer. The exploration of Bauxite resource using the GPR technique could reduce the number of holes to

  1. Through the looking glass: Applications of ground-penetrating radar in archaeology

    NASA Astrophysics Data System (ADS)

    Stamos, Antonia

    The focus of this dissertation is to present the results of four years' worth of geophysical surveying at four major archaeological sites in Greece and the benefits to the archaeological community. The ground penetrating radar offers an inexpensive, non-destructive solution to the problem of deciding how much of a site is worth excavating and which areas would yield the most promising results. An introduction to the ground penetrating radar, or GPR, the equipment necessary to conduct a geophysical survey in the field, and the methods of data collection and subsequent data processing are all addressed. The benefits to the archeological community are many, and future excavations will incorporate such an important tool for a greater understanding of the site. The history of GPR work in the archaeological field has grown at an astounding rate from its beginnings as a simple tool for petroleum and mining services in the beginning of the twentieth century. By mid-century, the GPR was first applied to archaeological sites rather than its common use by utility companies in locating pipes, cables, tunnels, and shafts. Although the preliminary surveys were little more than a search to locate buried walls, the success of these initial surveys paved the ground for future surveys at other archaeological sites, many testing the radar's efficacy with a myriad of soil conditions and properties. The four sites in which geophysical surveys with a ground penetrating radar were conducted are Azorias on the island of Crete, Kolonna on the island of Aegina, Mochlos Island and Coastal Mochlos on the island of Crete, and Mycenae in the Peloponnese on mainland Greece. These case studies are first presented in terms of their geographical location, their mythology and etymology, where applicable, along with a brief history of excavation and occupation of the site. Additional survey methods were used at Mycenae, including aerial photography and ERDAS Imagine, a silo locating program now

  2. Evaluation of a highway pavement using non destructive tests: Falling Weight Deflectometer and Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Marecos, Vania; Fontul, Simona; de Lurdes Antunes, Maria

    2015-04-01

    This paper presents the results of the application of Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR) to assess the bearing capacity of a rehabilitated flexible highway pavement that began to show the occurrence of cracks in the surface layer, about one year after the improvement works. A visual inspection of the surface of the pavement was performed to identify and characterize the cracks. Several core drills were done to analyse the cracks propagation in depth, these cores were also used for GPR data calibration. From the visual inspection it was concluded that the development of the cracks were top-down and that the cracks were located predominantly in the wheel paths. To determine the thickness of the bituminous and granular layers GPR tests were carried out using two horn antennas of 1,0 GHz and 1,8 GHz and a radar control unit SIR-20, both from GSSI. FWD load tests were performed on the wheel paths and structural models were established, based on the deflections measured, through back calculation. The deformation modulus of the layers was calculated and the bearing capacity of the pavement was determined. Summing up, within this study the GPR was used to continuously detect the layer thickness and the GPR survey data was calibrated with core drills. The results showed variations in the bituminous layer thickness in comparison to project data. From the load tests it was concluded that the deformation modulus of the bituminous layers were also vary variable. Limitations on the pavement bearing capacity were detected in the areas with the lower deformation modulus. This abstract is of interest for COST Action TU1208 Civil Engineering Applications of Ground Penetrating Radar.

  3. Measuring flood discharge in unstable stream channels using ground-penetrating radar

    USGS Publications Warehouse

    Spicer, K.R.; Costa, J.E.; Placzek, G.

    1997-01-01

    Field experiments were conducted to test the ability of ground-penetrating radar (GPR) to measure stream-channel cross sections at high flows without the necessity of placing instruments in the water. Experiments were conducted at four U.S. Geological Survey gaging stations in southwest Washington State. With the GPR antenna suspended above the water surface from a bridge or cableway, traverses were made across stream channels to collect radar profile plots of the streambed. Subsequent measurements of water depth were made using conventional depth-measuring equipment (weight and tape) and were used to calculate radar signal velocities. Other streamflow-parameter data were collected to examine their relation to radar signal velocity and to claritv of streambed definition. These initial tests indicate that GPR is capable of producing a reasonably accurate (??20%) stream-channel profile and discharge far more quickly than conventional stream-gaging procedures, while avoiding the problems and hazards associated with placing instruments in the water.

  4. Applicability of ground penetrating radar to subsurface studies of karst terrain in Florida

    SciTech Connect

    Kuo, S.S.; Beck, B.F.; Jenkins, D.T.; Tannous, B.S.; Sweeney, M.

    1985-01-01

    Karstic subsidence (sinkhole, or doline, collapse) is a serious problem in Florida; subsurface detection is important in foundation studies. It is critical to delineate subsoil karren and solution pipes in the buried limestone surface, which may cause subsidence sinkholes, as well as cavities which may cause collapse. To test the capabilities of ground penetrating radar (GPR) to detect underground cavities three air-filled model cavities, 0.3 to 0.9 m in diameter, were buried above the water table and one water-filled model cavity, 1.2 m in diameter, was emplaced below the water table, at various depths. The characteristic radar response to these voids is a function of the composition of the strata penetrated, the depth of the groundwater table, and the radar antenna frequency. In field investigations in Central and North Florida, where the karstified limestone is mantled by a variable thickness of sand and clay, GPR can profile the limestone surface and detect cavernous voids in the limestone to a depth of 12 m, if the overburden is primarily sand. In many cases, ongoing karst processes have deformed the overburden strata by gradual subsidence and the radar profile of shallow clay layers may reveal karstic foundation problems even when the signal cannot detect the limestone.

  5. Application of ground-penetrating radar at McMurdo Station, Antarctica

    SciTech Connect

    Stefano, J.E.

    1992-01-01

    Argonne National Laboratory initiated a site investigation program at McMurdo Station, Antarctica, to characterize environmental contamination. The performance and usefulness of ground-penetrating radar (GPR) was evaluated under antarctic conditions during the initial site investigation in January 1991. Preliminary surveys were successful in defining the contact between reworked pyroclastic material and in the prefill, undisturbed pyroclastics and basalts at some sites. Interference from radio traffic at McMurdo Station was not observed, but interference was a problem in work with unshielded antennas near buildings. In general, the results of this field test suggest that high-quality, high-resolution, continuous subsurface profiles can be produced with GPR over most of McMurdo Station.

  6. Application of ground-penetrating radar at McMurdo Station, Antarctica

    SciTech Connect

    Stefano, J.E.

    1992-05-01

    Argonne National Laboratory initiated a site investigation program at McMurdo Station, Antarctica, to characterize environmental contamination. The performance and usefulness of ground-penetrating radar (GPR) was evaluated under antarctic conditions during the initial site investigation in January 1991. Preliminary surveys were successful in defining the contact between reworked pyroclastic material and in the prefill, undisturbed pyroclastics and basalts at some sites. Interference from radio traffic at McMurdo Station was not observed, but interference was a problem in work with unshielded antennas near buildings. In general, the results of this field test suggest that high-quality, high-resolution, continuous subsurface profiles can be produced with GPR over most of McMurdo Station.

  7. Automated water content reconstruction of zero-offset borehole ground penetrating radar data using simulated annealing

    NASA Astrophysics Data System (ADS)

    Rucker, Dale F.; Ferré, Ty P. A.

    2005-07-01

    The automated inversion of water content profiles from first arrival travel time data collected with zero-offset borehole ground penetrating radar is discussed. The inversion algorithm sets out to find the water content profile that minimizes a least-squares objective function representing the difference between the modeled and measured first arrival travel time. Ray-tracing analysis is used to determine the travel time for direct and critically refracted paths to identify the first arrival travel time. This automated method offers improvement over a previously presented graphical solution that considers both direct and critical refractions. Specifically, this approach can identify thinner layers and allow for the incorporation of uncertainty in the travel time measurements to determine the depth-specific uncertainty of the inferred water content profile through multiple simulations using a stochastic approach.

  8. Monitoring infiltration processes with high-resolution surface-based Ground-Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Klenk, P.; Jaumann, S.; Roth, K.

    2015-11-01

    In this study, we present a series of high resolution Ground-Penetrating Radar (GPR) measurements monitoring two artificially induced infiltration pulses into two different sands with dual-frequency ground-based GPR. After the application of the second infiltration pulse, the water table in the subsoil was raised by pumping in water from below. The longterm relaxation of the system was then monitored over the course of several weeks. We focused on the capillary fringe reflection and on observed variations in soil water content as derived from direct wave travel times. We discuss the advantages of this dual-frequency approach and show the attainable precision in longterm monitoring of such relaxation processes. Reaching a relative precision of better than 0.001 [-] in water content, we can clearly discern the relaxation of the two investigated sands.

  9. Use of high-resolution ground-penetrating radar in kimberlite delineation

    USGS Publications Warehouse

    Kruger, J.M.; Martinez, A.; Berendsen, P.

    1997-01-01

    High-resolution ground-penetrating radar (GPR) was used to image the near-surface extent of two exposed Late Cretaceous kimberlites intruded into lower Permian limestone and dolomite host rocks in northeast Kansas. Six parallel GPR profiles identify the margin of the Randolph 1 kimberlite by the up-bending and termination of limestone reflectors. Five radially-intersecting GPR profiles identify the elliptical margin of the Randolph 2 kimberlite by the termination of dolomite reflectors near or below the kimberlite's mushroom-shaped cap. These results suggest GPR may augment magnetic methods for the delineation of kimberlites or other forceful intrusions in a layered host rock where thick, conductive soil or shale is not present at the surface.

  10. Urban soil exploration through multi-receiver electromagnetic induction and stepped-frequency ground penetrating radar.

    PubMed

    Van De Vijver, Ellen; Van Meirvenne, Marc; Vandenhaute, Laura; Delefortrie, Samuël; De Smedt, Philippe; Saey, Timothy; Seuntjens, Piet

    2015-07-01

    In environmental assessments, the characterization of urban soils relies heavily on invasive investigation, which is often insufficient to capture their full spatial heterogeneity. Non-invasive geophysical techniques enable rapid collection of high-resolution data and provide a cost-effective alternative to investigate soil in a spatially comprehensive way. This paper presents the results of combining multi-receiver electromagnetic induction and stepped-frequency ground penetrating radar to characterize a former garage site contaminated with petroleum hydrocarbons. The sensor combination showed the ability to identify and accurately locate building remains and a high-density soil layer, thus demonstrating the high potential to investigate anthropogenic disturbances of physical nature. In addition, a correspondence was found between an area of lower electrical conductivity and elevated concentrations of petroleum hydrocarbons, suggesting the potential to detect specific chemical disturbances. We conclude that the sensor combination provides valuable information for preliminary assessment of urban soils. PMID:26040331

  11. Fusion techniques for hybrid ground-penetrating radar: electromagnetic induction landmine detection systems

    NASA Astrophysics Data System (ADS)

    Laffin, Matt; Mohamed, Magdi A.; Etebari, Ali; Hibbard, Mark

    2010-04-01

    Hybrid ground penetrating radar (GPR) and electromagnetic induction (EMI) sensors have advanced landmine detection far beyond the capabilities of a single sensing modality. Both probability of detection (PD) and false alarm rate (FAR) are impacted by the algorithms utilized by each sensing mode and the manner in which the information is fused. Algorithm development and fusion will be discussed, with an aim at achieving a threshold probability of detection (PD) of 0.98 with a low false alarm rate (FAR) of less than 1 false alarm per 2 square meters. Stochastic evaluation of prescreeners and classifiers is presented with subdivisions determined based on mine type, metal content, and depth. Training and testing of an optimal prescreener on lanes that contain mostly low metal anti-personnel mines is presented. Several fusion operators for pre-screeners and classifiers, including confidence map multiplication, will be investigated and discussed for integration into the algorithm architecture.

  12. Tree Roots in Agroforestry: Evaluating Biomass and Distribution with Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Borden, Kira Alia

    The root systems of five tree species (Populus deltoides x nigra clone DN-177, Juglans nigra, Quercus rubra, Picea abies, and Thuja occidentalis) are described following non-intrusive imaging using ground penetrating radar (GPR). This research aimed to 1) assess the utility of GPR for in situ root studies and 2) employ GPR to estimate tree root biomass and distribution in an agroforestry system in southern Ontario, Canada. The mean coarse root biomass estimated from GPR analysis was 54.1 +/- 8.7 kg tree-1 (+/- S.E.; n=12), within 1 % of the mean coarse root biomass measured from matched excavations. The vertical distribution of detected roots varied among species, with T. occidentalis and P. abies roots concentrated in the top 20 cm and J. nigra and Q. rubra roots distinctly deeper. I evaluate these root systems based on their C storage potential and complementary root stratification with adjacent crops.

  13. Detection of explosive hazards using spectrum features from forward-looking ground penetrating radar imagery

    NASA Astrophysics Data System (ADS)

    Farrell, Justin; Havens, Timothy C.; Ho, K. C.; Keller, James M.; Ton, Tuan T.; Wong, David C.; Soumekh, Mehrdad

    2011-06-01

    Buried explosives have proven to be a challenging problem for which ground penetrating radar (GPR) has shown to be effective. This paper discusses an explosive hazard detection algorithm for forward looking GPR (FLGPR). The proposed algorithm uses the fast Fourier transform (FFT) to obtain spectral features of anomalies in the FLGPR imagery. Results show that the spectral characteristics of explosive hazards differ from that of background clutter and are useful for rejecting false alarms (FAs). A genetic algorithm (GA) is developed in order to select a subset of spectral features to produce a more generalized classifier. Furthermore, a GA-based K-Nearest Neighbor probability density estimator is employed in which targets and false alarms are used as training data to produce a two-class classifier. The experimental results of this paper use data collected by the US Army and show the effectiveness of spectrum based features in the detection of explosive hazards.

  14. Magnetometry and Ground-Penetrating Radar Studies in the Sihuas Valley, Peru

    NASA Astrophysics Data System (ADS)

    Wisnicki, E.; Papadimitrios, K.; Bank, C.

    2013-12-01

    The Quillcapampa la Antigua site in Peru's Sihuas Valley is a settlement from Peru's Middle Horizon (600-100 A.D.). Archaeological interest in the area stems from the question of whether ancient civilizations were able to have extensive state control of distant groups, or whether state influence occurred through less direct ties (e.g., marriage, religion, or trade). Our geophysical surveys are preliminary to archaeological digging in the area. Ground-penetrating radar and magnetometry attempt to locate areas of interest for focused archaeological excavation, characterize the design of architectural remains and burial mounds in the area, and allow archaeologists to interpret the amount of influence the Wari civilization had on the local residents.

  15. Research perspectives in the field of ground penetrating radars in Armenia

    NASA Astrophysics Data System (ADS)

    Baghdasaryan, Hovik; Knyazyan, Tamara; Hovhannisyan, Tamara

    2014-05-01

    Armenia is a country located in a very complicated region from geophysical point of view. It is situated on a cross of several tectonic plates and a lot of dormant volcanoes. The main danger is earthquakes and the last big disaster was in 1988 in the northwest part of contemporary Armenia. As a consequence, the main direction of geophysical research is directed towards monitoring and data analysis of seismic activity. National Academy of Sciences of Armenia is conducting these activities in the Institute of Geological Sciences and in the Institute of Geophysics and Engineering Seismology. Research in the field of ground penetrating radars is considered in Armenia as an advanced and perspective complement to the already exploiting research tools. The previous achievements of Armenia in the fields of radiophysics, antenna measurements, laser physics and existing relevant research would permit to initiate new promising area of research in the direction of theory and experiments of ground penetrating radars. One of the key problems in the operation of ground penetrating radars is correct analysis of peculiarities of electromagnetic wave interaction with different layers of the earth. For this, the well-known methods of electromagnetic boundary problem solutions are applied. In addition to the existing methods our research group of Fiber Optics Communication Laboratory at the State Engineering University of Armenia declares its interest in exploring the possibilities of new non-traditional method of boundary problems solution for electromagnetic wave interaction with the ground. This new method for solving boundary problems of electrodynamics is called the method of single expression (MSE) [1-3]. The distinctive feature of this method is denial from the presentation of wave equation's solution in the form of counter-propagating waves, i.e. denial from the superposition principal application. This permits to solve linear and nonlinear (field intensity-dependent) problems

  16. Uncertainties in peat volume and soil carbon estimated using ground penetrating radar and probing

    SciTech Connect

    Parsekian, Andrew D.; Slater, Lee; Ntarlagiannis, Dimitrios; Nolan, James; Sebestyen, Stephen D; Kolka, Randall K; Hanson, Paul J

    2012-01-01

    We evaluate the uncertainty in calculations of peat basin volume using high-resolution data . to resolve the three-dimensional structure of a peat basin using both direct (push probes) and indirect geophysical (ground penetrating radar) measurements. We compared volumetric estimates from both approaches with values from literature. We identified subsurface features that can introduce uncertainties into direct peat thickness measurements including the presence of woody peat and soft clay or gyttja. We demonstrate that a simple geophysical technique that is easily scalable to larger peatlands can be used to rapidly and cost effectively obtain more accurate and less uncertain estimates of peat basin volumes critical to improving understanding of the total terrestrial carbon pool in peatlands.

  17. Ground-penetrating radar research in Belgium: from developments to applications

    NASA Astrophysics Data System (ADS)

    Lambot, Sébastien; Van Meirvenne, Marc; Craeye, Christophe

    2014-05-01

    Ground-penetrating radar research in Belgium spans a series of developments and applications, including mainly ultra wideband radar antenna design and optimization, non-destructive testing for the characterization of the electrical properties of soils and materials, and high-resolution subsurface imaging in agricultural engineering, archeology and transport infrastructures (e.g., road inspection and pipe detection). Security applications have also been the topic of active research for several years (i.e., landmine detection) and developments in forestry have recently been initiated (i.e., for root zone and tree trunk imaging and characterization). In particular, longstanding research has been devoted to the intrinsic modeling of antenna-medium systems for full-wave inversion, thereby providing an effective way for retrieving the electrical properties of soils and materials. Full-wave modeling is a prerequisite for benefiting from the full information contained in the radar data and is necessary to provide robust and accurate estimates of the properties of interest. Nevertheless, this has remained a major challenge in geophysics and electromagnetics for many years, mainly due to the complex interactions between the antennas and the media as well as to the significant computing resources that are usually required. Efforts have also been dedicated to the development of specific inversion strategies to cope with the complexity of the inverse problems usually dealt with as well as ill-posedness issues that arise from a lack of information in the radar data. To circumvent this last limitation, antenna arrays have been developed and modeled in order to provide additional information. Moreover, data fusion ways have been investigated, by mainly combining GPR data with electromagnetic induction complementary information in joint interpretation analyses and inversion procedures. Finally, inversions have been regularized by combining electromagnetics models together with soil

  18. A quantitative investigation of the use of ground-penetrating radar in hydrogeology

    NASA Astrophysics Data System (ADS)

    Moysey, Stephen M. J.

    Ground-penetrating radar (GPR) has become a useful tool for non-invasive imaging of the subsurface. However, the qualitative nature of current methods for the interpretation of GPR makes it difficult to use in groundwater modeling applications, especially for problems where accounting for uncertainty is important. In this thesis, the need for quantitative interpretations is addressed using observational, theoretical, and computational approaches that explore how complex subsurface heterogeneities are expressed in GPR data. This understanding of how radar samples the earth is exploited to suggest quantitative methods that can be used for interpreting radar data. In the first part of this thesis, radar facies analysis is examined as an approach to determine the large-scale architecture of the subsurface using GPR surface reflection data; it is often assumed that radar facies can act as a valuable proxy for defining hydrologic facies, given that both types of facies are related to lithology. In the approach explored here, artificial neural networks are used to probabilistically segment the subsurface into radar facies based on characteristic signatures of the radar data. Specifically, radar texture---the pattern of reflections within a window of radar data---is used to discriminate between different radar facies. In the second part of this thesis, the nature of the relationship between dielectric constant, determined by GPR surveys, and water content, important in hydrologic investigations, is investigated. Using a stochastic averaging approach that accounts for the way radar averages over heterogeneity it is demonstrated that field-scale dielectric constant-water content relationships are not necessarily equivalent to those measured in the laboratory. As a result, a numerical analog method for building field-scale rock physics relationships that accounts for heterogeneity, the physics of sampling, and geophysical survey design is proposed. In synthetic studies, it

  19. Ground-penetrating radar and its use in sedimentology: principles, problems and progress

    NASA Astrophysics Data System (ADS)

    Neal, Adrian

    2004-08-01

    Ground-penetrating radar (GPR, also referred to as ground-probing radar, surface-penetrating radar, subsurface radar, georadar or impulse radar) is a noninvasive geophysical technique that detects electrical discontinuities in the shallow subsurface (<50 m). It does this by generation, transmission, propagation, reflection and reception of discrete pulses of high-frequency (MHz) electromagnetic energy. During the 1980s radar systems became commercially available, but it was not until the mid-1990s that sedimentary geologists and others began to widely exploit the technique. During the last decade numerous sedimentological studies have used GPR to reconstruct past depositional environments and the nature of sedimentary processes in a variety of environmental settings; to aid hydrogeological investigations, including groundwater reservoir characterisation, and to assist in hydrocarbon reservoir analogue studies. This is because in correctly processed radar profiles, and at the resolution of a survey, primary reflections usually parallel primary depositional structure. Despite the wide use of GPR, a number of fundamental problems remain in its application to sedimentary research. In particular, there are a wide range of approaches to the processing of radar data and interpretation techniques used on the final subsurface images vary widely, with little consensus over a common methodology. This review attempts to illustrate that methods for the collection, processing and interpretation of radar data are intimately linked and that thorough understanding of the nature, limitations and implications of each step is required if realistic sedimentological data are to be generated. In order to extract the maximum amount of meaningful information, the user must understand the scientific principles that underlie the technique, the effects of the data collection regime employed, the implications of the technique's finite resolution and depth of penetration, the nature and causes

  20. Orbital and Ground-penetrating Radar Studies of Mars-analog Terrain in Egypt

    NASA Astrophysics Data System (ADS)

    Maxwell, T. A.; Grant, J. A.; Campbell, B. A.

    2007-05-01

    Several study groups have endorsed the concept of flying an imaging synthetic aperture radar (SAR) in orbit that would penetrate areas of thin surface cover revealing underlying terrain and providing additional information on surface roughness, physical properties and composition. Egypt provides many excellent terrestrial field sites to study both the processes that we expect to be revealed in a Mars SAR Mission, as well as the stratigraphic setting of past depositional environments that are similar to those seen in southern Egypt. We have used terrestrial orbital radar data for southern Egypt, comparing geologic materials and boundaries mapped in the field and with visible wavelengths (from Landsat) to those discerned via Shuttle Imaging Radar (SIR) -C, and field checking key sites to determine the depth, physical characteristics and types of geologic boundaries that contribute to the radar returns. In addition to stratigraphic mapping of the thickness and extent of near-surface units in the field, we have used ground-penetrating radar (GPR) to determine the lateral extent and depth of subsurface interfaces. In this manner, we expect to learn more about the capabilities and limitations of orbital and ground-based systems, the trade-offs between frequency, polarization and resolution in Mars-like terrain for detecting buried interfaces and structures, and more about the geologic history of southern Egypt. Several studies have concentrated on one of the areas of prominent radar-detected channels near Bir Safsaf in the southwest desert, we have concentrated on the Bir Kiseiba region, an area where the mixture of gravel spreads, buried paleochannels, and alluvium creates a setting that may mimic outflow deposit locations on Mars. While bedrock incised channels may stand out in SAR images because of a near-surface, sharp dielectric interface (such as those at Safsaf and in northern Sudan), the more complex problem of distinguishing fluvial patterns in Mars

  1. The potentialities of ground-penetrating radar in the engineering geology using the radars GROT-12 and GROT-12E

    NASA Astrophysics Data System (ADS)

    Volkomirskaya, Liudmila; Gulevich, Oxana; Musalev, Dmitri

    2013-04-01

    The potentialities of ground-penetrating radar in the engineering geology using the radars GROT-12 and GROT-12E L.B. Volkomirskaya(1,2), O.A. Gulevich(1,2), D.N. Musalev(3) 1. IZMIRAN, 142190, Russia, Moscow, Troitsk, Kalugskoe 4 2. ZAO Timer, 142190, Russia, Moscow, Troitsk, Lesnaya str. 4B 3. OAO Belgorchemprom, Republic of Belarus, Minsk, Masherov str. 17 The article presents the potentialities of ground-penetrating radar in the engineering geology on the basis of the latest modifications of the GPR "GROT": the low-frequency GPR GROT-12 and the high-frequency GPR GROT-12E. The article gives technical specifications of the GPRs GROT-12 and GROT-12E and their particular characteristics that define them from analogues. The solutions of direct problems of ground penetrating radar on the basis of Maxwell's equations in general formulation with given wide-band signal source are confronted to experimental data received from different fields of the engineering geology, for example: 1. To secure mining in salt mines the method was adapted to locate in the working layers the investigating boreholes, fault lines, borders of displacement and blowout of productive layers, as well as working pits without access. 2. To monitor the reinforced concrete structures of airport runways the technology was worked out to collect and process GPR data so as to locate communications under the runways and examine basement condition. 3. To carry out the reconstruction of buildings and pre-project engineering geological works the GPR shooting technology was improved to process the examinations of the bearing capacity of soils and to locate lost communications. 4. To perform ecological monitoring of abandoned mines the technology of the GPR data collecting and processing was developed to assess the conditions of stowage materials in mouths of destroyed vertical mine shafts, the location of inclined mine shafts, the determination of hollow spaces and thinning zones, the localization of ground

  2. Orbital SAR and Ground-Penetrating Radar for Mars: Complementary Tools in the Search for Water

    NASA Technical Reports Server (NTRS)

    Campbell, B. A.; Grant, J. A.

    2000-01-01

    The physical structure and compositional variability of the upper martian crust is poorly understood. Optical and infrared measurements probe at most the top few cm of the surface layer and indicate the presence of layered volcanics and sediments, but it is likely that permafrost, hydrothermal deposits, and transient liquid water pockets occur at depths of meters to kilometers within the crust. An orbital synthetic aperture radar (SAR) can provide constraints on surface roughness, the depth of fine-grained aeolian or volcanic deposits, and the presence of strongly absorbing near-surface deposits such as carbonates. This information is crucial to the successful landing and operation of any rover designed to search for subsurface water. A rover-based ground-penetrating radar (GPR) can reveal layering in the upper crust, the presence of erosional or other subsurface horizons, depth to a permafrost layer, and direct detection of near-surface transient liquid water. We detail here the radar design parameters likely to provide the best information for Mars, based on experience with SAR and GPR in analogous terrestrial or planetary environments.

  3. Ground penetrating radar detection of subsnow liquid overflow on ice-covered lakes in interior Alaska

    NASA Astrophysics Data System (ADS)

    Gusmeroli, A.; Grosse, G.

    2012-07-01

    Lakes are abundant throughout the pan-Arctic region. For many of these lakes ice cover lasts for up to two thirds of the year. This frozen cover allows human access to these lakes, which are therefore used for many subsistence and recreational activities, including water harvesting, fishing, and skiing. Safe access to these lakes may be compromised, however, when, after significant snowfall, the weight of the snow acts on the ice and causes liquid water to spill through weak spots and overflow at the snow-ice interface. Since visual detection of subsnow liquid overflow (SLO) is almost impossible our understanding on SLO processes is still very limited and geophysical methods that allow SLO detection are desirable. In this study we demonstrate that a commercially available, lightweight 1GHz, ground penetrating radar system can detect and map extent and intensity of SLO. Radar returns from wet snow-ice interfaces are at least twice as much in strength than returns from dry snow-ice interface. The presence of SLO also affects the quality of radar returns from the base of the lake ice. During dry conditions we were able to profile ice thickness of up to 1 m, conversely, we did not retrieve any ice-water returns in areas affected by SLO.

  4. Ground penetrating radar detection of subsnow slush on ice-covered lakes in interior Alaska

    NASA Astrophysics Data System (ADS)

    Gusmeroli, A.; Grosse, G.

    2012-12-01

    Lakes are abundant throughout the pan-Arctic region. For many of these lakes ice cover lasts for up to two thirds of the year. The frozen cover allows human access to these lakes, which are therefore used for many subsistence and recreational activities, including water harvesting, fishing, and skiing. Safe traveling condition onto lakes may be compromised, however, when, after significant snowfall, the weight of the snow acts on the ice and causes liquid water to spill through weak spots and overflow at the snow-ice interface. Since visual detection of subsnow slush is almost impossible our understanding on overflow processes is still very limited and geophysical methods that allow water and slush detection are desirable. In this study we demonstrate that a commercially available, lightweight 1 GHz, ground penetrating radar system can detect and map extent and intensity of overflow. The strength of radar reflections from wet snow-ice interfaces are at least twice as much in strength than returns from dry snow-ice interface. The presence of overflow also affects the quality of radar returns from the base of the lake ice. During dry conditions we were able to profile ice thickness of up to 1 m, conversely, we did not retrieve any ice-water returns in areas affected by overflow.

  5. Simulation for ground penetrating radar (GPR) study of the subsurface structure of the Moon

    NASA Astrophysics Data System (ADS)

    Fa, Wenzhe

    2013-12-01

    Ground penetrating radar (GPR) is currently within the scope of China's Chang-E 3 lunar mission, to study the shallow subsurface of the Moon. In this study, key factors that could affect a lunar GPR performance, such as frequency, range resolution, and antenna directivity, are discussed firstly. Geometrical optics and ray tracing techniques are used to model GPR echoes, considering the transmission, attenuation, reflection, geometrical spreading of radar waves, and the antenna directivity. The influence on A-scope GPR echoes and on the simulated radargrams for the Sinus Iridum region by surface and subsurface roughness, dielectric loss of the lunar regolith, radar frequency and bandwidth, and the distance between the transmit and receive antennas are discussed. Finally, potential scientific return about lunar subsurface properties from GPR echoes is also discussed. Simulation results suggest that subsurface structure from several to hundreds of meters can be studied from GPR echoes at P and VHF bands, and information about dielectric permittivity and thickness of subsurface layers can be estimated from GPR echoes in combination with regolith composition data.

  6. Subsurface Feature Mapping of Mars using a High Resolution Ground Penetrating Radar System

    NASA Astrophysics Data System (ADS)

    Wu, T. S.; Persaud, D. M.; Preudhomme, M. A.; Jurg, M.; Smith, M. K.; Buckley, H.; Tarnas, J.; Chalumeau, C.; Lombard-Poirot, N.; Mann, B.

    2015-12-01

    As the closest Earth-like, potentially life-sustaining planet in the solar system, Mars' future of human exploration is more a question of timing than possibility. The Martian surface remains hostile, but its subsurface geology holds promise for present or ancient astrobiology and future habitation, specifically lava tube (pyroduct) systems, whose presence has been confirmed by HiRISE imagery.The location and characterization of these systems could provide a basis for understanding the evolution of the red planet and long-term shelters for future manned missions on Mars. To detect and analyze the subsurface geology of terrestrial bodies from orbit, a novel compact (smallsat-scale) and cost-effective approach called the High-resolution Orbiter for Mapping gEology by Radar (HOMER) has been proposed. Adapting interferometry techniques with synthetic aperture radar (SAR) to a ground penetrating radar system, a small satellite constellation is able to achieve a theoretical resolution of 50m from low-Mars orbit (LMO). Alongside this initial prototype design of HOMER, proposed data processing methodology and software and a Mars mission design are presented. This project was developed as part of the 2015 NASA Ames Academy for Space Exploration.

  7. Ground penetrating radar surveys over an alluvial DNAPL site, Paducah Gaseous Diffusion Plant, Kentucky

    SciTech Connect

    Carpenter, P.J. |; Doll, W.E.; Phillips, B.E.

    1994-09-01

    Ground penetrating radar (GPR) surveys were used to map shallow sands and gravels which are DNAPL migration pathways at the Paducah Gaseous Diffusion Plant in western Kentucky. The sands and gravels occur as paleochannel deposits, at depths of 17-25 ft, embedded in Pleistocene lacustrine clays. More than 30 GPR profiles were completed over the Drop Test Area (DTA) to map the top and base of the paleochannel deposits, and to assess their lateral continuity. A bistatic radar system was used with antenna frequencies of 25 and 50 MHz. An average velocity of 0.25 ft/ns for silty and clayey materials above the paleochannel deposits was established from radar walkaway tests, profiles over culverts of known depth, and comparison of radar sections with borings. In the south portion of the DTA, strong reflections corresponded to the water table at approximately 9-10 ft, the top of the paleochannel deposits at approximately 18 ft, and to gravel horizons within these deposits. The base of these deposits was not visible on the radar sections. Depth estimates for the top of the paleochannel deposits (from 50 records) were accurate to within 2 ft across the southern portion of the DTA. Continuity of these sands and gravels could not be assessed due to interference from air-wave reflections and lateral changes in signal penetration depth. However, the sands and gravels appear to extend across the entire southern portion of the DTA, at depths as shallow as 17 ft. Ringing, air-wave reflections and diffractions from powerlines, vehicles, well casings, and metal equipment severly degraded GPR profiles in the northern portion of the DTA; depths computed from reflection times (where visible) were accurate to within 4 ft in this area. The paleochannel deposits are deeper to the north and northeast where DNAPL has apparently pooled (DNAPL was not directly imaged by the GPR, however). Existing hydrogeological models of the DTA will be revised.

  8. Ground penetrating radar results at the Box Canyon Site - 1996 survey as part of infiltration test

    SciTech Connect

    Peterson, J.E. Jr.; Williams, K.H.

    1997-08-01

    This data report presents a discussion of the borehole radar tomography experiment conducted at Box Canyon, Idaho. Discussion concentrates on the survey methodology, data acquisition procedures, and the resulting tomographic images and interpretations. The entire geophysics field effort for FY96 centered around the collection of the borehole radar data within the inclined boreholes R1, R2, R3, and R4 before, during, and after the ponded infiltration experiment. The well pairs R1-R2, R2-R4, and R3-R4 comprised the bulk of the field survey; however, additional data were collected between vertical boreholes within and around the infiltration basin. The intent of the inclined boreholes was to allow access beneath the infiltration basin and to enhance the ability of the radar method to image both vertical and horizontal features where flow may dominate. This data report will concentrate on the inclined borehole data and the resulting tomograms. The borehole radar method is one in which modified ground penetrating radar antennas are lowered into boreholes and high frequency electromagnetic signals are transmitted through subsurface material to a receiving antenna. The transmitted signals may be represented as multiple raypaths crossing through the zone of interest. If sufficient raypaths are recorded, a tomographic image may be obtained through computer processing. The data normally recorded are signal amplitude versus time. The information extracted from such data includes the following: (a) the transit time which depends on the wave velocity, (b) the amplitude which depends on the wave attenuation, the dispersion which indicates a change in velocity and attenuation with frequency.

  9. MATERIAL PROPERTY ESTIMATION FOR DIRECT DETECTION OF DNAPL USING INTEGRATED GROUND-PENETRATING RADAR VELOCITY, IMAGING, AND ATTRIBUTE ANALYSIS

    EPA Science Inventory

    We propose to test and develop a suite of methodologies for direct detection of pooled and residual DNAPLs from surface ground-penetrating radar (GPR) data. This is a new, quantitative approach to the analysis of GPR data in which we determine material properties remotely by qua...

  10. The Use of Ground Penetrating Radar to extend the Results of Archaeological Excavation

    NASA Astrophysics Data System (ADS)

    Utsi, E.

    2009-04-01

    The condition of the Romano-British archaeological site in Wortley, Gloucestershire, UK is typical of sites of the period in that it has been heavily robbed out since it first fell into disuse. Building materials taken from the site have been re-used over the centuries to construct other local buildings. This makes both preservation of the extant remains and interpretation of the excavation problematic. Following the accidental discovery of the site in the 1980s, a programme of excavation was set in place. This excavation was run as a practical archaeological training school and, as a result, a wide range of archaeological and geophysical techniques were applied to the site. This included the introduction of Ground Penetrating Radar (GPR). The preliminary results of the first GPR used on site were not entirely satisfactory which led to the development of a new radar in the early 1990s, specifically developed for use on archaeological sites. The excavation and GPR results were published in a series of excavation reports [1] [2]. It was not possible to excavate fully for two reasons. Firstly the site crossed present day ownership boundaries and secondly the ownership of the excavation area changed. At this point the excavation was summarily terminated. In 2007, permission was given by the owner of an adjacent property to carry out a GPR survey over their land in order to derive additional information, if possible. An area survey was carried out in May 2007 with reduced transect spacing [3]. The radar data showed similar patterning to that of the original investigation i.e. substantial remains which had been subject to a high degree of post-occupational attrition. Time slices from the radar survey were matched to the principal excavation plans. It proved possible to deduce the full extent of certain partially excavated features, notably the courtyard and bath house. It was also possible to demonstrate that one part of the adjacent property did not contain similar

  11. Inspection of a large concrete block containing embedded defects using ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Eisenmann, David; Margetan, Frank J.; Koester, Lucas; Clayton, Dwight

    2016-02-01

    Ground penetrating radar (GPR), also known as impulse response radar, was used to examine a thick concrete block containing reinforcing steel bars (rebar) and embedded defects. The block was located at the University of Minnesota, measured approximately 7 feet tall by 7 feet wide by 40 inches deep, and was intended to simulate certain aspects of a concrete containment wall at a nuclear power plant. This paper describes the measurements that were made and various analyses of the data. We begin with a description of the block itself and the GPR equipment and methods used in our inspections. The methods include the application of synthetic aperture focusing techniques (SAFT). We then present and discuss GPR images of the block's interior made using 1600-MHz, 900-MHz, and 400-MHz antennas operating in pulse/echo mode. A number of the embedded defects can be seen, and we discuss how their relative detectability can be quantified by comparison to the response from nearby rebar. We next discuss through-transmission measurements made using pairs of 1600-MHz and 900-MHz antennas, and the analysis of that data to deduce the average electromagnetic (EM) wave speed and attenuation of the concrete. Through the 40-inch thickness, attenuation rises approximately linearly with frequency at a rate near 0.7 dB/inch/GHz. However, there is evidence that EM properties vary with depth in the block. We conclude with a brief summary and a discussion of possible future work.

  12. Multi-frequency synthetic-aperture imaging with a lightweight ground penetrating radar system

    NASA Astrophysics Data System (ADS)

    Koppenjan, Steven K.; Allen, Curt M.; Gardner, Duane; Wong, Howard R.; Lee, Hua; Lockwood, Stephanie J.

    2000-03-01

    The detection of buried objects, particularly hazardous waste containers and unexploded ordnance (UXO), has gained significant interest in the Unites States in the late 1990s. The desire to remediate the thousands of sites worldwide has become an increasing concern and the application of radar to this problem has received renewed attention. The US Department of Energy's Special Technologies Laboratory (STL), operated by Bechtel Nevada, has developed several frequency-modulated, continuous-wave (FM-CW) ground penetrating radar (GPR) units. To meet technical requirements for higher-resolution data, STL and the University of California, Santa Barbara (UCSB) is investigating advanced GPR hardware, signal processing, and synthetic-aperture imaging with the development of an innovative system. The goal is to design and fabricate a lightweight, battery-operated unit that does not require surface contact, can be operated by a novice user, and can achieve improved resolution. The latter is accomplished by using synthetic-aperture imaging, which forms the subsurface images by fully utilizing the data sequences collectively along a scan path. We also present the backward propagation algorithm as the basic structure of the multiple-frequency tomographic imaging technique, and the conventional fast Fourier transform (FFT) method which can be described as a degenerated case of the model where the computation procedure is approximated under the narrow-beam assumption.

  13. Subsurface object position and image correction for standoff Ground Penetrating Radar

    SciTech Connect

    Kane, R.J.

    1994-05-01

    Present applications of standoff (airborne) Ground Penetrating SAR (Synthetic Aperture Radar) allows objects near the surface to be detected but only provides an approximation for the actual location and image. When single media models are employed the lack of correction for the phase velocity and refractive changes at the air/soil interface result in object distortions. Positional errors and image distortions comparable to the size of the object are possible. Correction is possible, if the media properties are known, by modeling the scene as a two-layer medium and accounting for the propagation effects. The propagation parameters for the lower media are estimated in the migration of observable responses for surface and subsurface objects. This approach allows for corrected images to subsurface objects to be produced after data collection. Surface objects will be distorted as a result of this process. The modeling process, simulations, and results with field data will be discussed. An improvement by a factor of two would enable standoff radar to detect objects at depths of on meter or more benefiting Unexploded Ordnance (UXO) and hazardous waste site survey activities.

  14. Estimating the impulse response of buried objects from ground-penetrating radar signals

    NASA Astrophysics Data System (ADS)

    van der Lijn, Fedde; Roth, Friedrich; Verhaegen, Michel

    2003-09-01

    This paper presents a novel deconvolution algorithm designed to estimate the impulse response of buried objects based on ground penetrating radar (GPR) signals. The impulse response is a rich source of information about the buried object and therefore very useful for intelligent signal processing of GPR data. For example, it can be used in a target classification scheme to reduce the false alarm rate in demining operations. Estimating the target impulse response from the incident and scattered radar signals is a basic deconvolution problem. However, noise sensitivity and ground dispersion prevent the use of simple deconvolution methods like linear least squares deconvolution. Instead, a new deconvolution algorithm has been developed that computes estimates adhering to a physical impulse response model and that can be characterized by a limited number of parameters. It is shown that the new algorithm is robust with respect to noise and that it can deal with ground dispersion. The general performance of the algorithm has been tested on data generated by finite-difference time-domain (FDTD) simulations. The results demonstrate that the algorithm can distinguish between different dielectric and metal targets, making it very suitable for use in a classification scheme. Moreover, since the estimated impulse responses have physical meaning they can be related to target characteristics such as size and material properties. A direct application of this is the estimation of the permittivity of a dielectric target from its impulse response and that of a calibration target.

  15. Digital Terrestrial Video Broadcast Interference Suppression in Forward-Looking Ground Penetrating Radar Systems

    NASA Astrophysics Data System (ADS)

    Rial, F. I.; Mendez-Rial, Roi; Lawadka, Lukasz; Gonzalez-Huici, Maria A.

    2014-11-01

    In this paper we show how radio frequency interference (RFI) generated by digital video broadcasting terrestrial and digital audio broadcasting transmitters can be an important noise source for forward-looking ground penetrating radar (FLGPR) systems. Even in remote locations the average interference power sometimes exceeds ultra-wideband signals by many dB, becoming the limiting factor in the system sensitivity. The overall problem of RFI and its impact in GPR systems is briefly described and several signal processing approaches to removal of RFI are discussed. These include spectral estimation and coherent subtraction algorithms and various filter approaches which have been developed and applied by the research community in similar contexts. We evaluate the performance of these methods by simulating two different scenarios submitted to real RFI acquired with a FLGPR system developed at the Fraunhofer Institute for High Frequency Physics and Radar Techniques (FHR), (GER). The effectiveness of these algorithms in removing RFI is presented using some performance indices after suppression.

  16. Bistatic sounding of the deep subsurface with a Ground Penetrating Radar - Experimental validation

    NASA Astrophysics Data System (ADS)

    Ciarletti, Valérie; Le Gall, A.; Clifford, S. M.; Corbel, Ch.; Dolon, F.; Ney, R.; Berthelier, J. J.

    2015-11-01

    Electromagnetic Investigation of the Sub-Surface (EISS) is a Ground Penetrating Radar (GPR) operating at very low frequencies in the HF range (2-4 MHz) that was designed to investigate the composition and structure of the Martian subsurface to depths of ~1 km. EISS can operate in both a monostatic and bistatic configuration, the latter being made possible by the simultaneous operation of two separate instrument platforms. The first, a fixed lander, utilizes one surface-deployed dipole antenna made of two 35 m-long resistively-loaded monopoles to transmit radar pulses into the subsurface. Echoes from subsurface reflectors are then received by either similar electrical receiving antennas (on the lander) or by a much smaller magnetic sensor that can be mounted either on the lander or on a mobile platform, such as a rover. In this paper, we report on the successful test of EISS bistatic mode of operation during a field campaign in the West Egyptian desert. From the analysis of the measured propagation delays, the dielectric constant and the depth of several reflecting subsurface interfaces were retrieved. Up to 226 coherent additions (or stacking) were performed resulting in the detection of buried interfaces and in particular of the Nubian Aquifer at a depth >200 m. The results obtained with the small magnetic sensor were consistent with those obtained with the electrical antennas, suggesting that such an experiment can meet the constraints of a space mission.

  17. Deep belief networks for false alarm rejection in forward-looking ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Becker, John; Havens, Timothy C.; Pinar, Anthony; Schulz, Timothy J.

    2015-05-01

    Explosive hazards are one of the most deadly threats in modern conflicts. The U.S. Army is interested in a reliable way to detect these hazards at range. A promising way of accomplishing this task is using a forward-looking ground-penetrating radar (FLGPR) system. Recently, the Army has been testing a system that utilizes both L-band and X-band radar arrays on a vehicle mounted platform. Using data from this system, we sought to improve the performance of a constant false-alarm-rate (CFAR) prescreener through the use of a deep belief network (DBN). DBNs have also been shown to perform exceptionally well at generalized anomaly detection. They combine unsupervised pre-training with supervised fine-tuning to generate low-dimensional representations of high-dimensional input data. We seek to take advantage of these two properties by training a DBN on the features of the CFAR prescreener's false alarms (FAs) and then use that DBN to separate FAs from true positives. Our analysis shows that this method improves the detection statistics significantly. By training the DBN on a combination of image features, we were able to significantly increase the probability of detection while maintaining a nominal number of false alarms per square meter. Our research shows that DBNs are a good candidate for improving detection rates in FLGPR systems.

  18. Ground-penetrating radar surveying in support of archeological site investigations

    NASA Astrophysics Data System (ADS)

    Baker, Jesse A.; Anderson, Neil L.; Pilles, Peter J.

    1997-12-01

    In April and July of 1996, ground-penetrating radar (GPR) surveys were conducted in support of archeological investigations at Flagstaff, Arizona and Sebastian, Florida, respectively. A GSSI SIR System 8 radar unit with a 500-MHz monostatic antenna was used for both surveys. The Flagstaff, Arizona survey was conducted at Elden Pueblo Ruins. The site is located in a coniferous forest and characterized by a myriad of surficial and subsurface features. Surficial features consisted mostly of pottery shards and the remnants of rock walled structures. The subsurface features consist mostly of rock lined pits, stone walls, and grave sites covered by a soil layer of variable thickness. The soil is derived from volcanic clastics and the underlying Kaibab Limestone bedrock. GPR profiles were acquired across various locations, some of which had been previously excavated and backfilled by archeologists. The main objectives were to determine the utility of the GPR technique with respect to locating subsurface features of archeological interest, determine the optimum field parameters in the area, and direct further field work. The Sebastian, Florida survey was conducted along the Atlantic coastline. Data were acquired along five beaches and one coastal sand dune. The beaches and dunes of the area are composed of a medium to coarse grained sand, containing quartz grains and carbonates. The principle objective of the Sebastian, Florida survey was to locate wreckage from a Spanish treasure fleet. A secondary objective was to determine the utility of GPR in a near shore marine environment.

  19. Clutter and target discrimination in forward-looking ground penetrating radar using sparse structured basis pursuits

    NASA Astrophysics Data System (ADS)

    Camilo, Joseph A.; Malof, Jordan M.; Torrione, Peter A.; Collins, Leslie M.; Morton, Kenneth D.

    2015-05-01

    Forward-looking ground penetrating radar (FLGPR) is a remote sensing modality that has recently been investigated for buried threat detection. FLGPR offers greater standoff than other downward-looking modalities such as electromagnetic induction and downward-looking GPR, but it suffers from high false alarm rates due to surface and ground clutter. A stepped frequency FLGPR system consists of multiple radars with varying polarizations and bands, each of which interacts differently with subsurface materials and therefore might potentially be able to discriminate clutter from true buried targets. However, it is unclear which combinations of bands and polarizations would be most useful for discrimination or how to fuse them. This work applies sparse structured basis pursuit, a supervised statistical model which searches for sets of bands that are collectively effective for discriminating clutter from targets. The algorithm works by trying to minimize the number of selected items in a dictionary of signals; in this case the separate bands and polarizations make up the dictionary elements. A structured basis pursuit algorithm is employed to gather groups of modes together in collections to eliminate whole polarizations or sensors. The approach is applied to a large collection of FLGPR data for data around emplaced target and non-target clutter. The results show that a sparse structure basis pursuits outperforms a conventional CFAR anomaly detector while also pruning out unnecessary bands of the FLGPR sensor.

  20. A ground-penetrating radar survey for archaeological investigations in an urban area (Lecce, Italy)

    NASA Astrophysics Data System (ADS)

    Basile, V.; Carrozzo, M. T.; Negri, S.; Nuzzo, L.; Quarta, T.; Villani, A. V.

    2000-04-01

    A ground-penetrating radar (GPR) survey, using mostly a 500 MHz antenna, was carried out in an urban area (Lecce, Italy) to obtain a detailed characterization of the most superficial layers, where presumably archaeological structures are buried, and to quickly identify anomalous zones for excavation. In the area, the presence of remnants of a historical Franciscan friary (built in 1432 and pulled down in 1971) and, probably, of more ancient (Roman and/or Messapic) features was expected. The geological setting (mainly wet calcarenite named "Pietra Leccese") was not the most favourable for the application of GPR methodology because of an expected high attenuation of electromagnetic energy. The low penetration depth of the signal, not exceeding 1 m and even using a 100 MHz antenna, made it possible to obtain information only between the ground level and the top of the calcarenitic basement. Data recorded along parallel profiles, 1 m spaced, prevented the clear identification of the walls of the historical building constructed in "Pietra Leccese" blocks, because of the weak contrast in the electromagnetic parameters with respect to the hosting material. On the other hand, the analysis of the radar sections allowed for identification and reconstruction of the shape and extension of a barrel-vault cavity, subsequently confirmed by archaeological excavations. Time slice representations were used as a tool to locate other features including modern-day urban utilities and the planimetric development of the barrel-vault cavity.

  1. Stratigraphic profiling with ground-penetrating radar in permafrost: A review of possible analogs for Mars

    NASA Astrophysics Data System (ADS)

    Arcone, Steven A.; Prentice, Michael L.; Delaney, Allan J.

    2002-11-01

    We review our past and ongoing use of ground-penetrating radar to investigate permafrost in Alaska and in the Dry Valleys of Antarctica. The results may be relevant to radar efforts on Mars because of arid conditions and the presence of ice. The pulses were centered at 50, 100, and 400 MHz. We interpret profiles from two sites in the eastern Taylor Valley to show glaciolacustrine and glaciofluvial stratigraphy. The maximum depth of stratigraphy profiled there was about 33 m. Near Fairbanks, Alaska, the depth of penetration at 50 MHz was near 80 m in marginally frozen and stratified alluvial sands. At the Fairbanks sites, supplementary drilling was required to differentiate between reflections from conductive bedrock, a graphitic schist, and those from the water table at depths of 20-25 m. At a site on the North Slope of Alaska, we profiled present and remnant freezing fronts in an alluvial floodplain. The relative permittivity at most sites ranged between about 4 and 5.5, which is consistent with dry conditions, the mineralogy, and low ice content. Weak interface reflectivity or the lack of further interfaces may have limited the interpretation of maximum penetration where no water table was present because signal absorption should have been low and scarce diffractions imply that scattering was weak. The interface reflectivities beneath Taylor Valley may be a function of only density contrasts, since free water, and possibly ice, is absent.

  2. A Study of Clutter Reduction Techniques in Wide Bandwidth HF/VHF Deep Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Hammett, Darien J.

    2002-08-01

    Reducing clutter is one of the most daunting problems a radar processing engineer faces. Clutter causes a significant problem when attempting to detect sub-surface targets, as any significant change in the ground dielectric will produce a return at the receiver. The difficulty in reducing the clutter is compounded by the fact that the spectral characteristics of the clutter are similar to that of the target. While there are many methods that exist to reduce clutter, few do not require a prior information of either the target or the clutter. There are applications, of interest to the electromagnetic community, that are restricted in the amount of a prior information available to them. Estimation-subtraction filters calculate an estimate of the clutter from the statistics of the data collected and subtract that estimate from the original data. The Wiener filter has long been used as a way to suppress noise signals when a target reference is known. Using it to reduce clutter is a relatively new area of research. This research proposes estimation-subtraction filters and an application of the Wiener filter, which do not require a priori information to reduce the clutter of a bi-static synthetic aperture based, wideband deep ground penetrating radar system. The results of applying these filters to data collected in this way, at these depths, are illustrated here for the first time. x

  3. Migration-based SAR imaging for ground-penetrating radar systems

    NASA Astrophysics Data System (ADS)

    Gu, Kunlong; Wang, Gang; Li, Jian

    2003-09-01

    We consider migration based synthetic aperture radar (SAR) imaging of surfaced or shallowly buried objects using both down-looking and forward-looking ground penetrating radar (GPR). The well-known migration approaches devised to image the interior of the earth are based on wave equations and have been widely and successfully used in seismic signal processing for oil exploration for decades. They have exhibited great potentials and convenience to image the underground objects buried in complicated propagation medium. Compared to the ray-tracing based SAR imaging methods, the migration based SAR imaging approaches are more suited for the imaging of the underground objects due to their simple and direct treatment of the oblique incidence at the air-ground interface and the propagation velocity variation in the soil. In this paper, we apply the phase-shift migration approach to both the constant-offset and the common-shot experimental data collected by the PSI (Planning Systems Inc.) GPR systems. We will address the spatial aliasing problems related to the application of migration to the GPR data and the spatial zero-padding approach to circumvent the problem successfully.

  4. Curvelet filter based prescreener for explosive hazard detection in hand-held ground penetrating radar

    NASA Astrophysics Data System (ADS)

    White, Julie L.; Anderson, Derek T.; Ball, John E.; Parker, Brian

    2016-05-01

    Explosive hazards, above and below ground, are a serious threat to civilians and soldiers. In an attempt to mitigate these threats, different forms of explosive hazard detection (EHD) exist; e.g., multi-sensor hand-held platforms, downward looking and forward looking vehicle mounted platforms, etc. Robust detection of these threats resides in the processing and fusion of different data from multiple sensing modalities, e.g., radar, infrared, electromagnetic induction (EMI), etc. Herein, we focus on a new energy-based prescreener in hand-held ground penetrating radar (GPR). First, we Curvelet filter B-scan signal data using either Reverse-Reconstruction followed by Enhancement (RRE) or selectivity with respect to wedge information in the Curvelet transform. Next, we aggregate the result of a bank of matched filters and run a size contrast filter with Bhattacharyya distance. Alarms are then combined using weighted mean shift clustering. Results are demonstrated in the context of receiver operating characteristics (ROC) curve performance on data from a U. S. Army test site that contains multiple target and clutter types, burial depths and times of the day.

  5. Background adaptive division filtering for hand-held ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Lee, Matthew A.; Anderson, Derek T.; Ball, John E.; White, Julie L.

    2016-05-01

    The challenge in detecting explosive hazards is that there are multiple types of targets buried at different depths in a highlycluttered environment. A wide array of target and clutter signatures exist, which makes detection algorithm design difficult. Such explosive hazards are typically deployed in past and present war zones and they pose a grave threat to the safety of civilians and soldiers alike. This paper focuses on a new image enhancement technique for hand-held ground penetrating radar (GPR). Advantages of the proposed technique is it runs in real-time and it does not require the radar to remain at a constant distance from the ground. Herein, we evaluate the performance of the proposed technique using data collected from a U.S. Army test site, which includes targets with varying amounts of metal content, placement depths, clutter and times of day. Receiver operating characteristic (ROC) curve-based results are presented for the detection of shallow, medium and deeply buried targets. Preliminary results are very encouraging and they demonstrate the usefulness of the proposed filtering technique.

  6. Numerical parametric study of buried target ground-penetrating radar signature

    NASA Astrophysics Data System (ADS)

    van den Bosch, Idesbald C.; Druyts, Pascal; Acheroy, Marc; Huynen, Isabelle

    2006-05-01

    The assessment of the performances of ground-penetrating radar (GPR) in humanitarian demining is an important problem. These performances are related to the relative strength of the target radar response with respect to that of the soil. Many parameters influence both responses. The physical and geometrical parameters that influence the target signature include the soil electromagnetic (EM) constitutive parameters, the target depth and orientation with respect to the soil surface, the antenna height and the target EM and geometrical properties. This work presents a numerical parametric study of the soil and target radar signatures. The advantages of the numerical approach are: it allows for a separate study of the influence of each parameters on the radar responses, it is fast, cheap, generic with regards to hardware, and finally it is not prone to experimental errors and hardware failures or misuse. Moreover it is always possible to link the numerical experiments with a particular hardware by characterizing this latter. However, a number of simplifications, such as modeling the soil as a planar multilayered medium, are introduced to keep the problem tractable. This study yields surprising results, such as for example the possibility of considering the target in homogeneous space for computing its signature, as soon as it is a few centimeters deep. The target considered in the numerical experiments is a dielectric cylinder representing an AP mine, with diameter 6 cm and height 5 cm, and ɛ rt=3. These values are chosen to approach as much as possible the physical properties of the M35BG AP mine, which is small and therefore difficult to detect.

  7. In situ characterization of forest litter using ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    André, Frédéric; Jonard, François; Jonard, Mathieu; Lambot, Sébastien

    2016-03-01

    Decomposing litter accumulated on the soil surface in forests plays a major role in several ecosystem processes; its detailed characterization is therefore essential for thorough understanding of ecosystem functioning. In addition, litter is known to affect remote sensing radar data over forested areas and their proper processing requires accurate quantification of litter scattering properties. In the present study, ultrawideband (0.8-2.2 GHz) ground-penetrating radar (GPR) data were collected in situ for a wide range of litter types to investigate the potential of the technique to reconstruct litter horizons in undisturbed natural conditions. Radar data were processed resorting to full-wave inversion. Good agreement was generally found between estimated and measured litter layer thicknesses, with root-mean-square error values around 1 cm for recently fallen litter (OL layer) and around 2 cm for fragmented litter in partial decomposition (OF layer) and total litter (OL + OF). Nevertheless, significant correlations between estimated and measured thicknesses were found for total litter only. Inaccuracies in the reconstruction of the individual litter horizons were mainly attributed to weak dielectric contrasts amongst litter layers, with absolute differences in relative dielectric permittivity values often lower than 2 between humus horizons, and to uncertainties in the ground truth values. Radar signal inversions also provided reliable estimates of litter electromagnetic properties, with average relative dielectric permittivity values around 2.9 and 6.3 for OL and OF litters, respectively. These results are encouraging for the use of GPR for noninvasive characterization and mapping of forest litter. Perspectives for the application of the technique in biogeosciences are discussed.

  8. Use of Ground Penetrating Radar for Site Investigation of Low-Volume Roadways and Design Recommendations

    NASA Astrophysics Data System (ADS)

    Scullion, T.; Saarenketo, T.

    2002-07-01

    This report will present several case studies describing the use of ground penetrating radar (GPR) technology for site investigations. Two types of GPR will be described-the air-launched and ground-coupled systems. The use of air-launched radar is well established within the Texas Department of Transportation (TxDOT). The limitation of this technology is its depth of penetration. While providing very useful information on the surface and base layers, it provides little information on the sub-grade soils. The use of low-frequency ground-coupled radar systems will provide little useful near-surface information but it can provide data on sub-grade properties and how they vary along a project. Combining both radar types can potentially provide a comprehensive subsurface investigative tool for both new pavement construction and for major pavement rehabilitation projects. In this report a brief description will be provided of the different systems together with the software used to process the GPR signals. Air-launched data are processed with the COLORMAP system developed by the Texas Transportation Institute. The ground-coupled data are processed using the Road Doctor system developed by Roadscanners, Inc. of Finland. The case studies presented were collected on actual TxDOT evaluation projects mainly in the Bryan District. They range from near-surface applications where the goal was to identify changes in pavement structure which were not available in construction records to identifying the areas beneath the pavement subsidence associated with strip mining activities.

  9. The Feasibility of Ground-Penetrating Radar as a Tool for Snowpack Monitoring

    NASA Astrophysics Data System (ADS)

    Heilig, Achim; Schneebeli, Martin; Eisen, Olaf

    2009-04-01

    Ground-penetrating radar systems (GPR) offer a wide field of applications. Especially in cryospheric implementations GPR proved to be an adequate tool to determine fast and non-destructively media transitions. In this study, we analyse the feasibility of impulse radar in recording internal snowpack transitions of density or moisture content. The utilized impulse radar systems for this research purpose are commercially available and the gathered data needs no calibration measurement for interpretation, which is a distinct advantage in comparison to frequency modulated continuous wave (FMCW) systems. Currently available methods monitoring seasonal snowpacks are either destructive as snow profiling or insufficient for measuring in slope areas or to determine snow stratigraphy as ultra-sonic sensors. Additionally, the risk exposure for the profiling teams is often a limiting factor for the data acquisition, especially in avalanche paths and ridge areas. In such regions an all-season monitoring system must be secured against being destroyed by avalanches. Thus, the implemented system operates from beneath the snowpack measuring in upward direction. The GPR system was tested in several varying snow conditions as cold dry snow and wet snowpacks. Furthermore, different frequencies, polarisations and two different radar systems were analysed on their applicability for the snowpack monitoring from beneath and the system was utilized in periods with various meteorological parameter. The results of these preliminary tests showed, that with a moved antenna it is possible to record snow layers in dry snow with adequate density steps and layer thickness, supplementary to the snow depth. A one meter-thick wet snowpack was penetrateable although the signal was very much attenuated. GPR systems with frequencies above 1 GHz provided insufficient pentration depth in late season snowpacks. Analysis of reflection phases allowed interpretation of their physical origin in terms of

  10. Civil Engineering Applications of Ground Penetrating Radar Recent Advances @ the ELEDIA Research Center

    NASA Astrophysics Data System (ADS)

    Salucci, Marco; Tenuti, Lorenza; Nardin, Cristina; Oliveri, Giacomo; Viani, Federico; Rocca, Paolo; Massa, Andrea

    2014-05-01

    The application of non-destructive testing and evaluation (NDT/NDE) methodologies in civil engineering has raised a growing interest during the last years because of its potential impact in several different scenarios. As a consequence, Ground Penetrating Radar (GPR) technologies have been widely adopted as an instrument for the inspection of the structural stability of buildings and for the detection of cracks and voids. In this framework, the development and validation of GPR algorithms and methodologies represents one of the most active research areas within the ELEDIA Research Center of the University of Trento. More in detail, great efforts have been devoted towards the development of inversion techniques based on the integration of deterministic and stochastic search algorithms with multi-focusing strategies. These approaches proved to be effective in mitigating the effects of both nonlinearity and ill-posedness of microwave imaging problems, which represent the well-known issues arising in GPR inverse scattering formulations. More in detail, a regularized multi-resolution approach based on the Inexact Newton Method (INM) has been recently applied to subsurface prospecting, showing a remarkable advantage over a single-resolution implementation [1]. Moreover, the use of multi-frequency or frequency-hopping strategies to exploit the information coming from GPR data collected in time domain and transformed into its frequency components has been proposed as well. In this framework, the effectiveness of the multi-resolution multi-frequency techniques has been proven on synthetic data generated with numerical models such as GprMax [2]. The application of inversion algorithms based on Bayesian Compressive Sampling (BCS) [3][4] to GPR is currently under investigation, as well, in order to exploit their capability to provide satisfactory reconstructions in presence of single and multiple sparse scatterers [3][4]. Furthermore, multi-scaling approaches exploiting level

  11. Ground penetrating radar data analyzed in frequency and time domain for engineering issues

    NASA Astrophysics Data System (ADS)

    Capozzoli, Luigi; Giampaolo, Valeria; Votta, Mario; Rizzo, Enzo

    2014-05-01

    Non-destructive testing (NDT) allows to analyze reinforced concrete and masonry structures, in order to identify gaps, defects, delaminations, and fracture. In the field of engineering, non-invasive diagnostic is used to test the processes of construction and maintenance of buildings and artifacts of the individual components, to reduce analysis time and costs of intervention (Proto et al., 2010). Ground penetrating radar (GPR) allows to evaluate with a good effectiveness the state of conservation of engineering construction (Mellet 1995)). But there are some uncertainties in GPR data due to the complexity of artificial objects. In this work we try to evaluate the capability of GPR for the characterization of building structures in the laboratory and in-situ. In particular the focus of this research consists in integrate spectral analysis to time domain data to enhance information obtained in a classical GPR processing approach. For this reason we have applied spectral analysis to localize and characterize the presence of extraneous bodies located in a test site rebuilt in laboratory to simulate a part of a typical concrete road. The test site is a segment of a road superimposed on two different layers of sand and gravel of varying thickness inside which were introduced steel rebar, PVC and aluminium pipes. This structure has also been cracked in a predetermined area and hidden internal fractures were investigated. The GPR has allowed to characterize the panel in a non-invasive mode and radargrams were acquired using two-dimensional and three-dimensional models from data obtained with the use of 400, 900, 1500 and 2000 Mhz antennas. We have also studied with 2 GHz antenna a beam of 'to years precast bridge characterized by a high state of decay. The last case study consisted in the characterization of a radiant floor analyzed with an integrated use of GPR and infrared thermography. In the frequency domain analysis has been possible to determine variations in the

  12. Imaging of Archaeological Remains at Barcombe Roman Villa using Microwave Tomographic Depictions of Ground Penetrating Radar Data

    NASA Astrophysics Data System (ADS)

    Soldovieri, F.; Utsi, E.; Alani, A.; Persico, R.

    2012-04-01

    to 600MHz (the frequency range of the antennas used). The 2-dimensional plots were formed into a 3-dimensional cube and time slices extracted, on the basis of maximum signal return, at 16ns, 25ns and 29ns. In this work, we show the reprocessing of the GPR data via a microwave tomographic approach based on a linear approximation of the inverse scattering problem [4]. In particular, the effectiveness of this approach ensures a reliable and high resolution representation/visualization of the scene very large in terms of probing wavelength. This has been made possible thanks to the adoption of the approach presented in [5] where the 3D representation was achieved by performing 2D reconstruction and after obtaining the 3D Cube from these 2D reconstructed profiles. In particular, the re-examination of GPR data using microwave tomography has allowed to improve definition of the villa outline and to detect earlier prehistoric remains. [1] Rudling, D., & Butler, C. "Roundhouse to Villa" in Sussex Past & Present 95, pp 6 - 7, 2001. [2] Utsi, E., Wortley Villa paper currently in preparation of EAGE special issue. [3] Utsi, E., & Alani, A. "Barcombe Roman Villa: An Exercise in GPR Time Slicingand Comparative Geophysics", in Koppenjan, S., & Hua, L. (eds) Proceedings of the Ninth International Conference on Ground Penetrating Radar, 2002. [4] F. Soldovieri, R. Persico, E. Utsi, V. Utsi, "The application of inverse scattering techniques with ground penetrating radar to the problem of rebar location in concrete", NDT & E International, Vol. 39, Issue 7, October 2006, Pages 602-607. [5] R. Persico, F. Soldovieri, E. Utsi, "Microwave tomography for processing of GPR data at Ballachulish", Journal of Geophysics and Engineering, vol.7, no. 2, pp. 164-173, June 2010

  13. Snow Mass Quantification and Avalanche Victim Search by Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Jaedicke, Christian

    2003-11-01

    Ground penetrating radar (GPR) systems can be used in many applications of snow and ice research. The information from the GPR is used to identify and interpret layers, objects and different structures in the snow. A commercially available GPR system was further developed to work in the rough environment of snow and ice. The applied GPR is a 900 MHz system that easily reaches snow depths of up to 10 meters. The system was calibrated in the course of several manual snow depth measurements during each survey. The depth resolution depends on the snow type and is around +/-0.1 m. The GPR system is carried alongside a line of interest and is triggered by an odometer wheel at regular adjustable steps. All equipment is mounted in a sledge and is pulled by a snowmobile over the snow surface. This setup allows for an efficient coverage of several kilometers of terrain profiles. The radar profiles give a real time two-dimensional impression of structures and objects and the interface between snow and the underlying ground. The actual radar profile is shown on a screen on the sledge allowing the immediate marking of objects and structures. During the past three years the instrument was successfully used for the study of snow distributions, for the detection of glacier crevasses under the snow cover, and for the search of avalanche victims in avalanche debris. The results show the capability of the instrument to detect persons and objects in the snow cover. In the future, this device may be a new tool for avalanche rescue operations. Today, the size and weight of the system prevents the accessing of very steep slopes and areas not accessible to snowmobiles. Further developments will decrease the size of the system and make it a valuable tool to quantify snow masses in avalanche release zones and run-out areas.

  14. Characterization of forest litter horizons through full-wave inversion of ground-penetrating radar data

    NASA Astrophysics Data System (ADS)

    André, Frédéric; Jonard, Mathieu; Jonard, François; Lambot, Sébastien

    2015-04-01

    Decomposing litter accumulated at the soil surface in forest ecosystems play a major role in a series of ecosystem processes (soil carbon sequestration, nutrient release through decomposition, water retention, buffering of soil temperature variations, tree regeneration, population dynamics of ground vegetation and soil fauna, ...). Besides, the presence of litter is acknowledged to influence remote sensing radar data over forested areas and accurate quantification of litter radiative properties is essential for proper processing of these data. In these respects, ground-penetrating radar (GPR) presents particular interests, potentially allowing for fast and non-invasive characterization of organic layers with fine spatial and/or temporal resolutions as well as for providing detailed information on litter electrical properties which are required for modeling either active or passive microwave remote sensing data. We designed an experiment in order to analyze the backscattering from forest litter horizons and to investigate the potentialities of GPR for retrieving the physical properties of these horizons. For that purpose, we used an ultrawide band radar system connected to a transmitting and receiving horn antenna. The GPR data were processed resorting to full-wave inversion of the signal, through which antenna effects are accounted for. In a first step, GPR data were acquired over artificially reconstructed layers of three different beech litter types (i.e., (i) recently fallen litter with easily discernible plant organs (OL layer), (ii) fragmented litter in partial decomposition without entire plant organs (OF layer) and (iii) combination of OL and OF litter layers) and considering in each case a range of layer thicknesses. In a second step, so as to validate the adopted methodology in real natural conditions, GPR measurements were performed in situ along a transect crossing a wide range of litter properties in terms of thickness and composition through stands of

  15. Ground-penetrating radar exploration for ancient monuments at the Valley of Mummies -Kilo 6, Bahariya Oasis, Egypt

    NASA Astrophysics Data System (ADS)

    Shaaban, Fathy A.; Abbas, Abbas M.; Atya, Magdy A.; Hafez, Mahfouz A.

    2009-06-01

    A Valley of Mummies was discovered recently by an Egyptian team at Bahariya Oasis, located about 380 km west of the pyramids. Four tombs were excavated, and inside them were found one hundred and five mummies (105), many of them beautifully gilded. These mummies, many sumptuously decorated with religious scenes, are the very best Roman-Period mummies ever found in Egypt. These remains are around 2000 years old, but they are in remarkable condition. A Ground-Penetrating Radar (GPR) had proved successful in detecting the cavities in resistive soil in which the mummies were found. The GPR survey conducted near the earlier-discovered tombs at Kilo-6 El-Bahariya to Farafra Oasis road is the focus of this paper. The GPR survey was conducted using the SIR-2000 attached to a 200 MHz monostatic antenna. The two areas to be surveyed were selected by the archaeologists in situ. Area one was 40 m × 40 m and Area two was 30 m × 15 m. A grid pattern survey in one direction; with one-meter profile spacing was done to both areas. In addition, a focusing survey was undertaken over the entire Area one. In addition, twenty long GPR profiles were conducted in an attempt to determine the outer, expected limits of the burial area. After the data acquisition, Reflex software was used for data processing and presentation. The final results of the radar survey: in the form of 2D radar records, time slices and 3D block diagrams; were used to guide the archaeologists during the excavation process. The excavation processes have been completed by the archaeologists, and many tombs and mummies were discovered. It is worthy to mention that, the excavations and location of tombs and cavities matched strongly with the GPR results.

  16. Ground penetrating radar study of a strand shoreline in northeastern South Carolina.

    NASA Astrophysics Data System (ADS)

    Wright, E.; Harris, M.; Correia, K.

    2008-12-01

    The 75 km long Grand Strand is the primary shoreline type of northeastern South Carolina and is forming by landward retreat of the shoreline intersecting the paleo Myrtle Beach barrier system. Previous ground penetrating radar studies have examined the geologic architecture of different stages of the regional shoreline transgression: (1) current barrier island systems to the north and south of the central Grand Strand that have transgressed across irregular Pleistocene paleo landscape but have not yet intersected the emergent Quaternary terraces, (2) shorelines with shore-parallel coastal lakes and vegetated wetlands formed at the intersection of the transgressive shoreline and the emergent terraces, and (3) coastal shorelines that are fully welded to the Pleistocene headlands. This study uses GPR to examine the pre- transgressive architecture of shorelines along the emergent paleo barrier system, in particular sections of the coastline with linear paralic wetlands that occupy lows within the paleo barrier system. Study of this pre- transgressive architecture will help to better understand the geologic development of the compound paleo Myrtle Beach barriers as well as refine geologic interpretation of the transgressing shorelines to the north and south that are currently and will be intersecting this paleo barrier system.

  17. Improved analysis of zero offset profiling borehole ground penetrating radar measurements for hydrologic monitoring

    NASA Astrophysics Data System (ADS)

    Rucker, D. F.; Ferre, T. P. A.

    2003-04-01

    Zero Offset Profiling (ZOP) Borehole Ground Penetrating Radar (BGPR) offers the possibility of monitoring the water content to great depths with high spatial and temporal resolution. This could greatly enhance our ability to monitor transient hydrologic processes, such as the advance of a wetting front or the accumulation or removal of light nonaqueous phase liquids. However, the presence of critical refractions from subsurface layers of contrasting volumetric water contents can limit the utility of ZOP BGPR. We present a method to infer the volumetric water content of near surface sediments based on the slope of a ZOP BGPR travel time profile. In addition, we present a method whereby critical refractions can be accounted for, leading to reconstruction of the true velocity profile from measured ZOP travel time profiles. This method relies on rapid, efficient genetic algorithms to identify the velocity profile that corresponds with the measured first arrival travel time profile. Finally, we show that this velocity reconstruction approach can allow for the analysis of hydraulic properties from ZOP BGPR measurements made during the advance of a wetting front and can improve the ability of ZOP BGPR to identify thin horizons associated with textural changes or the presence of nonaqueous phase liquids in the subsurface.

  18. Monitoring soil moisture dynamics via ground-penetrating radar survey of agriculture fields after irrigation

    NASA Astrophysics Data System (ADS)

    Muro, G.

    2015-12-01

    It is possible to examine the quality of ground-penetrating radar (GPR) as a measure of soil moisture content in the shallow vadose zone, where roots are most abundant and water conservation best management practices are critical in active agricultural fields. By analyzing temporal samplings of 100 Mhz reflection profiles and common-midpoint (CMP) soundings over a full growing season, the variability of vertical soil moisture distribution directly after irrigation events are characterized throughout the lifecycle of a production crop. Reflection profiles produce high-resolution travel time data and summed results of CMP sounding data provide sampling depth estimates for the weak, but coherent reflections amid strong point scatterers. The high ratio of clay in the soil limits the resolution of downward propagation of infiltrating moisture after irrigation; synthetic data analysis compared against soil moisture lysimeter logs throughout the profile allow identification of the discrete soil moisture content variation in the measured GPR data. The nature of short duration irrigation events, evapotranspiration, and drainage behavior in relation to root depths observed in the GPR temporal data allow further examination and comparison with the variable saturation model HYDRUS-1D. After retrieving soil hydraulic properties derived from laboratory measured soil samples and simplified assumptions about boundary conditions, the project aims to achieve good agreement between simulated and measured soil moisture profiles without the need for excessive model calibration for GPR-derived soil moisture estimates in an agricultural setting.

  19. Thickness and air voids measurement on asphalt concrete pavements using ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Dhakal, Sharad Raj

    Layer thickness and air voids are important parameters in quality assurance of newly paved hot mix asphalt (HMA) pavements. A non-destructive testing (NDT) technique was used to collect layer thickness information. The thicknesses estimated by the technique were compared with core thicknesses. Ground penetrating radar (GPR) system with air coupled antennas was used for on-site pavement data collection. Two application softwares - RADAN and ROAD DOCTOR - were used to process the field data for estimating layer thicknesses and air voids along the scanned pavements. 150 mm diameter cores taken from random locations on the pavements were tested in the laboratory to determine layer thickness and air voids. Statistical analyses were conducted to compare thicknesses and generate a regression equation relating air voids and dielectric constant of the pavement material. No significant differences were found between thickness estimates from RADAN and ROAD DOCTOR softwares when compared to the core measurements. However, RADAN and ROAD DOCTOR results are marginally significantly different from each other. ROAD DOCTOR software was used to generate air voids for the pavements scanned. Laboratory results from cores were utilized to determine calibration factors for the air voids -- dielectric equation. A relationship between air voids and dielectric constant is presented. It is concluded that GPR system with air coupled antennas used alongside a reduced core testing has a potential for quality control of newly paved hot mixed asphalt pavements.

  20. Fault Detection Using Polarimetric Single-Input-Multi-Output Ground Penetrating Radar Technique in Mason, Texas

    NASA Astrophysics Data System (ADS)

    Amara, A.; Everett, M. E.

    2014-12-01

    At the Mason Mountain Wildlife Management Area (MMWMA) near Mason, Texas, we conducted a 2D ground penetrating radar (GPR) survey using single-input-multi-output (SIMO) acquisition technique to image a Pennsylvanian high-angle normal fault. At the MMWMA, the surface geology is mapped extensively but the subsurface remains largely unknown. The main objective of our study is to develop a detailed subsurface structural image of the fault and evaluate existing hypotheses on fault development. Also, to develop and apply a new methodology based on Polarimetric SIMO acquisition geometry. This new methodology allows the subsurface structures to be viewed simultaneously from different angles and can help reduce noise caused by the heterogeneities that affect the electromagnetic waves. We used a pulseEKKO pro 200 GPR with 200 MHz antennae to acquire 8 north-south lines across the fault. Each line is 30 meters long with the transmitter starting on the Town Mountain Granite, footwall, with the receiver stepping 40 cm until the end of the line crossing the fault on to the Hickory Sandstone, hanging wall. Each pass consisted of a stationary transmitter antenna and the moving receiver antenna. The data were initially processed with standard steps including low-cut dewow filter, background subtraction filter and gain control. Advanced processing techniques include migration, phased array processing, velocity analysis, and normal moveout. We will compare the GPR results with existing geophysical datasets at the same site, including electromagnetic (EM), seismic, and seismoelectric.

  1. Improving Indonesian peatland C stock estimates using ground penetrating radar (GPR) and electrical resistivity imaging (ERI)

    NASA Astrophysics Data System (ADS)

    Terry, N.; Comas, X.; Slater, L. D.; Warren, M.; Kolka, R. K.; Kristijono, A.; Sudiana, N.; Nurjaman, D.; Darusman, T.

    2014-12-01

    Tropical peatlands sequester an estimated 15% of the carbon pool from peatlands worldwide. Indonesian peatlands account for approximately 65% of all tropical peat, and are believed to be the largest global source of carbon dioxide emissions to the atmosphere from degrading peat. However, there is great uncertainty in these estimates due to insufficient data regarding the thickness of organic peat soils and their carbon content. Meanwhile, Indonesian peatlands are threatened by heightening pressure to drain and develop. Indirect geophysical methods have garnered interest for their potential to non-invasively estimate peat depth and gas content in boreal peatlands. Drawing from these techniques, we employed ground penetrating radar (GPR) and electrical resistivity imaging (ERI) in tandem with direct methods (core sampling) to evaluate the potential of these methods for tropical peatland mapping at 2 distinct study sites on West Kalimantan (Indonesia). We find that: [1] West Kalimantan peatland thicknesses estimated from GPR and ERI in intermediate/shallow peat can vary substantially over short distances (for example, > 2% over less than 0.02° surface topography gradient), [2] despite having less vertical resolution, ERI is able to better resolve peatland thickness in deep peat, and [3] GPR provides useful data regarding peat matrix attributes (such as the presence of wood layers). These results indicate GPR and ERI could help reduce uncertainty in carbon stocks and aid in responsible land management decisions in Indonesia.

  2. Advanced signal processing method for ground penetrating radar feature detection and enhancement

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Venkatachalam, Anbu Selvam; Huston, Dryver; Xia, Tian

    2014-03-01

    This paper focuses on new signal processing algorithms customized for an air coupled Ultra-Wideband (UWB) Ground Penetrating Radar (GPR) system targeting highway pavements and bridge deck inspections. The GPR hardware consists of a high-voltage pulse generator, a high speed 8 GSps real time data acquisition unit, and a customized field-programmable gate array (FPGA) control element. In comparison to most existing GPR system with low survey speeds, this system can survey at normal highway speed (60 mph) with a high horizontal resolution of up to 10 scans per centimeter. Due to the complexity and uncertainty of subsurface media, the GPR signal processing is important but challenging. In this GPR system, an adaptive GPR signal processing algorithm using Curvelet Transform, 2D high pass filtering and exponential scaling is proposed to alleviate noise and clutter while the subsurface features are preserved and enhanced. First, Curvelet Transform is used to remove the environmental and systematic noises while maintain the range resolution of the B-Scan image. Then, mathematical models for cylinder-shaped object and clutter are built. A two-dimension (2D) filter based on these models removes clutter and enhances the hyperbola feature in a B-Scan image. Finally, an exponential scaling method is applied to compensate the signal attenuation in subsurface materials and to improve the desired signal feature. For performance test and validation, rebar detection experiments and subsurface feature inspection in laboratory and field configurations are performed.

  3. Deep learning algorithms for detecting explosive hazards in ground penetrating radar data

    NASA Astrophysics Data System (ADS)

    Besaw, Lance E.; Stimac, Philip J.

    2014-05-01

    Buried explosive hazards (BEHs) have been, and continue to be, one of the most deadly threats in modern conflicts. Current handheld sensors rely on a highly trained operator for them to be effective in detecting BEHs. New algorithms are needed to reduce the burden on the operator and improve the performance of handheld BEH detectors. Traditional anomaly detection and discrimination algorithms use "hand-engineered" feature extraction techniques to characterize and classify threats. In this work we use a Deep Belief Network (DBN) to transcend the traditional approaches of BEH detection (e.g., principal component analysis and real-time novelty detection techniques). DBNs are pretrained using an unsupervised learning algorithm to generate compressed representations of unlabeled input data and form feature detectors. They are then fine-tuned using a supervised learning algorithm to form a predictive model. Using ground penetrating radar (GPR) data collected by a robotic cart swinging a handheld detector, our research demonstrates that relatively small DBNs can learn to model GPR background signals and detect BEHs with an acceptable false alarm rate (FAR). In this work, our DBNs achieved 91% probability of detection (Pd) with 1.4 false alarms per square meter when evaluated on anti-tank and anti-personnel targets at temperate and arid test sites. This research demonstrates that DBNs are a viable approach to detect and classify BEHs.

  4. Integration of Induced Polarization Imaging, Ground Penetrating Radar and geochemical analysis to characterize hydrocarbon spills

    NASA Astrophysics Data System (ADS)

    Flores Orozco, Adrian; Kreutzer, Ingrid; Bücker, Matthias; Nguyen, Frederic; Hofmann, Thilo; Döberl, Gernot

    2015-04-01

    Because of their capability to provide spatially continuous data, Induced Polarization (IP) Imaging and Ground Penetrating Radar (GPR) have recently emerged as alternative non-invasive methods for the characterization of contaminated sites. In particular, the IP method has demonstrated to be sensitive to both, changes in the chemical composition of groundwater as a result of dissolved pollutants, and to the geometry of the pore space due to the occurrence of contaminants in non-aqueous phase liquids (NAPL). Although promising, an adequate interpretation of the IP imaging results requires geochemical information obtained from the analysis of soil and water samples. However, to date just rare studies have investigated the IP response at the field scale due to different contaminant concentrations. To demonstrate the advantages of an integrated geophysical and geochemical site investigation, we present studies from different hydrocarbon-contaminated sites. We observed a linear correlation between the polarization effect and the contaminant concentration for dissolved contaminants in the saturated zone. A negligible polarization effect was observed, however, in areas associated with the occurrence of contaminants in NAPL. Compared to the contaminant distribution obtained from the geochemical analysis only, the images obtained from time-domain IP measurements significantly improved the delineation of the contaminant plume. As a first step, GPR data collected along the same profiles provided complementary structural information and improved the interpretation of the IP images. The resolution of the electrical images was further improved using regularization constraints, based on the GPR and geochemical data, in the inversion of IP data.

  5. Electromagnetic Simulations of Ground-Penetrating Radar Propagation near Lunar Pits and Lava Tubes

    NASA Technical Reports Server (NTRS)

    Zimmerman, M. I.; Carter, L. M.; Farrell, W. M.; Bleacher, J. E.; Petro, N. E.

    2013-01-01

    Placing an Orion capsule at the Earth-Moon L2 point (EML2) would potentially enable telerobotic operation of a rover on the lunar surface. The Human Exploration Virtual Institute (HEVI) is proposing that rover operations be carried out near one of the recently discovered lunar pits, which may provide radiation shielding for long duration human stays as well as a cross-disciplinary, science-rich target for nearer-term telerobotic exploration. Ground penetrating radar (GPR) instrumentation included onboard a rover has the potential to reveal many details of underground geologic structures near a pit, as well as characteristics of the pit itself. In the present work we employ the full-wave electromagnetic code MEEP to simulate such GPR reflections from a lunar pit and other subsurface features including lava tubes. These simulations will feed forward to mission concepts requiring knowledge of where to hide from harmful radiation and other environmental hazards such as plama charging and extreme diurnal temperatures.

  6. Spectral analysis of ground penetrating radar signals in concrete, metallic and plastic targets

    NASA Astrophysics Data System (ADS)

    Santos, Vinicius Rafael N. dos; Al-Nuaimy, Waleed; Porsani, Jorge Luís; Hirata, Nina S. Tomita; Alzubi, Hamzah S.

    2014-01-01

    The accuracy of detecting buried targets using ground penetrating radar (GPR) depends mainly on features that are extracted from the data. The objective of this study is to test three spectral features and evaluate the quality to provide a good discrimination among three types of materials (concrete, metallic and plastic) using the 200 MHz GPR system. The spectral features which were selected to check the interaction of the electromagnetic wave with the type of material are: the power spectral density (PSD), short-time Fourier transform (STFT) and the Wigner-Ville distribution (WVD). The analyses were performed with simulated data varying the sizes of the targets and the electrical properties (relative dielectric permittivity and electrical conductivity) of the soil. To check if the simulated data are in accordance with the real data, the same approach was applied on the data obtained in the IAG/USP test site. A noticeable difference was found in the amplitude of the studies' features in the frequency domain and these results show the strength of the signal processing to try to differentiate buried materials using GPR, and so can be used in urban planning and geotechnical studies.

  7. Ground penetrating radar antenna system analysis for prediction of earth material properties

    USGS Publications Warehouse

    Oden, C.P.; Wright, D.L.; Powers, M.H.; Olhoeft, G.

    2005-01-01

    The electrical properties of the ground directly beneath a ground penetrating radar (GPR) antenna very close to the earth's surface (ground-coupled) must be known in order to predict the antenna response. In order to investigate changing antenna response with varying ground properties, a series of finite difference time domain (FDTD) simulations were made for a bi-static (fixed horizontal offset between transmitting and receiving antennas) antenna array over a homogeneous ground. We examine the viability of using an inversion algorithm based on the simulated received waveforms to estimate the material properties of the earth near the antennas. Our analysis shows that, for a constant antenna height above the earth, the amplitude of certain frequencies in the received signal can be used to invert for the permittivity and conductivity of the ground. Once the antenna response is known, then the wave field near the antenna can be determined and sharper images of the subsurface near the antenna can be made. ?? 2005 IEEE.

  8. Model-based inversion algorithm for ground penetration radar signal processing with correlation for target classification

    NASA Astrophysics Data System (ADS)

    Patz, Mark David

    A non-intrusive buried object classifier for a ground penetrating radar (GPR) system is developed. Various GPR data sets and the implemented processing are described. A model based inversion algorithm that utilizes correlation methodology for target classification is introduced. Experimental data was collected with a continuous wave GPR. Synthetic data was generated with a newly developed software package that implements mathematical models to predict the electromagnetic returns from an underground object. Sample targets and geometries were chosen to produce nine configurations/scenarios for analysis. The real measurement sets for each configuration and the synthetic sets for a family of similar configurations were imaged with the same state-of-the-art signal processing algorithms. The imaged results for the real data measurements were correlated with the imaged results for the synthetic data sets to produce performance measurements, thus producing a procedure that provides a non-invasive assessment of the object and medium determined by the synthetic data set that maximally correlated with the real data return. Synthetic results and experiment results showed good correlations. For the synthetic data, a mathematical model was developed for electromagnetic returns from an object shape (i.e., cylinder, parallelepiped, sphere) composed of a uniform construction (i.e., metal, wood, plastic, clay) within a uniform dielectric material (i.e., air, sand, loam, clay, water). This model was then implemented within a software package, thus providing the ability to generate simulated measurements from any combination of object, construction, and dielectric.

  9. Convolutional neural network based sensor fusion for forward looking ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Rayn; Crosskey, Miles; Chen, David; Walenz, Brett; Morton, Kenneth

    2016-05-01

    Forward looking ground penetrating radar (FLGPR) is an alternative buried threat sensing technology designed to offer additional standoff compared to downward looking GPR systems. Due to additional flexibility in antenna configurations, FLGPR systems can accommodate multiple sensor modalities on the same platform that can provide complimentary information. The different sensor modalities present challenges in both developing informative feature extraction methods, and fusing sensor information in order to obtain the best discrimination performance. This work uses convolutional neural networks in order to jointly learn features across two sensor modalities and fuse the information in order to distinguish between target and non-target regions. This joint optimization is possible by modifying the traditional image-based convolutional neural network configuration to extract data from multiple sources. The filters generated by this process create a learned feature extraction method that is optimized to provide the best discrimination performance when fused. This paper presents the results of applying convolutional neural networks and compares these results to the use of fusion performed with a linear classifier. This paper also compares performance between convolutional neural networks architectures to show the benefit of fusing the sensor information in different ways.

  10. Lunar ground penetrating radar: Minimizing potential data artifacts caused by signal interaction with a rover body

    NASA Astrophysics Data System (ADS)

    Angelopoulos, Michael; Redman, David; Pollard, Wayne H.; Haltigin, Timothy W.; Dietrich, Peter

    2014-11-01

    Ground-penetrating radar (GPR) is the leading geophysical candidate technology for future lunar missions aimed at mapping shallow stratigraphy (<5 m). The instrument's exploration depth and resolution capabilities in lunar materials, as well as its small size and lightweight components, make it a very attractive option from both a scientific and engineering perspective. However, the interaction between a GPR signal and the rover body is poorly understood and must be investigated prior to a space mission. In doing so, engineering and survey design strategies should be developed to enhance GPR performance in the context of the scientific question being asked. This paper explores the effects of a rover (simulated with a vertical metal plate) on GPR results for a range of heights above the surface and antenna configurations at two sites: (i) a standard GPR testing site with targets of known position, size, and material properties, and; (ii) a frozen lake for surface reflectivity experiments. Our results demonstrate that the GPR antenna configuration is a key variable dictating instrument design, with the XX polarization considered optimal for minimizing data artifact generation. These findings could thus be used to help guide design requirements for an eventual flight instrument.

  11. Application of deterministic deconvolution of ground-penetrating radar data in a study of carbonate strata

    USGS Publications Warehouse

    Xia, J.; Franseen, E.K.; Miller, R.D.; Weis, T.V.

    2004-01-01

    We successfully applied deterministic deconvolution to real ground-penetrating radar (GPR) data by using the source wavelet that was generated in and transmitted through air as the operator. The GPR data were collected with 400-MHz antennas on a bench adjacent to a cleanly exposed quarry face. The quarry site is characterized by horizontally bedded carbonate strata with shale partings. In order to provide groundtruth for this deconvolution approach, 23 conductive rods were drilled into the quarry face at key locations. The steel rods provided critical information for: (1) correlation between reflections on GPR data and geologic features exposed in the quarry face, (2) GPR resolution limits, (3) accuracy of velocities calculated from common midpoint data and (4) identifying any multiples. Comparing the results of deconvolved data with non-deconvolved data demonstrates the effectiveness of deterministic deconvolution in low dielectric-loss media for increased accuracy of velocity models (improved at least 10-15% in our study after deterministic deconvolution), increased vertical and horizontal resolution of specific geologic features and more accurate representation of geologic features as confirmed from detailed study of the adjacent quarry wall. ?? 2004 Elsevier B.V. All rights reserved.

  12. Improving buried threat detection in ground-penetrating radar with transfer learning and metadata analysis

    NASA Astrophysics Data System (ADS)

    Colwell, Kenneth A.; Torrione, Peter A.; Morton, Kenneth D.; Collins, Leslie M.

    2015-05-01

    Ground-penetrating radar (GPR) technology has proven capable of detecting buried threats. The system relies on a binary classifier that is trained to distinguish between two classes: a target class, encompassing many types of buried threats and their components; and a nontarget class, which includes false alarms from the system prescreener. Typically, the training process involves a simple partition of the data into these two classes, which allows for straightforward application of standard classifiers. However, since training data is generally collected in fully controlled environments, it includes auxiliary information about each example, such as the specific type of threat, its purpose, its components, and its depth. Examples from the same specific or general type may be expected to exhibit similarities in their GPR data, whereas examples from different types may differ greatly. This research aims to leverage this additional information to improve overall classification performance by fusing classifier concepts for multiple groups, and to investigate whether structure in this information can be further utilized for transfer learning, such that the amount of expensive training data necessary to learn a new, previously-unseen target type may be reduced. Methods for accomplishing these goals are presented with results from a dataset containing a variety of target types.

  13. Design and validation of inert homemade explosive simulants for ground penetrating radar

    NASA Astrophysics Data System (ADS)

    VanderGaast, Brian W.; McFee, John E.; Russell, Kevin L.; Faust, Anthony A.

    2015-05-01

    The Canadian Armed Forces (CAF) identified a requirement for inert simulants to act as improvised, or homemade, explosives (IEs) when training on, or evaluating, ground penetrating radar (GPR) systems commonly used in the detection of buried landmines and improvised explosive devices (IEDs). In response, Defence R and D Canada (DRDC) initiated a project to develop IE simulant formulations using commonly available inert materials. These simulants are intended to approximate the expected GPR response of common ammonium nitrate-based IEs, in particular ammonium nitrate/fuel oil (ANFO) and ammonium nitrate/aluminum (ANAl). The complex permittivity over the range of electromagnetic frequencies relevant to standard GPR systems was measured for bulk quantities of these three IEs that had been fabricated at DRDC Suffield Research Centre. Following these measurements, published literature was examined to find benign materials with both a similar complex permittivity, as well as other physical properties deemed desirable - such as low-toxicity, thermal stability, and commercial availability - in order to select candidates for subsequent simulant formulation. Suitable simulant formulations were identified for ANFO, with resulting complex permittivities measured to be within acceptable limits of target values. These IE formulations will now undergo end-user trials with CAF operators in order to confirm their utility. Investigations into ANAl simulants continues. This progress report outlines the development program, simulant design, and current validation results.

  14. Soil water retention function hysteresis determined by ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Leger, E.; Saintenoy, A. C.; Coquet, Y.

    2014-12-01

    Soil hydraulic properties, represented by the soil water retentionθ and hydraulic conductivity K(h) functions, dictate waterflow in the vadose zone, as well as partition between infiltrationand runoff. Those functions can be described by several mathematicalexpressions, such as the Mualem-van Genuchten (M-vG) function. Thedetermination of the parameters defining the van Genuchten soil waterretention function is usually done using laboratory experiments, suchas the hanging water column method.For a few decades Ground Penetrating Radar (GPR) has been known to be anaccurate geophysical method to measure water content variations insoils. The work presented here is based on mono-offset detection ofhysteresis on the soil water retention curve with on-ground surfaceGPR.Soil surface GPR measurements were acquired above a large column ofsand (40 cm high and 60 cm diameter), using a 1600 MHz antenna, forvariable ground water table depths at hydraulic equilibrium. Weinverted the GPR data to obtain the M-vG parameters consideringhysteresis on the soil water retention curve, using the ShuffledComplex Evolution (SCE-UA) algorithm. The method is presented onsynthetic examples and on laboratory experiments. Modeling of thewater dynamics were made using Hydrus-1D, GPR data were computed usingGprMax suite programs. The estimated parameters were compared to thoseobtained from hanging water column experiments.

  15. Airborne Ground Penetrating Radar (GPR) for peat analyses in the Canadian Northern wetlands study

    NASA Technical Reports Server (NTRS)

    Pelletier-Travis, Ramona E.

    1991-01-01

    The study was conducted as part of the NASA Biospherics Research on Emissions from Wetlands (BREW) program. An important aspect of the program is to investigate the terrestrial production and atmospheric distribution of methane and other gases contributing to global warming. Multi-kilometer transects of airborne (helicopter) Ground Penetrating Radar (GPR) data were collected periodically along the 100 km distance from the coast inland so as to obtain a regional trend in peat depth and related parameters. Global Positioning System (GPS) data were simultaneously collected from the helicopter to properly georeference the GPR data. Additional 50 m ground-based transects of GPR data were also collected as a source of ground truthing, as a calibration aid for the airborne data sets, and as a source of higher resolution data for characterizing the strata within the peat. In situ peat depth probing and soil characterizations from excavated soil pits were used to verify GPR findings. Results from the ground-based data are presented.

  16. Recognizing subsurface target responses in ground penetrating radar data using convolutional neural networks

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Rayn T.; Morton, Kenneth D.; Collins, Leslie M.; Torrione, Peter A.

    2015-05-01

    Improved performance in the discrimination of buried threats using Ground Penetrating Radar (GPR) data has recently been achieved using features developed for applications in computer vision. These features, designed to characterize local shape information in images, have been utilized to recognize patches that contain a target signature in two-dimensional slices of GPR data. While these adapted features perform very well in this GPR application, they were not designed to specifically differentiate between target responses and background GPR data. One option for developing a feature specifically designed for target differentiation is to manually design a feature extractor based on the physics of GPR image formation. However, as seen in the historical progression of computer vision features, this is not a trivial task. Instead, this research evaluates the use of convolutional neural networks (CNNs) applied to two-dimensional GPR data. The benefit of using a CNN is that features extracted from the data are a learned parameter of the system. This has allowed CNN implementations to achieve state of the art performance across a variety of data types, including visual images, without the need for expert designed features. However, the implementation of a CNN must be done carefully for each application as network parameters can cause performance to vary widely. This paper presents results from using CNNs for object detection in GPR data and discusses proper parameter settings and other considerations.

  17. Interpretation of Ground Penetrating Radar data at the Hanford Site, Richland, Washington

    SciTech Connect

    Bergstrom, K.A.; Mitchell, T.H.; Kunk, J.R.

    1993-07-01

    Ground Penetrating Radar (GPR) is being used extensively during characterization and remediation of chemical and radioactive waste sites at the Hanford Site in Washington State. Time and money for GPR investigations are often not included during the planning and budgeting phase. Therefore GPR investigations must be inexpensive and quick to minimize impact on already established budgets and schedules. An approach to survey design, data collection, and interpretation has been developed which emphasizes speed and budget with minimal impact on the integrity of the interpretation or quality of the data. The following simple rules of thumb can be applied: (1) Assemble as much pre-survey information as possible, (2) Clearly define survey objectives prior to designing the survey and determine which combination of geophysical methods will best meet the objectives, (3) Continuously communicate with the client, before, during and after the investigation, (4) Only experienced GPR interpreters should acquire the field data, (5) Use real-time monitoring of the data to determine where and how much data to collect and assist in the interpretation, (6) Always ``error`` in favor of collecting too much data, (7) Surveys should have closely spaced (preferably 5 feet, no more than 10 feet), orthogonal profiles, (8) When possible, pull the antenna by hand.

  18. Investigation of the Roosevelt Road Transmitter Site, Fort Richardson, Alaska, using ground penetrating radar

    SciTech Connect

    Hunter, L.E.; Delaney, A.J.; Lawson, D.E.

    1999-03-01

    The Roosevelt Road Transmitter Site is the location of a decommissioned bunker on Fort Richardson, near Anchorage, Alaska. The site was used from World War II to the Korean War as part of an Alaskan communications network. The bunker and support buildings were vandalized following its decommissioning in the mid-1960s, resulting in PCB contamination of the bunker and soils around the above-ground transmitter annex. CRREL conducted a ground-penetrating radar (GPR) investigation of the site in June 1996, at the request of the Directorate of Public Works on Fort Richardson. Nine transect lines were established, each being profiled with 100- and 400-MHz antennas. Both antennas systems defined the extent of the bunker and identified the presence of buried utilities. The 100-MHz antenna provided large-scale resolution of the bunker, limits of site excavation, and large stratigraphic horizons in the undisturbed sediments. The 400-MHz antenna provided finer resolution that allowed identification of steel reinforcement in the bunker ceiling, utility walls and floor, and the walls of the inner and outer bunker. High amplitude resonance and hyperbolas in the record characterize the response from the Transmitter Annex foundation, buried pipes, and utilities. The GPR survey shows its utility for detecting the extent of abandoned underground structures and identifying the extent of original ground excavations.

  19. Electrical Resistivity and Ground Penetrating Radar Investigation of Presence and Extent of Hardpan Soil Layers

    NASA Astrophysics Data System (ADS)

    Thao, S. J.; Plattner, A.

    2015-12-01

    Farming in the San Joaquin Valley in central California is often impeded by a shallow rock-hard layer of consolidated soil commonly referred to as hardpan. To be able to successfully farm, this layer, if too shallow, needs to be removed either with explosives or heavy equipment. It is therefore of great value to obtain information about depth and presence of such a layer prior to agricultural operations. We tested the applicability of electrical resistivity tomography and ground penetrating radar in hardpan detection. On our test site of known hardpan depth (from trenching) and local absence (prior dynamiting to plant trees), we successfully recovered the known edge of a hardpan layer with both methods, ERT and GPR. The clay-rich soil significantly reduced the GPR penetration depth but we still managed to map the edges at a known gap where prior dynamiting had removed the hardpan. Electrical resistivity tomography with a dipole-dipole electrode configuration showed a clear conductive layer at expected depths with a clearly visible gap at the correct location. In our data analysis and representation we only used either freely available or in-house written software.

  20. Coarse root distribution of a semi-arid oak savanna estimated with ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Raz-Yaseef, N.; Koteen, L. E.; Baldocchi, D. D.

    2013-05-01

    Coarse root distribution of a semi-arid oak savanna estimated with ground penetrating radar North California enjoys wet and mild winters, but experiences extreme hot, dry summer conditions, with occasional drought years. Despite the severity of summer conditions, blue oaks in this ecosystem are winter-deciduous. Water uptake from groundwater helps explain the incongruity of tree growth with soil water availability in this ecosystem. We hypothesized that the binary nature of water availability, in which water is either abundantly available or scarce, would be reflected in blue oak root architecture. The objective of this research was to understand how the form of the root system facilitates ecosystem functioning. To do this, we sought to characterize the structure of the root system, and survey coarse root distribution with ground penetrating radar (GPR), due to its advantages in covering large areas rapidly and non-destructively. Because GPR remains a relatively new technology for examining root distribution, an ancillary objective was to test this methodology, and help facilitate its application more broadly. We used a GPR Noggin1000 SmartTow (Sensors and Software Inc., Ontario, Canada) 1 GHz configuration. In order to best represent the diversity of tree size and age found at the field site, we surveyed six 8x8 m locations with trees varying in size, age and clumping (i.e. isolated trees vs. tree clusters). GPR raw data was processed with designated software in order to construct three-dimensional values of radar reflection intensity for each surveyed grid. Radar signals were transformed to root biomass by calibrating them against excavated roots in twelve 60x100 cm pits. Our results indicate that coarse roots occupy the full soil profile, and that root biomass of old large trees peaks just above the bedrock. As opposed to other semi-arid regions, where trees often develop extensive shallow coarse lateral roots, in order to exploit the entire wet-soil medium, we

  1. Estimating Carbon Stocks Along Depressional Wetlands Using Ground Penetrating Radar (GPR) in the Disney Wilderness Preserve (Orlando, Florida)

    NASA Astrophysics Data System (ADS)

    McClellan, M. D.; Comas, X.; Wright, W. J.; Mount, G. J.

    2014-12-01

    Peat soils store a large fraction of the global carbon (C) in soil. It is estimated that 95% of carbon in peatlands is stored in the peat soil, while less than 5% occurs in the vegetation. The majority of studies related to C stocks in peatlands have taken place in northern latitudes leaving the tropical and subtropical latitudes clearly understudied. In this study we use a combination of indirect non-invasive geophysical methods (mainly ground penetrating radar, GPR) as well as direct measurements (direct coring) to calculate total C stocks within subtropical depressional wetlands in the Disney Wilderness Preserve (DWP, Orlando, FL). A set of three-dimensional (3D) GPR surveys were used to detect variability of the peat layer thickness and the underlying peat-sand mix layer across several depressional wetlands. Direct samples collected at selected locations were used to confirm depth of each interface and to estimate C content in the laboratory. Layer thickness estimated from GPR and direct C content were used to estimate total peat volume and C content for the entire depressional wetland. Through the use of aerial photos a relationship between surface area along the depressional wetlands and total peat thickness (and thus C content) was established for the depressions surveyed and applied throughout the entire preserve. This work shows the importance of depressional wetlands as critical contributors of the C budget at the DWP.

  2. Ground-penetrating radar observations of winter snow accumulation on Alaska Glaciers.

    NASA Astrophysics Data System (ADS)

    Gusmeroli, A.; Wolken, G. J.; Arendt, A. A.; Campbell, S. W.; O'Neel, S.; Marshall, H.

    2012-12-01

    Understanding the spatial variability of winter snow in glacierized watersheds is vital for estimating glacier changes, forecasting freshwater delivery to riverine and marine ecosystems and informing Earth loading models for studies of seasonal variations in crustal uplift. Accurately reproducing snow distribution within glacier-models still remains a challenge due to the difficulty obtaining in-situ measurements and large local or regional variability in snow thicknesses. Between March and July 2012, high frequency (200-500 MHz) Ground-Penetrating Radar (GPR) surveys designed to obtain spatially distributed measurements of snow accumulation, were collected on a number of different glaciers in south-central Alaska, USA. The surveys span a range of climatic zones including continental and maritime glaciers. Several modes of travel were employed, including helicopter-borne, snowmobile and ski-towed. Preliminary results from the Valdez Glacier suggest that the agreement between 200 MHz-GPR-derived snow-depth and 17 manually measured snow-depths is ± 10% using an estimated radar velocity of 0.22 m/ns, as one example. Additionally, GPR profiles in the accumulation areas showed firn-stratigraphy of previous summer surfaces, thus, making it possible to distinguish the elevation of the firn line and indicating that in the accumulation zone it may be possible to estimate annual net mass balance if density can be estimated. In this presentation we will illustrate the characteristics of snow accumulation on this suite of Alaska Glaciers as derived by GPR and discuss our results in terms of the usefulness and challenges associated with using GPR to determine the winter and annual mass balance of these glaciers.

  3. Improving ground-penetrating radar data in sedimentary rocks using deterministic deconvolution

    USGS Publications Warehouse

    Xia, J.; Franseen, E.K.; Miller, R.D.; Weis, T.V.; Byrnes, A.P.

    2003-01-01

    Resolution is key to confidently identifying unique geologic features using ground-penetrating radar (GPR) data. Source wavelet "ringing" (related to bandwidth) in a GPR section limits resolution because of wavelet interference, and can smear reflections in time and/or space. The resultant potential for misinterpretation limits the usefulness of GPR. Deconvolution offers the ability to compress the source wavelet and improve temporal resolution. Unlike statistical deconvolution, deterministic deconvolution is mathematically simple and stable while providing the highest possible resolution because it uses the source wavelet unique to the specific radar equipment. Source wavelets generated in, transmitted through and acquired from air allow successful application of deterministic approaches to wavelet suppression. We demonstrate the validity of using a source wavelet acquired in air as the operator for deterministic deconvolution in a field application using "400-MHz" antennas at a quarry site characterized by interbedded carbonates with shale partings. We collected GPR data on a bench adjacent to cleanly exposed quarry faces in which we placed conductive rods to provide conclusive groundtruth for this approach to deconvolution. The best deconvolution results, which are confirmed by the conductive rods for the 400-MHz antenna tests, were observed for wavelets acquired when the transmitter and receiver were separated by 0.3 m. Applying deterministic deconvolution to GPR data collected in sedimentary strata at our study site resulted in an improvement in resolution (50%) and improved spatial location (0.10-0.15 m) of geologic features compared to the same data processed without deterministic deconvolution. The effectiveness of deterministic deconvolution for increased resolution and spatial accuracy of specific geologic features is further demonstrated by comparing results of deconvolved data with nondeconvolved data acquired along a 30-m transect immediately adjacent

  4. Observations on syntactic landmine detection using impulse ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Nasif, Ahmed O.; Hintz, Kenneth J.

    2011-06-01

    We discuss some results and observations on applying syntactic pattern recognition (SPR) methodology for landmine detection using impulse ground-penetrating radar (GPR). In the SPR approach, the GPR A-scans are first converted into binary-valued strings by inverse filtering, followed by concavity detection to identify the peaks and valleys representing the locations of impedance discontinuities in the return signal. During the training phase, the characteristic binary strings for a particular landmine are found by looking at all the exemplars of that mine and selecting the collection of strings that yield the best detection results on these exemplars. These characteristic strings can be detected very efficiently using finite state machines (FSMs). Finally, the FSM detections are clustered to assign confidence to each detection, and discard sparse detections. Provided that the impulse GPR provides enough resolution in range, the SPR method can be a robust and high-speed solution for landmine detection and classification, because it aims to exploit the impedance discontinuity profile of the target, which is a description of the internal material structure of the target and little affected by external clutter. To evaluate the proposed methodology, the SPR scheme is applied to a set of impulse GPR data taken at a government test site. We suggest that coherent frequency-agile radar may be a better option for the SPR approach, since it addresses some of the drawbacks of a non-coherent impulse GPR caused by internally non-coherent within-channel signals which necessitate non-coherent integration and its attendant longer integration times, and non-coherent adjacent channels which severely limit the ability to do spatial, or at a minimum, cross-range processing if the GPR is in a linear array antenna.

  5. Design and field experiments of a ground-penetrating radar for Mars exploration

    NASA Astrophysics Data System (ADS)

    Leuschen, Carl; Kanagaratnam, Pannir; Yoshikawa, Kenji; Arcone, Steve; Gogineni, Prasad

    2003-03-01

    We developed a wideband, low-power, lightweight, prototype ground-penetrating radar (GPR) for subsurface exploration for Mars. The transmitter and receiver subsystems were constructed using a commercially available radio frequency (RF) and digital integrated circuits, connectorized components, and evaluation boards. The transmit/receive system, antennas, laptop controller, and batteries are all accommodated on a 2.5-m sled. Field experiments were conducted in Kansas and Alaska. The experiments in Kansas tested the operation of the system. The primary objective of the Alaska experiments was to investigate the ability of a GPR to detect and distinguish between subsurface deposits of ice and ice-cemented soils. The investigation depths of these experiments ranged from 1 m to 30 m, and the subsurface geology included near-surface thaw, discontinuous permafrost, water-saturated soils, and lenses of pure ice. Dielectric contrasts within the ground were detected with near-meter resolution; however, identifying the geologic context of an interface was difficult due to ambiguities associated with reflection data. These investigations demonstrate some of the difficulties associated with inverting reflection data to obtain dielectric properties of the subsurface. Fortunately, previous geophysical investigations such as drilled cores and seismic surveys helped to constrain the geology, and numerical simulations provided an additional resource for the interpretations. On Mars, additional geological context will be limited and numerical simulations will become extremely important for data interpretation. Due to these difficulties, we demonstrate in one experiment how dielectric information can be obtained directly from bistatic measurements with a fixed transmitter and mobile receiver. Finally, a comparison with a commercially available Geophysical Survey Systems, Inc. (GSSI) radar system is presented, and we discuss how the system can be modified and improved for future

  6. Reverse time migration imaging of ground-penetrating radar data in complex environments

    NASA Astrophysics Data System (ADS)

    Bradford, J. H.

    2014-12-01

    Because reverse-time migration (RTM) honors the physics of wave propagation more closely than other migration algorithms, it has become the preferred imaging tool in seismic exploration over the past 10-15 years. This shift has been facilitated by advances in computational power which have made it feasible to routinely migrate large datasets. Despite this evolution in exploration seismology, the use of RTM has remained relatively limited in ground-penetrating radar (GPR) applications even though the advantages in GPR imaging are comparable. For example, within the RTM framework it is possible to include antenna radiation directly in the imaging algorithm. Additionally complications such as irregular surface topography and highly heterogeneous subsurface electrical properties can be incorporated naturally into an RTM algorithm. I have implemented both pre- and post-stack RTM algorithms for GPR imaging. The post-stack algorithm utilizes the exploding reflector concept and an approximate formulation of the EM wave equation to account for propagation through lossy media. The pre-stack algorithm utilizes the full two way solution to Maxwell's equations, and includes radiation patterns directly in the imaging routine. Here, I investigate amplitude reconstruction using RTM in complex environments with a focus on complex topography and the interplay between radar radiation patterns and topography. Complex topography alters wavefield kinematics making for a challenging imaging problem; topographic variation can substantially distort radiation patterns, produce irregular spreading, and alter amplitudes by focusing and defocusing effects at the surface. The effects are magnified when the topographic variations are on the same order as the depth of investigation - a situation that is often encountered in GPR investigations. I consider both pre- and post-stack GPR imaging in the presence of large topographic and subsurface variability. Using both synthetic and field examples I

  7. A feature learning approach for classifying buried threats in forward looking ground penetrating radar data

    NASA Astrophysics Data System (ADS)

    Camilo, Joseph A.; Malof, Jordan M.; Collins, Leslie M.

    2016-05-01

    The forward-looking ground penetrating radar (FLGPR) is a remote sensing modality that has recently been investigated for buried threat detection. The FLGPR considered in this work uses stepped frequency sensing followed by filtered backprojection to create images of the ground, where each image pixel corresponds to the radar energy reflected from the subsurface at that location. Typical target detection processing begins with a prescreening operation where a small subset of spatial locations are chosen to consider for further processing. Image statistics, or features, are then extracted around each selected location and used for training a machine learning classification algorithm. A variety of features have been proposed in the literature for use in classification. Thus far, however, predominantly hand-crafted or manually designed features from the computer vision literature have been employed (e.g., HOG, Gabor filtering, etc.). Recently, it has been shown that image features learned directly from data can obtain state-of-the-art performance on a variety of problems. In this work we employ a feature learning scheme using k-means and a bag-of-visual-words model to learn effective features for target and non-target discrimination in FLGPR data. Experiments are conducted using several lanes of FLGPR data and learned features are compared with several previously proposed static features. The results suggest that learned features perform comparably, or better, than existing static features. Similar to other feature learning results, the features consist of edges or texture primitives, revealing which structures in the data are most useful for discrimination.

  8. Monitoring controlled graves representing common burial scenarios with ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Schultz, John J.; Martin, Michael M.

    2012-08-01

    Implementing controlled geophysical research is imperative to understand the variables affecting detection of clandestine graves during real-life forensic searches. This study focused on monitoring two empty control graves (shallow and deep) and six burials containing a small pig carcass (Sus scrofa) representing different burial forensic scenarios: a shallow buried naked carcass, a deep buried naked carcass, a deep buried carcass covered by a layer of rocks, a deep buried carcass covered by a layer of lime, a deep buried carcass wrapped in an impermeable tarpaulin and a deep buried carcass wrapped in a cotton blanket. Multi-frequency, ground penetrating radar (GPR) data were collected monthly over a 12-month monitoring period. The research site was a cleared field within a wooded area in a humid subtropical environment, and the soil consisted of a Spodosol, a common soil type in Florida. This study compared 2D GPR reflection profiles and horizontal time slices obtained with both 250 and 500 MHz dominant frequency antennae to determine the utility of both antennae for grave detection in this environment over time. Overall, a combination of both antennae frequencies provided optimal detection of the targets. Better images were noted for deep graves, compared to shallow graves. The 250 MHz antenna provided better images for detecting deep graves, as less non-target anomalies were produced with lower radar frequencies. The 250 MHz antenna also provided better images detecting the disturbed ground. Conversely, the 500 MHz antenna provided better images when detecting the shallow pig grave. The graves that contained a pig carcass with associated grave items provided the best results, particularly the carcass covered with rocks and the carcass wrapped in a tarpaulin. Finally, during periods of increased soil moisture levels, there was increased detection of graves that was most likely related to conductive decompositional fluid from the carcasses.

  9. Using pattern recognition to automatically localize reflection hyperbolas in data from ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Maas, Christian; Schmalzl, Jörg

    2013-08-01

    Ground Penetrating Radar (GPR) is used for the localization of supply lines, land mines, pipes and many other buried objects. These objects can be recognized in the recorded data as reflection hyperbolas with a typical shape depending on depth and material of the object and the surrounding material. To obtain the parameters, the shape of the hyperbola has to be fitted. In the last years several methods were developed to automate this task during post-processing. In this paper we show another approach for the automated localization of reflection hyperbolas in GPR data by solving a pattern recognition problem in grayscale images. In contrast to other methods our detection program is also able to immediately mark potential objects in real-time. For this task we use a version of the Viola-Jones learning algorithm, which is part of the open source library "OpenCV". This algorithm was initially developed for face recognition, but can be adapted to any other simple shape. In our program it is used to narrow down the location of reflection hyperbolas to certain areas in the GPR data. In order to extract the exact location and the velocity of the hyperbolas we apply a simple Hough Transform for hyperbolas. Because the Viola-Jones Algorithm reduces the input for the computational expensive Hough Transform dramatically the detection system can also be implemented on normal field computers, so on-site application is possible. The developed detection system shows promising results and detection rates in unprocessed radargrams. In order to improve the detection results and apply the program to noisy radar images more data of different GPR systems as input for the learning algorithm is necessary.

  10. Oil Detection In and Under Sea Ice Using Ground-Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Steinbronn, L.; Bradford, J.; Liberty, L.; Dickins, D.; Brandvik, P. J.

    2007-12-01

    Marine oil spills can occur in the Arctic due to pipeline breaks or leaks and spills from storage or production facilities. Depending on the time of year and scenario, a portion or all of the spill may become trapped under and/or encapsulated within the sea ice sheet. The current methods for locating spilled oil include visually inspecting drilled ice cores or sending divers under the ice. Speed is a key issue in oil clean-up. A non-invasive method of detecting oil quickly and reliably would greatly facilitate the clean-up and lessen the impact on the environment. First-year ice thicknesses of 0.5-2.0 m, typical of the Arctic region, can be well-resolved using radar. Oil film thicknesses can range from a few mm to 20 cm depending on the ice-water interface topography. For typical conditions a frequency of 500 MHz gives a 1/4 wavelength limit of 7 cm; therefore a typical spill scenario is a thin-bed problem for ground-penetrating radar (GPR). Interference due to thin-beds may cause amplitude, phase and frequency anomalies in the reflected wavelet. In April 2006, SINTEF conducted a contained oil-spill under natural Arctic sea ice conditions in a fjord on Svalbard. Using data collected during that experiment from a 500 MHz antenna and complex trace analysis we computed the instantaneous frequency, instantaneous phase and the envelope function and found significant differences in the data before and after the oil was inserted. These results demonstrated the potential of GPR to be a practical system for oil in ice detection under certain conditions. As a follow-on to the 2006 project, we have undertaken a detailed modeling effort to estimate GPR response to specific variables, such as ice and oil thicknesses, ice salinity and temperature.

  11. State-of-the-art and trends of Ground-Penetrating Radar antenna arrays

    NASA Astrophysics Data System (ADS)

    Vescovo, Roberto; Pajewski, Lara; Tosti, Fabio

    2016-04-01

    The aim of this contribution is to offer an overview on the antenna arrays for GPR systems, current trends and open issues. Antennas are a critical hardware component of a radar system, dictating its performance in terms of capability to detect targets. Nevertheless, most of the research efforts in the Ground-Penetrating Radar (GPR) area focus on the use of this imaging technique in a plethora of different applications and on the improvement of modelling/inversion/processing techniques, whereas a limited number of studies deal with technological issues related to the design of novel systems, including the synthesis, optimisation and characterisation of advanced antennas. Even fewer are the research activities carried out to develop innovative antenna arrays. GPR antennas operate in a strongly demanding environment and should satisfy a number of requirements, somehow unique and very different than those of conventional radar antennas. The same applies to GPR antenna arrays. The first requirement is an ultra-wide frequency band: the radar has to transmit and receive short-duration time-domain waveforms, in the order of a few nanoseconds, the time-duration of the emitted pulses being a trade-off between the desired radar resolution and penetration depth. Furthermore, GPR antennas should have a linear phase characteristic over the whole operational frequency range, predictable polarisation and gain. Due to the fact that a subsurface imaging system is essentially a short-range radar, the coupling between transmitting and receiving antennas has to be low and short in time. GPR antennas should have quick ring-down characteristics, in order to prevent masking of targets and guarantee a good resolution. The radiation patterns should ensure minimal interference with unwanted objects, usually present in the complex operational environment; to this aim, antennas should provide high directivity and concentrate the electromagnetic energy into a narrow solid angle. As GPR

  12. State-of-the-art and trends of Ground-Penetrating Radar antenna arrays

    NASA Astrophysics Data System (ADS)

    Vescovo, Roberto; Pajewski, Lara; Tosti, Fabio

    2016-04-01

    The aim of this contribution is to offer an overview on the antenna arrays for GPR systems, current trends and open issues. Antennas are a critical hardware component of a radar system, dictating its performance in terms of capability to detect targets. Nevertheless, most of the research efforts in the Ground-Penetrating Radar (GPR) area focus on the use of this imaging technique in a plethora of different applications and on the improvement of modelling/inversion/processing techniques, whereas a limited number of studies deal with technological issues related to the design of novel systems, including the synthesis, optimisation and characterisation of advanced antennas. Even fewer are the research activities carried out to develop innovative antenna arrays. GPR antennas operate in a strongly demanding environment and should satisfy a number of requirements, somehow unique and very different than those of conventional radar antennas. The same applies to GPR antenna arrays. The first requirement is an ultra-wide frequency band: the radar has to transmit and receive short-duration time-domain waveforms, in the order of a few nanoseconds, the time-duration of the emitted pulses being a trade-off between the desired radar resolution and penetration depth. Furthermore, GPR antennas should have a linear phase characteristic over the whole operational frequency range, predictable polarisation and gain. Due to the fact that a subsurface imaging system is essentially a short-range radar, the coupling between transmitting and receiving antennas has to be low and short in time. GPR antennas should have quick ring-down characteristics, in order to prevent masking of targets and guarantee a good resolution. The radiation patterns should ensure minimal interference with unwanted objects, usually present in the complex operational environment; to this aim, antennas should provide high directivity and concentrate the electromagnetic energy into a narrow solid angle. As GPR

  13. Detection of abandoned underground storage tanks in rights-of-way with ground-penetrating radar. Final report

    SciTech Connect

    Clemena, G.G.; French, A.W.

    1995-06-01

    Highway agencies need a simple, effective, nondestructive way to inspect certain properties in rights-of-way for the possible presence of abandoned underground storage tanks, without disturbing the ground, before actual construction begins. Overall, ground-penetrating radar (GPR) fills this need better than other nondestructive methods. The report explains why GPR was chosen over the other nondestructive methods available, discusses the principal of GPR, describes the basic radar equipment needed and the general procedures involved in conducting such inspections, and provides examples of the type of radar data such inspections produce.

  14. Data processing of ground-penetrating radar signals for the detection of discontinuities using polarization diversity

    NASA Astrophysics Data System (ADS)

    Tebchrany, Elias; Sagnard, Florence; Baltazart, Vincent; Tarel, Jean-Phillippe

    2014-05-01

    In civil engineering, ground penetrating radar (GPR) is used to survey pavement thickness at traffic speed, detect and localize buried objects (pipes, cables, voids, cavities), zones of cracks and discontinuities in concrete or soils. In this work, a ground-coupled radar made of a pair of transmitting and receiving bowtie-slot antennas is moved linearly on the soil surface to detect the reflected waves induced by discontinuities in the subsurface. The GPR system operates in the frequency domain using a step-frequency continuous wave (SFCW) using a Vector Network Analyzer (VNA) in an ultra-wide band [0.3 ; 4] GHz. The detection of targets is usually focused on time imaging. Thus, the targets (limited in size) are usually shown by diffraction hyperbolas on a Bscan image that is an unfocused depiction of the scatterers. The contrast in permittivity and the ratio between the size of the object and the wavelength are important parameters in the detection process. Thus, we have made a first study on the use of polarization diversity to obtain additional information relative to the contrast between the soil and the target and the dielectric characteristics of a target. The two main polarizations configurations of the radar have been considered in the presence of objects having a pipe geometry: the TM (Transverse Magnetic) and TE (Transverse Electric. To interpret the diffraction hyperbolas on a Bscan image, we have used pre-processing techniques are necessary to reduce the clutter signal which can overlap and obscure the target responses, particularly shallow objects. The clutter, which can be composed of the direct coupling between the antennas and the reflected wave from the soil surface, the scattering on the heterogeneities due to the granular nature of the subsurface material, and some additive noise, varies with soil dielectric characteristics and/or surface roughness and leads to uncertainty in the measurements (additive noise). Because of the statistical nature of

  15. The application of ground-penetrating radar method for detecting buried human bodies on the Cikutra graveyard, Indonesia

    NASA Astrophysics Data System (ADS)

    Aditama, Iqbal Fauzi; Syaifullah, Khalid Istiqlal; Saputera, Durra Handri; Widodo

    2015-04-01

    Ground-penetrating radar (GPR) can be used to study shallow subsurface of the earth. GPR can be utilized to detect buried human bodies that suffered landslides or buried by other causes. A detailed ground-penetrating survey was conducted in the Cikutra graveyard, Bandung on a corpse buried two weeks from the time of the survey. Processing the data was carried out to filter out noise and to improve the resolution. The radar profiles from this survey produced hyperbolic reflections, emanated from the corpse. The hyperbolic reflection was strongest in the abdomen region compared to the head and the legs of the corpse. The result of data processing shows similarity between data from the survey and the actual location of the human body. We obtained the hyperbolic reflection at around 1.5 meters depth which is consistent with the depth of the buried corpse.

  16. Civil Engineering Applications of Ground Penetrating Radar: Research Perspectives in COST Action TU1208

    NASA Astrophysics Data System (ADS)

    Pajewski, Lara; Benedetto, Andrea; Loizos, Andreas; Slob, Evert; Tosti, Fabio

    2013-04-01

    Ground Penetrating Radar (GPR) is a safe, non-destructive and non-invasive imaging technique that can be effectively used for advanced inspection of composite structures and for diagnostics affecting the whole life-cycle of civil engineering works. GPR provides high resolution images of structures and subsurface through wide-band electromagnetic waves. It can be employed for the surveying of roads, pavements, bridges, tunnels, for detecting underground cavities and voids, for utility sensing, for the inspection of buildings, reinforced concrete and pre-cast concrete structures, for geotechnical investigation, in foundation design, as well as for several other purposes. Penetration and resolution of GPR depend primarily on the transmitting frequency of the equipment, the antenna characteristics, the electrical properties of the ground or of the surveyed material, and the contrasting electrical properties of the targets with respect to the surrounding medium. Generally there is a direct relationship between the transmitter frequency and the resolution that can be obtained; conversely there is an inverse relationship between frequency and penetration depth. GPR works best in dry ground environments, but can also give good results in wet, saturated materials; it does not work well in saline conditions, in high-conductivity media and through dense clays which limit signal penetration. Different approaches can be employed in the processing of collected GPR data. Once data have been processed, they still have to be analysed. This is a challenging problem, since interpretation of GPR radargrams is typically non-intuitive and considerable expertise is needed. In the presence of a complex scenario, an accurate electromagnetic forward solver is a fundamental tool for the validation of data interpretation. It can be employed for the characterization of scenarios, as a preliminary step that precedes a survey, or to gain a posteriori a better understanding of measured data. It

  17. Ground penetrating radar examination of thin tsunami beds - A case study from Phra Thong Island, Thailand

    NASA Astrophysics Data System (ADS)

    Gouramanis, Chris; Switzer, Adam D.; Polivka, Peter M.; Bristow, Charles S.; Jankaew, Kruawun; Dat, Pham T.; Pile, Jeremy; Rubin, Charles M.; Yingsin, Lee; Ildefonso, Sorvigenaleon R.; Jol, Harry M.

    2015-11-01

    Coastal overwash deposits from tsunamis and storms have been identified and characterised from many coastal environments. To date, these investigations have utilised ad-hoc time, energy and cost intensive invasive techniques, such as, pits and trenches or taking core samples. Here, we present the application of high-frequency ground penetrating radar (GPR) to identify and characterise the 2004 Indian Ocean Tsunami (IOT) and palaeotsunami deposits from Phra Thong Island, Thailand. This site is one of the most intensively studied palaeotsunami sites globally and preserves a series of late-Holocene stacked sandy tsunami deposits within an organic, muddy low-energy backbeach environment. Using 100, 500 and 1000 MHz GPR antennas, 29 reflection profiles were collected from two swales (X and Y) inland of the modern beach, and two common mid-point (CMP) profiles using the 200 MHz antennas were collected from Swale Y. Detailed examination of the CMPs allowed accurate velocity estimates to be applied to each profile. The reflection profiles included across-swale profiles and a high-resolution grid in Swale X, and were collected to investigate the feasibility of GPR to image the palaeotsunami deposits, and two profiles from Swale Y where the tsunami deposits are poorly known. The 500 MHz antennas provided the best stratigraphic resolution which was independently validated from the stratigraphy and sedimentology recovered from 17 auger cores collected along the profiles. It is clear from the augers and GPR data, that the different dielectric properties of the individual layers allow the identification of the IOT and earlier tsunami deposits on Phra Thong Island. Although applied in a coastal setting here, this technique can be applied to other environments where thin sand beds are preserved, in order to prioritise sites for detailed examination.

  18. Compact programmable ground-penetrating radar system for roadway and bridge deck characterization

    NASA Astrophysics Data System (ADS)

    Busuioc, Dan; Xia, Tian; Venkatachalam, Anbu; Huston, Dryver; Birken, Ralf; Wang, Ming

    2011-04-01

    A compact, high-performance, programmable Ground Penetrating Radar (GPR) system is described based on an impulse generator transmitter, a full waveform sampling single shot receiver, and high directivity antennas. The digital programmable pulse generator is developed for the transmitter circuit and both the pulse width and pulse shape are tunable to adjust for different modes of operation. It utilizes a step-recovery diode (SRD) and short-circuited microstrip lines to produce sub-nanosecond wide ultra-wideband (UWB) pulses. Sharp step signals are generated by periodic clock signals that are connected to the SRD's input node. Up to four variable width pulses (0.8, 1.0, 1.5, and 2.1 ns) are generated through a number of PIN switches controlling the selection of different microstrip lengths. A schottky diode is used as a rectifier at the output of the SRD in order to pass only the positive part of the Gaussian pulses while another group of short-circuit microstrips are used to generate amplitude-reversed Gaussian pulses. The addition of the two pulses results in a Gaussian monocycle pulse which is more energy efficient for emission. The pulse generator is connected to a number of UWB antennas. Primarily, a UWB Vivaldi antenna (500 MHz to 5 GHz) is used, but a number of other high-performance GPR-oriented antennas are investigated as well. All have linear phase characteristic, constant phase center, constant polarization and flat gain. A number of methods including resistive loading are used to decrease any resonances due to the antenna structure and unwanted reflections from the ground. The antennas exhibit good gain characteristics in the design bandwidth.

  19. Fusion of ground-penetrating radar and electromagnetic induction sensors for landmine detection and discrimination

    NASA Astrophysics Data System (ADS)

    Kolba, Mark P.; Torrione, Peter A.; Collins, Leslie M.

    2010-04-01

    Ground penetrating radar (GPR) and electromagnetic induction (EMI) sensors provide complementary capabilities in detecting buried targets such as landmines, suggesting that the fusion of GPR and EMI modalities may provide improved detection performance over that obtained using only a single modality. This paper considers both pre-screening and the discrimination of landmines from non-landmine objects using real landmine data collected from a U.S. government test site as part of the Autonomous Mine Detection System (AMDS) landmine program. GPR and EMI pre-screeners are first reviewed and then a fusion pre-screener is presented that combines the GPR and EMI prescreeners using a distance-based likelihood ratio test (DLRT) classifier to produce a fused confidence for each pre-screener alarm. The fused pre-screener is demonstrated to provide substantially improved performance over the individual GPR and EMI pre-screeners. The discrimination of landmines from non-landmine objects using feature-based classifiers is also considered. The GPR feature utilized is a pre-processed, spatially filtered normalized energy metric. Features used for the EMI sensor include model-based features generated from the AETC model and a dipole model as well as features from a matched subspace detector. The EMI and GPR features are then fused using a random forest classifier. The fused classifier performance is superior to the performance of classifiers using GPR or EMI features alone, again indicating that performance improvements may be obtained through the fusion of GPR and EMI sensors. The performance improvements obtained both for pre-screening and for discrimination have been verified by blind test results scored by an independent U.S. government contractor.

  20. Mapping Spatial Moisture Content of Unsaturated Agricultural Soils with Ground-Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Shamir, O.; Goldshleger, N.; Basson, U.; Reshef, M.

    2016-06-01

    Soil subsurface moisture content, especially in the root zone, is important for evaluation the influence of soil moisture to agricultural crops. Conservative monitoring by point-measurement methods is time-consuming and expensive. In this paper we represent an active remote-sensing tool for subsurface spatial imaging and analysis of electromagnetic physical properties, mostly water content, by ground-penetrating radar (GPR) reflection. Combined with laboratory methods, this technique enables real-time and highly accurate evaluations of soils' physical qualities in the field. To calculate subsurface moisture content, a model based on the soil texture, porosity, saturation, organic matter and effective electrical conductivity is required. We developed an innovative method that make it possible measures spatial subsurface moisture content up to a depth of 1.5 m in agricultural soils and applied it to two different unsaturated soil types from agricultural fields in Israel: loess soil type (Calcic haploxeralf), common in rural areas of southern Israel with about 30% clay, 30% silt and 40% sand, and hamra soil type (Typic rhodoxeralf), common in rural areas of central Israel with about 10% clay, 5% silt and 85% sand. Combined field and laboratory measurements and model development gave efficient determinations of spatial moisture content in these fields. The environmentally friendly GPR system enabled non-destructive testing. The developed method for measuring moisture content in the laboratory enabled highly accurate interpretation and physical computing. Spatial soil moisture content to 1.5 m depth was determined with 1-5% accuracy, making our method useful for the design of irrigation plans for different interfaces.

  1. Ground penetrating radar and active seismic investigation of stratigraphically verified pyroclastic deposits

    NASA Astrophysics Data System (ADS)

    Gase, A.; Bradford, J. H.; Brand, B. D.

    2015-12-01

    We conducted ground-penetrating radar (GPR) and active seismic surveys in July and August, 2015 parallel to outcrops of the pyroclastic density current deposits of the May 18th, 1980 eruption of Mount St. Helens (MSH), Washington. The primary objective of this study is to compare geophysical properties that influence electromagnetic and elastic wave velocities with stratigraphic parameters in the un-saturated zone. The deposits of interest are composed of pumice, volcanic ash, and lava blocks comprising a wide range of intrinsic porosities and grain sizes from sand to boulders. Single-offset GPR surveys for reflection data were performed with a Sensors and Software pulseEKKO Pro 100 GPR using 50 MHz, 100 MHz, and 200 MHz antennae. GPR data processing includes time-zero correction, dewow filter, migration, elevation correction. Multi-offset acquisition with 100 MHz antennae and offsets ranging from 1 m to 16 m are used for reflection tomography to create 2 D electromagnetic wave velocity models. Seismic surveys are performed with 72 geophones spaced at two meters using a sledge hammer source with shot points at each receiver point. We couple p- wave refraction tomography with Rayleigh wave inversion to compute Vp/Vs ratios. The two geophysical datasets are then compared with stratigraphic information to illustrate the influence of lithological parameters (e.g. stratification, grain-size distribution, porosity, and sorting) on geophysical properties of unsaturated pyroclastic deposits. Future work will include joint petrophysical inversion of the multiple datasets to estimate porosity and water content in the unsaturated zone.

  2. Estimating Trapped Gas Concentrations as Bubbles Within Lake Ice Using Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Fantello, N.; Parsekian, A.; Walter Anthony, K. M.

    2015-12-01

    Climate warming is currently one of the most important issues that we are facing. The degradation of permafrost beneath thermokarst lakes has been associated with enhanced methane emissions and it presents a positive feedback to climate warming. Thermokarst lakes release methane to the atmosphere mainly by ebullition (bubbling) but there are a large number of uncertainties regarding the magnitude and variability of these emissions. Here we present a methodology to estimate the amount of gas released from thermokarst lakes through ebullition using ground-penetrating radar (GPR). This geophysical technique is well suited for this type of problem because it is non-invasive, continuous, and requires less effort and time than the direct visual inspection. We are studying GPR data collected using 1.2 GHz frequency antennas in Brooklyn Lake, Laramie, WY, in order to quantify the uncertainties in the method. Although this is not a thermokarst lake, gas bubbles are trapped in the ice and spatial variability in bubble concentration within the ice is evident. To assess the variability in bulk physical properties of the ice due to bubbles, we gathered GPR data from different types of ice. We compared the velocity of the groundwave and reflection obtained from radargrams, and found on each case a larger value for the groundwave velocity suggesting a non-homogeneous medium and that the concentration of bubbles is prone to be near the surface instead of at greater depths. We use a multi-phase dielectric-mixing model to estimate the amount of gas present in a sample of volume of ice and found an uncertainty in relative permittivity (estimated using reflection velocity) of 0.0294, which translates to an uncertainty of 1.1% in gas content; and employing groundwave velocity we found 0.0712 and 2.9%, respectively. If locations of gas seeps in lakes could be detected and quantified using GPR along with field measurements, this could help to constrain future lake-source carbon gas

  3. Algorithm for detecting defects in wooden logs using ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Devaru, Dayakar; Halabe, Udaya B.; Gopalakrishnan, B.; Agrawal, Sachin; Grushecky, Shawn

    2005-11-01

    Presently there are no suitable non-invasive methods for precisely detecting the subsurface defects in logs in real time. Internal defects such as knots, decays, and embedded metals are of greatest concern for lumber production. While defects such as knots and decays (rots) are of major concern related to productivity and yield of high value wood products, embedded metals can damage the saw blade and significantly increase the down time and maintenance costs of saw mills. Currently, a large number of logs end up being discarded by saw mills, or result in low value wood products since they include defects. Nondestructive scanning of logs using techniques such as Ground Penetrating Radar (GPR) prior to sawing can greatly increase the productivity and yield of high value lumber. In this research, the GPR scanned data has been analyzed to differentiate the defective part of the wooden log from the good part. The location and size of the defect has been found in the GPR scanned data using the MATLAB algorithm. The output of this algorithm can be used as an input for generating operating instructions for a CNC sawing machine. This paper explains the advantages of the GPR technique, experimental setup and parameters used, data processing using RADAN software for detection of subsurface defects in logs, GPR data processing and analysis using MATLAB algorithm for automated defect detection, and comparison of results between the two processing methods. The results show that GPR in conjunction with the proposed algorithm provides a very promising technique for future on-line implementation in saw mills.

  4. Groundwater Surface Trends at Van Norden Meadow, California, from Ground Penetrating Radar Profiles

    NASA Astrophysics Data System (ADS)

    Tadrick, N. I.; Blacic, T. M.; Yarnell, S. M.

    2014-12-01

    Van Norden meadow in the Donner Summit area west of Lake Tahoe is one of the largest sub-alpine meadows in the Sierra Nevada mountain range. As natural water retention basins, meadows attenuate floods, improve water quality and support vegetation that stabilizes stream banks and promotes high biodiversity. Like most meadows in the Sierras however, over-grazing, road-building, and development has resulted in localized stream incision, degradation, and partial conversion from wet to dry conditions in Van Norden. Additionally, a small dam at the base of the meadow has partially flooded the lower meadow creating reservoir conditions. Privately owned since the late 1800s, Van Norden was recently purchased by a local land trust to prevent further development and return the area to public ownership. Restoration of the natural meadow conditions will involve notching the dam in 2016 to reduce currently impounded water volumes from 250 to less than 50 acre-feet. To monitor the effects of notching the dam on the upstream meadow conditions, better understanding of the surface and groundwater hydrology both pre- and post-restoration is required. We surveyed the meadow in summer 2014 with ground penetrating radar (GPR) to map the groundwater surface prior to restoration activities using a 270MHz antenna to obtain a suite of longitudinal and transverse transects. Groundwater level within the meadow was assessed using both piezometer readings and sweeps of the GPR antenna. Seventeen piezometers were added this year to the 13 already in place to monitor temporal changes in the groundwater surface, while the GPR profiles provided information about lateral variations. Our results provide an estimate of the groundwater depth variations across the upper portion of the meadow before notching. We plan to return in 2015 to collect GPR profiles during wetter conditions, which will provide a more complete assessment of the pre-notching groundwater hydrology.

  5. Vehicle-mounted ground penetrating radar (Mine Stalker III) field evaluation in Angola

    NASA Astrophysics Data System (ADS)

    Laudato, Stephen; Hart, Kerry; Nevard, Michael; Lauziere, Steven; Grant, Shaun

    2014-05-01

    The U.S. Department of Defense Humanitarian Demining Research and Development (HD R&D) Program, Non-Intrusive Inspection Technology (NIITEK), Inc. and The HALO Trust have over the last decade funded, developed and tested various prototype vehicle mounted ground penetrating radar (GPR) systems named the Mine Stalker. The HD R&D Program and NIITEK developed the Mine Stalker to detect low metal anti-tank (LM-AT) mines in roads. The country of Angola is severely affected by LM-AT mines in and off road, some of which are buried beyond the effective range of detection sensors current used in country. The threat from LM-AT mines such as the South African Number 8 (No. 8) and the Chinese Type 72 (72AT) still persist from Angola's 30 years of civil war. These LM-AT threats are undetectable at depths greater than 5 to 10 centimeters using metal detection technology. Clearing commerce routes are a critical requirement before Angola can rebuild its infrastructure and improve safety conditions for the local populace. The Halo Trust, a non-governmental demining organization (NGO) focused on demining and clearance of unexploded ordnance (UXO), has partnered with the HD R&D Program to conduct an operational field evaluation (OFE) of the Mine Stalker III (MS3) in Angola. Preliminary testing and training efforts yielded encouraging results. This paper presents a review of the data collected, testing results, system limitations and deficiencies while operating in a real world environment. Our goal is to demonstrate and validate this technology in live minefield environments, and to collect data to prompt future developments to the system.

  6. Attribute-driven transfer learning for detecting novel buried threats with ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Colwell, Kenneth A.; Collins, Leslie M.

    2016-05-01

    Ground-penetrating radar (GPR) technology is an effective method of detecting buried explosive threats. The system uses a binary classifier to distinguish "targets", or buried threats, from "nontargets" arising from system prescreener false alarms; this classifier is trained on a dataset of previously-observed buried threat types. However, the threat environment is not static, and new threat types that appear must be effectively detected even if they are not highly similar to every previously-observed type. Gathering a new dataset that includes a new threat type is expensive and time-consuming; minimizing the amount of new data required to effectively detect the new type is therefore valuable. This research aims to reduce the number of training examples needed to effectively detect new types using transfer learning, which leverages previous learning tasks to accelerate and improve new ones. Further, new types have attribute data, such as composition, components, construction, and size, which can be observed without GPR and typically are not explicitly included in the learning process. Since attribute tags for buried threats determine many aspects of their GPR representation, a new threat type's attributes can be highly relevant to the transfer-learning process. In this work, attribute data is used to drive transfer learning, both by using attributes to select relevant dataset examples for classifier fusion, and by extending a relevance vector machine (RVM) model to perform intelligent attribute clustering and selection. Classification performance results for both the attribute-only case and the low-data case are presented, using a dataset containing a variety of threat types.

  7. Estimation of Biogenic Gas Distribution in a Northern Peatland Using Surface and Borehole Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Comas, X.; Slater, L.; Reeve, A.

    2005-05-01

    A combination of borehole and surface ground penetrating radar (GPR), time domain reflectometry (TDR) and direct gas sampling was performed to detect biogenic gas accumulation areas in Caribou Bog, a multi-unit peatland in central Maine (Orono). Areas of electromagnetic (EM) signal scattering (or shadow zones, similar to those reported with the seismic reflection method) observed in the surface GPR coincide with sampled zones of high CH4 and CO2 concentration. Shadow zones also correlate with areas of high EM wave velocity detected in zero offset profiles (ZOP) conducted with the borehole GPR, and with areas of low water content inferred with TDR. Application of the Complex Refractive Index Model (CRIM) to the EM wave velocities implies that the anomalous high velocity zones results from a volumetric gas content of 7% and 10% for a peat soil porosity of 91% and 94% respectively. In the absence of gas, the CRIM model predicts a porosity value of only 84% to reach the maximum EM wave velocity recorded, a value not supported by our peat porosity measurements in the laboratory and inconsistent with the high porosity of peat recorded by others. Strong reflectors detected with the surface GPR are interpreted as confining layers acting as biogenic gas traps and inducing overpressurized biogenic gas pockets as postulated by others. Spatial gas distribution and volumetric gas content can be roughly estimated considering the areas affected by EM wave blanking. These findings also have implications for the monitoring of temporal behavior of biogenic gas emissions to the atmosphere from peatlands.

  8. Fusion of forward looking infrared and ground penetrating radar for improved stopping distances in landmine detection

    NASA Astrophysics Data System (ADS)

    Malof, Jordan M.; Morton, Kenneth D.; Collins, Leslie M.; Torrione, Peter A.

    2014-06-01

    Ground penetrating radar (GPR) is a popular sensing modality for buried threat detection that offers low false alarm rates (FARs), but suffers from a short detection stopping or standoff distance. This short stopping distance leaves little time for the system operator to react when a threat is detected, limiting the speed of advance. This problem arises, in part, because of the way GPR data is typically processed. GPR data is first prescreened to reduce the volume of data considered for higher level feature-processing. Although fast, prescreening introduces latency that delays the feature processing and lowers the stopping distance of the system. In this work we propose a novel sensor fusion framework where a forward looking infrared (FLIR) camera is used as a prescreener, providing suspicious locations to the GPRbased system with zero latency. The FLIR camera is another detection modality that typically yields a higher FAR than GPR while offering much larger stopping distances. This makes it well-suited in the role of a zero-latency prescreener. In this framework, GPR-based feature processing can begin without any latency, improving stopping distances. This framework was evaluated using well-known FLIR and GPR detection algorithms on a large dataset collected at a Western US test site. Experiments were conducted to investigate the tradeoff between early stopping distance and FAR. The results indicate that earlier stopping distances are achievable while maintaining effective FARs. However, because an earlier stopping distance yields less data for feature extraction, there is a general tradeoff between detection performance and stopping distance.

  9. Uses of ground-penetrating radar in the Georgia coastal plain. Rview of past and current studies. Research report

    SciTech Connect

    Truman, C.C.; Bosch, D.D.; Allison, H.D.; Fletcher, R.G.

    1994-10-01

    Ground-penetrating radar (GPR) has been used by researchers at ARS's Southeast Watershed Research Laboratory (SEWRL) to nondestructively investigate soil properties (and their spatial variability) and geologic materials in this region. Uses of GPR include mapping soils and performing nondestructive site investigations; detecting and determining spatial variability of argilic horizons, water tables in coarse-textured soils, geologic materials, and hard pans; and mapping lake bottoms and defining lake storage conditions.

  10. Magnetic and ground penetrating radar surveys for the research of Medieval settlements in the inland of the Marche Region (Italy)

    NASA Astrophysics Data System (ADS)

    Bavusi, M.; Giocoli, A.; Balasco, M.; Favulli, G.; Moscatelli, U.; Minguzzi, S.; Gnesi, D.; Virgili, S.

    2009-04-01

    This work was carried out in the framework of the R.I.M.E.M. project (Research on Medieval settlements in the inland of the Marche Region, Italy.) leaded by the Universities of Macerata and Udine and having the aim to produce a significant contribution for the comprehension of the settlement process in the Central and Southern Italy during the Late Roman Period and Early Middle Ages. Then, an extensive gradiometric survey were carried out, by using a vapour caesium magnetometer, in the area included amongst the municipal districts of Caldarola, Cessapalombo and San Ginesio, sited in the area closed to Macerata between the valleys of Chienti and Fiastra rivers. Moreover, in the most interesting areas, a 400 MHz 3D ground penetrating radar (GPR)survey was carried out in order to get the precise overlapping with the magnetic method. The Magnetic method is now a standard practice in the archaeological research taken into great consideration for its non-destructivity and quickness and its capability of mapping wide areas in quite a short lapse of time (Bavusi et al., 2008). Moreover the method provides an information well correlable with remote sensing data (Gallo et al, 2008). The GPR method is extremely useful for archaeologists thanks to its non-destructivity and capability of giving real-time and high-resolution data (Basile et al., 2000). Today the effectiveness of this method was improved by powerful 3D visualisation methods as well as 3D space, time or depth slices and iso-amplitude surfaces, too (Nuzzo et al., 2002). The integrations of several geophysical methods are usual (Sambuelli et al.1999, De Domenico et al., 2001; Chianese et al., 2004) particularly when a simple comparison in cross section along the same profiles can be performed. In this work the overlapping between two kinds of data was complicated by different outputs coming from two methods: maps for the magnetic method and cross sections for the GPR one. The 3D survey design for the GPR survey and

  11. Ice thickness profile surveying with ground penetrating radar at Artesonraju Glacier, Peru

    NASA Astrophysics Data System (ADS)

    Chisolm, Rachel; Rabatel, Antoine; McKinney, Daene; Condom, Thomas; Cochacin, Alejo; Davila Roller, Luzmilla

    2014-05-01

    Tropical glaciers are an essential component of the water resource systems in the mountainous regions where they are located, and a warming climate has resulted in the accelerated retreat of Andean glaciers in recent decades. The shrinkage of Andean glaciers influences the flood risk for communities living downstream as new glacial lakes have begun to form at the termini of some glaciers. As these lakes continue to grow in area and volume, they pose an increasing risk of glacial lake outburst floods (GLOFs). Ice thickness measurements have been a key missing link in studying the tropical glaciers in Peru and how climate change is likely to impact glacial melt and the growth of glacial lakes. Ground penetrating radar (GPR) has rarely been applied to glaciers in Peru to measure ice thickness, and these measurements can tell us a lot about how a warming climate will affect glaciers in terms of thickness changes. In the upper Paron Valley (Cordillera Blanca, Peru), an emerging lake has begun to form at the terminus of the Artesonraju Glacier, and this lake has key features, including overhanging ice and loose rock likely to create slides, that could trigger a catastrophic GLOF if the lake continues to grow. Because the glacier mass balance and lake mass balance are closely linked, ice thickness measurements and measurements of the bed slope of the Artesonraju Glacier and underlying bedrock can give us an idea of how the lake is likely to evolve in the coming decades. This study presents GPR data taken in July 2013 at the Artesonraju Glacier as part of a collaboration between the Unidad de Glaciologia y Recursos Hidricos (UGRH) of Peru, the Institut de Recherche pour le Développement (IRD) of France and the University of Texas at Austin (UT) of the United States of America. Two different GPR units belonging to UGRH and UT were used for subsurface imaging to create ice thickness profiles and to characterize the total volume of ice in the glacier. A common midpoint

  12. Determining basin geometry, stability, and flow dynamics of valley glaciers with ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Campbell, Seth William

    Mountain glaciers and ice caps (GICs) currently contribute ~0% to annual sea level rise. Most are temperate, therefore having the potential for rapid retreat from rising atmospheric temperatures. This climate sensitivity makes GIC stability and their impact on sea level rise a scientific problem with societal implications. To accurately predict impacts from GIC changes, knowledge of glacier components (e.g., basin geometry, mass balance, and dynamics) is needed. The goal of my dissertation research is to determine information about glacier geometry, snow-fire, and englacial stratigraphy using ground-penetrating radar (GPR) to enhance our understanding of valley glacier mass balance, dynamics, and stability. I first examine glacier basin geometry and ice volume of two temperate glaciers (Jarvis Glacier, Alaska and Nisqually Glacier, Washington) and demonstrate that significant errors (≥30-50%) can arise when using empirically-based volume estimates without geophysical constraints. I next determine spatial variability of accumulation across the temperate Juneau Icefield in Alaska usina GPR to interpolate between snowpits. To accomplish this, the dependence of radar velocity on snow density (~.3-0.7 g cm -3) and water content (0-9% by volume) needs to be addressed. Results show that on average, 2.1+/-0.5 m (water equivalent) of winter snow accumulates across the icefield with accumulation patterns depending on elevation, aspect, and proximity to moisture source. The third component of my dissertation combines locally measured accumulation rates, ice flow velocities, and englacial structures imaged with GPR to calculate that a negative mass balance (-0.25 cm a -1) has existed in valley glaciers of the Pensacola Mountains, West Antarctica over the past 1200 years. Finally, 1 use a 3-dimensional finite element non-Newtonian model to characterize the stress fields and current dynamics of a small ice divide. GPR-derived basin geometry is used for model boundary

  13. Waveform Attributes of Ground-Penetrating Radar Profiles of Glaciofluvial Sedimentation

    NASA Astrophysics Data System (ADS)

    Arcone, S. A.; Friddell, J. E.

    2002-12-01

    We present several ground-penetrating radar (GPR) reflection and moveout profiles of a section of glaciofluvial sedimentation recorded in a gravel pit along the Connecticut River, Norwich, VT. Sediments in the pit are generally composed of silt to gravel size grains and suggest a high-energy depositional environment. Large channels are apparent in section on the pit walls. It is probable that these sediments were deposited during the last deglaciation at the mouth of the paleo-Ompompanoosuc River as it entered glacial Lake Hitchcock. The GPR profiles were recorded at 3 different pulse center frequencies with standard, commercially available short-pulse type radar. Our objective was to find the effects of the sedimentary dielectric properties on the waveform attributes of phase, pulse shape, spectral content, and horizon characteristics. We used antennas nominally rated by the manufacturer as having pulse center frequencies of 100, 400, and 900 MHz, the latter of particular interest because it is higher than previously reported for sedimentary studies. In practice, the pulse spectra were centered near 72, 300 and 600 MHz. The 72-MHz horizons are mainly resonances, while many of the 300- and 600-MHz horizons reproduce the transmitted wavelet, as expected. Given a near-surface (top 4 m) dielectric constant of 6.7, as measured by a 600-MHz moveout profile, the maximum resolution (separation of two interfaces) of the 600-MHz wavelet was about 15 cm. Localized, low frequency wavelet reflections centered at 400 MHz, for which we do not have an immediate explanation, were apparent in the 600-MHz moveout and reflection profiles. The 600-MHz reflection profile shows many solitary wavelet reflections whose phases indicate either reflections from interfaces between lower permittivity material beneath higher, or vice versa, while modeling indicates that other wavelets are responses to thin layers. More subtle yet distinct horizons at 300 MHz appear to be lost within scattering

  14. Large-scale, high-definition Ground Penetrating Radar prospection in archaeology

    NASA Astrophysics Data System (ADS)

    Trinks, I.; Kucera, M.; Hinterleitner, A.; Löcker, K.; Nau, E.; Neubauer, W.; Zitz, T.

    2012-04-01

    The future demands on professional archaeological prospection will be its ability to cover large areas in a time and cost efficient manner with very high spatial resolution and accuracy. The objective of the 2010 in Vienna established Ludwig Boltzmann Institute for Archaeological Prospection and Virtual Archaeology (LBI ArchPro) in collaboration with its eight European partner organisations is the advancement of state-of-the-art archaeological sciences. The application and specific further development of remote sensing, geophysical prospection and virtual reality applications, as well as of novel integrated interpretation approaches dedicated to non-invasive spatial archaeology combining near-surface prospection methods with advanced computer science is crucial for modern archaeology. Within the institute's research programme different areas for distinct case studies in Austria, Germany, Norway, Sweden and the UK have been selected as basis for the development and testing of new concepts for efficient and universally applicable tools for spatial, non-invasive archaeology. In terms of geophysical prospection the investigation of entire archaeological landscapes for the exploration and protection of Europe's buried cultural heritage requires new measurement devices, which are fast, accurate and precise. Therefore the further development of motorized, multichannel survey systems and advanced navigation solutions is required. The use of motorized measurement devices for archaeological prospection implicates several technological and methodological challenges. Latest multichannel Ground Penetrating Radar (GPR) arrays mounted in front off, or towed behind motorized survey vehicles permit large-scale GPR prospection surveys with unprecedented spatial resolution. In particular the motorized 16 channel 400 MHz MALÅ Imaging Radar Array (MIRA) used by the LBI ArchPro in combination with latest automatic data positioning and navigation solutions permits the reliable high

  15. Challenges and Strategies for Quantitive Ground Penetrating Radar Diagnostics of Cultural Heritage

    NASA Astrophysics Data System (ADS)

    di Donato, Loreto; Catapano, Ilaria; Crocco, Lorenzo

    2010-05-01

    High resolution non-invasive surveys based on Ground Penetrating Radar are exploited in many different applications, including cultural heritage diagnostics. In this framework, the interaction of the probing wave with an inaccessible region is useful for instance to provide information on the inner status of a structure, so to call for maintenance, or to characterize an underground scenario, so to address the following excavations. While the large part of GPR surveys is still based on 'traditional' radar-like techniques, which require a significant interpretation stage by an expert user, microwave tomography (MT) strategies based on inverse scattering have been recently gaining an increasing attention. As a matter of fact, these techniques are capable of achieving images which are stable with respect to measurement noise and uncertainties on the scenario, therefore being minimally dependent on the end-user's interpretation. So far, MT strategies adopted in GPR surveys are based on an approximated formulation which neglects the underlying non-linearity of the inverse problem. Such a circumstance, that greatly simplifies their practical application, limits the achievable performances, as it prevents one from achieving a quantitative assessment of the scenario under test in terms of location, shape and electormagnetic parameters of the embedded 'anomalies'. Obviously, the potential advantage resulting from such a completely objective assessment is apparent, since an imaging method able to deliver quantitative information entails a dramatic reduction of costs and a definite improvement in the effectiveness of maintenance operations. Therefore, a stimulating challenge is to proceed towards the development of imaging strategies that rely on full-wave models and which are thus capable of providing these added-value results. However, such an aim is not a trivial one pursue, since one has to tackle the inverse problem in its fully non-linearity and ill-posedness. Indeed

  16. Mars, accessing the third dimension: a software tool to exploit Mars ground penetrating radars data.

    NASA Astrophysics Data System (ADS)

    Cantini, Federico; Ivanov, Anton B.

    2016-04-01

    The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS), on board the ESA's Mars Express and the SHAllow RADar (SHARAD), on board the NASA's Mars Reconnaissance Orbiter are two ground penetrating radars (GPRs) aimed to probe the crust of Mars to explore the subsurface structure of the planet. By now they are collecting data since about 10 years covering a large fraction of the Mars surface. On the Earth GPRs collect data by sending electromagnetic (EM) pulses toward the surface and listening to the return echoes occurring at the dielectric discontinuities on the planet's surface and subsurface. The wavelengths used allow MARSIS EM pulses to penetrate the crust for several kilometers. The data products (Radargrams) are matrices where the x-axis spans different sampling points on the planet surface and the y-axis is the power of the echoes over time in the listening window. No standard way to manage this kind of data is established in the planetary science community and data analysis and interpretation require very often some knowledge of radar signal processing. Our software tool is aimed to ease the access to this data in particular to scientists without a specific background in signal processing. MARSIS and SHARAD geometrical data such as probing point latitude and longitude and spacecraft altitude, are stored, together with relevant acquisition metadata, in a geo-enabled relational database implemented using PostgreSQL and PostGIS. Data are extracted from official ESA and NASA released data using self-developed python classes and scripts and inserted in the database using OGR utilities. This software is also aimed to be the core of a collection of classes and script to implement more complex GPR data analysis. Geometrical data and metadata are exposed as WFS layers using a QGIS server, which can be further integrated with other data, such as imaging, spectroscopy and topography. Radar geometry data will be available as a part of the iMars Web

  17. Comparative Ground-Penetrating Radar Stratigraphy: Differentiation of Lithologies and Depositional Environments Using Bedform Geometry and Radar Facies Analysis

    NASA Astrophysics Data System (ADS)

    Bitting, K.; Earley, R.; Mountain, G.; Feibel, C.; Ashley, G.

    2008-12-01

    Ground-penetrating radar (GPR) profiles are valuable in the investigation of terrestrial subsurface stratigraphy at scales of cm to m, below the resolution of commonly-used acoustic profiling. One of the major benefits of GPR is its ability to characterize deposits non-invasively (without coring or trenching). Like nearly all efforts to invert true geology from geophysical data, attempts to derive lithology and depositional environment from radar-imaged layering provide non-unique solutions. However, we point out that qualitative and quantitative radar stratigraphy, including radar facies analysis, provides valuable information concerning depositional history in the shallow subsurface. Basic characteristics of any sedimentary deposit are generated by a combination of the depositional process and the nature of the particles themselves. For example, bedform height depends on the depth of the fluid in which it is created. Bedform steepness depends upon grain size, sorting, water velocity, and antecedent topography. Development of bedding depends upon grain size, sorting, and fluctuations in the transport capacity of the system. These characteristics can be understood from radar profiles in the absence of outcrop or core data. For example, properties of some clays cause energy absorption which decreases the depth of penetration. Extremely large grains, lateral heterogeneities, and irregular lithologic contacts cause EM energy to scatter, resulting in poorly resolved subsurface interfaces or chaotic reflector patterns. Analyses of radar wave velocity also yield information about water content, which is a function of grain size, sorting, and composition. Bedform geometry is often clearly visible in GPR profiles, and can be quantified after appropriate processing. GPR profiles from five different deposits accumulated during the past 18 ka in New Jersey are compared: fluvial deposits of the Delaware River; glacial outwash and an end moraine from the Wisconsinan glacial

  18. Ground Penetrating Radar Imaging of Ancient Clastic Deposits: A Tool for Three-Dimensional Outcrop Studies

    NASA Astrophysics Data System (ADS)

    Akinpelu, Oluwatosin Caleb

    The growing need for better definition of flow units and depositional heterogeneities in petroleum reservoirs and aquifers has stimulated a renewed interest in outcrop studies as reservoir analogues in the last two decades. Despite this surge in interest, outcrop studies remain largely two-dimensional; a major limitation to direct application of outcrop knowledge to the three dimensional heterogeneous world of subsurface reservoirs. Behind-outcrop Ground Penetrating Radar (GPR) imaging provides high-resolution geophysical data, which when combined with two dimensional architectural outcrop observation, becomes a powerful interpretation tool. Due to the high resolution, non-destructive and non-invasive nature of the GPR signal, as well as its reflection-amplitude sensitivity to shaly lithologies, three-dimensional outcrop studies combining two dimensional architectural element data and behind-outcrop GPR imaging hold significant promise with the potential to revolutionize outcrop studies the way seismic imaging changed basin analysis. Earlier attempts at GPR imaging on ancient clastic deposits were fraught with difficulties resulting from inappropriate field techniques and subsequent poorly-informed data processing steps. This project documents advances in GPR field methodology, recommends appropriate data collection and processing procedures and validates the value of integrating outcrop-based architectural-element mapping with GPR imaging to obtain three dimensional architectural data from outcrops. Case studies from a variety of clastic deposits: Whirlpool Formation (Niagara Escarpment), Navajo Sandstone (Moab, Utah), Dunvegan Formation (Pink Mountain, British Columbia), Chinle Formation (Southern Utah) and St. Mary River Formation (Alberta) demonstrate the usefulness of this approach for better interpretation of outcrop scale ancient depositional processes and ultimately as a tool for refining existing facies models, as well as a predictive tool for subsurface

  19. Estimation of soil water content for engineering and agricultural applications using ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Grote, Katherine Rose

    2003-10-01

    Near-surface water content is important for a variety of applications in engineering, agriculture, ecology, and environmental monitoring and is an essential input parameter for hydrological and atmospheric models. Water content is both spatially and temporally variable and is difficult to characterize using conventional measurement techniques, which are invasive, time-consuming to collect, and provide only a limited number of point measurements. The purpose of this study is to investigate ground penetrating radar (GPR) techniques for improved estimation of water content. GPR techniques have potential for providing accurate, high-resolution estimates of water content quickly and non-invasively, but the efficacy of these techniques for field-scale applications has not been previously determined. This study begins with a literature review of the application of GPR techniques for water content estimation, followed by a description of the principles employed in GPR surveying and the general methodology for converting electromagnetic GPR measurements to water content estimates. Next, a pilot experiment using GPR techniques for water content estimation is described; this experiment was performed under very controlled conditions and used common-offset GPR reflections to estimate the water content in sandy test pits. This experiment showed that GPR techniques can estimate water content very accurately (within 0.017 cm3/cm3 of the volumetric water content estimates obtained gravimetrically) and provided motivation for the second, less-controlled experiment. The second study used common-offset GPR reflections to estimate water content in a transportation engineering application, where the GPR data were used to monitor the water content in sub-asphalt aggregate layers and to estimate deformation under dynamic loading. This experiment showed that GPR data could be used to accurately monitor changes in the horizontal and vertical distributions of sub-asphalt water content with

  20. Mapping preferential flow pathways in a riparian wetland using ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Gormally, Kevin Hill

    Preferential flow of water through channels in the soil has been implicated as a vehicle for groundwater and surface water contamination in forested riparian wetland buffers. Water conducted through these by-pass channels can circumvent interaction with wetland biota, biomass, and soils, thereby reducing the buffering capacity of the riparian strips for adsorption and uptake of excess nutrient loads from neighboring agricultural fields and urbanized lands. Models of riparian function need to account for preferential flow to accurately estimate nutrient flux to stream channels, but there are currently no methods for determining the form and prevalence of these pathways outside of extensive destructive sampling. This research developed, tested, and validated a new application of non-invasive ground-penetrating radar technology (GPR) for mapping the three-dimensional structure of near-surface (0-1 m) lateral preferential flow channels. Manual and automated detection methodologies were created for analyzing GPR scan data to locate the channels in the subsurface. The accuracy of the methodologies was assessed in two field test plots with buried PVC pipes simulating the riparian channels. The manual methodology had a 0% Type I error rate and 8% Type II error rate; the automated version had a <1% Type I error rate and 29% Type II error rate. An automated mapping algorithm was also created to reconstruct channel geometries from the scan data detections. The algorithm was shown to robustly track the connectivity of PVC pipe segments arranged in a branching structure hypothesized to exist in the riparian soils. These methods and algorithms were then applied at a riparian wetland study site at USDA Beltsville Agricultural Research Center in Beltsville, MD. The predicted structure of preferential flow channels in the wetland was validated by transmission of tracer dye through the study site and ground truth generated from soil core samples (92% accurate). These GPR tools will

  1. Broadband Ground Penetrating Radar with conformal antennas for subsurface imaging from a rover

    NASA Astrophysics Data System (ADS)

    Stillman, D. E.; Oden, C. P.; Grimm, R. E.; Ragusa, M.

    2015-12-01

    Ground-Penetrating Radar (GPR) allows subsurface imaging to provide geologic context and will be flown on the next two martian rovers (WISDOM on ExoMars and RIMFAX on Mars 2020). The motivation of our research is to minimize the engineering challenges of mounting a GPR antenna to a spacecraft, while maximizing the scientific capabilities of the GPR. The scientific capabilities increase with the bandwidth as it controls the resolution. Furthermore, ultra-wide bandwidth surveys allow certain mineralogies and rock units to be discriminated based on their frequency-dependent EM or scattering properties. We have designed and field-tested a prototype GPR that utilizes bi-static circularly polarized spiral antennas. Each antenna has a physical size of 61 x 61 x 4 cm, therefore two antennas could be mounted to the underbelly of a MSL-class rover. Spiral antennas were chosen because they have an inherent broadband response and provide a better low frequency response compared with similarly sized linearly polarized antennas. A horizontal spiral radiator emits energy both upward and downward directions. After the radiator is mounted to a metal surface (i.e. the underside of a rover), a cavity is formed that causes the upward traveling energy to reverberate and cause unwanted interference. This interference is minimized by 1) using a high metallization ratio on the spiral to reduce cavity emissions, and 2) placing absorbing material inside the cavity. The resulting antennas provide high gain (0 to 8 dBi) from 200 to 1000 MHz. The low frequency response can be improved by increasing the antenna thickness (i.e., cavity depth). In an initial field test, the antennas were combined with impulse GPR electronics that had ~140 dB of dynamic range (not including antennas) and a sand/clay interface 7 feet deep was detected. To utilize the full bandwidth the antennas, a gated Frequency Modulated Continuous Waveform system will be developed - similar to RIMFAX. The goal is to reach a

  2. Getting saturated hydraulic conductivity from surface Ground-Penetrating Radar measurements inside a ring infiltrometer

    NASA Astrophysics Data System (ADS)

    Leger, E.; Saintenoy, A.; Coquet, Y.

    2013-12-01

    Hydraulic properties of soils, described by the soil water retention and hydraulic conductivity functions, strongly influence water flow in the vadoze zone, as well as the partitioning of precipitation between infiltration into the soil and runoff along the ground surface. Their evaluation has important applications for modelling available water resources and for flood forecasting. It is also crucial to evaluate soil's capacity to retain chemical pollutants and to assess the potential of groundwater pollution. The determination of the parameters involved in soil water retention functions, 5 parameters when using the van Genuchten function, is usually done by laboratory experiments, such as the water hanging column. Hydraulic conductivity, on the other hand can be estimated either in laboratory, or in situ using infiltrometry tests. Among the large panel of existing tests, the single or double ring infiltrometers give the field saturated hydraulic conductivity by applying a positive charge on soils, whereas the disk infiltrometer allows to reconstruct the whole hydraulic conductivity curve, by applying different charges smaller than or equal to zero. In their classical use, volume of infiltrated water versus time are fitted to infer soil's hydraulic conductivity close to water saturation. Those tests are time-consuming and difficult to apply to landscape-scale forecasting of infiltration. Furthermore they involve many assumptions concerning the form of the infiltration bulb and its evolution. Ground-Penetrating Radar (GPR) is a geophysical method based on electromagnetic wave propagation. It is highly sensitive to water content variations directly related to the dielectric permittivity. In this study GPR was used to monitor water infiltration inside a ring infiltrometer and retrieve the saturated hydraulic conductivity. We carried out experiments in a quarry of Fontainebleau sand, using a Mala RAMAC system with antennae centered on 1600 MHz. We recorded traces at

  3. Internal structure of a barrier beach as revealed by ground penetrating radar (GPR): Chesil beach, UK

    NASA Astrophysics Data System (ADS)

    Bennett, Matthew R.; Cassidy, Nigel J.; Pile, Jeremy

    2009-03-01

    Chesil Beach (Dorset) is one of the most famous coastal landforms on the British coast. The gravel beach is over 18 km long and is separated for much of its length from land by a tidal lagoon known as The Fleet. The beach links the Isle of Portland in the east to the mainland in the west. Despite its iconic status there is little available information on its internal geometry and evolutionary history. Here we present a three-fold model for the evolution of Chesil Beach based on a series of nine ground penetrating radar (GPR) traverses located at three sites along its length at Abbotsbury, Langton Herring and at Ferry Bridge. The GPR traverses reveal a remarkably consistent picture of the internal structure of this barrier beach. The first phase of evolution involves the landward transgression of a small sand and gravel beach which closed upon the coast leading to deposition of freshwater peat between 5 and 7 k yr BP. The second evolutionary phase involves the 'bulking-out' of the beach during continued sea level rise, but in the presence of abundant gravel supplied by down-drift erosion of periglacial slope deposits. This episode of growth was associated with a series of washover fans which accumulated on the landward flank of the barrier increasing its breadth and height but without significant landward transgression of the barrier as a whole. The final phase in the evolution of Chesil Beach involves the seaward progradation of the beach crest and upper beach face associated with continued sediment abundance, but during a still-stand or slight fall in relative sea level. This phase may provide further evidence of a slight fall in relative sea level noted elsewhere along the South Coast of Britain and dated to between 1.2 and 2.4 k yr BP. Subsequently the barrier appears to have become largely inactive, except for the reworking of sediment on the beach face during storm events. The case study not only refines the evolutionary picture of Chesil Beach, but

  4. Improving tomographic estimates of subsurface electromagnetic wave velocity obtained from ground-penetrating radar data

    NASA Astrophysics Data System (ADS)

    Irving, James D.

    Crosshole ground-penetrating radar (GPR) travel-time tomography is a popular geophysical technique for characterization of the shallow subsurface in environmental applications. With this technique, a critical factor determining the resolution of the velocity images obtained is the angular ray coverage of the subsurface region between the boreholes; when travel-time data representing a narrow range of ray angles are used for the tomography reconstruction, the resulting images contain undesirable directional smearing. Here, I investigate the problem that, even when the crosshole GPR survey geometry offers the potential for high-resolution imaging due to wide angular ray coverage of the inter-borehole region, two significant issues are commonly encountered when attempting to take advantage of this coverage. First, travel times corresponding to high-angle ray paths are often extremely difficult to pick because of low signal-to-noise ratios in the data. Secondly, even when high-angle travel-time data can be reliably determined, they often appear to be incompatible with the lower-angle data available, and tend to cause strong numerical artifacts when included in inversions. To address the high-angle picking problem noted above, I develop a method for determining first-break times in crosshole GPR data using cross-correlations. High-quality reference waveforms for this technique are obtained from the data through the stacking of common-ray-angle gathers. To address the incompatibility issue with high-angle data, I first develop finite-difference time-domain (FDTD) numerical modeling codes that allow for the determination of realistic crosshole GPR antenna current distributions, and the modeling of transmitted and received waveforms in heterogeneous media. Using these codes, I then find that the high-angle incompatibility issue is likely the result of assuming that first-arriving energy always travels directly between the antenna centers; at high transmitter

  5. The detectability of archaeological structures beneath the soil using the ground penetrating radar technique

    NASA Astrophysics Data System (ADS)

    Ferrara, C.; Barone, P. M.; Pajewski, L.; Pettinelli, E.; Rossi, G.

    2012-04-01

    The traditional excavation tools applied to Archaeology (i.e. trowels, shovels, bulldozers, etc.) produce, generally, a fast and invasive reconstruction of the ancient past. The geophysical instruments, instead, seem to go in the opposite direction giving, rapidly and non-destructively, geo-archaeological information. Moreover, the economic aspect should not be underestimated: where the former invest a lot of money in order to carry out an excavation or restoration, the latter spend much less to manage a geophysical survey, locating precisely the targets. Survey information gathered using non-invasive methods contributes to the creation of site strategies, conservation, preservation and, if necessary, accurate location of excavation and restoration units, without destructive testing methods, also in well-known archaeological sites [1]-[3]. In particular, Ground Penetrating Radar (GPR) has, recently, become the most important physical technique in archaeological investigations, allowing the detection of targets with both very high vertical and horizontal resolution, and has been successfully applied both to archaeological and diagnostic purposes in historical and monumental sites [4]. GPR configuration, antenna frequency and survey modality can be different, depending on the scope of the measurements, the nature of the site or the type of targets. Two-dimensional (2D) time/depth slices and radargrams should be generated and integrated with information obtained from other buried or similar artifacts to provide age, structure and context of the surveyed sites. In the present work, we present three case-histories on well-known Roman archaeological sites in Rome, in which GPR technique has been successfully used. To obtain 2D maps of the explored area, a bistatic GPR (250MHz and 500MHz antennas) was applied, acquiring data along several parallel profiles. The GPR results reveal the presence of similar circular anomalies in all the investigated archaeological sites. In

  6. Coarse root distribution of a semi-arid oak savanna estimated with ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Raz-Yaseef, N.; Koteen, L. E.; Baldocchi, D. D.

    2012-12-01

    North California enjoys wet and mild winters, but experiences extreme hot, dry summer conditions, with occasional drought years. Despite the severity of summer conditions, blue oaks are winter-deciduous. We hypothesized that the binary nature of water availability would be reflected in blue oak root architecture. Our objective was to understand how the form of the root system facilitates ecosystem functioning. To do this, we sought to characterize the structure of the root system, and survey coarse root distribution with ground penetrating radar (GPR), due to its advantages in covering large areas rapidly and non-destructively. Because GPR remains a relatively new technology for examining root distribution, an ancillary objective was to test this methodology, and help facilitate its application more broadly. A third objective was to test the potential for upscaling coarse root biomass by developing allometric relations based on LIDAR measurements of above ground canopy structure. We surveyed six 8x8 m locations with trees varying in size, age and clumping (i.e. isolated trees vs. tree clusters). GPR signals were transformed to root biomass by calibrating them against excavated roots. Toward this goal, we positioned two rectangles of size 60x100 cm in each of the grids, excavated and sieved soil to harvest roots. Our results indicate that coarse roots occupy the full soil profile, and that root biomass of old large trees peaks just above the bedrock. As opposed to other semi-arid regions, where trees often develop extensive shallow coarse lateral roots, in order to exploit the entire wet-soil medium, we found that coarse root density decreased with distance from the bole, and dropped sharply at a distance of 2 m. We upscaled root biomass to stand-scale (2.8±0.4 kg m-2) based on LiDAR analysis of the relative abundance of each tree configuration. We argue that the deep and narrow root structure we observed reflects the ecohydrology of oaks in this ecosystem, because

  7. Scoria Cone and Tuff Ring Stratigraphy Interpreted from Ground Penetrating Radar, Rattlesnake Crater, Arizona

    NASA Astrophysics Data System (ADS)

    Kruse, S. E.; McNiff, C. M.; Marshall, A. M.; Courtland, L. M.; Connor, C.; Charbonnier, S. J.; Abdollahzadeh, M.; Connor, L.; Farrell, A. K.; Harburger, A.; Kiflu, H. G.; Malservisi, R.; Njoroge, M.; Nushart, N.; Richardson, J. A.; Rookey, K.

    2013-12-01

    Numerous recent studies have demonstrated that detailed investigation of scoria cone and maar morphology can reveal rich details the eruptive and erosion histories of these volcanoes. A suite of geophysical surveys were conducted to images Rattlesnake Crater in the San Francisco Volcanic Field, AZ, US. We report here the results of ~3.4 km of ground penetrating radar (GPR) surveys that target the processes of deposition and erosion on the pair of cinder cones that overprint the southeast edge of Rattlesnake crater and on the tuff ring that forms the crater rim. Data were collected with 500, 250, 100, and 50 MHz antennas. The profiles were run in a radial direction down the northeast flanks of the cones (~1 km diameter, ~120 meters height) , and on the inner and outer margins of the oblong maar rim (~20-80 meters height). A maximum depth of penetration of GPR signal of ~15m was achieved high on the flanks of scoria cones. A minimum depth of essentially zero penetration occurred in the central crater. We speculate that maximum penetration occurs near the peaks of the cones and crater rim because ongoing erosion limits new soil formation. Soil formation would tend to increase surface conductivity and hence decrease GPR penetration. Soil is probably better developed within the crater, precluding significant radar penetration there. On the northeast side of the gently flattened rim of the easternmost scoria cone, the GPR profile shows internal layering that dips ~20 degrees northeast relative to the current ground surface. This clearly indicates that the current gently dipping surface is not a stratigraphic horizon, but reflects instead an erosive surface into cone strata that formed close to the angle of repose. Along much of the cone flanks GPR profiles show strata dipping ~4-5 degrees more steeply than the current surface, suggesting erosion has occurred over most of the height of the cone. An abrupt change in strata attitude is observed at the gradual slope

  8. Semi-automatic template matching based extraction of hyperbolic signatures in ground-penetrating radar images

    NASA Astrophysics Data System (ADS)

    Sagnard, Florence; Tarel, Jean-Philippe

    2015-04-01

    In civil engineering applications, ground-penetrating radar (GPR) is one of the main non destructive technique based on the refraction and reflection of electromagnetic waves to probe the underground and particularly detect damages (cracks, delaminations, texture changes…) and buried objects (utilities, rebars…). An UWB ground-coupled radar operating in the frequency band [0.46;4] GHz and made of bowtie slot antennas has been used because, comparing to a air-launched radar, it increases energy transfer of electromagnetic radiation in the sub-surface and penetration depth. This paper proposes an original adaptation of the generic template matching algorithm to GPR images to recognize, localize and characterize with parameters a specific pattern associated with a hyperbola signature in the two main polarizations. The processing of a radargram (Bscan) is based on four main steps. The first step consists in pre-processing and scaling. The second step uses template matching to isolate and localize individual hyperbola signatures in an environment containing unwanted reflections, noise and overlapping signatures. The algorithm supposes to generate and collect a set of reference hyperbola templates made of a small reflection pattern in the vicinity of the apex in order to further analyze multiple time signals of embedded targets in an image. The standard Euclidian distance between the template shifted and a local zone in the radargram allows to obtain a map of distances. A user-defined threshold allows to select a reduced number of zones having a high similarity measure. In a third step, each zone is analyzed to detect minimum or maximum discrete amplitudes belonging to the first arrival times of a hyperbola signature. In the fourth step, the extracted discrete data (i,j) are fitted by a parametric hyperbola modeling based on the straight ray path hypothesis and using a constraint least square criterion associated with parameter ranges, that are the position, the

  9. PROGRESS REPORT. MATERIAL PROPERTY ESTIMATION FOR DIRECT DETECTION OF DNAPL USING INTEGRATED GROUND-PENETRATING RADAR VELOCITY, IMAGING AND ATTRIBUTE ANALYSIS

    EPA Science Inventory

    The focus of our work is direct detection of DNAPLs, specifically chlorinated solvents, via material property estimation from surface ground-penetrating radar (GPR) data. We combine sophisticated GPR processing methodology with quantitative attribute analysis and material propert...

  10. ANNUAL REPORT. MATERIAL PROPERTY ESTIMATION FOR DIRECT DETECTION OF DNAPL USING INTEGRATED GROUND-PENETRATING RADAR VELOCITY, IMAGING, AND ATTRIBUTE ANALYSIS

    EPA Science Inventory

    The focus of our work is direct detection of DNAPLs, specifically chlorinated solvents, via material property estimation from surface ground-penetrating radar (GPR) data. We combine sophisticated GPR processing methodology with quantitative attribute analysis and material propert...

  11. Mapping a Pristine Glaciofluvial Aquifer on the Canadian Shield Using Ground-Penetrating Radar and Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Graves, L. W.; Shirokova, V.; Bank, C.

    2013-12-01

    Our study aims to construct a 3D structural model of an unconfined pristine aquifer in Laurentian Hills, Ontario, Canada. The stratigraphy of the study site, which covers about 5400 square meters, features reworked glaciofluvial sands and glacial till on top of Canadian Shield bedrock. A network of 25 existing piezometers provides ground-truth. We used two types of geophysical surveys to map the water table and the aquifer basin. Ground-penetrating radar (GPR) collected 40 profiles over distances up to 140 meters using 200MHz and 400MHz antennas with a survey wheel. The collected radargrams show a distinct reflective layer, which can be mapped to outcrops of glacial till within the area. This impermeable interface forms the aquitard. Depths of the subsurface features were calculated using hyperbolic fits on the radargrams in Matlab by determining wave velocity then converting measured two-way-time to depth. Electrical resistivity was used to determine the water table elevations because the unconfined water table did not reflect the radar waves. 20 resistivity profiles were collected in the same area using Wenner-Alpha and dipole-dipole arrays with both 24 and 48 electrodes and for 0.5, 0.75, 1.0 and 2.0 meter spacing. The inverted resistivity models show low resistivity values (<1000 Ohm.m) below 2 to 5 meter depths and higher resistivity values (2000-6000 Ohm.m) above 1 to 2 meter depths. These contrasting resistivity values correspond to saturated and wet sand (lower resistivity) to dry sand (higher resistivity); a correlation we could verify with several bore-hole logs. The water table is marked on the resistivity profiles as a steep resistivity gradient, and the depth can be added to the comprehensive 3D model. This model also incorporates hydrogeological characteristics and geochemical anomalies found within the aquifer. Ongoing seasonal and annual monitoring of the aquifer using geophysical methods will bring a fourth dimension to our understanding of this

  12. Exchanging knowledge and working together in COST Action TU1208: Short-Term Scientific Missions on Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Santos Assuncao, Sonia; De Smedt, Philippe; Giannakis, Iraklis; Matera, Loredana; Pinel, Nicolas; Dimitriadis, Klisthenis; Giannopoulos, Antonios; Sala, Jacopo; Lambot, Sébastien; Trinks, Immo; Marciniak, Marian; Pajewski, Lara

    2015-04-01

    creating a robust methodological foundation for the combined analysis of electromagnetic-induction and GPR data. The fifth STSM was carried out by Loredana Matera, who visited Jacopo Sala at 3d-radar (Norway). They tested an innovative reconfigurable stepped-frequency GPR, designed and realised in Italy. The prototype was compared with commercial equipment produced in Norway. Through laboratory experiments as well as outdoor campaigns in urban scenarios with archaeological remarks, a deeper knowledge of the Italian prototype was achieved and plans were made to improve it. Finally, Nicolas Pinel visited Sébastien Lambot at the Université catholique de Louvain (UCL); the last STSM presented in this abstract, was devoted to investigating how to model the effect of soil roughness in the inversion of ultra wide-band off-ground monostatic GPR signals. The aim of this research is the noninvasive quantification of soil properties through the use of GPR. The work focused on incorporating the improved asymptotic forward electromagnetic model developed by Pinel et al. in the multilayer Green function code developed at UCL. Acknowledgement The Authors thank COST, for funding the Action TU1208 'Civil Engineering Applications of Ground Penetrating Radar,' supporting these STSMs.

  13. Ground penetrating radar survey on the cross-stratified overbank deposits from the 2006 eruption of Tungurahua volcano, Ecuador.

    NASA Astrophysics Data System (ADS)

    Amin Douillet, Guilhem; Abolghasem, Amir; Rémi Dujardin, Jean; Kueppers, Ulrich; Hall, Jonathan; Mothes, Patricia; Dingwell, Donald

    2013-04-01

    The deposits of the 2006 pyroclastic density currents (PDCs) at Tungurahua are organized as 1) massive, coarse-grained deposits confined to valleys of the drainage network and 2) cross-stratified, ash-dominated overbank deposits from dilute PDCs. These overbank deposits are exceptionally well preserved and show dune bedforms shaping the surface of the outcrops. In order to gain insights into the depositional mechanisms of the latter, we combined a terrestrial laser scanner (TLS) survey with a ground penetrating radar (GPR) dense network of profiles. The GPR survey permits to look at the internal cross stratification patterns in a non-destructive way. Three antennas with frequencies at 250, 500 and 800 MHz, respectively, permitted to image down to 10, 7 and 3 m depth. While the 800 MHz antenna was found to be very efficient to image cross-lamination, the 250 MHz antenna permitted to recognize major flow units. The GPR dataset profits from the TLS topography data, which are integrated in the processing of the data. From a dense array (profiles at 10 cm spacing) over different types of dune bedforms with the 800 MHz antenna, we manage to reconstruct the 3D internal patterns. Using the 250 MHz antenna, >50 profiles (20-80 m length) over a zone ca. 300*300 m permit to reconstruct and follow the major flow units on the overbanks and their 3D evolution as well as the pre-eruptive paleosoil. Notable results are: (1) the revelation of several units of dense pyroclastic flow deposits below the dilute PDC deposits on the overbanks. This may indicate that the valleys were filled by the time of deposition of the dune bedforms, a result not inferred in previous studies. Moreover, the number of units is greater than previously accessed. (2) For dune bedforms, the root of a structure is found to be located deeper than expected with striking spatial stability during the whole deposition stage, indicating that these bedforms are triggered by basal topographic disturbance. (3

  14. Assimilation of Ground-Penetrating Radar Data to Update Vertical Soil Moisture Profile

    NASA Astrophysics Data System (ADS)

    Tran, Phuong; Vanclooster, Marnik; Lambot, Sébastien

    2013-04-01

    The root zone soil moisture has been long recognized as important information for hydrological, meteorological and agricultural research. In this study, we propose a closed-loop data assimilation procedure to update the vertical soil moisture profile from time-lapse ground-penetrating radar (GPR) data. The hydrodynamic model, Hydrus-1D (Simunek et al., 2009), is used to propagate the system state in time and a radar electromagnetic model (Lambot et al., 2004) to link the state variable (soil moisture profile) with the observation data (GPR data), which enables us to update the soil moisture profile by directly assimilating the GPR data. The assimilation was performed within the maximum likelihood ensemble filter (MLEF) framework developed by Zupanski et al., (2005), for which the problem of nonlinear observation operator is solved much more effectively than the Ensemble Kalman filter (EnKF) techniques. The method estimates the optimal state as the maximum of the probability density function (PDF) instead of the minimum variance like in most of the other ensemble data assimilation methods. Direct assimilation of GPR data is a prominent advantage of our approach. It avoids solving the time-consuming inverse problem as well as the estimation errors of the soil moisture caused by inversion. In addition, instead of using only surface soil moisture, the approach allows to use the information of the whole soil moisture profile, which is reflected via the ultra wideband (UWB) GPR data, for the assimilation. The use of the UWB antenna in this study is also an advantage as it provides more information about soil moisture profile with a better depth resolution compared to other classical remote sensing techniques. Our approach was validated by a synthetic study. We constructed a synthetic soil column with a depth of 80 cm and analyzed the effects of the soil type on the data assimilation by considering 3 soil types, namely, loamy sand, silt and clay. The assimilation of GPR

  15. Exchanging knowledge and working together in COST Action TU1208: Short-Term Scientific Missions on Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Santos Assuncao, Sonia; De Smedt, Philippe; Giannakis, Iraklis; Matera, Loredana; Pinel, Nicolas; Dimitriadis, Klisthenis; Giannopoulos, Antonios; Sala, Jacopo; Lambot, Sébastien; Trinks, Immo; Marciniak, Marian; Pajewski, Lara

    2015-04-01

    This work aims at presenting the scientific results stemming from six Short-Term Scientific Missions (STSMs) funded by the COST (European COoperation in Science and Technology) Action TU1208 'Civil Engineering Applications of Ground Penetrating Radar' (Action Chair: Lara Pajewski, STSM Manager: Marian Marciniak). STSMs are important means to develop linkages and scientific collaborations between participating institutions involved in a COST Action. Scientists have the possibility to go to an institution abroad, in order to undertake joint research and share techniques/equipment/infrastructures that may not be available in their own institution. STSMs are particularly intended for Early Stage Researchers (ESRs), i.e., young scientists who obtained their PhD since no more than 8 years when they started to be involved in the Action. Duration of a standard STSM can be from 5 to 90 days and the research activities carried out during this short stay shall specifically contribute to the achievement of the scientific objectives of the supporting COST Action. The first STSM was carried out by Lara Pajewski, visiting Antonis Giannopoulos at The University of Edinburgh (United Kingdom). The research activities focused on the electromagnetic modelling of Ground Penetrating Radar (GPR) responses to complex targets. A set of test scenarios was defined, to be used by research groups participating to Working Group 3 of COST Action TU1208, to test and compare different electromagnetic forward- and inverse-scattering methods; these scenarios were modelled by using the well-known finite-difference time-domain simulator GprMax. New Matlab procedures for the processing and visualization of GprMax output data were developed. During the second STSM, Iraklis Giannakis visited Lara Pajewski at Roma Tre University (Italy). The study was concerned with the numerical modelling of horn antennas for GPR. An air-coupled horn antenna was implemented in GprMax and tested in a realistically

  16. Predicting Short Term Runoff Efficiency Using Antecedent Soil Moisture Estimates From Ground Penetrating Radar Data

    NASA Astrophysics Data System (ADS)

    Hermance, J. F.; Bohidar, R. N.

    2002-05-01

    Hydrologists universally recognize the importance of antecedent soil moisture conditions for predicting the response of catchments to storm events. We describe a pilot study involving a series of repeat geophysical measurements over a 5 month period to determine the water content of the subsurface immediately before a sequence of precipitation events. We correlate the resultant streamflow "response" of the local catchment to each event with the antecedent soil moisture at our reference site using a metric commonly employed by hydrologists: the ratio Qef/W, referred to here as the "short term runoff efficiency", which is simply the time-integrated volume of event flow (Qef) at the catchment's outflow point normalized by the volume of total precipitation (W) over its area. To determine the volumetric water content (Cw) of soils, past studies suggest the effectiveness of pulsed radio frequency methods, such as time domain reflectometry (TDR), or ground-penetrating radar (GPR). To first order, for typical field conditions and procedures, the velocity of a radio pulse in the subsurface is inversely proportional to the square root of the bulk dielectric constant, which in turn is proportional to the soil's water content. For this study, the advantage of GPR over conventional TDR measurements is that the GPR procedure determines average velocities from two-way traveltimes to an interface at depth, resulting in estimates of average physical properties over much larger volumes of the subsurface than would TDR. Our hydrologic data are USGS daily averaged discharges from the Ten Mile River (watershed area = 138 km2; 53.2 mi2) in southern New England. Daily values of precipitation were provided by personnel from the Seekonk Water District Office (MA) adjacent to the field site. Our hydrograph separation was facilitated by the observation that the event flow seems to be adequately represented by a simple composite cascaded linear reservoir model. The GPR data involved a series

  17. Multi-offset ground-penetrating radar imaging of a lab-scale infiltration test

    NASA Astrophysics Data System (ADS)

    Mangel, A. R.; Moysey, S. M. J.; Ryan, J. C.; Tarbutton, J. A.

    2012-11-01

    A lab scale infiltration experiment was conducted in a sand tank to evaluate the use of time-lapse multi-offset ground-penetrating radar (GPR) data for monitoring dynamic hydrologic events in the vadose zone. Sets of 21 GPR traces at offsets between 0.44-0.9 m were recorded every 30 s during a 3 h infiltration experiment to produce a data cube that can be viewed as multi-offset gathers at unique times or common offset images, tracking changes in arrivals through time. Specifically, we investigated whether this data can be used to estimate changes in average soil water content during wetting and drying and to track the migration of the wetting front during an infiltration event. For the first problem we found that normal-moveout (NMO) analysis of the GPR reflection from the bottom of the sand layer provided water content estimates ranging between 0.10-0.30 volumetric water content, which underestimated the value determined by depth averaging a vertical array of six moisture probes by 0.03-0.05 volumetric water content. Relative errors in the estimated depth to the bottom of the 0.6 m thick sand layer were typically on the order of 2%, though increased as high as 25% as the wetting front approached the bottom of the tank. NMO analysis of the wetting front reflection during the infiltration event generally underestimated the depth of the front with discrepancies between GPR and moisture probe estimates approaching 0.15 m. The analysis also resulted in underestimates of water content in the wetted zone on the order of 0.06 volumetric water content and a wetting front velocity equal to about half the rate inferred from the probe measurements. In a parallel modeling effort we found that HYDRUS-1D also underestimates the observed average tank water content determined from the probes by approximately 0.01-0.03 volumetric water content, despite the fact that the model was calibrated to the probe data. This error suggests that the assumed conceptual model of laterally

  18. Material Property Estimation for Direct Detection of DNAPL using Integrated Ground-Penetrating Radar Velocity, Imaging and Attribute Analysis

    SciTech Connect

    John H. Bradford; Stephen Holbrook; Scott B. Smithson

    2004-12-09

    The focus of this project is direct detection of DNAPL's specifically chlorinated solvents, via material property estimation from multi-fold surface ground-penetrating radar (GPR) data. We combine state-of-the-art GPR processing methodology with quantitative attribute analysis and material property estimation to determine the location and extent of residual and/or pooled DNAPL in both the vadose and saturated zones. An important byproduct of our research is state-of-the-art imaging which allows us to pinpoint attribute anomalies, characterize stratigraphy, identify fracture zones, and locate buried objects.

  19. Efficiency evaluation of ground-penetrating radar by the results of measurement of dielectric properties of soils

    SciTech Connect

    Khakiev, Zelimkhan; Kislitsa, Konstantin; Yavna, Victor

    2012-12-15

    The work considers the depth evaluation of ground penetrating radar (GPR) surveys using the attenuation factor of electromagnetic radiation in a medium. A method of determining the attenuation factor of low-conductive non-magnetic soils is developed based on the results of direct measurements of permittivity and conductivity of soils in the range of typical frequencies of GPR. The method relies on measuring the shift and width of the resonance line after a soil sample is being placed into a tunable cavity resonator. The advantage of this method is the preservation of soil structure during the measurement.

  20. Analysis of subglacial hydrodynamics and ice dynamics through combined terrestrial laser scanning and ground penetrating radar survey

    NASA Astrophysics Data System (ADS)

    Gabbud, Chrystelle; Rüttimann, Sébastien; Micheletti, Natan; Irving, James; Lane, Stuart

    2015-04-01

    This study shows how high resolution surveys of subglacial channel morphology combined with high resolution terrestrial laser scanner survey of an Alpine glacier help to understand subglacial hydrological forcing of ice dynamics. The study area is the Haut Glacier d'Arolla in Switzerland, an Alpine valley glacier for which subglacial drainage system has been well studied. A new generation of terrestrial laser scanners was used to investigate glacier surface ablation and other elements of glacial hydrodynamics at exceptionally high spatial and temporal resolution. The LiDAR RIEGL VZ-6000 scanner, with a laser 3B specifically designed for measurements of snow and ice cover surfaces, was tested at seasonal and daily scales. The data revealed spatial variations in the patterns of surface melt, controlled by both aspect and differential debris cover at the seasonal scale, and controlled by ogive-related differences in ice surface debris content at the daily scale. More tentatively, intra-daily scale measurements pointed to possible hydraulic jacking of the glacier associated with short-term water pressure rises at the downstream part of the glacier. A ground-penetrating radar (GPR) field campaign was conducted a year later in the location where possible hydraulic jacking had been detected previously. The aims of this campaign were (i) to assess GPR usage for subglacial channel detection; (ii) identify more precisely the channel morphology; and (iii) investigate further the hydraulic jacking hypothesis. 100 MHz antennas were used to map a 240 x 34 m area near the glacier snout where the ice thickness did not exceed 50 m. The corresponding data, after processing, allowed reconstruction of the bed topography and the morphology of subglacial channels in 3D, showing two of the latter in this area. One channel was followed for approximately 20 m upglacier and corresponding morphology estimates were performed. These data allowed for 3D reconstructions of both the bed

  1. EXTRACTING A RADAR REFLECTION FROM A CLUTTERED ENVIRONMENT USING 3-D INTERPRETATION

    EPA Science Inventory

    A 3-D Ground Penetrating Radar (GPR) survey at 50 MHz center frequency was conducted at Hill Air Force Base, Utah, to define the topography of the base of a shallow aquifer. The site for the survey was Chemical Disposal Pit #2 where there are many man-made features that generate ...

  2. Detection capability of a pulsed Ground Penetrating Radar utilizing an oscilloscope and Radargram Fusion Approach for optimal signal quality

    NASA Astrophysics Data System (ADS)

    Seyfried, Daniel; Schoebel, Joerg

    2015-07-01

    In scientific research pulsed radars often employ a digital oscilloscope as sampling unit. The sensitivity of an oscilloscope is determined in general by means of the number of digits of its analog-to-digital converter and the selected full scale vertical setting, i.e., the maximal voltage range displayed. Furthermore oversampling or averaging of the input signal may increase the effective number of digits, hence the sensitivity. Especially for Ground Penetrating Radar applications high sensitivity of the radar system is demanded since reflection amplitudes of buried objects are strongly attenuated in ground. Hence, in order to achieve high detection capability this parameter is one of the most crucial ones. In this paper we analyze the detection capability of our pulsed radar system utilizing a Rohde & Schwarz RTO 1024 oscilloscope as sampling unit for Ground Penetrating Radar applications, such as detection of pipes and cables in the ground. Also effects of averaging and low-noise amplification of the received signal prior to sampling are investigated by means of an appropriate laboratory setup. To underline our findings we then present real-world radar measurements performed on our GPR test site, where we have buried pipes and cables of different types and materials in different depths. The results illustrate the requirement for proper choice of the settings of the oscilloscope for optimal data recording. However, as we show, displaying both strong signal contributions due to e.g., antenna cross-talk and direct ground bounce reflection as well as weak reflections from objects buried deeper in ground requires opposing trends for the oscilloscope's settings. We therefore present our Radargram Fusion Approach. By means of this approach multiple radargrams recorded in parallel, each with an individual optimized setting for a certain type of contribution, can be fused in an appropriate way in order to finally achieve a single radargram which displays all

  3. Comparative Analysis of Electrical Resistivity and Ground Penetrating Radar For Subsurface Parameters in a Basaltic Terrain, Nagpur

    NASA Astrophysics Data System (ADS)

    Ansari, T. A.; Vasudeo, A., Sr.

    2014-12-01

    Hard rock crystalline terrains pose difficulty in groundwater modeling as they present anisotropic conditions for groundwater storage. It is most important to estimate accurate parameters for better visualization and analysis of subsurface conditions for groundwater. Western Nagpur in central India is on Basalt formation which has low storing capacity. There are several Basaltic Flows in Nagpur area which have varying hydrogeological characteristics. Unconfined aquifer system and deep seated confined systems, both are present in the Nagpur Urban area. The half of the water demand in these areas mainly depends on groundwater. Water supply for domestic use, apart from the irrigation and Gardening etc in majority cases are fulfilled by groundwater sources. Electrical Resistivity Meter and Ground Penetrating Radar has been used to detect the subsurface parameters qualitatively. Using Electrical Resistivity Meter, apparent resistivity (ρ) is calculated for various depths. GPR is used for the same area to determine the characteristics of subsurface parameters. Data collected by both the instrument is analyzed and compared its accuracy. The results obtained through comparison from two geophysical methods are further seen with respect to the Land Use / Land Cover and surface morphology of the study area, generated from the high resolution satellite data. Key Words: Ground Penetrating Radar (GPR), Electrical Resistivity Meter, Apparent resistivity, Land Use/ Land Cover etc.

  4. Ground Penetrating Radar at Alcatraz Island: Imaging Civil-War Era Fortifications Beneath the Recreation Yard

    NASA Astrophysics Data System (ADS)

    Everett, M. E.; de Smet, T. S.; Warden, R.; Komas, T.; Hagin, J.

    2013-12-01

    As part of a cultural resources assessment and historical preservation project supported by the U.S. National Park Service, GPR surveys using 200 MHz antennas, with ~3.0 m depth of penetration and ~0.1 m lateral and vertical resolution, were conducted by our team in June 2012 over the recreation yard and parade ground at historic Alcatraz Island in order to image the underlying buried Civil War-era fortifications. The recreation yard at the Alcatraz high-security federal penitentiary served as a secure outdoor facility where the prisoners could take exercise. The facility, enclosed by a high perimeter wall and sentry walk, included basketball courts, a baseball diamond, and bleacher-style seating. The site previously consisted of coastal batteries built by the U.S. Army in the early to mid 1850's. As the need for harbor defense diminished, the island was converted into a military prison during the 1860's. In 1933, the military prison was transferred to federal control leading to the establishment of the high-security penitentiary. The rec yard was constructed in 1908-1913 directly over existing earthen fortifications, namely a trio of embankments known as 'traverses I, J, and K.' These mounds of earth, connected by tunnels, were in turn built over concrete and brick magazines. The processed GPR sections show good correlations between radar reflection events and the locations of the buried fortification structures derived from historical map analysis. A 3-D data cube was constructed and two of the cut-away perspective views show that traverse K, in particular, has a strong radar signature.

  5. Application of ground-penetrating radar imagery for three-dimensional visualisation of near-surface structures in ice-rich permafrost, Barrow, Alaska

    USGS Publications Warehouse

    Munroe, J.S.; Doolittle, J.A.; Kanevskiy, M.Z.; Hinkel, Kenneth M.; Nelson, F.E.; Jones, Benjamin M.; Shur, Y.; Kimble, J.M.

    2007-01-01

    Three-dimensional ground-penetrating radar (3D GPR) was used to investigate the subsurface structure of ice-wedge polygons and other features of the frozen active layer and near-surface permafrost near Barrow, Alaska. Surveys were conducted at three sites located on landscapes of different geomorphic age. At each site, sediment cores were collected and characterised to aid interpretation of GPR data. At two sites, 3D GPR was able to delineate subsurface ice-wedge networks with high fidelity. Three-dimensional GPR data also revealed a fundamental difference in ice-wedge morphology between these two sites that is consistent with differences in landscape age. At a third site, the combination of two-dimensional and 3D GPR revealed the location of an active frost boil with ataxitic cryostructure. When supplemented by analysis of soil cores, 3D GPR offers considerable potential for imaging, interpreting and 3D mapping of near-surface soil and ice structures in permafrost environments.

  6. Comparison of Ground-Penetrating Radar and Low-Frequency Electromagnetic Sounding for Detection and Characterization of Groundwater on Mars

    NASA Technical Reports Server (NTRS)

    Grimm, R. E.

    2003-01-01

    Two orbital, ground-penetrating radars, MARSIS and SHARAD, are scheduled for Mars flight, with detection of groundwater a high priority. While these radars will doubtlessly provide significant new information on the subsurface of Mars, thin films of adsorbed water in the cryosphere will strongly attenuate radar signals and prevent characterization of any true aquifers, if present. Scattering from 10-m scale layering or wavelength-size regolith heterogeneities will also degrade radar performance. Dielectric contrasts are sufficiently small for low-porosity, deep aquifers that groundwater cannot be reliably identified. In contrast, low-frequency (mHz-kHz) soundings are ideally suited to groundwater detection due to their great depths of penetration and the high electrical conductivity (compared to cold, dry rock) of groundwater. A variety of low-frequency methods span likely ranges of mass, volume, and power resources, but all require acquisition at or near the planetary surface. Therefore the current generation of orbital radars will provide useful global reconnaissance for subsequent targeted exploration at low frequency. Introduction: Electromagnetic (EM) methods

  7. COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar:" ongoing research activities and mid-term results

    NASA Astrophysics Data System (ADS)

    Pajewski, Lara; Benedetto, Andrea; Loizos, Andreas; Slob, Evert; Tosti, Fabio

    2015-04-01

    This work aims at presenting the ongoing activities and mid-term results of the COST (European COoperation in Science and Technology) Action TU1208 'Civil Engineering Applications of Ground Penetrating Radar.' Almost three hundreds experts are participating to the Action, from 28 COST Countries (Austria, Belgium, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Malta, Macedonia, The Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey, United Kingdom), and from Albania, Armenia, Australia, Egypt, Hong Kong, Jordan, Israel, Philippines, Russia, Rwanda, Ukraine, and United States of America. In September 2014, TU1208 has been praised among the running Actions as 'COST Success Story' ('The Cities of Tomorrow: The Challenges of Horizon 2020,' September 17-19, 2014, Torino, IT - A COST strategic workshop on the development and needs of the European cities). The principal goal of the COST Action TU1208 is to exchange and increase scientific-technical knowledge and experience of GPR techniques in civil engineering, whilst simultaneously promoting throughout Europe the effective use of this safe and non-destructive technique in the monitoring of infrastructures and structures. Moreover, the Action is oriented to the following specific objectives and expected deliverables: (i) coordinating European scientists to highlight problems, merits and limits of current GPR systems; (ii) developing innovative protocols and guidelines, which will be published in a handbook and constitute a basis for European standards, for an effective GPR application in civil- engineering tasks; safety, economic and financial criteria will be integrated within the protocols; (iii) integrating competences for the improvement and merging of electromagnetic scattering techniques and of data- processing techniques; this will lead to a novel freeware tool for the localization of buried objects

  8. Fast evaluation of zero-offset Green's function for layered media with application to ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Lambot, Sébastien; Slob, Evert; Vereecken, Harry

    2007-11-01

    We propose an efficient integration path for the fast evaluation of the three-dimensional spatial-domain Green's function for electromagnetic wave propagation in layered media for the particular case of zero-offset, source-receiver proximal ground-penetrating radar (GPR) applications. The integration path is deformed in the complex plane of the integration variable k ρ so that the oscillations of the dominant exponential term in the spectral Green's function are minimized. The contour does not need to be closed back on the real k ρ axis as the complex integrand rapidly damps. The accuracy and efficiency of the technique have been confirmed by comparison with traditional elliptic integration contours. The proposed algorithm appears to be promising development for fast, full-wave modeling and inversion of GPR data.

  9. Methane emission bursts from permafrost environments during autumn freeze-in: New insights from ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Pirk, Norbert; Santos, Telmo; Gustafson, Carl; Johansson, Anders J.; Tufvesson, Fredrik; Parmentier, Frans-Jan W.; Mastepanov, Mikhail; Christensen, Torben R.

    2015-08-01

    Large amounts of methane (CH4) are known to be emitted from permafrost environments during the autumn freeze-in, but the specific soil conditions leading up to these bursts are unclear. Therefore, we used an ultrawide band ground-penetrating radar in Northeast Greenland in autumn 2009 to estimate the volumetric composition inside the soil through dielectric characterization from 200 to 3200 MHz. Our results suggest a compression of the gas reservoir during the phase transition of soil water, which is accompanied by a peak in surface CH4 emissions. About 1 week thereafter, there seems to be a decompression event, consistent with ground cracking which allows the gas reservoir to expand again. This coincides with the largest CH4 emission, exceeding the summer maximum by a factor of 4. We argue that these complementary measurement techniques are needed to come to an understanding of tundra CH4 bursts connected to soil freezing.

  10. The internal structure of sand bars on the Colorado River, Grand Canyon, as determined by ground-penetrating radar

    USGS Publications Warehouse

    Barnhardt, Walter A.; Kayen, Robert; Rubin, David; Minasian, Diane L.

    2001-01-01

    High-resolution, subsurface imagery from ground-penetrating radar (GPR) has revealed the internal structure of sand bars at seven sites on the Colorado River, Grand Canyon. Based on reconnaissance-level surveys, we recognized three stratigraphic units and several intervening unconformities. Unit A, which exhibits hyperbolic reflections and always occurs at the base of the section, is interpreted as bedrock and/or talus. Unit B is a commonly observed sand deposit that overlies unit A and is characterized by reflections that gently dip down toward the river axis. Unit C is a sand deposit up to 2 m thick that always occurs at the top of the section and may represent a flood deposit from 1983. This study demonstrates the utility of GPR for non-destructive investigation of sand-bar thickness and the stratigraphic record of flood events in the Grand Canyon.

  11. Characteristics of ejecta and alluvial deposits at Meteor Crater, Arizona and Odessa Craters, Texas: Results from ground penetrating radar

    NASA Technical Reports Server (NTRS)

    Grant, J. A.; Schultz, P. H.

    1991-01-01

    Previous ground penetrating radar (GRP) studies around 50,000 year old Meteor Crater revealed the potential for rapid, inexpensive, and non-destructive sub-surface investigations for deep reflectors (generally greater than 10 m). New GRP results are summarized focusing the shallow sub-surfaces (1-2 m) around Meteor Crater and the main crater at Odessa. The following subject areas are covered: (1) the thickness, distribution, and nature of the contact between surrounding alluvial deposits and distal ejecta; and (2) stratigraphic relationships between both the ejecta and alluvium derived from both pre and post crater drainages. These results support previous conclusions indicating limited vertical lowering (less than 1 m) of the distal ejecta at Meteor Crater and allow initial assessment of the gradational state if the Odessa craters.

  12. Ground-penetrating radar and differential global positioning system data collected from Long Beach Island, New Jersey, April 2015

    USGS Publications Warehouse

    Zaremba, Nicholas J.; Smith, Kathryn E.L.; Bishop, James M.; Smith, Christopher G.

    2016-01-01

    Scientists from the United States Geological Survey, St. Petersburg Coastal and Marine Science Center, U.S. Geological Survey Pacific Coastal and Marine Science Center, and students from the University of Hawaii at Manoa collected sediment cores, sediment surface grab samples, ground-penetrating radar (GPR) and Differential Global Positioning System (DGPS) data from within the Edwin B. Forsythe National Wildlife Refuge–Holgate Unit located on the southern end of Long Beach Island, New Jersey, in April 2015 (FAN 2015-611-FA). The study’s objective was to identify washover deposits in the stratigraphic record to aid in understanding barrier island evolution. This report is an archive of GPR and DGPS data collected from Long Beach Island in 2015. Data products, including raw GPR and processed DGPS data, elevation corrected GPR profiles, and accompanying Federal Geographic Data Committee metadata can be downloaded from the Data Downloads page.

  13. Use of Ground Penetrating Radar in tunnel maintenance: detection of loose rocks on top of the concrete inner lining

    NASA Astrophysics Data System (ADS)

    Lalagüe, A.; Hoff, I.

    2012-04-01

    The purpose of this study is to find a fast method for increasing the safety against collapse and rockfall in tunnels using Ground Penetrating Radar (GPR). Rockfall or collapse of the roof in tunnels may occur both during construction and operation of the completed tunnel, as evidenced by major accidents in recent years. The Norwegian expertise is not spared and experienced a serious setback a couple of years ago when a part of a tunnel roof collapsed due to insufficient rock support. It is therefore important to carry out regular inspections and risk management activities to ensure an adequate level of safety. The access to the rock surface is often difficult due to the precast concrete lining placed to preserve the road lanes from frost and water leakages. Traditional inspection methods usually consist in drilling randomly in the concrete elements, which is both time consuming and hazardous for the personnel involved. To remedy this, the Ground Penetrating Radar (GPR) technique has been introduced to best locate drilling sites. GPR is a nondestructive method generally used to image the subsurface. It has now proved its usefulness in tunnel investigations. Used as a distance measuring tool, it determines the thickness of the precast concrete lining; it detects with success the cavities behind the concrete lining and measures the distance to the rock surface. Such scanning technology provides very satisfactory data; it is time-saving and safer to use than random manual inspections. New GPR surveys also revealed the applicability of GPR in detecting loose rocks of different sizes on top of the concrete lining. Presence of loose rock indicates instabilities that should be further investigated; the results presented in this paper are of a great interest for tunnel engineers and it is likely that GPR measurements could become a routine activity in tunnel maintenance.

  14. Application of pre-stack reverse time migration based on FWI velocity estimation to ground penetrating radar data

    NASA Astrophysics Data System (ADS)

    Liu, Sixin; Lei, Linlin; Fu, Lei; Wu, Junjun

    2014-08-01

    Reverse-time migration (RTM) is used for subsurface imaging to handle complex velocity models including steeply dipping interfaces and dramatic lateral variations and promises better imaging results compared to traditional migration method such as Kirchhoff migration algorithm. RTM has been increasingly used in seismic surveys for hydrocarbon resource explorations. Based on the similarity of kinematics and dynamics between electromagnetic wave and elastic wave, we develop pre-stack RTM method and apply it to process ground penetrating radar (GPR) data. Finite-difference time domain (FDTD) numerical method is used to simulate the electromagnetic wave propagation including forward and backward extrapolations, the cross-correlation imaging condition is used to obtain the final image. In order to provide a velocity model with relatively higher accuracy as the initial velocity model for RTM, we apply a full waveform inversion (FWI) in time domain to estimate the subsurface velocity structure based on reflection radar data. For testing the effectiveness of the algorithm, we have constructed a complex geological model, common-offset radar data and common-shot profile (CSP) radar reflection data are synthesized. All data are migrated with traditional Kirchhoff migration method and pre-stack RTM method separately, the migration results from pre-stack RTM show better coincidence with the true model. Furthermore, we have performed a physical experiment in a sandbox where a polyvinyl chloride (PVC) box is buried in the sand, the obtained common-offset radar data and common-shot radar data are migrated by using Kirchhoff migration method and pre-stack RTM algorithm separately, the pre-stack RTM result shows that RTM algorithm could get better imaging results.

  15. Polarization differences in airborne ground penetrating radar performance for landmine detection

    NASA Astrophysics Data System (ADS)

    Dogaru, Traian; Le, Calvin

    2016-05-01

    The U.S. Army Research Laboratory (ARL) has investigated the ultra-wideband (UWB) radar technology for detection of landmines, improvised explosive devices and unexploded ordnance, for over two decades. This paper presents a phenomenological study of the radar signature of buried landmines in realistic environments and the performance of airborne synthetic aperture radar (SAR) in detecting these targets as a function of multiple parameters: polarization, depression angle, soil type and burial depth. The investigation is based on advanced computer models developed at ARL. The analysis includes both the signature of the targets of interest and the clutter produced by rough surface ground. Based on our numerical simulations, we conclude that low depression angles and H-H polarization offer the highest target-to-clutter ratio in the SAR images and therefore the best radar performance of all the scenarios investigated.

  16. Using Ground Penetrating Radar to Image Paleotopography and Structural Controls at Coral Pink Sand Dunes, Kane County, Utah

    NASA Astrophysics Data System (ADS)

    Rozar, E. J.; Bradford, J. H.; Ford, R. L.; Wilkins, D. E.

    2014-12-01

    The Coral Pink Sand Dunes (CPSD) are one of the largest dune fields in the Great Basin-Colorado Plateau Transition Zone. The dune field rests on Navajo Sandstone, and is bisected by the Sevier Normal Fault, which also forms the bedrock escarpment along the eastern boundary of the lower dune field (LDF). Limited ground penetrating radar (GPR) collected previously, as well as recent ground-based LiDAR data and geomorphic observations, suggest that underlying bedrock is topographically lower in the center of the LDF than on its margins. In order to image the dune-bedrock interface and any structures contained within the bedrock, including buried faults, 50-MHz and 100-MHz GPR antennae with 400-V transmitters were used to conduct over 25 transects, totaling several kilometers, across the LDF. We recorded radar reflections at depths of up to 30 m within the bedrock beneath the modern dunes. Outcrops and/or shallow boreholes along some transects provide ground truth for dune-bedrock contacts. The resulting radar profiles suggest at least two antithetic fault zones within the LDF that, in places, appear to control the location of smaller dunes. Further examination of the relationship between these fault zones and dune forms, as imaged with LiDAR, will help inform whether or not these structural controls affect variation in dune type and patterning across the LDF, and may also explain why the CPSD exist in this location.

  17. Ground-penetrating radar study of beach-ridge deposits in Huangqihai Lake, North China: the imprint of washover processes

    NASA Astrophysics Data System (ADS)

    Shan, Xin; Yu, Xinghe; Clift, Peter D.; Tan, Chengpeng; Li, Shunli; Wang, Zhixing; Su, Dongxu

    2016-03-01

    Determining the origin of beach ridges in lacustrine basins can often be problematic. The sedimentary processes responsible for formation of beach ridges on the north shore of Huangqihai Lake were investigated by using ground penetrating radar (GPR). A 400 MHz GPR antenna was used to achieve a high vertical resolution of 0.04-0.08 m. The radar stratigraphy was then determined using principles of seismic stratigraphy. The radar facies (RF) were determined by analyzing internal configuration and continuity of reflections, as well as reflection termination patterns. The identified RF fall into three groups (inclined, horizontal and irregular). The inclined group consists of RF that display inclined reflections. The horizontal group consists of RF that exhibit predominantly horizontal reflections. In the irregular group, the reflections are typically weak. RF with reflections with gently landward dips in the shore-normal profile are interpreted as washover sheet deposits. RF with steeply landward-dipping and imbricated reflections are interpreted as washover lobes. Washover sheets develop when overwash fails to enter a significant body of water and sedimentation takes place entirely on the relatively flattened topography. Washover lobe development occurs when overwash enters a region in which topography dips steeply landward, and sedimentation takes place on the surface of washover sheets or previous washover lobes. The beach-ridge deposits are interpreted as being formed entirely from vertically and laterally stacked washover sheets and washover lobes. They were formed by wave-dominated processes and secondary overwash processes supplemented by longshore currents.

  18. Preliminary results of sequential monitoring of simulated clandestine graves in Colombia, South America, using ground penetrating radar and botany.

    PubMed

    Molina, Carlos Martin; Pringle, Jamie K; Saumett, Miguel; Hernández, Orlando

    2015-03-01

    In most Latin American countries there are significant numbers of missing people and forced disappearances, 68,000 alone currently in Colombia. Successful detection of shallow buried human remains by forensic search teams is difficult in varying terrain and climates. This research has created three simulated clandestine burial styles at two different depths commonly encountered in Latin America to gain knowledge of optimum forensic geophysics detection techniques. Repeated monitoring of the graves post-burial was undertaken by ground penetrating radar. Radar survey 2D profile results show reasonable detection of ½ clothed pig cadavers up to 19 weeks of burial, with decreasing confidence after this time. Simulated burials using skeletonized human remains were not able to be imaged after 19 weeks of burial, with beheaded and burnt human remains not being able to be detected throughout the survey period. Horizontal radar time slices showed good early results up to 19 weeks of burial as more area was covered and bi-directional surveys were collected, but these decreased in amplitude over time. Deeper burials were all harder to image than shallower ones. Analysis of excavated soil found soil moisture content almost double compared to those reported from temperate climate studies. Vegetation variations over the simulated graves were also noted which would provide promising indicators for grave detection. PMID:25596556

  19. Performance analysis of spectrally versatile forward-looking ground-penetrating radar for detection of concealed targets

    NASA Astrophysics Data System (ADS)

    Phelan, Brian R.; Ressler, Marc A.; Ranney, Kenneth I.; Smith, Gregory D.; Kirose, Getachew A.; Sherbondy, Kelly D.; Narayanan, Ram M.

    2015-05-01

    Stepped-Frequency Radars (SFRs) have become increasingly popular with the advent of new technologies and increasingly congested RF spectrum. SFRs have inherently high dynamic range due to their small IF bandwidths, allowing for the detection of weak target returns in the presence of clutter. The Army Research Laboratory's (ARL) Partnership in Research Transition program has developed a preliminary SFR for imaging buried landmines and improvised explosive devices. The preliminary system utilizes two transmit antennas and four receive antennas and is meant to act as a transitional system to verify the system's design and imaging capabilities. The SFR operates between 300 MHz and 2000 MHz, and is capable of 1-MHz step-sizes. The SFR system will eventually utilize 16-receive channels and will be mounted on ARL's existing Forward-Looking Ground Penetrating Radar platform, as a replacement for the existing Synchronous Impulse REconstruction (SIRE) radar. An analysis of the preliminary SFRs radio frequency interference mitigation, spectral purity dynamic range, and maximum detectable range is presented here.

  20. Three-dimensional ground penetrating radar imaging using multi-frequency diffraction tomography

    SciTech Connect

    Mast, J.E.; Johansson, E.M.

    1994-11-15

    In this talk we present results from a three-dimensional image reconstruction algorithm for impulse radar operating in monostatic pule-echo mode. The application of interest to us is the nondestructive evaluation of civil structures such as bridge decks. We use a multi-frequency diffraction tomography imaging technique in which coherent backward propagations of the received reflected wavefield form a spatial image of the scattering interfaces within the region of interest. This imaging technique provides high-resolution range and azimuthal visualization of the subsurface region. We incorporate the ability to image in planarly layered conductive media and apply the algorithm to experimental data from an offset radar system in which the radar antenna is not directly coupled to the surface of the region. We present a rendering in three-dimensions of the resulting image data which provides high-detail visualization.

  1. Root distribution in a California semi-arid oak savanna ecosystem as determined by conventional sampling and ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Koteen, L. E.; Raz-Yaseef, N.; Baldocchi, D. D.

    2011-12-01

    Koteen, Laura E., Raz-Yaseef, Naama, and Dennis D. Baldocchi University of California, Berkeley California's blue oak, Quercus douglasii, is a unique tree in several ways. Despite the intense heat of California's central valley and Sierra foothills, and absence of precipitation during dry summer months, blue oaks are winter deciduous, and rely on a suite of drought adaptation measures for highly-efficient water use. To date, much more is known about aboveground dynamics in semi-arid oak savanna ecosystems than belowground. Yet, the root system is instrumental in ensuring oak survival and in determining the magnitude and timing of land-atmospheric fluxes via its control of water and nutrient supply to aboveground processes and soil moisture content. Tree root distribution is notoriously heterogeneous. Therefore a comprehensive sampling effort is needed in order to optimally represent it. To further understand the patterns of water use in oak savanna ecosystems in the Sierra foothills of California, we have sought to characterize the root system by depth. To accomplish this goal, we have sampled the root system using conventional sampling methods (i.e. pit and core sampling), in conjunction with ground penetrating radar (GPR). Using both methods together made it possible to compensate for the limitations of each: Fine roots can only be detected by conventional sampling, and involve time intensive work in the lab, limiting sample size. GPR, on the other hand, allows for much greater spatial coverage and therefore more comprehensive characterization of the coarse root component. An extensive field campaign was executed during May 2011. 7 tree areas where chosen, representing the range of tree sizes and composition at the research site: 2 small trees, 2 large trees and 2 tree clusters. One additional very large tree that has undergone extensive additional physiological measurements was also chosen in order to posit and test hypotheses about linkages among root, soil

  2. Advancing Understanding of the Role of Belowground Processes in Terrestrial Carbon Sinks trhrough Ground-Penetrating Radar. Final Report

    SciTech Connect

    Day, Frank P.

    2015-02-06

    Coarse roots play a significant role in belowground carbon cycling and will likely play an increasingly crucial role in belowground carbon sequestration as atmospheric CO2 levels continue to rise, yet they are one of the most difficult ecosystem parameters to quantify. Despite promising results with ground-penetrating radar (GPR) as a nondestructive method of quantifying biomass of coarse roots, this application of GPR is in its infancy and neither the complete potential nor limitations of the technology have been fully evaluated. The primary goals and questions of this study fell into four groups: (1) GPR methods: Can GPR detect change in root biomass over time, differentiate live roots from dead roots, differentiate between coarse roots, fine roots bundled together, and a fine root mat, remain effective with varied soil moisture, and detect shadowed roots (roots hidden below larger roots); (2) CO2 enrichment study at Kennedy Space Center in Brevard County, Florida: Are there post-fire legacy effects of CO2 fertilization on plant carbon pools following the end of CO2application ? (3) Disney Wilderness Study: What is the overall coarse root biomass and potential for belowground carbon storage in a restored longleaf pine flatwoods system? Can GPR effectively quantify coarse roots in soils that are wetter than the previous sites and that have a high percentage of saw palmetto rhizomes present? (4) Can GPR accurately represent root architecture in a three-dimensional model? When the user is familiar with the equipment and software in a setting that minimizes unsuitable conditions, GPR is a relatively precise, non-destructive, useful tool for estimating coarse root biomass. However, there are a number of cautions and guidelines that should be followed to minimize inaccuracies or situations that are untenable for GPR use. GPR appears to be precise as it routinely predicts highly similar values for a given area across multiple

  3. Intrinsic modeling of near-field ground penetrating radar and electromagnetic induction antennas for layered medium characterization

    NASA Astrophysics Data System (ADS)

    André, Frédéric; Phuong Tran, Anh; Mourmeaux, Nicolas; Lambot, Sébastien

    2013-04-01

    We developed a closed-form equation for intrinsic modeling of near-field ground-penetrating radar (GPR) and electromagnetic induction (EMI) antennas for reconstructing the electrical properties of planar layered media. Resorting to plane wave decomposition, the antennas operating on the ground or in near-field conditions are modeled using a set of infinitesimal dipoles and characteristic, frequency-dependent, global reflection and transmission coefficients. Wave propagation and diffusion in the medium are described using a set of three-dimensional planar layered media Green's functions. Both GPR and EMI antennas were calibrated using measurements collected at different heights, ranging from near-field to far-field conditions, over a perfect electrical conductor. The GPR and EMI models were then validated for measurements collected over water subject to different salinity levels. The models showed a high degree of accuracy for reproducing the observed data and model inversion provided good estimates of the medium electrical properties. Yet, for EMI, discrepancies between measured and estimated electrical conductivity values were observed for the lowest salinity levels, resulting mainly from the limited sensitivity of the prototype EMI system used for this study. Technical possibilities for increasing the sensitivity of the EMI system are currently under examination. In addition, in order to further improve the model performances for EMI, we also investigate different configurations for the set of infinitesimal dipoles used to model the EMI antenna. The proposed approach is applicable to any GPR and EMI system, either prototypes or commercially available sensors and operating either in the time domain or in the frequency domain. It is in particular promising for joint analysis of GPR and EMI data in an inverse data fusion framework, especially as the modeling procedures are identical for both instruments. Index Terms: Ground-penetrating radar, electromagnetic

  4. Study of High Robust Three Dimensional Finite Difference Time Domain (FDTD) Modeling of Ground Penetrating Radar for a Heterogeneous Environment

    NASA Astrophysics Data System (ADS)

    Eyuboglu, S.; Daniels, J. J.; Lee, R.; Yeh, J. T.

    2006-12-01

    Ground Penetrating Radar (GPR) is a non-invasive tool commonly used to characterize the physical properties of the subsurface. The translation of the physical measurements of geologic and hydrogeologic conditions is the culmination of many geophysical investigations. When numerical modeling is applied parallel to GPR data, it allows understanding of the effects of complex electromagnetic phenomena by defining and solving problems, as well as predicting the performance of radar in a complex heterogeneous environment. Finite difference time domain (FDTD) has been widely used for numerical modeling of GPR, but most of the previous algorithms are limited in their ability to model the electrical conductivity and permittivity. In this research, a highly efficient robust algorithm was developed to enhance the effectiveness of the FDTD forward modeling in surroundings characterized by an arbitrary distribution of all electrical properties in three dimensional space. In the first part of this research, two different FDTD codes which include different absorbing boundary conditions, Enquist and Majda absorbing boundary condition (ABC) and perfectly matched layer (PML), were used and compared. In the second part, the modeling algorithm was developed for a heterogeneous half-space medium to facilitate statistical modeling of complex distributions of electrical properties in the subsurface. The results produced by the simulation compared with real GPR results reveal high accuracy using the robust algorithm to optimize three dimensional FDTD forward modeling of GPR responses in heterogeneous surroundings.

  5. COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar": first-year activities and results

    NASA Astrophysics Data System (ADS)

    Pajewski, Lara; Benedetto, Andrea; Loizos, Andreas; Slob, Evert; Tosti, Fabio

    2014-05-01

    This work aims at presenting the first-year activities and results of COST (European COoperation in Science and Technology) Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar". This Action was launched in April 2013 and will last four years. The principal aim of COST Action TU1208 is to exchange and increase scientific-technical knowledge and experience of GPR techniques in civil engineering, whilst simultaneously promoting throughout Europe the effective use of this safe and non-destructive technique in the monitoring of infrastructures and structures. Moreover, the Action is oriented to the following specific objectives and expected deliverables: (i) coordinating European scientists to highlight problems, merits and limits of current GPR systems; (ii) developing innovative protocols and guidelines, which will be published in a handbook and constitute a basis for European standards, for an effective GPR application in civil- engineering tasks; safety, economic and financial criteria will be integrated within the protocols; (iii) integrating competences for the improvement and merging of electromagnetic scattering techniques and of data- processing techniques; this will lead to a novel freeware tool for the localization of buried objects, shape-reconstruction and estimation of geophysical parameters useful for civil engineering needs; (iv) networking for the design, realization and optimization of innovative GPR equipment; (v) comparing GPR with different NDT techniques, such as ultrasonic, radiographic, liquid-penetrant, magnetic-particle, acoustic-emission and eddy-current testing; (vi) comparing GPR technology and methodology used in civil engineering with those used in other fields; (vii) promotion of a more widespread, advanced and efficient use of GPR in civil engineering; and (viii) organization of a high-level modular training program for GPR European users. Four Working Groups (WGs) carry out the research activities. The first WG

  6. Ground-penetrating radar investigation of St. Leonard's Crypt under the Wawel Cathedral (Cracow, Poland) - COST Action TU1208

    NASA Astrophysics Data System (ADS)

    Benedetto, Andrea; Pajewski, Lara; Dimitriadis, Klisthenis; Avlonitou, Pepi; Konstantakis, Yannis; Musiela, Małgorzata; Mitka, Bartosz; Lambot, Sébastien; Żakowska, Lidia

    2016-04-01

    The Wawel ensemble, including the Royal Castle, the Wawel Cathedral and other monuments, is perched on top of the Wawel hill immediately south of the Cracow Old Town, and is by far the most important collection of buildings in Poland. St. Leonard's Crypt is located under the Wawel Cathedral of St Stanislaus BM and St Wenceslaus M. It was built in the years 1090-1117 and was the western crypt of the pre-existing Romanesque Wawel Cathedral, so-called Hermanowska. Pope John Paul II said his first Mass on the altar of St. Leonard's Crypt on November 2, 1946, one day after his priestly ordination. The interior of the crypt is divided by eight columns into three naves with vaulted ceiling and ended with one apse. The tomb of Bishop Maurus, who died in 1118, is in the middle of the crypt under the floor; an inscription "+ MAVRVS EPC MCXVIII +" indicates the burial place and was made in 1938 after the completion of archaeological works which resulted in the discovery of this tomb. Moreover, the crypt hosts the tombs of six Polish kings and heroes: Michał Korybut Wiśniowiecki (King of the Polish-Lithuanian Commonwealth), Jan III Sobieski (King of the Polish-Lithuanian Commonwealth and Commander at the Battle of Vienna), Maria Kazimiera (Queen of the Polish-Lithuanian Commonwealth and consort to Jan III Sobieski), Józef Poniatowski (Prince of Poland and Marshal of France), Tadeusz Kościuszko (Polish general, revolutionary and a Brigadier General in the American Revolutionary War) and Władysław Sikorski (Prime Minister of the Polish Government in Exile and Commander-in-Chief of the Polish Armed Forces). The adjacent six crypts and corridors host the tombs of the other Polish kings, from Sigismund the Old to Augustus II the Strong, their families and several Polish heroes. In May 2015, the COST (European COoperation in Science and Technology) Action TU1208 "Civil engineering applications of Ground Penetrating Radar" organised and offered a Training School (TS) on the

  7. Use of ground-penetrating radar technology in construction of the Los Angeles MetroRail subway system

    NASA Astrophysics Data System (ADS)

    Hebert, Christopher D.; Olson, Mark G.

    1995-05-01

    State-of-the-art ground penetrating radar (GPR) technology was used successfully in tunneling through the former L.A. City Oil Field to search for uncharted, abandoned oil wells. A magnetometer probe was previously used for this purpose, because it was felt abandoned oil wells with steel casings may exist ahead of tunneling. These wells were suspected to contain methane gases which could be released into the tunnels. Studies revealed the abandoned wells could be wooden-cased or uncased open holes, indicating they would not be detected using a magnetometer probe. GPR was therefore selected as a geophysical technique more capable of detecting both steel-cased and uncased oil wells. After some initial testing from inside the tunnel, a commercially available GPR system was selected. Procedures were developed for conducting the surveys and evaluating the data profiles for possible oil wells. The profiles were obtained by moving the radar antenna across the smoothed tunnel face. During tunnelling of the oil field area abandoned oil wells were not encountered. However, the GPR surveys did detect anomalous radar reflections that the machine operator was alerted to as possible oil wells. Review of the data indicates that other changes in ground conditions were detected, such as transitions from soft- to hard-ground conditions and zones of oil bearing sands. These results suggest GPR could be useful for other exploratory applications during mining. GPR was also used as an investigative tool to check for possible shallow subsurface voids from the ground surface. Air-filled cavities or voids beneath city streets can sometimes be formed as a result of deeper tunneling-induced ground movements, resulting in dangerous sink-hole forming conditions. The GPR surveys were conducted from the street surface above the tunnels in areas where geotechnical data measured greater ground movements. These surveys helped rule out the possibility of voids beneath the street pavement in an area

  8. Ground-Penetrating Radar (GPR) Examination at the Fanta Stream Site, Central Ethiopia

    NASA Astrophysics Data System (ADS)

    Lanzarone, P. M.

    2009-12-01

    The use of near-surface geophysical analysis for paleontological and archaeological site detection has been a relatively unexplored field in sub-Saharan Africa. A new site discovered in 2007 within the city limits of Addis Ababa, Ethiopia is currently under imminent destruction due to urban and industrial entrenchment. Located along the banks of the Fanta Stream, this site contains visible exposures of dense in-situ fossiliferous deposits and archaeological remains. The Fanta Stream Site is important because of the widespread deposition of fossil deposits possibly dating to the early or middle Pleistocene epoch from a rare high altitude context of the east African region. A detailed GPR survey over a large study area (> 1000 m2) utilizing a GSSI SIR-2 with 100 and 500 MHz antennas provides a multi-scalar data visualization of fossil bearing stratigraphic units and information about the vertical and lateral distribution of these deposits across the site. The GPR profiles exhibit strong radar reflections at the contact zones between sedimentary units known to contain fossil and artifactual deposits. Shallow (< 3 m) hand-augured geological cores along GPR transects provide a correlative ground truth for the depth and extent of primary deposits across the site. These geophysical data situate the known and associated fossil and artifact assemblages into their appropriate spatial and geoenvironmental contexts and this information will be useful for developing a regional natural and cultural resource management plan for the Fanta Site.

  9. A Study of Concrete Hydration and Dielectric Relaxation Mechanism Using Ground Penetrating Radar and Short-Time Fourier Transform

    NASA Astrophysics Data System (ADS)

    Lai, W. L.; Kind, T.; Wiggenhauser, H.

    2010-12-01

    Ground penetrating radar (GPR) was used to characterize the frequency-dependent dielectric relaxation phenomena in ordinary Portland cement (OPC) hydration in concrete changing from fresh to hardened state. The study was experimented by measuring the changes of GPR A-scan waveforms over a period of 90 days, and processed the waveforms with short-time Fourier transform (STFT) in joint time-frequency analysis (JTFA) domain rather than a conventional time or frequency domain alone. The signals of the direct wave traveled at the concrete surface and the reflected wave from an embedded steel bar were transformed with STFT, in which the changes of peak frequency over ages were tracked. The peak frequencies were found to increase with ages and the patterns were found to match closely with primarily the well-known OPC hydration process and secondarily, the evaporation effect. The close match is contributed to the simultaneous effects converting free to bound water over time, on both conventional OPC hydration and dielectric relaxation mechanisms.

  10. Geological disaster survey based on Curvelet transform with borehole Ground Penetrating Radar in Tonglushan old mine site.

    PubMed

    Tang, Xinjian; Sun, Tao; Tang, Zhijie; Zhou, Zenghui; Wei, Baoming

    2011-06-01

    Tonglushan old mine site located in Huangshi City, China, is very famous in the world. However, some of the ruins had suffered from geological disasters such as local deformation, surface cracking, in recent years. Structural abnormalities of rock-mass in deep underground were surveyed with borehole ground penetrating radar (GPR) to find out whether there were any mined galleries or mined-out areas below the ruins. With both the multiresolution analysis and sub-band directional of Curvelet transform, the feature information of targets' GPR signals were studied on Curvelet transform domain. Heterogeneity of geotechnical media and clutter jamming of complicated background of GPR signals could be conquered well, and the singularity characteristic information of typical rock mass signals could be extracted. Random noise had be removed by thresholding combined with Curvelet and the statistical characteristics of wanted signals and the noise, then direct wave suppression and the spatial distribution feature extraction could obtain a better result by making use of Curvelet transform directional. GprMax numerical modeling and analyzing of the sample data have verified the feasibility and effectiveness of our method. It is important and applicable for the analyzing of the geological structure and the disaster development about the Tonglushan old mine site. PMID:25084600

  11. Identifying damaged areas inside a masonry monument using a combined interpretation of resistivity and ground-penetrating radar data

    NASA Astrophysics Data System (ADS)

    Onishi, Kyosuke 19Tokunaga, Tomochika 2Sugimoto, Yoshihiro 3Yamada, Naoyuki 3Metwaly, Mohamed 456Mogi, Katsuro 2Shimoda, Ichita 7Iwasaki, Yoshinori

    2014-03-01

    The Bayon Complex in the Angkor heritage site, Cambodia, has been damaged by weathering. To plan its long-term preservation, it is essential to investigate its internal structure and the degree of damage within the masonry monument. This study shows results of ground-penetrating radar (GPR) and electrical exploration surveys, and an interpreted section of the internal structure and moisture distribution in the masonry monument. The GPR can detect boundaries between stone blocks and between stone blocks and compacted soil. Electrical resistivity can indicate moisture distribution with high reliability in combination with GPR sections. The top surface zone of the terrace structure of this monument is composed of three layers of stone blocks, and the zone below a depth of 55-60 cm is composed of compacted soil. Rainwater penetrates into the terrace through gaps between the stone blocks and drains from vertical walls through cavities in the top part of the compacted soil. Damaged areas are limited to a part of the terrace, and a large area has remained in good condition. This study shows that a combination of electrical resistivity and GPR data is useful for investigating the internal structures and classifying the degree of damage to old stone structures.

  12. Nonparametric Bayesian time-series modeling and clustering of time-domain ground penetrating radar landmine responses

    NASA Astrophysics Data System (ADS)

    Morton, Kenneth D., Jr.; Torrione, Peter A.; Collins, Leslie

    2010-04-01

    Time domain ground penetrating radar (GPR) has been shown to be a powerful sensing phenomenology for detecting buried objects such as landmines. Landmine detection with GPR data typically utilizes a feature-based pattern classification algorithm to discriminate buried landmines from other sub-surface objects. In high-fidelity GPR, the time-frequency characteristics of a landmine response should be indicative of the physical construction and material composition of the landmine and could therefore be useful for discrimination from other non-threatening sub-surface objects. In this research we propose modeling landmine time-domain responses with a nonparametric Bayesian time-series model and we perform clustering of these time-series models with a hierarchical nonparametric Bayesian model. Each time-series is modeled as a hidden Markov model (HMM) with autoregressive (AR) state densities. The proposed nonparametric Bayesian prior allows for automated learning of the number of states in the HMM as well as the AR order within each state density. This creates a flexible time-series model with complexity determined by the data. Furthermore, a hierarchical non-parametric Bayesian prior is used to group landmine responses with similar HMM model parameters, thus learning the number of distinct landmine response models within a data set. Model inference is accomplished using a fast variational mean field approximation that can be implemented for on-line learning.

  13. Estimating flow parameters using ground-penetrating radar and hydrological data during transient flow in the vadose zone

    SciTech Connect

    Kowalsky, Michael; Finsterle, Stefan; Rubin, Yoram

    2003-05-12

    Methods for determining the parameters necessary for modeling fluid flow and contaminant transport in the shallow subsurface are in great demand. Soil properties such as permeability, porosity, and water retention are typically estimated through the inversion of hydrological data (e.g., measurements of capillary pressure and water saturation). However, ill-posedness and non-uniqueness commonly arise in such inverse problems making their solutions elusive. Incorporating additional types of data, such as from geophysical methods, may greatly improve the success of inverse modeling. In particular, ground-penetrating radar (GPR) has proven sensitive to subsurface fluid flow processes. In the present work, an inverse technique is presented in which permeability distributions are generated conditional to time-lapsed GPR measurements and hydrological data collected during a transient flow experiment. Specifically, a modified pilot point framework has been implemented in iTOUGH2 allowing for the generation of permeability distributions that preserve point measurements and spatial correlation patterns while reproducing geophysical and hydrological measurements. Through a numerical example, we examine the performance of this method and the benefit of including synthetic GPR data while inverting for fluid flow parameters in the vadose zone. Our hypothesis is that within the inversion framework that we describe, our ability to predict flow across control planes greatly improves with the use of both transient hydrological measurements and geophysical measurements (GPR-derived estimates of water saturation, in particular).

  14. Ground-penetrating radar investigation of St. Leonard's Crypt under the Wawel Cathedral (Cracow, Poland) - COST Action TU1208

    NASA Astrophysics Data System (ADS)

    Benedetto, Andrea; Pajewski, Lara; Dimitriadis, Klisthenis; Avlonitou, Pepi; Konstantakis, Yannis; Musiela, Małgorzata; Mitka, Bartosz; Lambot, Sébastien; Żakowska, Lidia

    2016-04-01

    The Wawel ensemble, including the Royal Castle, the Wawel Cathedral and other monuments, is perched on top of the Wawel hill immediately south of the Cracow Old Town, and is by far the most important collection of buildings in Poland. St. Leonard's Crypt is located under the Wawel Cathedral of St Stanislaus BM and St Wenceslaus M. It was built in the years 1090-1117 and was the western crypt of the pre-existing Romanesque Wawel Cathedral, so-called Hermanowska. Pope John Paul II said his first Mass on the altar of St. Leonard's Crypt on November 2, 1946, one day after his priestly ordination. The interior of the crypt is divided by eight columns into three naves with vaulted ceiling and ended with one apse. The tomb of Bishop Maurus, who died in 1118, is in the middle of the crypt under the floor; an inscription "+ MAVRVS EPC MCXVIII +" indicates the burial place and was made in 1938 after the completion of archaeological works which resulted in the discovery of this tomb. Moreover, the crypt hosts the tombs of six Polish kings and heroes: Michał Korybut Wiśniowiecki (King of the Polish-Lithuanian Commonwealth), Jan III Sobieski (King of the Polish-Lithuanian Commonwealth and Commander at the Battle of Vienna), Maria Kazimiera (Queen of the Polish-Lithuanian Commonwealth and consort to Jan III Sobieski), Józef Poniatowski (Prince of Poland and Marshal of France), Tadeusz Kościuszko (Polish general, revolutionary and a Brigadier General in the American Revolutionary War) and Władysław Sikorski (Prime Minister of the Polish Government in Exile and Commander-in-Chief of the Polish Armed Forces). The adjacent six crypts and corridors host the tombs of the other Polish kings, from Sigismund the Old to Augustus II the Strong, their families and several Polish heroes. In May 2015, the COST (European COoperation in Science and Technology) Action TU1208 "Civil engineering applications of Ground Penetrating Radar" organised and offered a Training School (TS) on the

  15. Application of ground-penetrating radar to investigation of near-surface fault properties in the San Francisco Bay region

    USGS Publications Warehouse

    Cai, J.; McMechan, G.A.; Fisher, M.A.

    1996-01-01

    In many geologic environments, ground-penetrating radar (GPR) provides high-resolution images of near-surface Earth structure. GPR data collection is nondestructive and very economical. The scale of features detected by GPR lies between those imaged by high-resolution seismic reflection surveys and those exposed in trenches and is therefore potentially complementary to traditional techniques for fault location and mapping. Sixty-two GPR profiles were collected at 12 sites in the San Francisco Bay region. Results show that GPR data correlate with large-scale features in existing trench observations, can be used to locate faults where they are buried or where their positions are not well known, and can identify previously unknown fault segments. The best data acquired were on a profile across the San Andreas fault, traversing Pleistocene terrace deposits south of Olema in Marin County; this profile shows a complicated multi-branched fault system from the ground surface down to about 40 m, the maximum depth for which data were recorded.

  16. Application of ground-penetrating radar methods in determining hydrogeologic conditions in a karst area, west-central Florida

    USGS Publications Warehouse

    Barr, G.L.

    1993-01-01

    Ground-penetrating radar (GPR) is useful as a surface geophysical method for exploring geology and subsurface features in karst settings. Interpretation of GPR data was used to infer lithology and hydrogeologic conditions in west-central Florida. This study demonstrates how GPR methods can be used to investigate the hydrogeology of an area. GPR transmits radio- frequency electromagnetic waves into the ground and receives reflected energy waves from subsurface interfaces. Subsurface profiles showing sediment thickness, depth to water table and clay beds, karst development, buried objects, and lake-bottom structure were produced from GPR traverses obtained during December 1987 and March 1990 in Pinellas, Hillsborough, and Hardee Counties in west-central Florida. Performance of the GPR method is site specific, and data collected are principally affected by the sediment and pore fluids, conductances and dielectric constants. Effective exploration depths of the GPR surveys through predominately unsaturated and saturated sand and clay sediments at five study sites ranged from a few feet to greater than 50 feet below land surface. Exploration depths were limited when high conductivity clay was encountered, whereas greater exploration depths were possible in material composed of sand. Application of GPR is useful in profiling subsurface conditions, but proper interpretation depends upon the user's knowledge of the equipment and the local hydrogeological setting, as well as the ability to interpret the graphic profile.

  17. Integration of electrical resistivity imaging and ground penetrating radar to investigate solution features in the Biscayne Aquifer

    NASA Astrophysics Data System (ADS)

    Yeboah-Forson, Albert; Comas, Xavier; Whitman, Dean

    2014-07-01

    The limestone composing the Biscayne Aquifer in southeast Florida is characterized by cavities and solution features that are difficult to detect and quantify accurately because of their heterogeneous spatial distribution. Such heterogeneities have been shown by previous studies to exert a strong influence in the direction of groundwater flow. In this study we use an integrated array of geophysical methods to detect the lateral extent and distribution of solution features as indicative of anisotropy in the Biscayne Aquifer. Geophysical methods included azimuthal resistivity measurements, electrical resistivity imaging (ERI) and ground penetrating radar (GPR) and were constrained with direct borehole information from nearby wells. The geophysical measurements suggest the presence of a zone of low electrical resistivity (from ERI) and low electromagnetic wave velocity (from GPR) below the water table at depths of 4-9 m that corresponds to the depth of solution conduits seen in digital borehole images. Azimuthal electrical measurements at the site reported coefficients of electrical anisotropy as high as 1.36 suggesting the presence of an area of high porosity (most likely comprising different types of porosity) oriented in the E-W direction. This study shows how integrated geophysical methods can help detect the presence of areas of enhanced porosity which may influence the direction of groundwater flow in a complex anisotropic and heterogeneous karst system like the Biscayne Aquifer.

  18. Investigating fluvial features with electrical resistivity imaging and ground-penetrating radar: The Guadalquivir River terrace (Jaen, Southern Spain)

    NASA Astrophysics Data System (ADS)

    Rey, J.; Martínez, J.; Hidalgo, M. C.

    2013-09-01

    A geophysical survey has been conducted on the lowest terrace levels and the present day floodplain of the current course of the Guadalquivir River, passing through the province of Jaen (Spain), using two techniques: electrical resistivity imaging (ERI) and ground-penetrating radar (GPR). Three areas have been selected. In one of these sectors (Los Barrios) there is an old quarry where there are excellent outcrops that allow for the calibration of the survey techniques. Facies associations on these outcrops are typical of meandering rivers with sequences of channel fills, lateral accretion of point-bars and floodplain facies. The usefulness of the two methods is analysed and compared as a support for stratigraphic and sedimentological studies. The geometry and lithofacies of subsurface deposits were characterised using ERI and compared with field observations. A total of 5 electrical resistivity imaging profiles were obtained. The changes in electric resistivity highlight granulometric differences in terrace sediments. This technique can thus be used to identify the morphology of these bodies, the lithofacies (silt, sand or gravel) and buried channel pattern. In addition, 16 GPR profiles using 100 and 250 MHz antennas were acquired, indicating terrace morphology and the filling of the sedimentary bodies in a more detailed manner than in ERI. The study thus allows for inferring the existence of channel migration, the lateral accretion of point bars and the presence of vertical accretion deposits attributable to the floodplains.

  19. Sensitivity analysis of soil heterogeneity for ground-penetrating radar measurements by means of a simple modeling

    NASA Astrophysics Data System (ADS)

    Takahashi, Kazunori; Igel, Jan; Preetz, Holger; Sato, Motoyuki

    2015-02-01

    Higher-frequency ground-penetrating radar (GPR) is becoming more common for various applications. While it can achieve a higher resolution than low-frequency measurements, it also becomes more sensitive to heterogeneous soils. The increased sensitivity in small-scale measurements often creates the problem of unwanted scattering in the data. Unwanted scattering is commonly called clutter. If clutter contaminates the data significantly, data analysis and interpretation become difficult. Our study analyzes the sensitivity of soil heterogeneity by evaluating the amount of clutter caused by soils. Clutter is calculated by simple modeling that takes into account soil heterogeneity. The method constructs a dielectric sphere model that uses statistical properties of permittivity distribution and calculates backscattering power from the sphere that emulates the backscattering observed from heterogeneous soil. The modeling was carried out for a range of heterogeneities. The results show that the level of permittivity variation of soil mostly dominates the clutter power. However, the influence of correlation length becomes greater when the correlation length of soil permittivity distribution is a multiple of wavelength. Therefore, to observe the influence of heterogeneous soils on GPR measurements, the spatial distribution of soil permittivity must be taken into account in addition to the variation.

  20. Ground penetrating radar coal measurements demonstration at the U.S. Bureau of Mines Research Center, Pittsburgh, Pennsylvania. Final report

    SciTech Connect

    Gardner, D.; Guerrier, J.; Martinez, M.

    1994-01-04

    In situ and near real-time measurements of coal seam thickness have been identified by industry as a highly desirable component of robotic mining systems. With it, a continuous mining machine can be guided close to the varying boundary of the seam while the cutting operation is underway. This provides the mining operation the ability to leave behind the high-sulfur, high-particulate coal which is concentrated near the seam boundary. The result is near total recovery of high quality coal resources, an increase in mining efficiency, and opportunities for improved safety through reduction in personnel in the most hazardous coal cutting areas. In situ, real-time coal seam measurements using the Special Technologies Laboratory (STL) ground penetrating radar (GPR) technology were shown feasible by a demonstration in a Utah coal mine on April 21, 1994. This report describes the October 18, 1994 in situ GPR measurements of coal seam thickness at the US Bureau of Mines (USBM) robotic mining testing laboratory. In this report, an overview of the measurements at the USBM Laboratory is given. It is followed by a description of the technical aspects of the STL frequency modulated-continuous wave (FM-CW) GPR system. Section 4 provides a detailed description of the USBM Laboratory measurements and the conditions under which they were taken. Section 5 offers conclusions and possibilities for future communications.

  1. Ground Penetrating Radar imaging of two large sand blow craters related to the 2001 Bhuj earthquake, Kachchh, Western India

    NASA Astrophysics Data System (ADS)

    Maurya, D. M.; Goyal, B.; Patidar, A. K.; Mulchandani, N.; Thakkar, M. G.; Chamyal, L. S.

    2006-10-01

    The 2001 Bhuj earthquake (Mw 7.7) formed several medium to large sand blow craters due to extensive liquefaction of the sediments comprising the Banni plain and Great Rann of Kachchh. We investigated two large closely spaced sand blow craters of different morphologies using Ground Penetrating Radar (GPR) with a view to understand the subsurface deformation, identify the vents and source of the vented sediments. The study comprises velocity surveys, GPR surveys using 200 MHz antennae along three selected transects that is supplemented by data from two trenches excavated. The GPR was able to provide good data on stratigraphy and deformation up to a depth of 6.5 m with good resolution. The GPR successfully imaged the subsurface characteristics of the craters based on the contrasting lithologies of the host sediments and the sediments emplaced in the craters. The GPR also detected three vertical vents of ˜ 1 m width continuing throughout the profile which are reflected as high amplitude vertical events. We conclude that the large sand blows during the 2001 Bhuj earthquake were produced due to liquefaction of sediments in the subsurface at > 6.5 m depth and that the clay-rich sediments of the Banni plain have behaved as the fine grained cap over it. The present study provides a modern analogue for comparing the liquefaction features of past great earthquakes (for example, the 1819 earthquake) that have occurred in the Kachchh region to understand the phenomena of liquefaction.

  2. Integration of ground-penetrating radar, ultrasonic tests and infrared thermography for the analysis of a precious medieval rose window

    NASA Astrophysics Data System (ADS)

    Nuzzo, L.; Calia, A.; Liberatore, D.; Masini, N.; Rizzo, E.

    2010-04-01

    The integration of high-resolution, non-invasive geophysical techniques (such as ground-penetrating radar or GPR) with emerging sensing techniques (acoustics, thermography) can complement limited destructive tests to provide a suitable methodology for a multi-scale assessment of the state of preservation, material and construction components of monuments. This paper presents the results of the application of GPR, infrared thermography (IRT) and ultrasonic tests to the 13th century rose window of Troia Cathedral (Apulia, Italy), affected by widespread decay and instability problems caused by the 1731 earthquake and reactivated by recent seismic activity. This integrated approach provided a wide amount of complementary information at different scales, ranging from the sub-centimetre size of the metallic joints between the various architectural elements, narrow fractures and thin mortar fillings, up to the sub-metre scale of the internal masonry structure of the circular ashlar curb linking the rose window to the façade, which was essential to understand the original building technique and to design an effective restoration strategy.

  3. Autonomous ground penetrating radar (GPR) measurements for exploring biogenic gas dynamics of peat soils in a northern peatland

    NASA Astrophysics Data System (ADS)

    Wright, W. J.; Comas, X.; Heij, G.; Slater, L. D.; Schafer, K. V.; Reeve, A. S.

    2012-12-01

    It is widely accepted that northern peat soils are responsible for up to 10% of methane flux to the atmosphere yet act as a net sink for as much as 75% of the global mass of atmospheric carbon. A better understanding of the processes by which peat soils store and release carbon products must be gained in order to more accurately model the contributions that peatlands make to global atmospheric carbon budgets. Rapid ebullition events of biogenic methane and carbon dioxide gases from peat soils are currently not well understood, particularly since the timing of the releases are poorly constrained. Ground penetrating radar (GPR) is a geophysical tool that has successfully been used in the past to non-invasively investigate the release of biogenic gasses from peat soils. In the work presented here, measurement frequency is expanded by including daily arrays of common offset and common midpoint GPR measurements combined with hourly autonomous GPR measurements to investigate biogenic gas dynamics during times of variable atmospheric pressure in a northern peatland in Maine. Geophysical data were supported by peat matrix deformation measurements using terrestrial LiDAR (TLS) and direct gas flux measurements using gas traps combined with time-lapse cameras at the sub-daily scale. A vertical array of moisture probes was also used to further constrain GPR measurements. Results from this study show the viability of autonomous GPR methods for improving temporal resolution of geophysical data in order to better understand the dynamics of biogenic gas releases from peat soils.

  4. Quantifying landscape morphology influence on peatland lateral expansion using ground-penetrating radar (GPR) and peat core analysis

    NASA Astrophysics Data System (ADS)

    Loisel, Julie; Yu, Zicheng; Parsekian, Andrew; Nolan, James; Slater, Lee

    2013-06-01

    peatlands contain vast amounts of organic carbon. Large-scale datasets have documented spatial patterns of peatland initiation as well as vertical peat accumulation rates. However, the rate, pattern, and timing of lateral expansion across the northern landscape remain largely unknown. As peatland lateral extent is a key boundary condition constraining the dynamics of peatland systems, understanding this process is essential. Here we use ground penetrating radar (GPR) and peat core analysis to study the effect of local slope and topography on peatland development at a site in south-central Alaska. The study site is unique in that a thick tephra (volcanic ash) layer, visible in the GPR data, interrupted the peatland development for about one thousand years during the mid Holocene. In our analysis, this tephra layer serves as a re-initiation point for peatland development. By comparing the initial mineral basin vs. the post-tephra surfaces, the influence of topography and slope on peatland expansion rate and peat-carbon sequestration was analyzed. Our results show that (1) peatland surface slope becomes progressively shallower over the Holocene, (2) slope affects peatland lateral expansion nonlinearly, (3) the relationship between lateral expansion rate and slope follows a power-law behavior, and (4) peatland expansion becomes slope-limited above a threshold (0.5°). Furthermore, we propose a conceptual model linking slope to peatland lateral expansion where slope gradient and basin topography exert deterministic controls on peatland lateral expansion directly or through hydrology and vertical accumulation rates.

  5. Hydrodynamic parameters of a sandy soil determined by ground-penetrating radar inside a single ring infiltrometer

    NASA Astrophysics Data System (ADS)

    Léger, Emmanuel; Saintenoy, Albane; Coquet, Yves

    2014-07-01

    This study shows how Mualem-van Genuchten (M-vG) parameters can be obtained from GPR data acquired during water infiltration from a single ring infiltrometer in the case of a sandy soil. Water content profiles were generated at various time steps using HYDRUS-1D, based on particular values of the M-vG parameters and were converted to dielectric permittivity profiles using the Complex Refractive Index Method. The GprMax suite of programs was used to generate radargrams and to follow the wetting front progression in depth using the arrival time of the electromagnetic waves recorded by a ground-penetrating radar (GPR). Theoretically, the 1-D time convolution between reflectivity and GPR signal at any infiltration time step is related to the peak of the reflected signal recorded in the corresponding trace in the radargram. We used this relationship to invert the M-vG parameters for constant and falling head infiltrations using the Shuffled Complex Evolution (SCE-UA) algorithm. The method is presented on synthetic examples and on experiments carried out for a sandy soil. The parameters inverted are compared with values obtained in laboratory on soil samples and with disk infiltrometer measurements.

  6. The dielectric permittivity of terrestrial ground ice formations: Considerations for planetary exploration using ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Thomson, Laura I.; Osinski, Gordon R.; Pollard, Wayne H.

    2012-09-01

    Exploration of the polar ice caps and apparent glacial and periglacial landforms on Mars will aid our understanding of its ancient climate conditions and the history of water on the planet. Given that ground-penetrating radar (GPR) is likely to be used to understand these features, we investigated the real component of the complex dielectric permittivity of stratified segregation ice, non-stratified segregation ice, and polygonal ice wedge deposits in the Canadian Arctic. We acquired moveout profiles with a 450 MHz GPR on ground ice formations that had active layer sediments excavated prior to surveying. Using ice core data collected from these sites, we found that the volumetric fraction of ice plays the greatest role in defining the dielectric permittivity of the deposit and that it can be described using a modified complex refractive index method (CRIM) dielectric mixing model. Using the modified CRIM model, we estimate the dielectric permittivity of several ground ice deposits on Earth and present further estimates for similar features on Mars using permittivity values for Martian sediments derived from both theory and laboratory methods.

  7. The utility of ground-penetrating radar and its time-dependence in the discovery of clandestine burials.

    PubMed

    Salsarola, Dominic; Poppa, Pasquale; Amadasi, Alberto; Mazzarelli, Debora; Gibelli, Daniele; Zanotti, Emma; Porta, Davide; Cattaneo, Cristina

    2015-08-01

    In the field of forensic investigation burial is a relatively common method of hiding a corpse. The location of clandestine graves is, however, a particularly difficult task in which multiple forensic disciplines such as anthropology, botany or archaeology can provide valuable assistance. The use of GPR (ground-penetrating radar) has recently been introduced as a method in the detection of these graves, but what is the true potential of this tool in an operative search scenario? In this study a total of 11 pig carcasses were buried in two wooded areas, each presenting a similar soil composition. The animals were subsequently exhumed at regular intervals, ranging from 2 to 111 weeks, using systematic GPR analysis of the burial sites and archaeological recovery of the subjects that were then autopsied. GPR proved to be useful in recognizing anomalies at the chosen depths of burial and appeared to be dependent on the state of decay of the samples, producing only slight anomalous readings in the presence of skeletal remains: at 92 weeks from burial the difference in signal was weak and at 111 weeks GPR survey offered no helpful information as to burial location. The experiment, in this particular context, determined the technique as being successful in the presence of recent burials, highlighting the need for a multidisciplinary approach in the operative search for buried human remains. PMID:26119388

  8. Comparison of annual accumulation rates derived from in situ and ground penetrating radar methods across Alaskan glaciers

    NASA Astrophysics Data System (ADS)

    McGrath, D.; Gusmeroli, A.; Oneel, S.; Sass, L. C.; Arendt, A. A.; Wolken, G. J.; Kienholz, C.; McNeil, C.

    2013-12-01

    Constraining annual snowfall accumulation in mountain glacier environments is essential for determining the annual mass balance of individual glaciers and predicting seasonal meltwater runoff to river and marine ecosystems. However, large spatial and elevation gradients, coupled with sparse point measurements preclude accurate quantification of this variable using traditional methods. Here, we report on an extensive field campaign conducted in March-May 2013 on key benchmark glaciers in Alaska, including Taku Glacier near Juneau, Scott Glacier near Cordova, both Eklutna and Wolverine Glacier near Anchorage and Gulkana Glacier in the interior Alaska Range. Over 50 km of 500 MHz common-offset ground penetrating radar (GPR) surveys were collected on each glacier, with an emphasis on capturing spatial variability in the accumulation zone. Frequent in situ observations were collected for comparison with the GPR, including probe depths, snow pits and shallow firn cores (~8 m). We report on spatial and elevation gradients across this suite of glaciers and across numerous climatic zones and discuss differences between GPR and in situ derived annual accumulation estimates. This comparison is an essential first step in order to effectively evaluate regional atmospheric re-analysis products.

  9. Giving perspective to cliff exposures with ground penetrating radar: Devonian lacustrine shore zone architecture

    NASA Astrophysics Data System (ADS)

    Andrews, Steven; Moreau, Julien; Archer, Stuart

    2015-04-01

    The orbitally-controlled cyclic lacustrine successions of the Middle Devonian in Northern Scotland contains repeated developments of shore zone sandstones. However, due to the cliff-forming nature of the succession and the attitude of the sections through these sandstones, interpretation of this facies has been problematic. To better understand the shore zone systems, we carried out very high resolution sedimentary logging and constructed photo-panels which were combined with high resolution GPR profiling (250 MHz). To ensure close ties between the sedimentary logs and the GPR data, the cliffs were accessed using rope access techniques while GPR grids were shot directly above. The profiles were shot mainly in the strike direction of what was thought to be the shore elongation every 5-10 m and every 20-30 m in the dip direction. Shore zone systems of 3 different sequences have been imaged for a total of 1155 m of GPR profile collected. This configuration has allowed 3D visualisation of the architecture of the shore zone systems and, in combination with detailed sedimentology, provided insights into the generation of the dynamic shore zone environments. The coastal cliffs of northern Scotland expose sedimentary cycles on average 16-m-thick which record deep lake, perennial lake and playa environments. The shore zone deposits reach 2 to 3.5 m in thickness. Loading and discrete channel forms are recognised in both the GPR data and sedimentary logs through the lower portion of the lake shore zone successions. Up-section the sandstone beds appear to become amalgamated forming subtle low angle accretionary bar complexes which although visible in outcrop, after careful investigation, can be fully visualised and examined in the GPR data. The 3D visualisation allowed mapping the architecture and distribution of the bars . The orientation of these features, recognised from the survey, is consistent with extensive palaeocurrent measurements from oscillation ripples. Further

  10. Time-lapse ground penetrating radar (GPR) measurements for exploring biogenic gas distribution and releases from peat soils in the Florida Everglades

    NASA Astrophysics Data System (ADS)

    Wright, W. J.; Comas, X.; Berber, M.

    2013-12-01

    Peat soils are known to release significant amounts of methane (CH4) and carbon dioxide (CO2) to the atmosphere. However, uncertainties still remain regarding the spatio-temporal distribution of gas accumulations and the triggering mechanisms of gas releasing events. Furthermore, most peatland gas dynamics research has historically been focused on high latitude peatlands, while recent works have suggested that gas production rates from low-latitude peat soils may be higher than those from colder climates. Ground penetrating radar (GPR) is a geophysical tool that has successfully been used in the past to non-invasively investigate the release of biogenic gasses from peat soils. This study is conducted in the Loxahatchee Impoundment Landscape Assessment (LILA), a hydrologically controlled, landscape scale (30 HA) model of the Florida Everglades. Here, temporal and spatial heterogeneity of gas releases from peat soil at the plot scale (<100 m2) are shown using a time series of three-dimensional (3D) GPR measurements. GPR data are supported by direct gas flux measurements using flux chambers combined with time-lapse photography, and surface deformation measurements using terrestrial LiDAR scanning and differential leveling.

  11. High resolution shallow geologic characterization of a late Pleistocene eolian environment using ground penetrating radar and optically stimulated luminescence techniques: North Carolina, USA

    USGS Publications Warehouse

    Mallinson, D.; Mahan, S.; Moore, Christine

    2008-01-01

    Geophysical surveys, sedimentology, and optically-stimulated luminescence age analyses were used to assess the geologic development of a coastal system near Swansboro, NC. This area is a significant Woodland Period Native American habitation and is designated the "Broad Reach" archaeological site. 2-d and 3-d subsurface geophysical surveys were performed using a ground penetrating radar system to define the stratigraphic framework and depositional facies. Sediment samples were collected and analyzed for grain-size to determine depositional environments. Samples were acquired and analyzed using optically stimulated luminescence techniques to derive the depositional age of the various features. The data support a low eolian to shallow subtidal coastal depositional setting for this area. Li-DAR data reveal ridge and swale topography, most likely related to beach ridges, and eolian features including low-relief, low-angle transverse and parabolic dunes, blowouts, and a low-relief eolian sand sheet. Geophysical data reveal dominantly seaward dipping units, and low-angle mounded features. Sedimentological data reveal mostly moderately-well to well-sorted fine-grained symmetrical to coarse skewed sands, suggesting initial aqueous transport and deposition, followed by eolian reworking and bioturbation. OSL data indicate initial coastal deposition prior to ca. 45,000 yBP, followed by eolian reworking and low dune stabilization at ca. 13,000 to 11,500 yBP, and again at ca. 10,000 yBP (during, and slightly after the Younger Dryas chronozone).

  12. Time-lapse Monitoring of Two-dimensional Non-uniform Unsaturated Flow Processes Using Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Lytle, B. A.; Mangel, A. R.; Moysey, S. M.

    2015-12-01

    Unsaturated flow in the vadose zone often manifests as preferential flow resulting in transport of water and solutes through the soil much faster than would occur for uniform matrix flow. Time-lapse ground-penetrating radar (GPR) monitoring shows significant potential for identifying the presence of non-uniform flow and quantitative monitoring of the hydrologic response of a soil system. We investigate non-uniform flow in the vadose zone for an infiltration experiment performed in a 60 cm deep sand-filled tank that is continuously monitored with 1000 MHz reflection GPR. During the experiment, 100 constant offset and 300 common mid-point (CMP) time-lapse radar profiles were collected using an automated gantry system to rapidly position the antennas, allowing for a set of 1 constant offset and 3 CMP profiles to be collected every 13 seconds. The constant offset profiles were interpreted to evaluate spatial and temporal changes of reflected arrivals over the course of the experiment, whereas the CMPs were used to estimate the initial EM wave velocity in the tanks using a normal moveout analysis. Changes in traveltime to a static reflector were used to estimate spatial changes in velocity and to create two-dimensional velocity models. The GPR data were then migrated using the estimated 2D velocity model to improve GPR reflection images, which could then be interpreted to identify evidence of non-uniform flow phenomena. To verify the approach, the methodology was also applied to GPR data simulated using transient water contents generated by the unsaturated flow simulator HYDRUS2D given lab-measured hydraulic properties for the soil. For both the empirical and simulated data, we found that the 2D velocity analysis was effective in monitoring changes in the wetting front and that migration of the reflection profiles was able to improve the interpretation of non-uniform flow.

  13. Potential of Probing the Lunar Regolith using Rover-Mounted Ground Penetrating Radar: Moses Lake Dune Field Analog Study

    NASA Technical Reports Server (NTRS)

    Horz, F.; Heggy, E.; Fong, T.; Kring, D.; Deans, M.; Anglade, A.; Mahiouz, K.; Bualat, M.; Lee, P.; Bluethmann, W.

    2009-01-01

    Probing radars have been widely recognized by the science community to be an efficient tool to explore lunar subsurface providing a unique capability to address several scientific and operational issues. A wideband (200 to 1200 MHz) Ground Penetrating Radar (GPR) mounted on a surface rover can provide high vertical resolution and probing depth from few tens of centimeters to few tens of meters depending on the sounding frequency and the ground conductivity. This in term can provide a better understand regolith thickness, elemental iron concentration (including ilmenite), volatile presence, structural anomalies and fracturing. All those objectives are of important significance for understanding the local geology and potential sustainable resources for future landing sites in particular exploring the thickness, structural heterogeneity and potential volatiles presence in the lunar regolith. While the operation and data collection of GPR is a straightforward case for most terrestrial surveys, it is a challenging task for remote planetary study especially on robotic platforms due to the complexity of remote operation in rough terrains and the data collection constrains imposed by the mechanical motion of the rover and limitation in data transfer. Nevertheless, Rover mounted GPR can be of great support to perform systematic subsurface surveys for a given landing site as it can provide scientific and operational support in exploring subsurface resources and sample collections which can increase the efficiency of the EVA activities for potential human crews as part of the NASA Constellation Program. In this study we attempt to explore the operational challenges and their impact on the EVA scientific return for operating a rover mounted GPR in support of potential human activity on the moon. In this first field study, we mainly focused on the ability of GPR to support subsurface sample collection and explore shallow subsurface volatiles.

  14. Use of ground penetrating radar for determination of water table depth and subsurface soil characteristics at Kennedy Space Center

    NASA Astrophysics Data System (ADS)

    Hengari, Gideon M.; Hall, Carlton R.; Kozusko, Tim J.; Bostater, Charles R.

    2013-10-01

    Sustainable use and management of natural resources require strategic responses using non-destructive tools to provide spatial and temporal data for decision making. Experiments conducted at John F. Kennedy Space Center (KSC) demonstrate ground penetrating radar (GPR) can provide high-resolution images showing depth to water tables. GPR data at KSC were acquired using a MALÅ Rough Terrain 100 MHz Antenna. Data indicate strong correlation (R2=0.80) between measured water table depth (shallow monitoring wells and soil auger) and GPR estimated depth. The study demonstrated the use of GPR to detect Holocene and Pleistocene depositional environments such as Anastasia Formation that consists of admixtures of sand, shell and coquinoid limestone at a depth of 20-25 ft. This corresponds well with the relatively strong reflections from 7.5 to 13 m (125-215 ns) in GPR images. Interpretations derived from radar data coupled with other non-GPR data (wells data and soil auger data) will aid in the understanding of climate change impacts due to sea level rise on the scrub vegetation composition at KSC. Climate change is believed to have a potentially significant impact potential on near coastal ground water levels and associated water table depth. Understanding the impacts of ground water levels changes will, in turn, lead to improved conceptual conservation efforts and identifications of climate change adaptation concepts related to the recovery of the Florida scrub jay (Aphelocoma coerulescens) and other endangered or threatened species which are directly dependent on a healthy near coastal scrub habitat. Transfer of this inexpensive and non-destructive technology to other areas at KSC, Florida, and to other countries, may prove useful in the development of future conservation programs.

  15. Improving soil moisture profile reconstruction from ground-penetrating radar data: a maximum likelihood ensemble filter approach

    NASA Astrophysics Data System (ADS)

    Tran, A. P.; Vanclooster, M.; Lambot, S.

    2013-07-01

    The vertical profile of shallow unsaturated zone soil moisture plays a key role in many hydro-meteorological and agricultural applications. We propose a closed-loop data assimilation procedure based on the maximum likelihood ensemble filter algorithm to update the vertical soil moisture profile from time-lapse ground-penetrating radar (GPR) data. A hydrodynamic model is used to propagate the system state in time and a radar electromagnetic model and petrophysical relationships to link the state variable with the observation data, which enables us to directly assimilate the GPR data. Instead of using the surface soil moisture only, the approach allows to use the information of the whole soil moisture profile for the assimilation. We validated our approach through a synthetic study. We constructed a synthetic soil column with a depth of 80 cm and analyzed the effects of the soil type on the data assimilation by considering 3 soil types, namely, loamy sand, silt and clay. The assimilation of GPR data was performed to solve the problem of unknown initial conditions. The numerical soil moisture profiles generated by the Hydrus-1D model were used by the GPR model to produce the "observed" GPR data. The results show that the soil moisture profile obtained by assimilating the GPR data is much better than that of an open-loop forecast. Compared to the loamy sand and silt, the updated soil moisture profile of the clay soil converges to the true state much more slowly. Decreasing the update interval from 60 down to 10 h only slightly improves the effectiveness of the GPR data assimilation for the loamy sand but significantly for the clay soil. The proposed approach appears to be promising to improve real-time prediction of the soil moisture profiles as well as to provide effective estimates of the unsaturated hydraulic properties at the field scale from time-lapse GPR measurements.

  16. Improving soil moisture profile prediction from ground-penetrating radar data: a maximum likelihood ensemble filter approach

    NASA Astrophysics Data System (ADS)

    Tran, A. P.; Vanclooster, M.; Lambot, S.

    2013-02-01

    The vertical profile of root zone soil moisture plays a key role in many hydro-meteorological and agricultural applications. We propose a closed-loop data assimilation procedure based on the maximum likelihood ensemble filter algorithm to update the vertical soil moisture profile from time-lapse ground-penetrating radar (GPR) data. A hydrodynamic model is used to propagate the system state in time and a radar electromagnetic model to link the state variable with the observation data, which enables us to directly assimilate the GPR data. Instead of using the surface soil moisture only, the approach allows to use the information of the whole soil moisture profile for the assimilation. We validated our approach by a synthetic study. We constructed a synthetic soil column with a depth of 80 cm and analyzed the effects of the soil type on the data assimilation by considering 3 soil types, namely, loamy sand, silt and clay. The assimilation of GPR data was performed to solve the problem of unknown initial conditions. The numerical soil moisture profiles generated by the Hydrus-1D model were used by the GPR model to produce the "observed" GPR data. The results show that the soil moisture profile obtained by assimilating the GPR data is much better than that of an open-loop forecast. Compared to the loamy sand and silt, the updated soil moisture profile of the clay soil converges to the true state much more slowly. Increasing update interval from 5 to 50 h only slightly improves the effectiveness of the GPR data assimilation for the loamy sand but significantly for the clay soil. The proposed approach appears to be promising to improve real-time prediction of the soil moisture profiles as well as to provide effective estimates of the unsaturated hydraulic properties at the field scale from time-lapse GPR measurements.

  17. A multi-static ground-penetrating radar with an array of resistively loaded vee dipole antennas for landmine detection

    NASA Astrophysics Data System (ADS)

    Kim, Kangwook; Gurbuz, Ali C.; Scott, Waymond R., Jr.; McClellan, James H.

    2005-06-01

    A multi-static ground-penetrating radar (GPR) has been developed to investigate the potential of multi-static inversion algorithms. The GPR consists of a linear array of six resistively-loaded vee dipoles (RVDs), a network analyzer, and a microwave switch matrix all under computer control. The antennas in the array are spaced 12cm apart so the spacing between the transmitter and the receiver pairs in the measurements are from 12cm to 96cm in 12cm increments. The size of the array is suitable for the landmine problem and scaled measurements of the buried structure problem. The RVD is chosen as an array element because it is very "clean" in that it has very little self clutter and a very low radar cross section to lessen the reflections between the ground and the antenna. The shape and the loading profile of the antenna are designed to decrease the reflection at the drive point of the antenna while increasing the forward gain. The antenna and balun are made in a module, which is mechanically reliable without significant performance degradation. The multi-static GPR operation is demonstrated on targets buried in clean sand and targets buried under the ground covered by rocks. The responses of the targets are measured by each transmitter-receiver pair. A synthetic aperture, multi-static GPR imaging algorithm is extended from conventional monostatic back-projection techniques and used to process the data. Initial images obtained from the multi-static data are clearer than those obtained from bistatic data.

  18. Identifying unsaturated soil hydraulic parameters using integrated hydrogeophysical inversion approach on time-lapse ground-penetrating radar data

    NASA Astrophysics Data System (ADS)

    Jadoon, K. Z.; Weihermüller, L.; Scharnagl, B.; Kowalsky, M. B.; Bechtold, M.; Hubbard, S. S.; Vereecken, H.; Lambot, S.

    2012-04-01

    Recently, ground-penetrating radar (GPR) has proven to have a great potential for high resolution, non-invasive mapping of the soil hydrogeophysical properties at the scale of interest. Common GPR techniques are usually based on ray-based travel time or reflection analyses to retrieve soil dielectric permittivity, which is strongly correlated to soil water content. These methods suffer, however, from two major limitations. First, only a part of the information in the GPR signal is considered (e.g., propagation time). Second, the forward model describing the radar data is subject to relatively strong simplifications with respect to electromagnetic wave propagation phenomena. These limitations typically results in errors in the reconstructed water content images and, moreover, this does not permit to exploit all information contained in the radar data. We explored an alternative method by using full-waveform hydrogeophysical inversion of time-lapse, proximal GPR data to remotely estimate the unsaturated soil hydraulic properties. The radar system is based on international standard vector network analyzer technology and a full-waveform model is used to describe wave propagation in the antenna-air-soil system, including antenna-soil interactions. A hydrodynamic model is used to constrain the inverse electromagnetic problem in reconstructing continuous vertical water content profiles. In that case the estimated parameters reduce to the soil hydraulic properties, thereby strongly reducing the dimensionality of the inverse problem. In this study, we present an application of the proposed method to a data set collected in a field experiment. The GPR model involves a full-waveform frequency-domain solution of Maxwell's equations for wave propagation in three-dimensional multilayered media. The hydrodynamic model used in this work is based on a one-dimensional solution of Richards equation and the hydrological simulator HYDRUS 1-D was used with a single- and dual

  19. Inversion for the statistical structure of subsurface water content from ground-penetrating radar reflection data: Initial results and interpretation

    NASA Astrophysics Data System (ADS)

    Irving, J.; Knight, R.; Holliger, K.

    2007-12-01

    The distribution of subsurface water content can be an excellent indicator of soil texture, which strongly influences the unsaturated hydraulic properties controlling vadose zone contaminant transport. Characterizing the heterogeneity in subsurface water content for use in numerical transport models, however, is an extremely difficult task as conventional hydrological measurement techniques do not offer the combined high spatial resolution and coverage required for accurate simulations. A number of recent studies have shown that ground-penetrating radar (GPR) reflection images may contain useful information regarding the statistical structure of subsurface water content. Comparisons of the horizontal correlation structures of radar images and those obtained from water content measurements have shown that, in some cases, the statistical characteristics are remarkably similar. However, a key issue in these studies is that a reflection GPR image is primarily related to changes in subsurface water content, and not the water content distribution directly. As a result, statistics gathered on the reflection image have a very complex relationship with the statistics of the underlying water content distribution, this relationship depending on a number of factors including the frequency of the GPR antennas used. In this work, we attempt to address the above issue by posing the estimation of the statistical structure of water content from reflection GPR data as an inverse problem. Using a simple convolution model for a radar image, we first derive a forward model relating the statistical structure of a radar image to that of the underlying water content distribution. We then use this forward model to invert for the spatial statistics of the water content distribution, given the spatial statistics of the GPR reflection image as data. We do this within a framework of uncertainty, such that realistic statistical bounds can be placed on the information that is inferred. In other

  20. Initial Analysis of Internal Layers in the Snow Cover of the Ross Island Region using Ground Penetrating Radar Measurements

    NASA Astrophysics Data System (ADS)

    Kruetzmann, N. C.; George, S. E.; McDonald, A. J.; Rack, W.

    2009-04-01

    In snow and ice, internal layers are created by changes in the ambient conditions at the time of deposition, and represent contrasts in density, electrical conductivity, and ice crystal orientation. By identifying and tracing internal layers in ground penetrating radar (GPR) measurements of the Antarctic snow cover, these layers can be used to measure snow accumulation over time. This is particularly relevant for determining the Antarctic mass balance, as the areal coverage can be greatly expanded from the common, but potentially unrepresentative, point measurements from firn-cores, snow pits, or stake farms. This presentation discusses high-resolution GPR data acquired at three research sites in the vicinity of Scott Base (Antarctica), each site being characterised by different snow and surface properties. The first two sites examined, are located on the flat McMurdo Ice Shelf in zones with significantly different wind and accumulation patterns. The final site is located on the lower slopes of Mt. Erebus (Ross Island), in the dry snow zone, at approximately 350m above sea level. Using a pulseEKKO PRO GPR system, data was acquired at two frequencies simultaneously (500MHz and 1GHz; wavelength in dry snow: 40cm and 20cm, respectively). At the first two sites, transects were collected in an 800m x 800m grid at 100m intervals. Due to difficult terrain, the third site was restricted to a 400m x 400m domain. Radar shots were taken at 5cm intervals along each transect. This both provides a very high horizontal data resolution, and facilitates internal horizon tracking. The acquisition time-window of 135ns allows horizon detection down to a depth of approximately 12m. In order to convert layer depth to accumulation, information on snow density derived from snow pit- and CMP-measurements was also collected. The acquired data provides high-resolution ground-truth information required for the validation of CRYOSAT-2 satellite data (launch date in 2009). An additional reason

  1. Ground-penetrating radar as a tool for characterizing ground ice in the Canadian High Arctic: Implications for future Mars based radar investigations

    NASA Astrophysics Data System (ADS)

    Thomson, L. I.; Osinski, G.

    2010-12-01

    On Earth, ground-penetrating radar (GPR) is commonly used for the detection of ground ice in permafrost regions preceding infrastructure development and for unveiling paleoclimate conditions. Elsewhere in our solar system, other icy bodies, whether they make up an entire satellite or are intermittent subsurface deposits, are increasingly of scientific interest. This curiosity concerning the origins and nature of this ice is motivated by our drive to understand both the evolution of volatile materials through our solar system, and the climate processes that defined the cold and dry neighbouring Mars we observe today. What are implications for climate and potential for life in the event of discovering segregation, polygon-wedge, buried sea, glacial, or lake ice on another planet? This study is motivated by our desire to determine the properties, and subsequently the nature, of extraterrestrial ice by remote sensing means. We have developed a technique to test the aptitude of high-frequency ground penetrating radar (GPR) systems for applications in the characterization of sub-surface ice deposits. This technique follows from the hypothesis that chemical and bulk properties of the ground ice can be characterized according to the electrical properties of the ice and its inclusions. Field based research followed remote sensing practices, which identified of terrains capable of hosting subsurface ice. At sites in the Canadian High Arctic Islands of Axel Heiberg, Ellesmere, and Devon, surface radar surveys confirmed the existence of ice predicted from remote sensing work, then common offset, common-midpoint and cross-polarimetric surveys over the deposit were collected both atop the active layer and on the ice surface itself. We explored three methods of measuring radar velocity. Of these methods, two follow from modified survey design, and one stems from a geophysical post-processing technique involving the theoretical removal of adverse overburden affects. Following the

  2. A Critical Evaluation of Ground-Penetrating Radar Methodology on the Kalavasos and Maroni Built Environments (KAMBE) Project, Cyprus (Invited)

    NASA Astrophysics Data System (ADS)

    Leon, J.; Urban, T.; Gerard-Little, P.; Kearns, C.; Manning, S. W.; Fisher, K.; Rogers, M.

    2013-12-01

    at these settlements. Having just completed this first phase of the project, we report on the results of large-scale geophysical survey, including the identification of at least two previously unknown building complexes (one at each site). Here we focus particularly on ground-penetrating radar (GPR) data and survey methodology, in an effort to critically examine the range of approaches applied throughout the project (e.g. various antennae frequencies, data-collection densities, soil moisture/seasonality of survey, and post-collection data processing [2]), and to identify the most effective parameters for archaeological geophysical survey in the region. This paper also advocates for the role of geophysical survey within a multi-component archaeological project, not simply as a prospection tool but as an archaeological data collection method in its own right. 1]Fisher, K. D., J. Leon, S. Manning, M. Rogers, and D. Sewell. In Press. 2011-2012. 'The Kalavasos and Maroni Built Environments Project: Introduction and preliminary report on the 2008 and 2010 seasons. Report of the Department of Antiquities, Cyprus. 2] e.g. Rogers, M., J. F. Leon, K. D. Fisher, S. W. Manning and D. Sewell. 2012. 'Comparing similar ground-penetrating radar surveys under different soil moisture conditions at Kalavasos-Ayios Dhimitrios, Cyprus.' Archaeological Prospection 19 (4): 297-305.

  3. COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar": first-year activities and results

    NASA Astrophysics Data System (ADS)

    Pajewski, Lara; Benedetto, Andrea; Loizos, Andreas; Slob, Evert; Tosti, Fabio

    2014-05-01

    This work aims at presenting the first-year activities and results of COST (European COoperation in Science and Technology) Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar". This Action was launched in April 2013 and will last four years. The principal aim of COST Action TU1208 is to exchange and increase scientific-technical knowledge and experience of GPR techniques in civil engineering, whilst simultaneously promoting throughout Europe the effective use of this safe and non-destructive technique in the monitoring of infrastructures and structures. Moreover, the Action is oriented to the following specific objectives and expected deliverables: (i) coordinating European scientists to highlight problems, merits and limits of current GPR systems; (ii) developing innovative protocols and guidelines, which will be published in a handbook and constitute a basis for European standards, for an effective GPR application in civil- engineering tasks; safety, economic and financial criteria will be integrated within the protocols; (iii) integrating competences for the improvement and merging of electromagnetic scattering techniques and of data- processing techniques; this will lead to a novel freeware tool for the localization of buried objects, shape-reconstruction and estimation of geophysical parameters useful for civil engineering needs; (iv) networking for the design, realization and optimization of innovative GPR equipment; (v) comparing GPR with different NDT techniques, such as ultrasonic, radiographic, liquid-penetrant, magnetic-particle, acoustic-emission and eddy-current testing; (vi) comparing GPR technology and methodology used in civil engineering with those used in other fields; (vii) promotion of a more widespread, advanced and efficient use of GPR in civil engineering; and (viii) organization of a high-level modular training program for GPR European users. Four Working Groups (WGs) carry out the research activities. The first WG

  4. COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar": ongoing research activities and third-year results

    NASA Astrophysics Data System (ADS)

    Pajewski, Lara; Benedetto, Andrea; Loizos, Andreas; Tosti, Fabio

    2016-04-01

    This work aims at disseminating the ongoing research activities and third-year results of the COST (European COoperation in Science and Technology) Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar." About 350 experts are participating to the Action, from 28 COST Countries (Austria, Belgium, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Malta, Macedonia, The Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey, United Kingdom), and from Albania, Armenia, Australia, Colombia, Egypt, Hong Kong, Jordan, Israel, Philippines, Russia, Rwanda, Ukraine, and United States of America. In September 2014, TU1208 has been recognised among the running Actions as "COST Success Story" ("The Cities of Tomorrow: The Challenges of Horizon 2020," September 17-19, 2014, Torino, IT - A COST strategic workshop on the development and needs of the European cities). The principal goal of the COST Action TU1208 is to exchange and increase scientific-technical knowledge and experience of GPR techniques in civil engineering, whilst simultaneously promoting throughout Europe the effective use of this safe and non-destructive technique in the monitoring of infrastructures and structures. Moreover, the Action is oriented to the following specific objectives and expected deliverables: (i) coordinating European scientists to highlight problems, merits and limits of current GPR systems; (ii) developing innovative protocols and guidelines, which will be published in a handbook and constitute a basis for European standards, for an effective GPR application in civil- engineering tasks; safety, economic and financial criteria will be integrated within the protocols; (iii) integrating competences for the improvement and merging of electromagnetic scattering techniques and of data- processing techniques; this will lead to a novel freeware tool for the localization of

  5. Recent Advancements in Quantitative Full-Wavefield Electromagnetic Induction and Ground Penetrating Radar Inversion for Shallow Subsurface Characterization

    NASA Astrophysics Data System (ADS)

    Van Der Kruk, J.; Yang, X.; Klotzsche, A.; von Hebel, C.; Busch, S.; Mester, A.; Huisman, J. A.; Vereecken, H.

    2014-12-01

    Ray-based or approximate forward modeling techniques have been often used to reduce the computational demands for inversion purposes. Due to increasing computational power and possible parallelization of inversion algorithms, accurate forward modeling can be included in advanced inversion approaches such that the full-wavefield content can be exploited. Here, recent developments of large-scale quantitative electromagnetic induction (EMI) inversion and full-waveform ground penetrating radar (GPR) inversions are discussed that yield higher resolution of quantitative medium properties compared to conventional approaches due to the use of accurate modeling tools that are based on Maxwell's equations. For a limited number of parameters, a combined global and local search using the simplex search algorithm or the shuffled complex evolution (SCE) can be used for inversion. Examples will be shown where calibrated large-scale multi-configuration EMI data measured with new generation multi-offset EMI systems are inverted for a layered electrical conductivity earth, and quantitative permittivity and conductivity values of a layered subsurface can be obtained using on-ground GPR full-waveform inversion that includes the estimation of the unknown source wavelet. For a large number of unknowns, gradient-based optimization methods are commonly used that need a good start model to prevent it from being trapped in a local minimum. Examples will be shown where the non-linearity invoked by the presence of high contrast media can be tamed by using a novel combined frequency-time-domain full-waveform inversion, and a low-velocity waveguide layer can be imaged by using crosshole GPR full-waveform inversion, after adapting the starting model using waveguide identification in the measured data. Synthetic data calculated using the inverted permittivity and conductivity models show similar amplitudes and phases as observed in the measured data, which indicates the reliability of the

  6. Investigating the Spatial and Temporal Variability of Water Saturation Within the Greenland Firn Aquifer Using Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Brautigam, N.

    2015-12-01

    Ground Penetrating Radar (GPR) is used to investigate the spatial and temporal saturation of the Greenland firn aquifer, using a method recently developed on a Svalbard icesheet (Christianson et. al., 2015). Currently, saturation of the firn is assumed to be 100% (Koenig et. al., 2014; Forster et. al., 2014), and using a firn density correction this saturation level drives the present liquid water volume estimate (140±20 Gt) of the Greenland firn aquifer (Koenig et. al., 2014). Based on earlier studies on mountain glacier firn aquifers, we suspect that saturation levels vary with depth, annual precipitation patterns, and local topography (Fountain, 1989; Christianson et. al., 2015). Refining the liquid water volume estimation is an important parameter as it allows for a better determination of the amount of water potentially available for release and consequent sea level rise, as well as to better model glacial processes such as englacial flow, crevasse fracture, and basal lubrication. GPR and GPS data collected along a 2.6 km transect in 2011, 2013, and 2014 in southeastern Greenland is used to measure the spatial and temporal variability of saturation levels within the aquifer. A bright reflector seen in the GPR at the water table depth responds to local topography. At surface lows, the reflector rises, intersecting annual density change layers visible in the GPR data. At these intersections, the annual layers deflect down beneath the water table before being lost due to signal attenuation. We assume that this deflection is due to a change in dielectric permittivity, and that by measuring the angle of deflection, and implementing a mixing model and density correction from nearby firn cores, we can determine the saturation level at each point along a deflection. This allows us to investigate the spatial and temporal variability of saturation within the firn aquifer.

  7. Spatial Variability in Biogenic Gas Dynamics in Relation to Vegetation Cover in a Northern Peatland from Ground Penetrating Radar (GPR)

    NASA Astrophysics Data System (ADS)

    Terry, N.; Slater, L. D.; Comas, X.; Mwakanyamale, K. E.; Wright, W. J.; Freeburg, Z.; Goldman, B.; Morocho, A.

    2015-12-01

    Ground penetrating radar (GPR) has been used for the last decade to investigate several aspects related to the distribution and release of biogenic gases (i.e. methane and carbon dioxide) in peat soils through well-established petrophysical relationships. We use this approach to investigate how differences in vegetation/land cover at three different field sites in Caribou Bog, Maine may alter such gas dynamics. The three study sites are characterized by: [1] a site amid standing pools of water with approximately 6 m of peat overlying an esker deposit, [2] a site dominated by low shrubs near the pools with peat down to 6.75 m, and [3] a site consisting of shrubs and trees with peat down to 6.4 m. A time-lapse series of GPR common offset (CO) and common midpoint (CMP) data were collected within hours of each other at all three sites using 100 MHz antennas during July 2013. In many cases, reciprocal data (transmitter and receiver positions switched) were also collected to gain insight on systematic errors. Water level variations and other environmental parameters were logged continuously at or near the sites, and limited gas sampling data were collected at sites [2] and [3]. Vertical 1D distributions of gas content with depth from each GPR dataset were estimated through CMP velocity analysis and application of a three component mixing model. These results were compared with CO data to observe changes in gas content along transects at each site. Preliminary results suggest site [1] (the pools site) has the highest overall gas content and exhibits the most variability in gas content through time. Despite several failed attempts to automate data acquisition in the field, manual acquisition still proves immensely valuable for quantitatively estimating spatiotemporal variability of gas content in a rapid and efficient manner in peatland ecosystems. In this case, the non-invasive monitoring of gas content variations demonstrates how free phase gas dynamics in peatlands

  8. Methane emission bursts from permafrost environments during autumn freeze-in: new insights from ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Pirk, Norbert; Santos, Telmo; Gustafson, Carl; Johansson, Anders J.; Tufvesson, Fredrik; Parmentier, Frans-Jan W.; Mastepanov, Mikhail; Christensen, Torben R.

    2016-04-01

    Large amounts of methane (CH4) are known to be emitted from permafrost environments during the autumn freeze-in, but the specific soil conditions leading up to these bursts are unclear. We therefore assessed the possibility to complement surface flux measurements with ground penetrating radar (GPR), which can estimate the amounts of ice, water and gas in the soil through their different dielectric properties. We developed an ultra-wide band (UWB) transmission GPR setup operating in the frequency range from 200 to 3200 MHz, which was tested in laboratory experiments on a soil sample during an induced freeze-thaw cycle, and applied in a field campaign in Northeast Greenland during autumn 2009. In the laboratory case, the GPR signals captured the same dynamics as the surface CH4 flux, featuring a series of large and sharp peaks during the thawing phase of the experiment. The CH4 emission peak during the freezing period, however, could not be reproduced in this laboratory experiment. The results of our field campaign suggest a compression of the gas reservoir during the freezing period in the autumn, which is accompanied by a peak in surface CH4 emissions. About one week thereafter, there seemed to be a decompression event, consistent with ground cracking which allows the gas reservoir to expand again. This coincided with the largest CH4 emission, exceeding the summer maximum by a factor of 4. We argue that subsurface GPR measurements open new possibilities to come to an understanding of tundra CH4 bursts connected to soil freezing.

  9. Integrating Ground Penetrating Radar, Electrical Resistivity, Seismic Refraction, and Borehole Data to Image an Alluvial Aquifer in Three Dimensions

    NASA Astrophysics Data System (ADS)

    Bailey, B. L.; Marshall, S. T.; Anderson, W. P.

    2010-12-01

    In this study we image the subsurface of a mountain stream floodplain in order to determine the three-dimensional aquifer geometry and degree of hydrologic connectivity. On site borehole data provides detailed information about the subsurface including direct measurements of depth to the water table; however, boreholes are not cost effective over a large area, the existing boreholes only have a penetration depth of ~3 meters, and subsurface stratigraphic features may only be locally present. We therefore combine borehole data with ground-penetrating radar (GPR), electrical resistivity, and seismic refraction data collected in linear transects perpendicular to the stream in order to effectively image a larger portion of the subsurface in three-dimensions. GPR data images several buried/abandoned channels, but no significant hydrologic barriers, such as clay lenses, have been found. Strong shallow reflectors in GPR data correlate to borehole measurements of water table depth and indicate a relatively flat water table surface. Furthermore, the GPR data show strong reflectors at the bedrock/sedimentary basin interface, which appears to dip towards the river mimicking the nearby surface topography. Resistivity transects also clearly delineate the water table and bedrock interface, reinforcing the GPR results. Seismic refraction data successfully resolves the dipping nature of the bedrock interface beyond the GPR penetration depth. Because bedrock was only encountered in one borehole, integrating the geophysical data provides constraints on overall aquifer volume. Future modeling studies of groundwater dynamics will better represent realistic aquifer properties by utilizing the data gathered here. Our continuing work will involve comparing the effectiveness of each geophysical technique for specific geologic targets, determining which techniques have the best resolution, and expanding the survey region.

  10. Investigation on Thawing and Freezing Processes Using High-frequency Ground Penetrating Radar in Amdo catchment, Central Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Ma, Yingzhao; Zubrzycki, Sebastian

    2014-05-01

    We have applied 250MHz ground penetrating radar (GPR) to investigate subsurface thawing and freezing processes in Amdo catchment, central Tibetan Plateau. Also, the topography and geography environments were surveyed to better understand the regional thaw/freeze cycles. Generally, the GPR images clearly illustrated the development of thawing and freezing events, which would be learned from the CMP soundings and reflection profiles. Our results showed that a strong lower EM velocity of upper layers was detected in the thawing conditions, while a rather higher velocity could be monitored in the frozen grounds, which was mainly based on the large contrast in dielectric permittivity between liquid water and ice. In addition, on the north-facing slopes, the EM velocity was smaller than that of sunny slopes in thawing and freezing periods on the whole, which illustrated that the average soil moisture in the upper subsurface was higher in north-facing slopes than the opposite side. Furthermore, during the thawing periods, both of the velocity and thawing depth decreased as the slope became deeper on the south-facing slope basically; on the shade side, the velocity increased slightly when the slope got sharper, but the thawed depth had no obvious trend. As for the freezing periods, both the velocity and frozen depth were not found clear tendency on both sides. Moreover, the subsurface thawing and freezing developments were significantly affected by local surface environments (e.g, stream, grassland or bare soil) though in similar topographic conditions. In all, the non-invasive GPR technique allowed the interpretation of spatial and temporal thaw/freeze processes, which played an important role on hydrothermal regimes in cold regions.

  11. Investigating Hydrogeologic Controls on Sandhill Wetlands in Covered Karst with 2D Resistivity and Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Downs, C. M.; Nowicki, R. S.; Rains, M. C.; Kruse, S.

    2015-12-01

    In west-central Florida, wetland and lake distribution is strongly controlled by karst landforms. Sandhill wetlands and lakes are sand-filled upland basins whose water levels are groundwater driven. Lake dimensions only reach wetland edges during extreme precipitation events. Current wetland classification schemes are inappropriate for identifying sandhill wetlands due to their unique hydrologic regime and ecologic expression. As a result, it is difficult to determine whether or not a wetland is impacted by groundwater pumping, development, and climate change. A better understanding of subsurface structures and how they control the hydrologic regime is necessary for development of an identification and monitoring protocol. Long-term studies record vegetation diversity and distribution, shallow ground water levels and surface water levels. The overall goals are to determine the hydrologic controls (groundwater, seepage, surface water inputs). Most recently a series of geophysical surveys was conducted at select sites in Hernando and Pasco County, Florida. Electrical resistivity and ground penetrating radar were employed to image sand-filled basins and the top of the limestone bedrock and stratigraphy of wetland slopes, respectively. The deepest extent of these sand-filled basins is generally reflected in topography as shallow depressions. Resistivity along inundated wetlands suggests the pools are surface expressions of the surficial aquifer. However, possible breaches in confining clay layers beneath topographic highs between depressions are seen in resistivity profiles as conductive anomalies and in GPR as interruptions in otherwise continuous horizons. These data occur at sites where unconfined and confined water levels are in agreement, suggesting communication between shallow and deep groundwater. Wetland plants are observed outside the historic wetland boundary at many sites, GPR profiles show near-surface layers dipping towards the wetlands at a shallower

  12. Long-term sequential monitoring of controlled graves representing common burial scenarios with ground penetrating radar: Years 2 and 3

    NASA Astrophysics Data System (ADS)

    Schultz, John J.; Walter, Brittany S.; Healy, Carrie

    2016-09-01

    Geophysical techniques such as ground-penetrating radar (GPR) have been successfully used for forensic searches to locate clandestine graves and physical evidence. However, additional controlled research is needed to fully understand the applicability of this technology when searching for clandestine graves in various environments, soil types, and for longer periods of time post-burial. The purpose of this study was to determine the applicability of GPR for detecting controlled graves in a Spodosol representing multiple burial scenarios for Years 2 and 3 of a three-year monitoring period. Objectives included determining how different burial scenarios are factors in producing a distinctive anomalous response; determining how different GPR imagery options (2D reflection profiles and horizontal time slices) can provide increased visibility of the burials; and comparing GPR imagery between 500 MHz and 250 MHz dominant frequency antennae. The research site contained a grid with eight graves representing common forensic burial scenarios in a Spodosol, a common soil type of Florida, with six graves containing a pig carcass (Sus scrofa). Burial scenarios with grave items (a deep grave with a layer of rocks over the carcass and a carcass wrapped in a tarpaulin) produced a more distinctive response with clearer target reflections over the duration of the monitoring period compared to naked carcasses. Months with increased precipitation were also found to produce clearer target reflections than drier months, particularly during Year 3 when many grave scenarios that were not previously visible became visible after increased seasonal rainfall. Overall, the 250 MHz dominant frequency antenna imagery was more favorable than the 500 MHz. While detection of a simulated grave may be difficult to detect over time, long term detection of a grave in a Spodosol may be possible if the disturbed spodic horizon is detected. Furthermore, while grave visibility increased with the 2D

  13. Ground Penetrating Radar and Magnetic Investigations of Phreatomagmatic Tephra Rings in the San Francisco Volcanic Field, Northern Arizona

    NASA Astrophysics Data System (ADS)

    Marshall, A. M.; Kruse, S.; Macorps, E.; Charbonnier, S. J.

    2015-12-01

    Ground Penetrating Radar (GPR) can be a valuable geophysical tool for studying near-surface volcanic stratigraphy in areas where outcrops do not exist. Likewise, high resolution ground-based magnetic surveys have the potential to reveal significant features not exposed at the surface, especially in the case of small-volume basaltic volcanoes. Here we present the results of geophysical studies to investigate the eruptive history of deposits surrounding phreatomagmatic eruption sites, and why some may become magnetized. Magnetic surveys undertaken at basaltic phreatomagmatic sites suggest that some tuff rings carry no discernable magnetic signature, while others reveal slight to significant magnetic anomalies. Material deposited in the tephra ring could become magnetized through Thermal Remanent Magnetization - emplacement of magnetically susceptible material above 560° C. In this case tephra layers would need to be deposited in sufficient thickness to retain high temperatures long enough for the magnetic material to orient itself to the magnetic field. To test this hypothesis we examine GPR data collected at Rattlesnake Maar in the San Francisco Volcanic Field, Arizona, and we will collect GPR data at two other tephra rings in the same volcanic field. The first site, Sugarloaf Mountain, is an active quarry with excellent exposures of tephra ring stratigraphy. Although this site is rhyolitic in composition and not suitable for magnetic study, it is an excellent site to determine how well GPR reflectors correlate with actual stratigraphy. The second site, an un-named phreatomagmatic ring nearby, will then be studied by GPR and walking magnetic survey. GPR reflectors will be compared to depositional patterns defined in previous studies and correlated with magnetic survey results to determine if a correlation can be made - little to no magnetization where only thin units are recorded by GPR, and positive magnetization where thick units are recorded.

  14. Imaging saline tracer infiltration into unsaturated sandy soil using full-waveform inversion of cross-borehole ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Looms, M. C.; Haarder, E. B.; Keskinen, J.; Nielsen, L.; Van Der Kruk, J.; Klotzsche, A.

    2015-12-01

    Cross-borehole ground penetrating radar (GPR) can provide high-resolution (tens of centimeter) information of the subsurface between boreholes located 5-10 m apart. The method is minimal invasive and therefore provides a unique opportunity to image subsurface variability not possible with standard point-scale equipment, such as TDR- and/or capacitance probes. Full-waveform inversion (FWI) of cross-borehole GPR uses the entire waveform of the transmitted electromagnetic signal. The recorded data contains information on the travel time of the pulse, as well as the attenuation, resulting in moisture content and electrical conductivity images of the subsurface using just one method. Few case studies of cross-borehole GPR FWI using real data have been published to date. The majority of these studies focus on estimating the variation in porosity in the saturated zone (e.g. in gravel aquifers, fractured metamorphic rock, and heterogeneous chalk sediments). In this study, we use cross-borehole GPR to monitor the infiltration of a saline tracer into an unsaturated sandy soil. In September 2011, saline water was added across a 142 m2 area at an agricultural field site in Denmark. A total of 3.3 mm saline water was applied mimicking a natural infiltration event. During the following year, the tracer infiltration into the subsurface was monitored using cross-borehole GPR at weekly to monthly intervals. Furthermore, five cores were extracted within the field site to obtain independent profiles of soil moisture and pore water conductivity for comparison. The cross-borehole GPR data were inverted using ray-based and FWI techniques. For the FWI an appropriate starting model and an effective wavelet must be estimated. Preliminary results indicate that the data modeled for the FWI results mimic better the measured data compared to the ray-based results. However, more research is needed to investigate the influence of the used starting model and the effective wavelet estimation.

  15. Geophysical conceptualization of a fractured sedimentary bedrock riverbed using ground-penetrating radar and induced electrical conductivity

    NASA Astrophysics Data System (ADS)

    Steelman, C. M.; Kennedy, C. S.; Parker, B. L.

    2015-02-01

    Bedrock rivers exhibit very different hydraulic and ecological regimes compared to alluvial rivers. Groundwater-surface water interaction in rivers that flow directly on sedimentary bedrock surfaces with exposed fracture and conduit networks is generally based on alluvial river conceptual models. However, the dual and triple porosity systems of sedimentary rock (e.g., matrix, fractures and vugs) leads to highly variable hydraulic pathways and groundwater velocities that, in turn, result in processes that are very different than those derived from alluvial concepts. Relative to alluvial rivers there has been very little direct examination of dynamic interactions, such as fluxes, groundwater velocities, and mechanisms affecting water quality across the channel interface; this is largely because bedrock rivers are difficult to instrument and monitor given their heterogeneous and anisotropic flow systems. In this study, we evaluate the capacity of non-invasive, low impact ground-penetrating radar and frequency-domain electromagnetic induction methods capable of detecting discrete fracture and conduit features, mapping complex distributions of lithostratigraphic interfaces, and providing information about formation properties along a partially exposed section of the Eramosa River located in Ontario, Canada. Geophysical data are supported by direct hydrogeologic and geologic information obtained from a nearby borehole piezometer cluster and a continuous 15 m rock core. Valuable insights were gained into the lateral extent and geometry of structurally-controlled whydrostratigraphic units (e.g., dissolution-enhanced fractures, epikarst and karst features), which are expected to strongly influence groundwater and surface water interaction along the channel. An integrated application of GPR and EMI methods was necessary to fully understand the complex geometry of geologic boundaries and karst features within the shallow bedrock aquifer. The identification of epikarst below

  16. Geophysical Field Work for Educators: Teachers Use Ground-Penetrating Radar to Study San Jacinto Battlefield Park

    NASA Astrophysics Data System (ADS)

    Henning, A. T.; Sawyer, D. S.; Milliken, K.

    2008-12-01

    In July 2008, a group of Houston area K-12 teachers investigated San Jacinto Battlefield Park in La Porte, Texas, utilizing ground-penetrating radar (GPR) to image the subsurface and global positioning system (GPS) units to map surface features. Participants were in-service K-12 teachers from urban Houston school districts where the majority of students are members of historically underrepresented minority groups. Over a period of two weeks, participants acquired and interpreted GPR profiles in the park, mapped surface features using hand-held GPS units, and analyzed the data using ArcGIS software. This summer experience was followed by a content-intensive academic year course in Earth Science. The Battle of San Jacinto took place on April 21, 1836, and was the decisive battle in the Texas Revolution. The site is thought to contain numerous in-situ artifacts dropped by the Texan and Mexican armies, as well as unmarked burials from the early 1800's. Two stratigraphic units were identified from the GPR profiles and matched to strata exposed through archaeological excavations. The stratigraphic units are interpreted as recent flood/storm deposits with soil formation on Pleistocene deltaic deposits of a previous sea-level highstand. In addition to the stratigraphy, a number of isolated subsurface anomalies (possibly artifacts) were identified. Participants also interpreted past shoreline positions using vintage aerial photographs and acquired several transects of GPS positions along the shoreline. Participants confirmed that the area is in fact subsiding, rather than being eroded. Participants not only experienced the scientific process but also utilized geophysics for community service (i.e. contributing educational material to the park). Through background research, they derived a rich historical context for their investigation and learned to appreciate the multi-disciplinary aspect of solving real- world scientific problems.

  17. An investigation of recent storm histories using Ground Penetrating Radar at Bay-Bay Spit, Bicol, Central Philippines

    NASA Astrophysics Data System (ADS)

    Switzer, Adam D.; Pile, Jeremy; Soria, Janneli Lea A.; Siringan, Fernando; Daag, Arturo; Brill, Dominik

    2016-04-01

    The Philippine archipelago lies in the path of seasonal tropical cyclones, and much of the coast is prone to periodic inundation and overwash during storm surges. On example is typhoon Durian a category 3 storm that made landfall on the 30th November 2006, in Bicol province, on the east central Philippine coast. Satellite imagery from May 2007 reveal that Durian breached a sandy spit that runs southeast from the mouth of the Quinale River at Bay-Bay village towards Tabaco City. The imagery also showed that, although the breach site showed signs of partial recovery, geomorphological evidence of the inundation event associated with typhoon Durian still remains. In 2012 we mapped the geomorphological features of Durian. In June 2013 we returned to conduct Ground Penetrating Radar (GPR) surveys on the Bay-Bay spit to investigate potential subsurface evidence of previous storm events. The GPR surveys comprised five, 1.5 km, longshore profiles and 12 cross-shore profiles, of 50 m - 200 m in length. The GPR system used for this study was a Sensors and Software Noggin with 100 Mhz antennas. Near surface velocities were determine using Hyperbolae matching in order to estimate depth. Topographic and positional data were collected using a dGPS system. After minimal processing depth of penetration during the survey varied from 2 - 8 m. The cross-shore GPR profiles reveal at least two erosional events prior to 2006 typhoon Durian, with approximately 10 m of recovery and progradation between each erosion surface. The GPR profiles that captured the erosional features were revisited in September 2013 for trial pitting, stratigraphic description, and sediment sampling. Sediment cores were taken horizontally from the trench walls and vertically from the trench bases to date sediments using Optically Stimulated Luminescence (OSL), which eventually could constrain the timing of the erosional surfaces.

  18. A ground penetrating radar investigation of a glacial-marine ice- contact delta, Pineo Ridge, eastern coastal Maine

    USGS Publications Warehouse

    Tary, A.K.; Duncan, M. FitzGerald; Weddle, T.K.

    2007-01-01

    In eastern coastal Maine, many flat-topped landforms, often identified as glacial-marine deltas, are cultivated for blueberry production. These agriculturally valuable features are not exploited for aggregate resources, severely limiting stratigraphic exposure. Coring is often forbidden; where permissible, coarse-grained surficial sediments make coring and sediment retrieval difficult. Ground penetrating radar (GPR) has become an invaluable tool in an ongoing study of the otherwise inaccessible subsurface morphology in this region and provides a means of detailing the large-scale sedimentary structures comprising these features. GPR studies allow us to reassess previous depositional interpretations and to develop alternative developmental models. The work presented here focuses on Pineo Ridge, a large, flat-topped ice-marginal glacial-marine delta complex with a strong linear trend and two distinct landform zones, informally termed East Pineo and West Pineo. Previous workers have described each zone separately due to local morphological variation. Our GPR work further substantiates this geomorphic differentiation. East Pineo developed as a series of deltaic lobes prograding southward from an ice-contact margin during the local marine highstand. GPR data do not suggest postdepositional modification by ice-margin re-advance. We suggest that West Pineo has a more complex, two-stage depositional history. The southern section of the feature consists of southward-prograding deltaic lobes deposited during retreat of the Laurentide ice margin, with later erosional modification during marine regression. The northern section of West Pineo formed as a series of northward-prograd- ing deltaic lobes as sediment-laden meltwater may have been diverted by the existing deposits of the southern section of West Pineo. ?? 2007 The Geological Society of America. All rights reserved.

  19. Distribution of ice- and soil wedges in Kapp Linné, Svalbard, mapped by two- and three-dimensional ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Watanabe, T.; Matsuoka, N.; Christiansen, H.

    2009-12-01

    Wedges along non-sorted polygons are consisting of ice or sediments. The wedge infill is often difficult to judge from the surface pattern, since the type of wedge filling depends on both climate and sediment characteristics. In fact, previous studies have reported that ice and active-layer soil wedges can coexist within a small area. We applied two- and three-dimensional ground-penetrating radar (2D and 3D GPR) for mapping subsurface ice and active-layer soil wedges in Kapp Linné, one of the warmest coastal areas in Svalbard. GPR surveys were conducted at six sites on beach ridges, which had emerged in different periods (11-5.5 ka BP). Shallow trenches and boreholes at four sites complemented the interpretation of the GPR results. On the 2D GPR profiles, most of the troughs delimiting the polygons are underlain by a single hyperbolic reflection spreading downward from the ground surface, which represents an active-layer soil wedge. Some troughs are underlain by double hyperbolic reflections extending downward from the ground surface and the frost table, which correspond to a soil wedge penetrating into the top permafrost and an underlying ice-wedge, respectively. However, radar interpretations are sometimes obscured by similar hyperbolic reflections from large stones and unclear reflections from small, narrow (< 50 cm) ice-wedges. The 3D GPR images delineate subsurface ice-wedges underlying the polygon troughs by radar amplitude anomalies more clearly than the 2D profiles. GPR results show that ice-wedges underlie primary polygon troughs and extraordinarily long and wide troughs on lower (younger) beach ridges. This suggests that ice-wedges have been active in the last 5,500 years since beach ridge formation ceased. In contrast, no ice-wedges were detected on higher (older) beach ridges even below the primary polygon troughs. This would be due to the low thermal coefficient of expansion of the material as the high lying snowfree blown ridges are lacking in

  20. Accuracy and precision of porosity estimates based on velocity inversion of surface ground-penetrating radar data: A controlled experiment at the Boise Hydrogeophysical Research Site

    NASA Astrophysics Data System (ADS)

    Bradford, J.; Clement, W.

    2006-12-01

    Although rarely acquired, ground penetrating radar (GPR) data acquired in continuous multi-offset geometries can substantially improve our understanding of the subsurface compared to conventional single offset surveys. This improvement arises because multi-offset data enable full use of the information that the GPR signal can carry. The added information allows us to maximize the material property information extracted from a GPR survey. Of the array of potential multi-offset GPR measurements, traveltime vs offset information enables laterally and vertically continuous electromagnetic (EM) velocity measurements. In turn, the EM velocities provide estimates of water content via petrophysical relationships such as the CRIM or Topp's equations. In fully saturated media the water content is a direct measure of bulk porosity. The Boise Hydrogeophysical Research Site (BHRS) is a experimental wellfield located in a shallow alluvial aquifer near Boise, Idaho. In July, 2006 we conducted a controlled 3D multi-offset GPR experiment at the BHRS designed to test the accuracy of state-of-the-art velocity analysis methodologies. We acquired continuous multi-offset GPR data over an approximately 20 x 30 m 3D area. The GPR system was a Sensors and Software pulseEkko Pro multichannel system with 100 MHz antennas and was configured with 4 receivers and a single transmitter. Data were acquired in off-end geometry for a total of 16 offsets with a 1 m offset interval and 1 m near offset. The data were acquired on a 1 m x 1m grid in four passes, each consisting of a 3 m range of equally spaced offsets. The survey encompassed 13 wells finished to the ~20 m depth of the unconfined aquifer. We established velocity control by acquiring vertical radar profiles (VRPs) in all 13 wells. Preliminary velocity measurements using an established method of reflection tomography were within about 1 percent of local 1D velocity distributions determined from the VRPs. Vertical velocity precision from the

  1. The usefulness of ground-penetrating radar images for the research of a large sand-bed braided river: case study from the Vistula River (central Poland)

    NASA Astrophysics Data System (ADS)

    Lejzerowicz, Anna; Kowalczyk, Sebastian; Wysocka, Anna

    2014-03-01

    Ground-penetrating radar (GPR) surveys and sedimentological outcrop analyses were combined in order to determine the reflection patterns and internal architecture of terrace deposits of the Vistula River at Kępa Zawadowska in the southern part of Warsaw (central Poland). The sedimentary analyses concerned the granulometric composition and lithofacies analysis. The 34 GPR profiles, which were obtained in two outcrops, using a Malå RAMAC/GPR system with 500-MHz and 250-MHz shielded antennas, were up to 100 m long. The most characteristic ground-penetrating radar profiles are presented; they show a high-resolution data set of radar facies. The GPR data suggest the presence of three geophysically different units, namely with high-angle inclined reflections (radar facies 1), with discontinuous undulating or trough-shaped reflections (radar facies 2), and with low-angle reflections (radar facies 3). The internal structure of the fluvial deposits was obtained by integration of the GPR and sedimentological data, which combination provides a more accurate visualisation of sedimentary units than do reconstructions that are based only on standard lithologic point data.

  2. Use of a ground-penetrating radar system to detect pre-and post-flood scour at selected bridge sites in New Hampshire, 1996-98

    USGS Publications Warehouse

    Olimpio, Joseph R.

    2000-01-01

    Ground-penetrating radar was used to measure the depth and extent of existing and infilled scour holes and previous scour surfaces at seven bridges in New Hampshire from April 1996 to November 1998. Ground-penetrating-radar survey techniques initially were used by the U.S. Geological Survey to study streambed scour at 30 bridges. Sixteen of the 30 bridges were re-surveyed where floods exceeded a 2-year recurrence interval. A 300-megahertz signal was used in the ground-penetrating radar system that penetrated through depths as great as 20 feet of water and as great as 32 feet of streambed materials. Existing scour-hole dimensions, infilled thickness, previous scour surfaces, and streambed materials were detected using ground-penetrating radar. Depths to riprap materials and pier footings were identified and verified with bridge plans. Post data-collection-processing techniques were applied to assist in the interpretation of the data, and the processed data were displayed and printed as line plots. Processing included distance normalization, migration, and filtering but processing was kept to a minimum and some interference from multiple reflections was left in the record. Of the 16 post-flood bridges, 22 ground-penetrating-radar cross sections at 7 bridges were compared and presented in this report. Existing scour holes were detected during 1996 (pre-flood) data collection in nine cross sections where scour depths ranged from 1 to 3 feet. New scour holes were detected during 1998 (post-flood) data collection in four cross sections where scour depths were as great as 4 feet deep. Infilled scour holes were detected in seven cross sections, where depths of infilling ranged from less than 1 to 4 feet. Depth of infilling by means of steel rod and hammer was difficult to verify in the field because of cobble and boulder streambeds or deep water. Previous scour surfaces in streambed materials were identified in 15 cross sections and the depths to these surfaces ranged from

  3. Ground Penetrating Radar and Microwave Tomography for high resolution post-earthquake damage assessment of a public building in L'Aquila City (Abruzzo Region, Italy)

    NASA Astrophysics Data System (ADS)

    Bavusi, M.; Loperte, A.; Lapenna, V.; Soldovieri, F.; Moroni, C.

    2009-12-01

    After the earthquake occurred in Abruzzo Region (Italy) on the 6th April 2009, non invasive diagnostics investigations of public infrastructures were performed with the aim of providing an early damage assessment. This work deals with the exploitation of the Ground Penetrating Radar (GPR) technique in order to get information about a reinforced concrete element of a public building in L'Aquila City. The structural element was a 400 x 30 cm x 100 cm cracked joist and the aim of the investigation was to gain information about the presence and location of the rebar layers and evaluate the result of injections of epoxy resin in the cracks. A GSSI SIR 3000 system with a 1500 MHz antenna was used to gain information about the corner formed by the joist and a pillar. Fifty profiles were acquired along orthogonal directions and making a measurement grid with 4 cm x 4 cm square cells. A 2D processing (trace removal, marker interpolation, zero time correction, hyperbolae velocity analysis , migration was) performed for each profile. Then, a 3D data representation for a volume 130 cm x 50 cm x 30 cm was built. Results show two layers of rebars: the first one located close to the investigation surface is made up by point reflectors well focused. A slice at the depth 8 cm allows to point out in a clear way the geometry of the upper layer of rebar. Differently, the deeper layer of rebar suffered focussing problems and no detailed information about the geometry of the layer was achieved. The possibility of overcome this drawback was offered by a novel data processing approach as the microwave-tomography (MT) technique. This technique faces an inverse scattering problem [1,2] and the adoption of the Born Approximation (BA) [2] makes it possible to tackle the realistic cases of large domains in a reasonable amount of time, as is usually for the civil engineering problems. The MT technique were first tested by processing one of the fifty collected profiles acquired on the joist and

  4. Monitoring near surface soil moisture profiles during evaporation using off-ground zero-offset ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Moghadas, D.; Jadoon, K. Z.; Lambot, S.; Vanderborght, J.; Vereecken, H.

    2012-04-01

    Soil evaporation is important as it controls many processes in the physics of land-surface, including the mass and energy flows between the ground and the atmosphere, and fundamental biological processes such as seed sprouting and plant growth. In order to associate soil surface states to subsurface states and properties, it is important to have a perception about the vertical profiles of subsurface soil water contents and temperatures. However, the derivation of these profiles from local scale measurements would demand interpolation and may overlook variations that are at a smaller scale than the distance between the local soil sensors. In particular, for the detection of non-uniform and unstable infiltration and drying, it is questionable whether the wetting and drying front instabilities can be obtained from local scale measurements. In this respect, resorting to the geophysical methods like ground-penetrating radar (GPR) is vital as a continuous image of the subsurface states can be obtained by applying these techniques. In this study, we investigated the potentiality of the off-ground GPR data to monitor drying front of soil evaporation at the lysimeter scale. We simulated evaporation of near surface soil layers by using a sand box filled with the very fine sand. The bottom of tank was covered by a planar copper sheet playing the role of complete reflector. The room temperature was kept constant and the surface of the sand was exposed to evaporation. The time-lapse GPR, temperature and weight of the setup was constantly measured for a period of thirty days to monitor the upward water flow. The effect of the evaporation can be visualized in the high frequencies of the GPR signal. The full-waveform GPR model was integrated with hydrological model to estimate the soil hydraulic properties. Since the GPR method is sensitive to the soil moisture profile close to the soil surface, interpretation of the measured GPR signals with a water flow model in the soil

  5. Void detection beneath reinforced concrete sections: The practical application of ground-penetrating radar and ultrasonic techniques

    NASA Astrophysics Data System (ADS)

    Cassidy, Nigel J.; Eddies, Rod; Dods, Sam

    2011-08-01

    Ground-penetrating radar (GPR) and ultrasonic 'pulse echo' techniques are well-established methods for the imaging, investigation and analysis of steel reinforced concrete structures and are important civil engineering survey tools. GPR is, arguably, the more widely-used technique as it is suitable for a greater range of problem scenarios (i.e., from rebar mapping to moisture content determination). Ultrasonic techniques are traditionally associated with the engineering-based, non-destructive testing of concrete structures and their integrity analyses (e.g., flaw detection, shear/longitudinal velocity determination, etc). However, when used in an appropriate manner, both techniques can be considered complementary and provide a unique way of imaging the sub-surface that is suited to a range of geotechnical problems. In this paper, we present a comparative study between mid-to-high frequency GPR (450 MHz and 900 MHz) and array-based, shear wave, pulse-echo ultrasonic surveys using proprietary instruments and conventional GPR data processing and visualisation techniques. Our focus is the practical detection of sub-metre scale voids located under steel reinforced concrete sections in realistic survey conditions (e.g., a capped, relict mine shaft or vent). Representative two-dimensional (2D) sections are presented for both methods illustrating the similarities/differences in signal response and the temporal-spatial target resolutions achieved with each technique. The use of three-dimensional data volumes and time slices (or 'C-scans') for advanced interpretation is also demonstrated, which although common in GPR applications is under-utilised as a technique in general ultrasonic surveys. The results show that ultrasonic methods can perform as well as GPR for this specific investigation scenario and that they have the potential of overcoming some of the inherent limitations of GPR investigations (i.e., the need for careful antenna frequency selection and survey design in

  6. Application of sub-image multiresolution analysis of Ground-penetrating radar data in a study of shallow structures

    NASA Astrophysics Data System (ADS)

    Jeng, Yih; Lin, Chun-Hung; Li, Yi-Wei; Chen, Chih-Sung; Yu, Hung-Ming

    2011-03-01

    Fourier-based algorithms originally developed for the processing of seismic data are applied routinely in the Ground-penetrating radar (GPR) data processing, but these conventional methods of data processing may result in an abundance of spurious harmonics without any geological meaning. We propose a new approach in this study based essentially on multiresolution wavelet analysis (MRA) for GPR noise suppression. The 2D GPR section is similar to an image in all aspects if we consider each data point of the GPR section to be an image pixel in general. This technique is an image analysis with sub-image decomposition. We start from the basic image decomposition procedure using conventional MRA approach and establish the filter bank accordingly. With reasonable knowledge of data and noise and the basic assumption of the target, it is possible to determine the components with high S/N ratio and eliminate noisy components. The MRA procedure is performed further for the components containing both signal and noise. We treated the selected component as an original image and applied the MRA procedure again to that single component with a mother wavelet of higher resolution. This recursive procedure with finer input allows us to extract features or noise events from GPR data more effectively than conventional process. To assess the performance of the MRA filtering method, we first test this method on a simple synthetic model and then on experimental data acquired from a control site using 400 MHz GPR system. A comparison of results from our method and from conventional filtering techniques demonstrates the effectiveness of the sub-image MRA method, particularly in removing ringing noise and scattering events. Field study was carried out in a trenched fault zone where a faulting structure was present at shallow depths ready for understanding the feasibility of improving the data S/N ratio by applying the sub-image multiresolution analysis. In contrast to the conventional

  7. Using Ground Penetration Radar for Imaging and Mapping of Thin, Shallow Tsunami Deposits in Washington, Pacific Northwest United States

    NASA Astrophysics Data System (ADS)

    Cakir, R.; Garrison-Laney, C.; Meng, X.; Butler, Q.; Walsh, T. J.

    2015-12-01

    A tidal marsh at Discovery Bay, on the Strait of Juan de Fuca, has the longest record of tsunami deposition in Washington, with nine described tsunami deposits. One of the youngest continuous deposits Bed 1is likely from the 1700 A.D. M9+ Cascadia Earthquake, based on its stratigraphic position and radiocarbon age. Bed 1 is typically found at a depth of ~ 0.45 m, has a maximum thickness of 8 cm, and is composed grains of silt to fine sand. Ground Penetration Radar (GPR) is useful to study such tsunami deposits, because it can "see" characteristics of the deposits that could be missed in cores or outcrops. Tsunami deposits typically extend over wide areas. GPR imaging can trace a layer over a wide area in the subsurface of a tidal marsh. Correlation of layers between coring or outcrops is often difficult across distances in a marsh. GPR technology allows in situ correlation of potential tsunami deposits in the subsurface. We used GPR to map subsurface images of previously described tsunami deposits in the top 2 m at Discovery Bay. We used MALA 450 MHz antenna and recording unit, and ran the survey during the low tide time range (3-4 hours). After adjusting the soil velocity (dielectric constants) and scan parameters we ran various transects correlated the shallow soil cores in 0-1.5m of the soil column. Tsunami sand layer is relatively distinct among other layers on radargrams. Maximum penetration depth reached was about 2 meters and saltwater effect is dominant at 2 meters and greater depths. In addition to this success, there is also the potential to use GPR to"see" characteristic tsunami deposit features such as draping and infilling of low spots. This imaging could help guide locations to sample with strategic cores or pits. We think that our preliminary results are promising,and plan to use the GPR technology to investigate potential tsunami deposits inPuget Sound and other coastal areas of Washington.

  8. Mapping of soil moisture at the field scale using full-waveform inversion of proximal ground penetrating radar data

    NASA Astrophysics Data System (ADS)

    Minet, Julien; Lambot, Sébastien; Vanclooster, Marnik

    2010-05-01

    Characterizing the spatial and temporal variability of soil moisture using geophysical methods is an important issue in many hydrological researches and applications. In order to bridge the scale gap between large-scale remote sensing of soil moisture and small-scale invasive methods, we developed a proximal ground penetrating radar (GPR) technique based on vector network analyzer technology and an off-ground antenna. Soil dielectrical properties are retrieved by resorting to full-waveform inversion of the GPR signal and soil moisture is derived from the dielectric permittivity using petrophysical relationships. The method is particularly suited for high-resolution mapping of soil moisture at the field scale and was widely applied for that purpose. In addition, the full-waveform inversion of the GPR signal on a large frequency bandwidth allows for the characterization of soil moisture at different depths, as it inherently maximizes the extraction of information. Hence, inversions of GPR data from field acquisition with different soil models permit to reconstruct two-layered or continuously-variable profiles, at locations where soil moisture profiles conditions are encountered. We conducted field campaigns in agricultural fields in the loess belt area in Belgium using the GPR system mounted on a 4-wheel motorcycle, allowing for real-time acquisition of the GPR signals. Inversions of the GPR signals for the retrieval of surface, two-layered and continuous profiles of soil moisture were subsequently performed. Surface soil moisture maps were in good agreement with field observations and surface volumetric sampling measurements. At the field scale, patterns were mainly explained by the topography, i.e., soil moisture values were positively correlated with the topographic wetness index. Furthermore, the total variance of soil moisture within the fields appeared to be related to the mean soil moisture itself. Finally, two-layered and continuous profile inversions showed

  9. Ground-penetrating radar (GPR) stratigraphy of late-Pleistocene relict foredunes on a coastal barrier: Matakana Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Brook, M.; Shepherd, M.; Tinkler, R.; Williams, J.

    2012-04-01

    Matakana Island, North Island, New Zealand, forms a c. 24 km long barrier island between the Bay of Plenty and Tauranga Harbour, which it encloses. The island is of two distinct parts, with the larger seaward part comprising a Holocene sand barrier, extending parallel to the shoreline, and a harbourward (Pleistocene) part, adjoining the centre of the Holocene barrier. The Pleistocene section of the barrier consists of three terraces at 10, 40 and 70 m above sea level, although the precise process-origin and significance of the features are unknown. We focus on the relatively flat lowest (1.0-1.5 km wide) terrace, as oblique aerial photography indicates the presence of subdued ridges (amplitude 1 m) trending NW-SE, parallel to the current coastline. An investigation of this lower terrace using a 100 MHz pulseEKKO ground penetrating radar (GPR) along a 1 km SW-NE profile normal to the axis of the subdued ridges was undertaken. Following topographic correction, the profile revealed a continuous undulating reflector at 8-12 m depth, which corresponds with the low ridges visible on the surface. The ridge-and-swale nature of the reflector, coupled with the surface topography indicates it represents a relict foredune plain, mainly below present-day sea level. The age of the relict foredune plain is intriguing, with a maximum age of 780,000 due to the absence of Te Puna Ignimbrite, which is present on the higher terraces. Published maps indicate the lowest terrace is covered by lacustrine beds of the Matua Subgroup (minimum age c. 220,000 yr), yet it is difficult to reconcile the survival of ridge-and-swale foredune morphology under several metres of lacustrine deposits, suggesting that a tephra origin for the coverbeds is more likely. Nevertheless, the presence of a Pleistocene foredune plain slightly below present-day sea level indicates no significant long-term uplift, and possibly minor subsidence in this sector of the North Island.

  10. Evaluating local-scale anisotropy and heterogeneity along a fractured sedimentary bedrock river using EM azimuthal resistivity and ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Steelman, C. M.; Parker, B. L.; Kennedy, C. S.

    2015-05-01

    Fractured sedimentary bedrock rivers exhibit complicated flow patterns controlled by the geometry, extent and connectivity of fractures and dissolution-enhanced conduits. In a bedrock river environment these features variably connect surface water to groundwater. Given the nature of discrete fracture and conduit networks, these flow systems can be anisotropic and heterogeneous over a wide range of scales. Portable and non-invasive geophysical methods are ideal for the initial characterization of shallow hydrogeologic systems in ecologically sensitive environments. Here, we evaluate the utility of the electromagnetic (EM) azimuthal resistivity method for characterizing shallow vertical and subvertical fracture set orientations in the presence of localized dissolution-enhanced features near a sedimentary bedrock river located in Southern Ontario, Canada. Multiple EM coil spacings ranging from 1 to 10 m in vertical and horizontal dipole modes were applied at two locations within a 10 × 25 m study plot; azimuthal rotations were conducted using symmetric and asymmetric geometries. The observed anisotropic response was evaluated using 100 MHz ground-penetrating radar (GPR) measurements collected across the study plot area. A joint analysis of EM and GPR data revealed that fracture-based anisotropy can be identified in the presence of local heterogeneities (i.e., dissolution-enhanced features) at scales considerably smaller than those of previous studies. These non-invasive geophysical data sets can be used to optimize the design of multi-borehole groundwater monitoring stations along bedrock river channels, such that angled boreholes could be emplaced and orientated to intercept major fracture networks and local dissolution features. These data could also improve 3-D fracture network conceptualizations utilizing discrete information from angled and vertical boreholes.

  11. The Triglav Glacier (South-Eastern Alps, Slovenia): Volume Estimation, Internal Characterization and 2000-2013 Temporal Evolution by Means of Ground Penetrating Radar Measurements

    NASA Astrophysics Data System (ADS)

    Del Gobbo, Costanza; Colucci, Renato R.; Forte, Emanuele; Triglav Čekada, Michaela; Zorn, Matija

    2016-08-01

    It is well known that small glaciers of mid latitudes and especially those located at low altitude respond suddenly to climate changes both on local and global scale. For this reason their monitoring as well as evaluation of their extension and volume is essential. We present a ground penetrating radar (GPR) dataset acquired on September 23 and 24, 2013 on the Triglav glacier to identify layers with different characteristics (snow, firn, ice, debris) within the glacier and to define the extension and volume of the actual ice. Computing integrated and interpolated 3D using the whole GPR dataset, we estimate that at the moment of data acquisition the ice area was 3800 m2 and the ice volume 7400 m3. Its average thickness was 1.95 m while its maximum thickness was slightly more than 5 m. Here we compare the results with a previous GPR survey acquired in 2000. A critical review of the historical data to find the general trend and to forecast a possible evolution is also presented. Between 2000 and 2013, we observed relevant changes in the internal distribution of the different units (snow, firn, ice) and the ice volume reduced from about 35,000 m3 to about 7400 m3. Such result can be achieved only using multiple GPR surveys, which allow not only to assess the volume occupied by a glacial body, but also to image its internal structure and the actual ice volume. In fact, by applying one of the widely used empirical volume-area relations to infer the geometrical parameters of the glacier, a relevant underestimation of ice-loss would be achieved.

  12. The Triglav Glacier (South-Eastern Alps, Slovenia): Volume Estimation, Internal Characterization and 2000-2013 Temporal Evolution by Means of Ground Penetrating Radar Measurements

    NASA Astrophysics Data System (ADS)

    Del Gobbo, Costanza; Colucci, Renato R.; Forte, Emanuele; Triglav Čekada, Michaela; Zorn, Matija

    2016-07-01

    It is well known that small glaciers of mid latitudes and especially those located at low altitude respond suddenly to climate changes both on local and global scale. For this reason their monitoring as well as evaluation of their extension and volume is essential. We present a ground penetrating radar (GPR) dataset acquired on September 23 and 24, 2013 on the Triglav glacier to identify layers with different characteristics (snow, firn, ice, debris) within the glacier and to define the extension and volume of the actual ice. Computing integrated and interpolated 3D using the whole GPR dataset, we estimate that at the moment of data acquisition the ice area was 3800 m2 and the ice volume 7400 m3. Its average thickness was 1.95 m while its maximum thickness was slightly more than 5 m. Here we compare the results with a previous GPR survey acquired in 2000. A critical review of the historical data to find the general trend and to forecast a possible evolution is also presented. Between 2000 and 2013, we observed relevant changes in the internal distribution of the different units (snow, firn, ice) and the ice volume reduced from about 35,000 m3 to about 7400 m3. Such result can be achieved only using multiple GPR surveys, which allow not only to assess the volume occupied by a glacial body, but also to image its internal structure and the actual ice volume. In fact, by applying one of the widely used empirical volume-area relations to infer the geometrical parameters of the glacier, a relevant underestimation of ice-loss would be achieved.

  13. Wire-grid electromagnetic modelling of metallic cylindrical objects with arbitrary section, for Ground Penetrating Radar applications

    NASA Astrophysics Data System (ADS)

    Adabi, Saba; Pajewski, Lara

    2014-05-01

    Authors demonstrated that the well-known same-area criterion yields affordable results but is quite far from being the optimum: better results can be obtained with a wire radius shorter than what is suggested by the rule. In utility detection, quality controls of reinforced concrete, and other civil-engineering applications, many sought targets are long and thin: in these cases, two-dimensional scattering methods can be employed for the electromagnetic modelling of scenarios. In the present work, the freeware tool GPRMAX2D [6], implementing the Finite-Difference Time-Domain method, is used to implement the wire-grid modelling of buried two-dimensional objects. The source is a line of current, with Ricker waveform. Results obtained in [5] are confirmed in the time domain and for different geometries. The highest accuracy is obtained by shortening the radius of about 10%. It seems that fewer (and larger) wires need minor shortening; however, more detailed investigations are required. We suggest to use at least 8 - 10 wires per wavelength if the field scattered by the structure has to be evaluated. The internal field is much more sensitive to the modelling configuration than the external one, and more wires should be employed when shielding effects are concerned. We plan to conduct a more comprehensive analysis, in order to extract guidelines for wire sizing, to be validated on different shapes. We also look forward to verifying the possibility of using the wire-grid modelling method for the simulation of slotted objects. This work is a contribution to COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar". The Authors thanks COST for funding COST Action TU1208. References [1] J.H. Richmond, A wire grid model for scattering by conducting bodies, IEEE Trans. Antennas Propagation AP-14 (1966), pp. 782-786. [2] S.M. Rao, D.R. Wilton, A.W. Glisson, Electromagnetic scattering by surfaces of arbitrary shape, IEEE Trans. Antennas Propagation AP-30 (1982

  14. Ground Penetrating Radar Profiles of Breached Anticlinal Ridges in the Northern Piedmont of the San Bernardino Mountains in Southern California

    NASA Astrophysics Data System (ADS)

    Bobyarchick, A. R.; Eppes, M. C.; Diemer, J. A.; Cathey, R. B.; Cottingham, M. A.; Eckardt, I. J.; Shiflet, J. E.; Waldron, A. J.

    2006-12-01

    The northern piedmont of the San Bernardino Mountains contains kinematic elements characteristic of the Mojave block dextral plate boundary zone between the North American and Pacific plates and the complex convergent Transverse Ranges partition of that motion here represented by the North Frontal thrust system. Predominantly lateral slip in the central Mojave block is carried by the Helendale fault through Lucerne Valley and southward to intersect the North Frontal thrust system in the San Bernardino Mountains. Active anticlinal flexures and partially emergent north-verging thrust faults have deformed Pleistocene alluvial fans and older rocks into east-trending ridges in the piedmont on both sides of the Helendale fault. The Cougar Buttes anticline underlies such a ridge east of the fault and is breached by contemporaneous orthogonal washes in several places along strike of the anticline. Greater relief occurs where the alluvial fans comprise carbonate- cemented soils and particularly resistant, prominent petrocalcic horizons. It is within these incised valleys that the sequence of Tertiary through Pleistocene deposits show that the asymmetric anticline is cored by a thrust fault. In order to examine more closely the fold-fault association in the Cougar Buttes anticline and suggest possible kinematic models, we conducted several ground penetrating radar (GPR) profiles at different levels across the ridge. Relatively superior relief in some washes allowed us to conduct profiles along the present topographic ridge crests (and thus along the crestal zone of the fold) and also along wash bottoms to provide profiles at the level of the fold's core. We used a GSSI SIR-3000 GPR system equipped with a monostatic 100 MHz antennae set to continuous recording mode; traverses over very irregular ground were done in point data mode. The system was set up with nominal high and low cutoff filters and automatic gain control, but we found that AGC overly amplified multiples or

  15. Targeted full-waveform inversion for ultra-thin layer properties using ground-penetrating radar data

    NASA Astrophysics Data System (ADS)

    Babcock, E.; Bradford, J. H.

    2013-12-01

    Detection and characterization of thin-layers is a ubiquitous problem in near-surface investigations using ground-penetrating radar (GPR). The ability to estimate thin-layer parameters from GPR data is crucial for quantification and location of subsurface contaminants such as non-aqueous phase liquids (NAPLs). As NAPLS migrate in the subsurface in response to density and hydraulic gradients, they often become trapped in thin layers at permeability barriers or smeared at the vadose-saturated zone interface. Another similar example is an oil layer trapped under snow or floating on water. In such cases, layer thickness are often much less than 1/2λ, and accurate characterization of these thin NAPL layers is difficult or impossible with conventional data analysis. Here, we implement a full-waveform inversion to quantify thin layer permittivity, conductivity, thickness, and depth for ultra-thin layers on model and real GPR data. The inversion uses a non-linear grid search with a Monte-Carlo scheme to initialize starting values to find the global minimum. Using synthetic radar data and layer thicknesses less than 0.1λ, we tested the inversion for three thin-layer models with 20% added Gaussian noise: air-oil-seawater, dry sand-saturated sand-granite, and saturated sand-DNAPL saturated sand-clay. The inversion retrieved thin-layer permittivity, thickness, and depth within 10% of the true solution for the first two models and within 15% for the third model even when input background parameters deviated up to 20% from the true parameters. Inverted thin-layer conductivity was within 22% of the true value when conductivity was above 0.001 S/m. However, the solution for thin-layer conductivity diverged significantly when modeled thin-layer conductivity was less than 0.001 S/m, indicating a low sensitivity to low conductivity. Subsequently, we tested the inversion on two 1 GHz GPR data sets collected with antennas suspended in air: 1) an ultrathin-layer of oil (2.5 cm) on

  16. Ground-penetrating rada

    NASA Astrophysics Data System (ADS)

    Thuma, W. R.

    The theory and applications of digital Ground-Penetrating Radar were discussed at a 5-day seminar held at the China University of Geosciences in Wuhan, People's Republic of China, in April. Cohosted by the Department of Applied Geophysics and Canada-China Geoscience, more than 60 senior geophysicists, engineers, technical specialists, university professors and researchers attended.Focus of the meeting was the expanded uses of the new deep-penetrating fully digital PulseEKKO, which is gaining wide acceptance around the world. Attendees showed intense interest in this new and unique technology. Applications covered were groundwater and mineral exploration; engineering, construction and toxic waste site surveying; tunnel and underground mine probing for potential geological hazards, blind ore zones, karst cavities and solution pathways; and locating buried objects such as petroleum storage tanks, unexploded bombs and archeological remains.

  17. Research of Stability Problems on Ankara-Konya High Speed Railway Line (Turkey) using Ground Penetrating Radar and Petrographical Methods

    NASA Astrophysics Data System (ADS)

    Kadioglu, S.; Kadioglu, Y. K.

    2012-04-01

    The aim of the study is to research the stability problems according to rock properties and their discontinuities such as fractures, faults and karstic cavities on the new high-speed railway line between the capital city Ankara and the largest city Konya in Turkey. The Ankara-Konya high speed railway including a tunnel managed from The Turkish State Railways (TCDD). Geological surveys, polarizing microscope and confocal Raman spectrometry studies were used to determine rock properties. Ground penetrating radar (GPR) method was used to determine faults, fractures and karstic cavities. The railway line has been mainly constructed on inner Tauride Ocean suture of the Central Anatolia. The basement unit of the railway line mainly has been composed of ophiolitic complex of the inner Tauride Ocean. The main lithology of this ophiolitic complex has been formed by radiolarite, pelagic sediments, dolarite, gabbro, serpentinized peridotite and limestone blocks. The Jurassic alloctonous limestone which has been thrust on the ophiolitic complex. Neogene cover young units with minor amount of Alluvium deposits have been formed by the upper litholgy in the region. The serpentinite and altered radiolarite formation are formed by lubricous ground for the railway line in the region. A RAMAC CUII GPR system was used with a bi-static 100 MHz center band shielded antenna to acquire profile data. Totaly 35 km was surveyed on different parts of the railway line by considering the results of the geologic research and petrograpical studies. When we started to study, rail construction of some parts of the line had already been completed. Therefore, during studies, we gathered the data on the backfilled way on the three parallel profiles spaced 1m apart or on the service way next to the railway line. There was a tunnel on the line. We also gathered two parallel profiles data on the tunnel and four profiles data next to the tunnel to evaluate the stability according to the discontinuities

  18. COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar:" ongoing research activities and mid-term results

    NASA Astrophysics Data System (ADS)

    Pajewski, Lara; Benedetto, Andrea; Loizos, Andreas; Slob, Evert; Tosti, Fabio

    2015-04-01

    This work aims at presenting the ongoing activities and mid-term results of the COST (European COoperation in Science and Technology) Action TU1208 'Civil Engineering Applications of Ground Penetrating Radar.' Almost three hundreds experts are participating to the Action, from 28 COST Countries (Austria, Belgium, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Malta, Macedonia, The Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey, United Kingdom), and from Albania, Armenia, Australia, Egypt, Hong Kong, Jordan, Israel, Philippines, Russia, Rwanda, Ukraine, and United States of America. In September 2014, TU1208 has been praised among the running Actions as 'COST Success Story' ('The Cities of Tomorrow: The Challenges of Horizon 2020,' September 17-19, 2014, Torino, IT - A COST strategic workshop on the development and needs of the European cities). The principal goal of the COST Action TU1208 is to exchange and increase scientific-technical knowledge and experience of GPR techniques in civil engineering, whilst simultaneously promoting throughout Europe the effective use of this safe and non-destructive technique in the monitoring of infrastructures and structures. Moreover, the Action is oriented to the following specific objectives and expected deliverables: (i) coordinating European scientists to highlight problems, merits and limits of current GPR systems; (ii) developing innovative protocols and guidelines, which will be published in a handbook and constitute a basis for European standards, for an effective GPR application in civil- engineering tasks; safety, economic and financial criteria will be integrated within the protocols; (iii) integrating competences for the improvement and merging of electromagnetic scattering techniques and of data- processing techniques; this will lead to a novel freeware tool for the localization of buried objects

  19. Geophysical Investigation of Subsurface Characteristics of Icy Debris Fans with Ground Penetrating Radar in the Wrangell Mountains, Alaska

    NASA Astrophysics Data System (ADS)

    Sun, L. F.; Pun, W.; Milkereit, B.

    2011-12-01

    Authors Tracey Smith^1, Rob Jacob^1, Jeffrey Trop^1, Keith Williams^2 and Craig Kochel^1 Bucknell University, Geology and Environmental Geoscience Department, Lewisburg, PA UNAVCO, 6350 Nautilus Dr., Boulder, CO 80301 Icy debris fans have recently been described as deglaciation features on Earth and similar features have been observed on Mars, however, the subsurface characteristics remain unknown. We used ground penetrating radar (GPR) to non-invasively investigate the subsurface characteristics of icy debris fans near McCarthy, Alaska, USA. The three fans investigated in Alaska are the East, West, and Middle fans which are between the Nabesna ice cap and the McCarthy Glacier. Icy debris fans in general are a largely unexplored suite of paraglacial landforms and processes in alpine regions. Recent field studies focused on direct observations and depositional processes. The results showed that each fan's composition is primarily influenced by the type and frequency of mass wasting processes that supply the fan. Photographic studies show that the East fan receives far more ice and snow avalanches whereas the Middle and West fan receive fewer mass wasting events but more clastic debris is deposited on the Middle and West fan from rock falls and icy debris flows. GPR profiles and WARR surveys consisting of both, common mid-point (CMP), and common shot-point (CSP) surveys investigated the subsurface geometry of the fans and the McCarthy Glacier.All GPR surveys were collected in 2013 with 100MHz bi-static antennas. Four axial profiles and three cross-fan profiles were done on the West and Middle fans as well as the McCarthy Glacier in order to investigate the relationship between the three features. Terrestrial laser surveying of the surface and real-time kinematic GPS provided the surface elevation used to correct the GPR data for topographic changes. GPR profiles yielded reflectors that were continuous for 10+ m and hyperbolic reflections in the subsurface. The WARR

  20. Geophysical Investigation of Subsurface Characteristics of Icy Debris Fans with Ground Penetrating Radar in the Wrangell Mountains, Alaska

    NASA Astrophysics Data System (ADS)

    Smith, T. D.; Jacob, R. W.

    2013-12-01

    Authors Tracey Smith^1, Rob Jacob^1, Jeffrey Trop^1, Keith Williams^2 and Craig Kochel^1 Bucknell University, Geology and Environmental Geoscience Department, Lewisburg, PA UNAVCO, 6350 Nautilus Dr., Boulder, CO 80301 Icy debris fans have recently been described as deglaciation features on Earth and similar features have been observed on Mars, however, the subsurface characteristics remain unknown. We used ground penetrating radar (GPR) to non-invasively investigate the subsurface characteristics of icy debris fans near McCarthy, Alaska, USA. The three fans investigated in Alaska are the East, West, and Middle fans which are between the Nabesna ice cap and the McCarthy Glacier. Icy debris fans in general are a largely unexplored suite of paraglacial landforms and processes in alpine regions. Recent field studies focused on direct observations and depositional processes. The results showed that each fan's composition is primarily influenced by the type and frequency of mass wasting processes that supply the fan. Photographic studies show that the East fan receives far more ice and snow avalanches whereas the Middle and West fan receive fewer mass wasting events but more clastic debris is deposited on the Middle and West fan from rock falls and icy debris flows. GPR profiles and WARR surveys consisting of both, common mid-point (CMP), and common shot-point (CSP) surveys investigated the subsurface geometry of the fans and the McCarthy Glacier.All GPR surveys were collected in 2013 with 100MHz bi-static antennas. Four axial profiles and three cross-fan profiles were done on the West and Middle fans as well as the McCarthy Glacier in order to investigate the relationship between the three features. Terrestrial laser surveying of the surface and real-time kinematic GPS provided the surface elevation used to correct the GPR data for topographic changes. GPR profiles yielded reflectors that were continuous for 10+ m and hyperbolic reflections in the subsurface. The WARR

  1. Ground Penetrating Radar Field Studies of Lunar-Analog Geologic Settings and Processes: Barringer Meteor Crater and Northern Arizona Volcanics

    NASA Astrophysics Data System (ADS)

    Russell, P. S.; Grant, J. A.; Williams, K. K.; Bussey, B.

    2010-12-01

    Ground-Penetrating Radar (GPR) data from terrestrial analog environments can help constrain models for evolution of the lunar surface, aid in interpretation of orbital SAR data, and help predict what might be encountered in the subsurface during future, landed, scientific or engineering operations on the Moon. GPR can yield insight into the physical properties, clast-size distribution, and layering of the subsurface, granting a unique view of the processes affecting an area over geologic time. The purpose of our work is to demonstrate these capabilities at sites at which geologic processes, settings, and/or materials are similar to those that may be encountered on the moon, especially lava flows, impact-crater ejecta, and layered materials with varying properties. We present results from transects obtained at Barringer Meteor Crater, SP Volcano cinder cone, and Sunset Crater Volcano National Monument, all in northern Arizona. Transects were taken at several sites on the ejecta of Meteor Crater, all within a crater radius (~400 m) of the crater rim. Those taken across ejecta lobes or mounds reveal the subsurface contact of the ejecta upper surface and overlying, embaying sediments deposited by later alluvial, colluvial, and/or aeolian processes. Existing mine shafts and pits on the south side of the crater provide cross sections of the subsurface against which we compare adjacent GPR transects. The ‘actual’ number, size, and depth of clasts in the top 1-2 m of the subsurface are estimated from photos of the exposed cross sections. In GPR radargrams, reflections attributed to blocks in the top 2-5 m of the subsurface are counted, and their depth distribution noted. Taking GPR measurements along a transect at two frequencies (200 and 400 MHz) and to various depths, we obtain the ratio of the actual number of blocks in the subsurface to the number detectable with GPR, as well as an assessment of how GPR detections in ejecta decline with depth and depend on antenna

  2. Detection and discrimination of landmines in ground-penetrating radar using an EigenMine and fuzzy-membership-function approach

    NASA Astrophysics Data System (ADS)

    Frigui, Hichem; Gader, Paul D.; Satyanarayana, Kotturu

    2004-09-01

    This paper introduces a system for landmine detection using sensor data generated by a Ground Penetrating Radar (GPR). The GPR produces a three-dimensional array of intensity values, representing a volume below the surface of the ground. First, a constant false alarm rate (CFAR) detector is used to focus attention and identify candidates that resemble mines. Next, translation invariant features are extracted by projecting the magnitude of the Fourier transformation onto the dominant eigenvectors in the training data. The training signatures are then clustered to identify prototypes. Crisp and fuzzy k-nearest neighbor rules are used to distinguish true detections from false alarms.

  3. Ground penetrating radar data used in discovery of the early Christian church of Notre Dame de Baudes near Labastide-du-Temple, France

    PubMed Central

    Gragson, Ted L; Thompson, Victor D.; Leigh, David S.; Hautefeuille, Florent

    2016-01-01

    Data on ground-penetrating radar transect files are provided that support the research presented in "Discovery and Appraisal of the Early Christian Church of Notre Dame de Baudes near Labastide-du-Temple, France" [1]. Data consist of 102 transect files obtained with a GSSI SIR-3000 controller and a 400 MHz center frequency antenna in two grid blocks covering ca. 2700 m2. The data are distributed raw without post-processing in SEG-Y rev. 1 format (little endian). PMID:27222858

  4. Ground penetrating radar data used in discovery of the early Christian church of Notre Dame de Baudes near Labastide-du-Temple, France.

    PubMed

    Gragson, Ted L; Thompson, Victor D; Leigh, David S; Hautefeuille, Florent

    2016-06-01

    Data on ground-penetrating radar transect files are provided that support the research presented in "Discovery and Appraisal of the Early Christian Church of Notre Dame de Baudes near Labastide-du-Temple, France" [1]. Data consist of 102 transect files obtained with a GSSI SIR-3000 controller and a 400 MHz center frequency antenna in two grid blocks covering ca. 2700 m(2). The data are distributed raw without post-processing in SEG-Y rev. 1 format (little endian). PMID:27222858

  5. SURFACE GEOPHYSICAL EXPLORATION OF TX-TY TANK FARMS AT THE HANFORD SITE RESULTS OF BACKGROUND CHARACTERIZATION WITH GROUND PENETRATING RADAR

    SciTech Connect

    MYERS DA; CUBBAGE R; BRAUCHLA R; O'BRIEN G

    2008-07-24

    Ground penetrating radar surveys of the TX and TY tank farms were performed to identify existing infrastructure in the near surface environment. These surveys were designed to provide background information supporting Surface-to-Surface and Well-to-Well resistivity surveys of Waste Management Area TX-TY. The objective of the preliminary investigation was to collect background characterization information with GPR to understand the spatial distribution of metallic objects that could potentially interfere with the results from high resolution resistivity{trademark} surveys. The results of the background characterization confirm the existence of documented infrastructure, as well as highlight locations of possible additional undocumented subsurface metallic objects.

  6. Ground-Penetrating Radar vertical resolution, signal attenuation, and penetration in temperate and polar glaciers: Case studies from North America and Antarctica

    NASA Astrophysics Data System (ADS)

    Campbell, S. W.; Kreutz, K. J.; Arcone, S. A.

    2013-12-01

    The application of commercially available ground-penetrating radar (GPR) has become a standard routine for many field glaciological research efforts. However, the success of glaciological radar surveys often depends on frequency selection, tunable parameters, and data collection methods relative to the glaciological setting. Specifically, glaciers exhibit a range of thermal properties (i.e. cold, polythermal, temperate) and exist under diverse settings (e.g. maritime, continental, mountain glaciers, ice sheets, ice streams), each which present unique and complex challenges for conducting radar surveys. Herein, we review over 1000 km of ground collected GPR data from polar and temperate settings and distill vertical resolution, signal attenuation, and depth of penetration for various recording and antenna configurations ranging between 15-900 MHz. Snow and firn studies, ice thickness measurements, and ice flow dynamics studies from Alaska, Antarctica, Canada, and the Western United States will be referenced.

  7. Violent Strombolian or not? Using ground-penetrating radar to distinguish deposits of low- and high-energy scoria cone eruptions

    NASA Astrophysics Data System (ADS)

    Courtland, Leah; Kruse, Sarah; Connor, Charles

    2013-12-01

    Scoria cones often grow by the accumulation of individual particles transported ballistically in Strombolian-type eruptions. Alternative models of cone formation suggest that cones are built primarily of fallout from the eruption column in more explosive eruptions, often termed violent Strombolian. Currently, the distinction between normal Strombolian and violent Strombolian is based on direct observations of eruptions or by inference of eruption characteristics from mapping of tephra fall deposits. Unfortunately, medial to distal tephra fall deposits erode rapidly, leaving behind only the near-vent facies of scoria cones which are thicker and less easily eroded. Therefore, a tool that is capable of delineating differences between low-energy Strombolian deposits and higher energy violent Strombolian deposits from investigation of the preserved scoria edifice is necessary. Ground-penetrating radar imaging of Cerro Negro, an active basaltic scoria cone in Nicaragua, has revealed details of cone deposits at depths of up to 12 m. The record of the 1992 eruption, which was observed to be violent Strombolian, shows quantifiable differences from normal Strombolian near-vent facies, including reflections in the downwind profile that are continuous for hundreds of meters and through the slope break. The ability to differentiate between tephra fallout and ballistically emplaced deposits at Cerro Negro suggests ground-penetrating radar imaging may be useful in distinguishing eruptive style in older scoria cones, where the medial to distal tephra deposits are eroded or buried.

  8. The Ground Penetrating Radar facies and architecture of a Paleo-spit from Huangqihai Lake, North China: Implications for genesis and evolution

    NASA Astrophysics Data System (ADS)

    Shan, Xin; Yu, Xinghe; Clift, Peter D.; Tan, Chengpeng; Jin, Lina; Li, Mingtao; Li, Wen

    2015-06-01

    A paleo-spit is identified from Huangqihai Lake in North China and proposed as a classic example for investigating the influence of lake level changes and storms on the construction of these bodies. Ground Penetrating Radar (GPR) data, collected with a 400 MHz antenna, are used together with sedimentologic observations from trenches to define the facies and sedimentary architecture of the spit. Six types of radar surface, both depositional and erosional, were identified. Radar facies bounded by radar surfaces were interpreted from reflection characteristics and termination patterns. Eight different radar facies were identified in the profiles, and we assign these to three groups (inclined, horizontal and irregular). The whole barrier spit system comprises spit bar and salt marsh units, distinguished using GPR profiles. Linked radar and sedimentologic data are used to develop a model for spit bar evolution. The spit was formed during a cycle of lake-level change spanning ~ 200 years. The characteristics of the different building blocks (washover lobes, sheets and swash laminated sands) within the spit bar unit and their depositional regimes are defined and interpreted. Based on the known lake evolution during the Holocene, a relative chronological framework is presented. Two storms in the 1880s and 1960s may have played an important role in building the spit bar.

  9. More Than the Sum of Its Parts: Increased Information Content through a Combination of Ground-Penetrating-Radar and Seismic Methods on Temperate Glaciers.

    NASA Astrophysics Data System (ADS)

    Rabenstein, L.; Maurer, H.; Merz, K.; Lüthi, M. P.

    2014-12-01

    Over temperate glaciers images obtained from ground-penetrating-radar (GPR) are often blurred because electromagnetic waves are scattered on water pockets or by complex glacial bed topography, or damped due to a higher overall water content within the glacier. A combination of seismic and GPR surveying can increase the data information content and aid interpretation of subsurface structure. In September 2012 we acquired surface and borehole GPR and seismic data in the ablation zone of the Rhone Glacier located in central Switzerland. GPR data were acquired using antenna frequencies of 25, 50 and 100 MHz. Active reflection seismic data were recorded along a coincident profile across the glacier. Seismic waves were generated with small explosive sources spaced at 4m, and recorded on 30 Hz geophones at 2 m spacing. Both methods resulted in images showing a maximum depth of the glacier of approximately 130 m. However, the seismic image of the glacier bed was of much higher resolution and showed a clear primary reflection from the base, whereas the GPR image often showed several reflections of similar amplitude, above and from the bedrock interface, or no reflection at all. We interpreted a series of crenulations along the glacier bed reflector in the seismic image as melt water channels. This interpretation was supported by the intermittent nature of GPR glacier bed reflections, which are expected to be more sensitive to changes in water content than to the ice-rock interface. First break travel time inversions of the surface seismic data yielded velocities of 3320 m/s near the top of the glacier, and remarkably constant values of 3720 m/s at depths below 4.5m. However, travel time inversion of seismic data between boreholes which penetrated as far as the glacier bed, indicate a 3D anisotropy of seismic velocity, ranging from 3650 m/s horizontally across the glacier to 3850 m/s horizontally along the line of the glacier. Vertical seismic velocity was found to lie

  10. High-resolution mapping of soil moisture at the field scale using ground-penetrating radar for improving remote sensing data products

    NASA Astrophysics Data System (ADS)

    Lambot, Sébastien; Mahmoudzadeh, Mohammad Reza; Phuong Tran, Anh; Nottebaere, Martijn; Leonard, Aline; Defourny, Pierre; Neyt, Xavier

    2014-05-01

    Characterizing the spatiotemporal distribution of soil moisture at various scales is essential in agricultural, hydrological, meteorological, and climatological research and applications. Soil moisture determines the boundary condition between the soil and the atmosphere and governs key processes of the hydrological cycle such as infiltration, runoff, root water uptake, evaporation, as well as energy exchanges between the Earth's surface and the atmosphere. In that respect, ground-penetrating radar (GPR) is of particular interest for field-scale soil moisture mapping as soil moisture is highly correlated to its permittivity, which controls radar wave propagation in the soil. Yet, accurate determination of the electrical properties of a medium using GPR requires full-wave inverse modeling, which has remained a major challenge in applied geophysics for many years. We present a new near-field radar modeling approach for wave propagation in layered media. Radar antennas are modeled using an equivalent set of infinitesimal electric dipoles and characteristic, frequency-dependent, global reflection and transmission coefficients. These coefficients determine wave propagation between the radar reference plane, point sources, and field points. The interactions between the antenna and the soil are inherently accounted for. The fields are calculated using three-dimensional Green's functions. We validated the model using both time and frequency domain radars. The radars were mounted on a quad and controlled by a computer for real-time radar and dGPS data acquisition. Several fields were investigated and time-lapse measurements were performed on some of them to analyze temporal stability in soil moisture patterns and the repeatability of the measurements. The results were compared to ground-truths. The proposed technique is presently being applied to improve space-borne remote sensing data products for soil moisture by providing high-resolution observational information that

  11. Ground penetrating radar and terrestrial laser scanner surveys on deposits of dilute pyroclastic density current deposits: insights for dune bedform genesis

    NASA Astrophysics Data System (ADS)

    Rémi Dujardin, Jean; Amin Douillet, Guilhem; Abolghasem, Amir; Cordonnier, Benoit; Kueppers, Ulrich; Bano, Maksim; Dingwell, Donald B.

    2014-05-01

    Dune bedforms formed by dilute pyroclastic density currents (PDC) are often described or interpreted as antidunes and chute and pools. However, the interpretation remains essentially speculative and is not well understood. This is largely due to the seeming impossibility of in-situ measurements and experimental scaling, as well as the lack of recent, 3D exposures. Indeed, most dune bedform cross-stratifications from the dilute PDC record outcrop in 2D sections. The 2006 eruption of Tungurahua has produced well-developed bedforms that are well-exposed on the surface of the deposits with easy access. We performed a survey of these deposits combining ground penetrating radar (GPR) profiling with terrestrial laser scanning of the surface. The GPR survey was carried in dense arrays (from 10 to 25 cm spacing between profiles) over ca. 10 m long bedforms. GPR profiles were corrected for topography from photogrammetry data. An in-house software, RadLab (written in matlab), was used for common processing of individual profiles and 2D & 3D topographic migration. Each topography-corrected profile was then loaded into a seismic interpretation software, OpenDtect, for 3D visualization and interpretation. Most bedforms show high lateral stability that is independent of the cross-stratification pattern (that varies between stoss-aggrading bedsets, stoss-erosive bedsets and stoss-depositional lensoidal layers). Anecdotic bedforms have their profiles that evolve laterally (i.e. in a direction perpendicular to the flow direction). Cannibalization of two dune bedforms into a single one on one end of the profile can evolve into growth of a single bedform at the other lateral end. Also, lateral variation in the migration direction occurs, i.e. a single bedform can show upstream aggradation at one lateral end of the bedform, but show downstream migration at the other end. Some bedforms have great variations in their internal structure. Several episodes of growth and erosion can be

  12. Implementation of ground penetrating radar and electrical resistivity tomography for inspecting the Greco-Roman Necropolis at Kilo 6 of the Golden Mummies Valley, Bahariya Oasis, Egypt

    NASA Astrophysics Data System (ADS)

    Abbas, Abbas M.; Ghazala, Hosni H.; Mesbah, Hany S.; Atya, Magdy A.; Radwan, Ali; Hamed, Diaa E.

    2016-06-01

    Bahariya Oasis is one of the lately inspected spots in Egypt and has a long historical record extending from the old kingdom till the emergence of Islam. Since June 1999, the Valley of the Golden Mummies near Bawiti (at kilometer 6 on the road leads to Farafra Oasis) became significant due to the discoveries of amazing mummies of gelded faces. The archeologists believe that the Valley has more valuable tombs that still unrevealed. Also, the possibility that the Greco-Roman Necropolis extends to areas other than Kilo-6 is sustainable. The ground penetrating radar and electrical resistivity tomography are two geophysical tools that have successful applications in archeological assessment. The two techniques were used in integration plan to assert the archeological potentiality of the studied site and to map the feasible tombs. Sum of 798 GPR profiles and 19 ERT cross sections was carried out over the study area. The results of them were analyzed to envisage these results in archeological terms.

  13. Evaluation of ground penetrating radar and resistivity profilings for characterizing lithology and moisture content changes: a case study of the high-conductivity United Kingdom Triassic sandstones

    NASA Astrophysics Data System (ADS)

    Hossain, Delwar

    2013-12-01

    High-resolution geophysical techniques can be employed as a means of characterizing the lithological changes within materials frequently known to be variable. Ground penetrating radar (GPR) profiling using 50, 100, 200, and 400 MHz antennae and electrical resistivity imaging have been used to investigate high-conductivity United Kingdom Triassic sandstone lithology and moisture content changes. The investigation site is located outside the School of Geography, Earth and Environmental Sciences at the University of Birmingham on a gentle grassy slope. Three GPR and electrical imaging lines were completed over this site. The results of the observations reveal a higher degree of both vertical and lateral heterogeneity of the highly conductive sandstones. The results obtained using these two high-resolution geophysical tools agree reasonably well with each other. These techniques appear to be useful for high resolution and continuous mapping of the subsurface sediments.

  14. Tests of ground-penetrating radar and induced polarization for mapping fluvial mine tailings on the floor of the Couer d'Alene River, Idaho

    USGS Publications Warehouse

    Campbell, David L.; Wynn, Jefferey C.; Box, Stephen E.; Bookstrom, Arthur A.; Horton, Robert J.

    1997-01-01

    In order to investigate sequences of toxic mine tailings that have settled in the bed of the Coeur d'Alene River, Idaho, (see figure 1) we improvised ways to make geophysical measurements on the river floor. To make ground penetrating radar (GPR) profiles, we mounted borehole antennas on a skid that was towed along the river bottom. To make induced polarization (IP) profiles, we devised a bottom streamer from a garden hose, lead strips, PVC standoffs, and insulated wire. Each approach worked and provided uniquely different information about the buried toxic sediments. GPR showed shallow stratigraphy, but did not directly detect the presence of contaminating metals. IP showed a zone of high chargeability that is probably due to pockets of relatively higher metal content. Neither method was able to define the base of the fluvial tailings section, at least in part because the IP streamer was deliberately designed to sample only the top three meters of sediments to maximize horizontal resolution.

  15. Combining Ground Penetrating Radar and Terrestrial Laser Scanning techniques to non-destructively image the 2006 cross-stratified overbank deposits of Tungurahua volcano (Ecuador)

    NASA Astrophysics Data System (ADS)

    Douillet, G. A.; Dujardin, J.; Abolghasem, A.; Kueppers, U.; Bano, M.; Mothes, P. A.; Dingwell, D. B.

    2012-12-01

    Tungurahua volcano (Ecuador) generated Pyroclastic Density Currents (PDCs) in August 2006. The deposits are characterized by two lithofacies: a massive, unsorted, coarse-grained lithofacies confined to the valleys that directed the parent PDCs and interpreted as deposited from dense pyroclastic flows and a finer-grained and better-sorted cross-stratified lithofacies that outcrop on the overbanks of valleys downstream of cliffs and bends in the valleys deposited from dilute PDCs. The pristine surface exhibits a variety of dune-bedform (DBs) shapes. In order to better record the deposits characteristics and constrain the sedimentation processes, a field survey combining terrestrial laser scanner and ground penetrating radars (GPR) was yield. The terrestrial laser scanner records an accurate topography model of the surface of the deposits (<1 cm precision). The shape parameters of the DBs are then analyzed systematically and the size evolution calculated. Three GPR antennas were used (250, 500, 800 MHz). They permit to image the stratification within the deposits at different scales and in a non-destructive way. More than 450 profiles were collected, covering three key sectors of the volcano. A large-scale griding (profiles separated by 20 m and crossing perpendicularly) was executed with the 250 MHz antenna in three main overbank deposition zones (each zone c.a. 50.000 m^2). Of particular interest is a 200 m long ash body with a wedge shape. It has a sharp upstream onset with the shape of a quarter pipe and decreases in thickness downstream with DBs on its surface. Eight layers were identified on the GPR data and interpolated in between the profiles for a 3D image. At least three successive cross-stratified units are found on top of five units that more likely correspond to massive layers. While the cross-stratified units seem to aggrade as stoss-side backstep-strata, the massive layers are either gently thinning downstream or continuous. The data reveal the

  16. An in situ approach to detect tree root ecology: linking ground-penetrating radar imaging to isotope-derived water acquisition zones

    PubMed Central

    Isaac, Marney E; Anglaaere, Luke C N

    2013-01-01

    Tree root distribution and activity are determinants of belowground competition. However, studying root response to environmental and management conditions remains logistically challenging. Methodologically, nondestructive in situ tree root ecology analysis has lagged. In this study, we tested a nondestructive approach to determine tree coarse root architecture and function of a perennial tree crop, Theobroma cacao L., at two edaphically contrasting sites (sandstone and phyllite–granite derived soils) in Ghana, West Africa. We detected coarse root vertical distribution using ground-penetrating radar and root activity via soil water acquisition using isotopic matching of δ18O plant and soil signatures. Coarse roots were detected to a depth of 50 cm, however, intraspecifc coarse root vertical distribution was modified by edaphic conditions. Soil δ18O isotopic signature declined with depth, providing conditions for plant–soil δ18O isotopic matching. This pattern held only under sandstone conditions where water acquisition zones were identifiably narrow in the 10–20 cm depth but broader under phyllite–granite conditions, presumably due to resource patchiness. Detected coarse root count by depth and measured fine root density were strongly correlated as were detected coarse root count and identified water acquisition zones, thus validating root detection capability of ground-penetrating radar, but exclusively on sandstone soils. This approach was able to characterize trends between intraspecific root architecture and edaphic-dependent resource availability, however, limited by site conditions. This study successfully demonstrates a new approach for in situ root studies that moves beyond invasive point sampling to nondestructive detection of root architecture and function. We discuss the transfer of such an approach to answer root ecology questions in various tree-based landscapes. PMID:23762519

  17. Inference of Fractured Rock Transport Properties by Joint Inversion of Push-Pull and Single-Hole Ground Penetrating Radar Data

    NASA Astrophysics Data System (ADS)

    Shakas, A.; Linde, N.; Bour, O.; Le Borgne, T.

    2015-12-01

    Flow and transport characterization of fractured rock formations is very challenging and important for a multitude of applications that include groundwater extraction, nuclear waste storage and geothermal energy production. One popular hydrogeological method to study fractured rock is a push-pull test, in which injection and retrieval of a tracer is made at the same depth interval in a borehole. In theory, push-pull tests are not sensitive to changes in the heterogeneity of the tracer flow path since the retrieval at the injection location minimizes advective effects and makes the test more sensitive to time-dependent transport processes. This assumption is limiting in the presence of a natural hydraulic gradient or if non-neutrally buoyant tracers are used, but these limitations can be reduced by monitoring push-pull tests with ground penetrating radar (GPR). We present a methodology for combined modeling and inversion of a series of push-pull tests that we monitored with the single hole ground penetrating radar (GPR) method. For the GPR modeling we use a newly developed approach to simulate the GPR response in fractured rock. We coupled the GPR model to a flow-and-transport simulator that we use to define the electrical properties of the fracture filling. The combined model can cope with heterogeneous fractures of any orientation, aperture and size and allows for the effect of density driven flow (that is strong during the saline tracer tests). We use the combined simulator to create synthetic datasets for both the time-series of the GPR traces at different locations and the tracer breakthrough curves. Since the combined problem is highly non-linear and the inverse solution is ill-posed, we use stochastic inversion techniques to obtain probabilistic estimates of the parameters of interest (fracture length, orientation and aperture distribution) and assess the use of different measures to compare the simulated and experimental data.

  18. Hidden faults in the Gobi Desert (Inner Mongolia, China) revealed by microtremor analysis, ground-penetrating radar and SQUID-supported transient electromagnetics

    NASA Astrophysics Data System (ADS)

    Rudersdorf, Andreas; Hölz, Sebastian; Torgoev, Almaz; Havenith, Hans-Balder; Reicherter, Klaus

    2013-04-01

    The endorheic Gaxun Nur Basin (GNB, also Ejina Basin, Hei river Basin, Ruoshui Basin) in the eastern Gobi desert is situated between the northern Tibetan Plateau and the Gobi Altai mountains. Recent fault activity is concentrated on the sinistral Altyn Tagh Fault, its eastern continuations and the Qilian Shan frontal thrust in the south, which are induced by the stress field of the India-Eurasia continental collision. In the north, the basin is bound by the Gobi Altai mountains with the major sinistral Gobi-Tien Shan Fault System. The basin is dominated by a very flat topography, active alluvial sedimentation from the south and eolian erosion by northwesterly winds. The basin formation and basement structure is poorly known. The sedimentary succession of up to 300 m thickness comprises intercalations of alluvial fan deposits, dune sands, lake sediments and playa evaporites. The latter tend to concentrate in the northern part of the basin, where the basin is limited by the Gobi Altai mountains. The top of the diversified successions and the Gobi surface itself is covered by gravels. Instrumental seismicity and paleoseismic records are rather low and earlier tectonic and paleoseismological investigations are sparse. We, therefore, conducted microtremor analyses and transient electromagnetics with a liquid nitrogen cooled SQUID magnetometer to reveal basement-basin interaction structures; ground-penetrating radar surveys were also carried out to investigate shallow reworking processes. First results show connections between subsurface data and a large-scale (>20 km long) lineament fingerprint from remote sensing studies. Here, we focus on a NW-SE striking lineament west of the city of Ejina, which shows only minor topographic evidence for fault activity. An earlier drill core nearby resulted in dating irregularities in the upper 60m, which are believed to be related to the lineament. Microtremor analysis shows a significant offset of the basement topography and ground-penetrating

  19. A STUDY TO DETERMINE THE FEASIBILITY OF USING A GROUND-PENETRATING RADAR FOR MORE EFFECTIVE REMEDIATION OF SUBSURFACE CONTAMINATION

    EPA Science Inventory

    A study was conducted (1) to assess the capability of groundpenetrating radar (GPR) to identify natural subsurface features, detect man-made objects burled in the soil, and both detect and define the extent of contaminated soil or ground water due to a toxic spill, and (2) to det...

  20. The use of Ground Penetrating Radar in coastal research, archeaological investigations, lake studies, peat layer measurments and applied research in Estonia

    NASA Astrophysics Data System (ADS)

    Vilumaa, Kadri; Tõnisson, Hannes; Orviku, Kaarel

    2014-05-01

    Ground Penetrating Radar (GPR) is mainly used for scientific research in coastal geology in the Institute of Ecology at Tallinn University. We currently use SIR-3000 radar with 100, 270 , 300 and 500 MHz antennae. Our main targets have been detecting the thickness of soil and sand layers and finding out the layers in coastal sediments which reflect extreme storm events. Our GPR studies in various settings have suggested that the internal structures of the ridge-dune complexes are dominated by numerous layers dipping in various directions. Such information helps us to reconstruct and understand prevailing processes during their formation (e.g. seaward dipping lamination in coastal ridge-dune complexes indicating cross-shore and wave-induced transport of the sediments). Currently, we are trying to elaborate methodology for distinguishing the differences between aeolian and wave transported sediments by using GPR. However, paludified landscapes (often covered by water), very rough surface (numerous bushes and soft surface), moderate micro topography has slowed this process significantly. Moreover, we have been able to use GPR during the winter period (applied on ice or snow) and compare the quality of our results with the measurements taken during the summer period. We have found that smooth surface (in winter) helps detecting very strong signal differences (border between different sediment types - sand, peat, silt, etc.) but reduces the quality of the signal to the level where the detection of sedimentation patterns within one material (e.g. tilted layers in sand) is difficult. We have carried out several other science-related studies using GPR. These studies include determining the thickness of peat layer in bogs (to calculate the volume of accumulated peat or to find most suitable locations for coring), measuring the thickness of mud and gyttja layer in lakes (to find most suitable locations for coring, reconstructing initial water level of the lake or calculating

  1. Shelly cheniers on a modern macrotidal flat (Mont-Saint-Michel bay, France) — Internal architecture revealed by ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Weill, Pierre; Tessier, Bernadette; Mouazé, Dominique; Bonnot-Courtois, Chantal; Norgeot, Christophe

    2012-11-01

    The relationship between short-term morphodynamics and internal structure of shelly chenier ridges is investigated using ground-penetrating radar and core X-ray analysis, complemented with a comparison of aerial photographs. These cheniers are located on the uppermost part of a macrotidal flat in Mont-Saint-Michel bay (North-Western France). They actively migrate landward over the salt-marshes by washover processes when they are submerged during the coincidence of spring tides and enhanced wave activity. The architecture of the cheniers is imaged using high-frequency radar antennas (400 MHz to 2.6 GHz). Three types of cheniers are recognized, featuring differences in morphology and internal structure. The altitude of the banks on the tidal flat relative to the level of tidal flooding, as well as local sediment supply, seem to be important forcing parameters in chenier development and stages of evolution. On a multi-annual time scale, evolution of this chenier system is influenced by a combination of the 18-year and the 4-year tidal cycles, superimposed on wave activity. During minima of the 18-year cycle, spring tide level is globally lower on the tidal flat, allowing salt marsh progradation and chenier ridge development. During peak periods of the tidal cycle, former barriers are reworked by wave action and experience onshore migration associated with salt marsh erosion. The 4-year tidal cycle coupled with enhanced wave activity is probably responsible for the deposition of large washover units, observed in GPR reflection profiles.

  2. Ground-penetrating radar investigations along the North Anatolian fault near Izmit, Turkey: Constraints on the right-lateral movement and slip history

    NASA Astrophysics Data System (ADS)

    Ferry, Matthieu; Meghraoui, Mustapha; Girard, Jean-François; Rockwell, Thomas K.; Kozaci, Özgur; Akyuz, Serdar; Barka, Aykut

    2004-01-01

    We analyze ground-penetrating radar (GPR) profiles made across and parallel to the August 1999 earthquake ruptures of the North Anatolian fault in Turkey. The profiles document cumulative right-lateral offset of stream channels and the successive faulting of a medieval (Ottoman) canal. The dominance of fine sand to coarse gravel in the sections imaged allows for reasonably deep penetration, and processed radar signals clearly image visible reflectors within the uppermost 5 m. Near Köseköy, buried fluvial-channel deposits, exposed in some trenches dug to determine paleoseismicity, are also visible on profiles and show a maximum 6.7 7.4 m of lateral displacement. Younger channel units display 4.5 4.9 m of right-lateral displacement at 2 3 m depth and show that the penultimate rupture along the Izmit segment produced a similar amount of displacement as in 1999. At the Ottoman canal site, GPR profiles complement a trench study and provide consistent results showing the occurrence of three faulting events after A.D. 1591, the date of canal construction. This study demonstrates that the use of GPR method in paleoseismology contributes to better identification of cumulative slip along active faults.

  3. Three Dimensional Finite Difference Time Domain Modeling of Ground Penetrating Radar with an Efficient and Robust Algorithm to Define and Predict Hydrologic Properties in the Subsurface

    NASA Astrophysics Data System (ADS)

    Eyuboglu, S.; Daniels, J. J.; Pyke, K.

    2005-12-01

    Ground Penetrating Radar (GPR) is a commonly used non-invasive tool to characterize the physical properties of the subsurface. The translation of the physical measurements to geologic and hydrogeologic conditions is the culmination of many geophysical investigations. Numerical modeling increases the applicability of GPR in the geophysics area when applied parallel to the GPR data, allowing to understand the effects of complex electromagnetic phenomena by defining and solving problems, as well as predicting the performance of radar in a complex heterogeneous environment. Finite difference time domain (FDTD) has been widely used for numerical modeling of GPR, but most of the previous algorithms are limited in their ability to model the electrical conductivity and permittivity. In this research, a highly efficient robust algorithm was developed to enhance the effectiveness of the FDTD forward modeling in surroundings characterized by an arbitrary distribution of all electrical properties in three dimensional space. The modeling algorithm was developed for a heterogeneous half-space medium to facilitate statistical modeling of complex distributions of hydrologic properties in the subsurface. The results produced by the simulation reveal high accuracy using the robust algorithm to optimize three dimensional FDTD forward modeling of GPR responses in heterogeneous surroundings.

  4. Mapping of saltwater intrusions into the McMurdo Ice Shelf, Antarctica, using electromagnetic induction sounding and ground penetrating radar measurements

    NASA Astrophysics Data System (ADS)

    Rack, Wolfgang; Haas, Christian; Krützmann, Nikolai

    2010-05-01

    Ice Shelves, interacting with both the ocean and the atmosphere, are a sensitive indicator of a changing environment. The repeated observation of ice shelf thickness as a result of surface and bottom mass balance and ice shelf dynamics yields insight into this sensitive balance. Ice shelf thickness is normally measured by radar, or derived from freeboard height using knowledge about ice density and sea level height. Seismic methods may also be used but are usually limited to smaller areas. In general, melting at the underside of the ice shelf is expected to be highest near the grounding line, and the rise and outflow of diluted undercooled water may result in bottom freezing. In the presence of saline ice at the ice shelf bottom the use of radar for ice thickness measurements is limited, as the radar energy is effectively absorbed. This is also the case near the ice shelf edge where saltwater intrusions may be observed. In November 2009 we conducted helicopter-borne electromagnetic induction measurements in the McMurdo Sound to measure sea ice and ice shelf thickness within a validation experiment for the CryoSat-2 satellite. The instrument used was an "EM bird", which is more frequently operated in the Arctic to map sea ice thickness. The thickness of the ice shelf could be detected for values less than about 50 m, with a strong gradient perpendicular to the ice shelf front and significant undulations parallel to the ice shelf front. At the same time, we used a ground penetrating radar system in order to detect the transition depth between fresh water and saline ice. In this contribution we present the results of this combined airborne and ground based method, which could be further developed to a fully airborne or ground based technology detecting larger ice shelf thickness and ice shelf morphology in the presence of marine ice.

  5. Automated monitoring of subglacial hydrological processes with ground-penetrating radar (GPR) at high temporal resolution: scope and potential pitfalls

    NASA Astrophysics Data System (ADS)

    Kulessa, B.; Booth, A. D.; Hobbs, A.; Hubbard, A. L.

    2008-12-01

    We demonstrate that automated GPR techniques can monitor, at repeat timescales of minutes, hydrological processes beneath glaciers experiencing perennial surface melting. At Grubengletscher, Swiss Alps, melt penetrates into porous near-surface ice during the day, modifying the transmitted radar energy and thus the amplitudes of the targeted subglacial reflections. Normalising these reflections by early-time radar arrivals, integrated over a suitable time window, minimises such artefacts. In mid afternoon peak surface ablation, a diagnostic pulse in englacial reflectivity, sharp increases in subglacial reflectivity and glacier surface uplift precede the onset of transient glacier acceleration. Sliding terminates as the glacier surface lowers and the magnitude of subglacial reflectivity decreases. We infer a prominent episode of basal sliding as subglacial water pressure rises rapidly in response to englacially-routed melt delivery, jacking the glacier off its bed and modifying the observed reflectivity. Quantification of such processes is pertinent for any measurement and interpretation of basal reflection strength or bed reflection power from a GPR dataset.

  6. Seismic Tomography and Ground Penetrating Radar Applied On Rock Slope Instability Analysis. Application On A Limestone Cliff In The Chartreuse Massif, France

    NASA Astrophysics Data System (ADS)

    Dussauge-Peisser, C.; Wathelet, M.; Jongmans, D.; Havenith, H.; Couturier, B.; Teerlynck, H.

    Evaluating the stability state of a rock slope is a complex problem, mainly due to the number of possible failure mechanisms, and to the lack of knowledge of the real present state of the rock mass. Geophysical methods appear as a useful tool for inves- tigating the deep discontinuity pattern, which is poorly known from surface observa- tions. However they have seldom been applied on steep rock slopes. The aim of this study is to test some of these methods on subvertical cliffs. We investigate the quality of information that they can provide when investigating the stability of rock slopes in a rock-slide prone area. This test will lead to developp a proper methodology for rock-slide hazard evaluation. Among other methods, seismic tomography and ground penetrating radar proved suitable for assessing geometrical and physical properties of the rock cliff. The test site is located is the Chartreuse massif, 50 km north of Grenoble, France. It is a 10 m high limestone cliff , characterised by one main discontinuity set, subvertical with some widely open fractures. Seismic tomography has been conducted between the vertical free surface and the plateau above, along three parallel profiles. First, results show low P-wave velocities (1000-1800 m/s) in a corner bounded by the two free surfaces, with an increase of the velocity up to 3500-4000 m/s obliquely to the cliff. This corner can be interpreted as the decompression zone due to gravity effects. Second, areas with low velocities also appear where open fractures cross the seismic profile. Ground penetrating radar has also been conducted along vertical profiles on the cliff. We used three different antennas of 35, 120 and 500 MHz. The penetration depth varies from 10-12 m for the 120 MHz antenna to about 20 m with the 35 MHz an- tenna.nThe observed reflectors are subvertical, corresponding to the dip of the main discontinuity set. The reflectivity strongly varies along some reflectors, particularly for the high frequency

  7. Design and testing of Ground Penetrating Radar equipment dedicated for civil engineering applications: ongoing activities in Working Group 1 of COST Action TU1208

    NASA Astrophysics Data System (ADS)

    Pajewski, Lara; Manacorda, Guido; Persico, Raffaele

    2015-04-01

    This work aims at presenting the ongoing research activities carried out in Working Group 1 'Novel GPR instrumentation' of the COST (European COoperation in Science and Technology) Action TU1208 'Civil Engineering Applications of Ground Penetrating Radar' (www.GPRadar.eu). The principal goal of the COST Action TU1208 is to exchange and increase scientific-technical knowledge and experience of GPR techniques in civil engineering, simultaneously promoting throughout Europe the effective use of this safe and non-destructive technique in the monitoring of infrastructures and structures. Working Group 1 (WG1) of the Action focuses on the development of innovative GPR equipment dedicated for civil engineering applications. It includes three Projects. Project 1.1 is focused on the 'Design, realisation and optimisation of innovative GPR equipment for the monitoring of critical transport infrastructures and buildings, and for the sensing of underground utilities and voids.' Project 1.2 is concerned with the 'Development and definition of advanced testing, calibration and stability procedures and protocols, for GPR equipment.' Project 1.3 deals with the 'Design, modelling and optimisation of GPR antennas.' During the first year of the Action, WG1 Members coordinated between themselves to address the state of the art and open problems in the scientific fields identified by the above-mentioned Projects [1, 2]. In carrying our this work, the WG1 strongly benefited from the participation of IDS Ingegneria dei Sistemi, one of the biggest GPR manufacturers, as well as from the contribution of external experts as David J. Daniels and Erica Utsi, sharing with the Action Members their wide experience on GPR technology and methodology (First General Meeting, July 2013). The synergy with WG2 and WG4 of the Action was useful for a deep understanding of the problems, merits and limits of available GPR equipment, as well as to discuss how to quantify the reliability of GPR results. An

  8. Estimations of moisture content in the active layer in an Arctic ecosystem by using ground-penetrating radar profiling

    NASA Astrophysics Data System (ADS)

    Gacitúa, Guisella; Tamstorf, Mikkel Peter; Kristiansen, Søren Munch; Uribe, José Andrés

    2012-04-01

    We applied high-frequency GPR at a study site in the high arctic ecosystem of Northeast Greenland to evaluate its usefulness in assessing depth of, and water content in, the active layer at Zackenberg Valley (74°N; 20°W) to evaluate its usefulness in the high arctic ecosystems. The study site includes different vegetation types, and it well represents of the entire valley, for which we aimed to determine the conditions and characteristics that influence the GPR performance in the active layer. The spatial distribution of moisture content along the transect studied was estimated using GPR data (400 MHz antenna), depth to permafrost, soil samples and vegetation observations. Vertical distribution of the water content in the unfrozen soil bulk was predicted for several points on the transect by combining data that influence the behavior of the radar waves with that of capacitive moisture probes. The statistical models resulted to be highly significant, thus assuming common conditions of the soil to the classified vegetation, we can obtain from the GPR data, truthful estimations of water content, and, moreover, we can predict the distribution to the bottom of the active layer. Hence, we conclude that GPR is a viable option for improving active layer spatial quantification of water contents that can be used to assess changes in the active layer in arctic regions.

  9. An MM-Based Algorithm for ℓ1-Regularized Least-Squares Estimation With an Application to Ground Penetrating Radar Image Reconstruction.

    PubMed

    Ndoye, Mandoye; Anderson, John M M; Greene, David J

    2016-05-01

    An estimation method known as least absolute shrinkage and selection operator (LASSO) or ℓ1-regularized LS estimation has been found to perform well in a number of applications. In this paper, we use the majorize-minimize method to develop an algorithm for minimizing the LASSO objective function, which is the sum of a linear LS objective function plus an ℓ1 penalty term. The proposed algorithm, which we call the LASSO estimation via majorization-minimization (LMM) algorithm, is straightforward to implement, parallelizable, and guaranteed to produce LASSO objective function values that monotonically decrease. In addition, we formulate an extension of the LMM algorithm for reconstructing ground penetrating radar (GPR) images, that is much faster than the standard LMM algorithm and utilizes significantly less memory. Thus, the GPR specific LMM (GPR-LMM) algorithm is able to accommodate the big data associated with GPR imaging. We compare our proposed algorithms to the state-of-the-art ℓ1-regularized LS algorithms using a time and space complexity analysis. The GPR-LMM greatly outperforms the competing algorithms in terms of the performance metrics we considered. In addition, the reconstruction results of the standard LMM and GPR-LMM algorithms are evaluated using both simulated and real GPR data. PMID:26800538

  10. Estimating porosity and solid dielectric permittivity in the Miami Limestone using high-frequency ground penetrating radar (GPR) measurements at the laboratory scale

    NASA Astrophysics Data System (ADS)

    Mount, Gregory J.; Comas, Xavier

    2014-10-01

    Subsurface water flow in South Florida is largely controlled by the heterogeneous nature of the karst limestone in the Biscayne aquifer and its upper formation, the Miami Limestone. These heterogeneities are amplified by dissolution structures that induce changes in the aquifer's material and physical properties (i.e., porosity and dielectric permittivity) and create preferential flow paths. Understanding such patterns are critical for the development of realistic groundwater flow models, particularly in the Everglades, where restoration of hydrological conditions is intended. In this work, we used noninvasive ground penetrating radar (GPR) to estimate the spatial variability in porosity and the dielectric permittivity of the solid phase of the limestone at centimeter-scale resolution to evaluate the potential for field-based GPR studies. A laboratory setup that included high-frequency GPR measurements under completely unsaturated and saturated conditions was used to estimate changes in electromagnetic wave velocity through Miami Limestone samples. The Complex Refractive Index Model was used to derive estimates of porosity and dielectric permittivity of the solid phase of the limestone. Porosity estimates of the samples ranged between 45.2 and 66.0% and showed good correspondence with estimates of porosity using analytical and digital image techniques. Solid dielectric permittivity values ranged between 7.0 and 13.0. This study shows the ability of GPR to image the spatial variability of porosity and dielectric permittivity in the Miami Limestone and shows potential for expanding these results to larger scales and other karst aquifers.

  11. Holographic neural networks versus conventional neural networks: a comparative evaluation for the classification of landmine targets in ground-penetrating radar images

    NASA Astrophysics Data System (ADS)

    Mudigonda, Naga R.; Kacelenga, Ray; Edwards, Mark

    2004-09-01

    This paper evaluates the performance of a holographic neural network in comparison with a conventional feedforward backpropagation neural network for the classification of landmine targets in ground penetrating radar images. The data used in the study was acquired from four different test sites using the landmine detection system developed by General Dynamics Canada Ltd., in collaboration with the Defense Research and Development Canada, Suffield. A set of seven features extracted for each detected alarm is used as stimulus inputs for the networks. The recall responses of the networks are then evaluated against the ground truth to declare true or false detections. The area computed under the receiver operating characteristic curve is used for comparative purposes. With a large dataset comprising of data from multiple sites, both the holographic and conventional networks showed comparable trends in recall accuracies with area values of 0.88 and 0.87, respectively. By using independent validation datasets, the holographic network"s generalization performance was observed to be better (mean area = 0.86) as compared to the conventional network (mean area = 0.82). Despite the widely publicized theoretical advantages of the holographic technology, use of more than the required number of cortical memory elements resulted in an over-fitting phenomenon of the holographic network.

  12. Holocene evolution of the Xagó dune field (Asturias, NW Spain) reconstructed by means of morphological mapping and ground penetrating radar surveys

    NASA Astrophysics Data System (ADS)

    Flor-Blanco, G.; Rubio-Melendi, D.; Flor, G.; Fernández-Álvarez, J. P.; Jackson, D. W. T.

    2016-02-01

    Morphological mapping and ground penetrating radar (GPR) profiling were carried out in the Xagó aeolian dune field along the Asturias coast of NW Spain to reconstruct its Holocene evolution. Such data provide a much more accurate picture than can be inferred from surficial morphological studies alone. Three successive dune sequences were identified: an inner (climbing dunes), a middle (large transverse ridge and minor elongated dunes) and an outer dune field (foredune with lee-projection dunes and incipient foredune). A late Holocene sea-level fall is inferred from the relative position of the dunes together with a prograding tendency. Long intervals of stabilisation, during which each dune sequence was formed, are interspersed within the deposit. The GPR records also reveal a period of erosion in the southern middle field, which was followed by accretion. The results show that both progradational and erosional processes occurred during the Holocene evolution of the dune field, features that can be extended to other dune fields in similar settings at these latitudes. Stratigraphically, the Xagó dune field is an excellent example where internal reflectors reveal an erosion surface representing a transgressive or sea-level stillstand event that had previously remained undetected.

  13. Ground-penetrating radar survey on the island of Pantelleria (Italy) reveals an ancient architectural complex with likely Punic and Roman components

    NASA Astrophysics Data System (ADS)

    Urban, Thomas M.; Murray, Carrie Ann; Vella, Clive; Lahikainen, Amanda

    2015-12-01

    A ground-penetrating radar (GPR) survey conducted on the small volcanic island of Pantelleria, in the Strait of Sicily, south-central Mediterranean, revealed an apparent complex of Punic/Roman architecture. The survey focused on the Lago di Venere area, where a previously investigated ritual Punic site was built alongside a brackish volcanic lake. The site also exhibits evidence of earlier Eneolithic components and later Roman components. The full extent of the site has remained undetermined, however, with only the small area of the Punic ritual complex having been excavated from 1996 to 2002. The GPR survey was intended to explore whether additional architecture remained unseen in surrounding areas, thus taking a first step toward determining the site's full spatial extent and archaeological potential. This survey revealed a complex of architectural ruins beneath an active agricultural field immediately west of the previously excavated features, and extending to a depth of approximately 2 m. These newly discovered features expand the known architectural footprint of the immediate site by three-fold. This GPR study is the first published archaeo-geophysical investigation on the island.

  14. Imaging tropical peatlands in Indonesia using ground penetrating radar (GPR) and electrical resistivity imaging (ERI): implications for carbon stock estimates and peat soil characterization

    NASA Astrophysics Data System (ADS)

    Comas, X.; Terry, N.; Slater, L.; Warren, M.; Kolka, R.; Kristijono, A.; Sudiana, N.; Nurjaman, D.; Darusman, T.

    2015-01-01

    Current estimates of carbon (C) storage in peatland systems worldwide indicate tropical peatlands comprise about 15% of the global peat carbon pool. Such estimates are uncertain due to data gaps regarding organic peat soil thickness and C content. Indonesian peatlands are considered the largest pool of tropical peat carbon (C), accounting for an estimated 65% of all tropical peat while being the largest source of carbon dioxide emissions from degrading peat worldwide, posing a major concern regarding long-term sources of greenhouse gases to the atmosphere. We combined a set of indirect geophysical methods (ground penetrating radar, GPR, and electrical resistivity imaging, ERI) with direct observations from core samples (including C analysis) to better understand peatland thickness in West Kalimantan (Indonesia) and determine how geophysical imaging may enhance traditional coring methods for estimating C storage in peatland systems. Peatland thicknesses estimated from GPR and ERI and confirmed by coring indicated variation by less than 3% even for small peat-mineral soil interface gradients (i.e. below 0.02°). The geophysical data also provide information on peat matrix attributes such as thickness of organomineral horizons between peat and underlying substrate, the presence of wood layers, buttressed trees and soil type. These attributes could further constrain quantification of C content and aid responsible peatland management in Indonesia.

  15. Hydrogeophysical characterization of transport processes in fractured rock by combining push-pull and single-hole ground penetrating radar experiments

    NASA Astrophysics Data System (ADS)

    Shakas, Alexis; Linde, Niklas; Baron, Ludovic; Bochet, Olivier; Bour, Olivier; Le Borgne, Tanguy

    2016-02-01

    The in situ characterization of transport processes in fractured media is particularly challenging due to the considerable spatial uncertainty on tracer pathways and dominant controlling processes, such as dispersion, channeling, trapping, matrix diffusion, ambient and density driven flows. We attempted to reduce this uncertainty by coupling push-pull tracer experiments with single-hole ground penetrating radar (GPR) time-lapse imaging. The experiments involved different injection fractures, chaser volumes and resting times, and were performed at the fractured rock research site of Ploemeur in France (H+ network, hplus.ore.fr/en). For the GPR acquisitions, we used both fixed and moving antenna setups in a borehole that was isolated with a flexible liner. During the fixed-antenna experiment, time-varying GPR reflections allowed us to track the spatial and temporal dynamics of the tracer during the push-pull experiment. During the moving antenna experiments, we clearly imaged the dominant fractures in which tracer transport took place, fractures in which the tracer was trapped for longer time periods, and the spatial extent of the tracer distribution (up to 8 m) at different times. This demonstrated the existence of strongly channelized flow in the first few meters and radial flow at greater distances. By varying the resting time of a given experiment, we identified regions affected by density-driven and ambient flow. These experiments open up new perspectives for coupled hydrogeophysical inversion aimed at understanding transport phenomena in fractured rock formations.

  16. Evolution of a highly dilatant fault zone in the grabens of Canyonlands National Park, Utah, USA - integrating fieldwork, ground-penetrating radar and airborne imagery analysis

    NASA Astrophysics Data System (ADS)

    Kettermann, M.; Grützner, C.; van Gent, H. W.; Urai, J. L.; Reicherter, K.; Mertens, J.

    2015-07-01

    The grabens of Canyonlands National Park are a young and active system of sub-parallel, arcuate grabens, whose evolution is the result of salt movement in the subsurface and a slight regional tilt of the faulted strata. We present results of ground-penetrating radar (GPR) surveys in combination with field observations and analysis of high-resolution airborne imagery. GPR data show intense faulting of the Quaternary sediments at the flat graben floors, implying a more complex fault structure than visible at the surface. Direct measurements of heave and throw at several locations to infer fault dips at depth, combined with observations of primary joint surfaces in the upper 100 m, suggest a highly dilatant fault geometry. Sinkholes observed in the field as well as in airborne imagery give insights in local dilatancy and show where water and sediments are transported underground. Based on correlations of paleosols observed in outcrops and GPR profiles, we argue that either the grabens in Canyonlands National Park are older than previously assumed or that sedimentation rates were much higher in the Pleistocene.

  17. Ground Penetrating Radar Investigation of Sinter Deposits at Old Faithful Geyser and Immediately Adjacent Hydrothermal Features, Yellowstone National Park, Wyoming, USA

    NASA Astrophysics Data System (ADS)

    Foley, D.; Lynne, B. Y.; Jaworowski, C.; Heasler, H.; Smith, G.; Smith, I.

    2015-12-01

    Ground Penetrating Radar (GPR) was used to evaluate the characteristics of the shallow subsurface siliceous sinter deposits around Old Faithful Geyser. Zones of fractures, areas of subsurface alteration and pre-eruption hydrologic changes at Old Faithful Geyser and surrounding hydrothermal mounds were observed. Despite being viewed directly by about 3,000,000 people a year, shallow subsurface geologic and hydrologic conditions on and near Old Faithful Geyser are poorly characterized. GPR transects of 5754 ft (1754m) show strong horizontal to sub-horizontal reflections, which are interpreted as 2.5 to 4.5 meters of sinter. Some discontinuities in reflections are interpreted as fractures in the sinter, some of which line up with known hydrothermal features and some of which have little to no surface expression. Zones with moderate and weak amplitude reflections are interpreted as sinter that has been hydrothermally altered. Temporal changes from stronger to weaker reflections are correlated with the eruption cycle of Old Faithful Geyser, and are interpreted as post-eruption draining of shallow fractures, followed by pre-eruption fracture filling with liquid or vapor thermal fluids.

  18. Archive of ground penetrating radar data collected during USGS field activity 13BIM01—Dauphin Island, Alabama, April 2013

    USGS Publications Warehouse

    Forde, Arnell S.; Smith, Christopher G.; Reynolds, Billy J.

    2016-01-01

    From April 13 to 20, 2013, scientists from the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center (USGS-SPCMSC) conducted geophysical and sediment sampling surveys on Dauphin Island, Alabama, as part of Field Activity 13BIM01. The objectives of the study were to quantify inorganic and organic accretion rates in back-barrier and mainland marsh and estuarine environments. Various field and laboratory methods were used to achieve these objectives, including subsurface imaging using Ground Penetrating Radar (GPR), sediment sampling, lithologic and microfossil analyses, and geochronology techniques to produce barrier island stratigraphic cross sections to help interpret the recent (last 2000 years) geologic evolution of the island.This data series report is an archive of GPR and associated Global Positioning System (GPS) data collected in April 2013 from Dauphin Island and adjacent barrier-island environments. In addition to GPR data, marsh core and vibracore data were also collected collected but are not reported (or included) in the current report. Data products, including elevation-corrected subsurface profile images of the processed GPR data, unprocessed digital GPR trace data, post-processed GPS data, Geographic Information System (GIS) files and accompanying Federal Geographic Data Committee (FGDC) metadata, can be downloaded from the Data Downloads page.

  19. High Resolution ground penetrating radar (GPR) measurements at the laboratory scale to model porosity and permeability in the Miami Limestone in South Florida.

    NASA Astrophysics Data System (ADS)

    Mount, G. J.; Comas, X.

    2015-12-01

    Subsurface water flow within the Biscayne aquifer is controlled by the heterogeneous distribution of porosity and permeability in the karst Miami Limestone and the presence of numerous dissolution and mega-porous features. The dissolution features and other high porosity areas can create preferential flow paths and direct recharge to the aquifer, which may not be accurately conceptualized in groundwater flow models. As hydrologic conditions are undergoing restoration in the Everglades, understanding the distribution of these high porosity areas within the subsurface would create a better understanding of subsurface flow. This research utilizes ground penetrating radar to estimate the spatial variability of porosity and dielectric permittivity of the Miami Limestone at centimeter scale resolution at the laboratory scale. High frequency GPR antennas were used to measure changes in electromagnetic wave velocity through limestone samples under varying volumetric water contents. The Complex Refractive Index Model (CRIM) was then applied in order to estimate porosity and dielectric permittivity of the solid phase of the limestone. Porosity estimates ranged from 45.2-66.0% from the CRIM model and correspond well with estimates of porosity from analytical and digital image techniques. Dielectric permittivity values of the limestone solid phase ranged from 7.0 and 13.0, which are similar to values in the literature. This research demonstrates the ability of GPR to identify the cm scale spatial variability of aquifer properties that influence subsurface water flow which could have implications for groundwater flow models in the Biscayne and potentially other shallow karst aquifers.

  20. GLACIER MONITORING SYSTEM IN COLOMBIA - complementing glaciological measurements with laser-scanning and ground-penetrating radar surveys

    NASA Astrophysics Data System (ADS)

    Ceballos, Jorge; Micheletti, Natan; Rabatel, Antoine; Mölg, Nico; Zemp, Michael

    2015-04-01

    Colombia (South America) has six small glaciers (total glacierized area of 45 Km2); their geographical location, close to zero latitude, makes them very sensitive to climate changes. An extensive monitoring program is being performed since 2006 on two glaciers, with international cooperation supports. This presentation summarizes the results of glacier changes in Colombia and includes the latest results obtained within the CATCOS Project - Phase 1 (Capacity Building and Twinning for Climate Observing Systems) signed between Colombia and Switzerland, and within the Joint Mixte Laboratory GREAT-ICE (IRD - France), with the application of LiDAR technology and GPR-based ice thickness measurements at Conejeras Glacier. Conejeras Glacier (Lat. N. 4° 48' 56"; Long. W. 75° 22' 22"; Alt. Max. 4915m.; Alt. Min. 4730m. Area 0.2 Km2) is located on the north-western side of Santa Isabel Volcano. This glacier belongs to global glacier monitoring network of the World Glacier Monitoring Service (WGMS-ID: 2721). The surface mass balance is calculated monthly using the direct glaciological method. Between April 2006 and May 2014, Conejeras Glacier showed a cumulative loss of -21 m w.e. The CATCOS Project allowed to improve the glacier monitoring system in Colombia with two main actions: (1) a terrestrial laser scanner survey (RIEGL VZ-6000 terrestrial laser scanner, property of Universities of Lausanne and Fribourg); and (2) ice thickness measurements (Blue System Integration Ltd. Ice Penetrating Radar of property of IRD). The terrestrial laser-scanning survey allowed to realize an accurate digital terrain model of the glacier surface with 13 million points and a decimetric resolution. Ice thickness measurements showed an average glacier thickness of 22 meters and a maximum of 52 meters.

  1. Electrical resistivity imaging (ERI) and ground-penetrating radar (GPR) survey at the Giribaile site (upper Guadalquivir valley; southern Spain)

    NASA Astrophysics Data System (ADS)

    Martínez, J.; Rey, J.; Gutiérrez, L. M.; Novo, A.; Ortiz, A. J.; Alejo, M.; Galdón, J. M.

    2015-12-01

    The Giribaile archaeological site is one of the most important Iberian enclaves of the Alto Guadalquivir (Southern Spain). However, to date, only minimal excavation work has been performed at the site. Evaluation requires a preliminary, non-destructive general analysis to determine high-interest areas. This stage required a geophysical survey. Specifically, a 100 m2 grid was selected, where an initial campaign of nine electrical resistivity imaging (ERI) profiles was performed, where each profile was 111 m in length; these profiles were previously located using a detailed topographical survey. A total of 112 electrodes were used for each profile, spaced at 1 m apart with a Wenner-Schlumberger configuration. Secondly, 201 GPR profiles were created using a 500 MHz antenna. The 100 m long profiles were spaced 0.5 m apart and parallel to one another. The present research analyses the efficiency of each of these geophysical tools in supporting archaeological research. Using these methodologies, the position, morphology, and depth of different buried structures can be determined. 3D interpretation of the geophysical survey in 100 × 100 m grid allowed to differentiate structures square and rectangular, interesting buildings in a semicircle (interpreted as ovens) plus delineate different streets. From the geophysical survey follows the Carthaginian presence inside this ancient Iberian enclave.

  2. Past sea-level data from Lakse Bugt, Disko Island, West Greenland from ground-penetrating radar data

    NASA Astrophysics Data System (ADS)

    Souza, Priscila E.; Nielsen, Lars; Kroon, Aart; Clemmensen, Lars B.

    2016-04-01

    Beach-ridge deposits have been used as sea-level indicators in numerous studies from temperate coastal regions. However, their present surface morphology in artic regions may not accurately correspond to past sea-level, because subsequent surface erosion, solifluction processes and/or later sediment deposition may have altered the surface significantly. The internal structure of these beach ridges, however, is often well-preserved and thus constitutes an important key to reconstruction of past sea levels as seen elsewhere. In the present study, high-resolution reflection GPR data and high-precision topographic data were collected at Lakse Bugt (Disko Island, West Greenland) using a shielded 250 MHz antennae system and a RTK-Trimble R8 DGPS, respectively. Three transects were collected across a sequence of fossil, raised beach ridge deposits, and two transects were obtained across modern beach deposits at the shoreline of the mesotidal regime. Along all radar profiles we observed downlap reflection points, which we interpret to represent the boundary between sediments deposited on the beachface and sediments deposited in the upper shoreface regime. Both the upper shoreface and the beachface deposits exhibit reflection patterns dipping in the seaward direction. The beachface deposits show the strongest dip. At or just below the downlap points strong diffractions are often observed indicating the presence of a layer containing stones. These stones are large enough to generate significant signal scattering. At the present day beach a sharp transition defined by the presence of large stones is observed near the low tide water level: cobbles characterize the seaside, while the land side is characterized by sand and gravel. Therefore, it seems reasonable to conclude that downlap points observed in the GPR data serve as indicators of past low-tide levels (at the time of deposition). The downlap points show a consistent offset with respect to present surface topography

  3. Collection, processing, and interpretation of ground-penetrating radar data to determine sediment thickness at selected locations in Deep Creek Lake, Garrett County, Maryland, 2007

    USGS Publications Warehouse

    Banks, William S.L.; Johnson, Carole D.

    2011-01-01

    This investigation focused on selected regions of the study area, particularly in the coves where sediment accumulations were presumed to be thickest. GPR was the most useful tool for interpreting sediment thickness, especially in these shallow coves. The radar profiles were interpreted for two surfaces of interest-the water bottom, which was defined as the "2007 horizon," and the interface between Lake sediments and the original Lake bottom, which was defined as the "1925 horizon"-corresponding to the year the Lake was impounded. The ground-penetrating radar data were interpreted on the basis of characteristics of the reflectors. The sediments that had accumulated in the impounded Lake were characterized by laminated, parallel reflections, whereas the subsurface below the original Lake bottom was characterized by more discontinuous and chaotic reflections, often with diffractions indicating cobbles or boulders. The reflectors were picked manually along the water bottom and along the interface between the Lake sediments and the pre-Lake sediments. A simple graphic approach was used to convert traveltimes to depth through water and depth through saturated sediments using velocities of the soundwaves through the water and the saturated sediments. Nineteen cross sections were processed and interpreted in 9 coves around Deep Creek Lake, and the difference between the 2007 horizon and the 1925 horizon was examined. In most areas, GPR data indicate a layer of sediment between 1 and 7 feet thick. When multiple cross sections from a single cove were compared, the cross sections indicated that sediment thickness decreased toward the center of the Lake.

  4. Building of shore-oblique transverse dune ridges revealed by ground-penetrating radar and optical dating over the last 500 years on Tottori coast, Japan Sea

    NASA Astrophysics Data System (ADS)

    Tamura, Toru; Bateman, Mark D.; Kodama, Yoshinori; Saitoh, Yu; Watanabe, Kazuaki; Yamaguchi, Naofumi; Matsumoto, Dan

    2011-09-01

    Coastal dunes provide valuable information on the past aeolian activity. Better characterization of internal dune structures and their chronology potentially can greatly improve the interpretation of past environmental changes. Ground-penetrating radar (GPR) and optically-stimulated luminescence (OSL) dating was applied to two transverse dune ridges which are arranged obliquely to the shoreline on the Tottori coast, Japan Sea. Data shows that the inner ridge has a core of Pleistocene dune draped with Holocene sand, while the outer ridge consists only of Holocene sand. The Holocene dune is generally dominated by landward migration, but the outer ridge shows a clear seaward accretion during the 18th century AD. OSL dating showed concordant results with radar stratigraphy and topographic changes since AD 1932 revealed by maps. From this we were able to present the first detailed report of the multi-decadal- to centennial-scale dune formation for the last 500 years in East Asia, contemporaneous with the Little Ice Age, during which many European coastal and inland dunes were activated. In East Asia, it is thought that the winter monsoon plays an important role for aeolian processes. The seaward migration during the 18th century reflects a decrease in wind capacity, which restricted sand transport nearshore, being related to decline in winter monsoon revealed by Chinese historical documents. In contrast, two remarkable events of landward accretion occurred in AD 1580-1640 and around AD 1840, respectively, corresponding to periods of increased dust fall in China, which suggest enhanced winter monsoon. The zone of maximum sedimentation shifted through time from the inner to outer ridges, and also towards the seaward end of the shore-oblique dune ridge, reflecting an expansion of the dune field caused by shoreline progradation. These suggest that the effective combination of GPR and OSL dating was critical in detailed characterization of the complicated depositional

  5. Interpretation of Stratified Fill, Frost Depths, Water Tables, and Massive Ice within Multi-Frequency Ground-Penetrating Radar Profiles Recorded Beneath Highways in Interior Alaska

    NASA Astrophysics Data System (ADS)

    Arcone, S. A.

    2014-12-01

    Road Radar generally refers to ground-penetrating radar (GPR) surveys intended to investigate pavement construction using pulses centered above 1 GHz. In interior Alaska thick sand and gravel grading and its frozen state by late winter generally afford up to 10 m of signal penetration at lower frequencies. Consequently, this penetration potentially allows identification of pavement issues involving frost heave and thaw settlement, while the smooth surface allows assessment of GPR performance in permafrost areas under ideal survey conditions. Here I discuss profiles using pulse center frequencies from 50 to 360 MHz, recorded over sections of the Steese and Elliott Highways within and just north of Fairbanks, respectively, and of the Tok Highway near Glennallen. Construction fill is easily recognized by its stratification; where marginally present along the Elliott it is replaced by steeply dipping horizons from the underlying schist. The frost depth and water table horizons are recognized by phase attributes of the reflected pulse, as dictated by the contrasts present in dielectric permittivity, their relative depths, and their continuity. Undulating stratification in the sand and gravel fill indicates thaw settlement, as caused by the melting of buried massive ice. The Tok section reveals the top and likely the bottom of massive ice. Generally, signal penetration is greatly reduced beneath the water table and so the highest resolution, at 360 MHz, covers all horizons. There is rare evidence of a permafrost table because it is most likely masked or nearly coincident with the water table. Permafrost penetration in frozen silts is a long-standing problem for GPR, for which I discuss a possible cause related to Maxwell-Wagner dielectric relaxation losses associated with unfrozen water.

  6. Evaluation of ground-penetrating radar to detect free-phase hydrocarbons in fractured rocks - Results of numerical modeling and physical experiments

    USGS Publications Warehouse

    Lane, J.W., Jr.; Buursink, M.L.; Haeni, F.P.; Versteeg, R.J.

    2000-01-01

    The suitability of common-offset ground-penetrating radar (GPR) to detect free-phase hydrocarbons in bedrock fractures was evaluated using numerical modeling and physical experiments. The results of one- and two-dimensional numerical modeling at 100 megahertz indicate that GPR reflection amplitudes are relatively insensitive to fracture apertures ranging from 1 to 4 mm. The numerical modeling and physical experiments indicate that differences in the fluids that fill fractures significantly affect the amplitude and the polarity of electromagnetic waves reflected by subhorizontal fractures. Air-filled and hydrocarbon-filled fractures generate low-amplitude reflections that are in-phase with the transmitted pulse. Water-filled fractures create reflections with greater amplitude and opposite polarity than those reflections created by air-filled or hydrocarbon-filled fractures. The results from the numerical modeling and physical experiments demonstrate it is possible to distinguish water-filled fracture reflections from air- or hydrocarbon-filled fracture reflections, nevertheless subsurface heterogeneity, antenna coupling changes, and other sources of noise will likely make it difficult to observe these changes in GPR field data. This indicates that the routine application of common-offset GPR reflection methods for detection of hydrocarbon-filled fractures will be problematic. Ideal cases will require appropriately processed, high-quality GPR data, ground-truth information, and detailed knowledge of subsurface physical properties. Conversely, the sensitivity of GPR methods to changes in subsurface physical properties as demonstrated by the numerical and experimental results suggests the potential of using GPR methods as a monitoring tool. GPR methods may be suited for monitoring pumping and tracer tests, changes in site hydrologic conditions, and remediation activities.The suitability of common-offset ground-penetrating radar (GPR) to detect free-phase hydrocarbons

  7. Joint full-waveform analysis of off-ground zero-offset ground penetrating radar and electromagnetic induction synthetic data for estimating soil electrical properties

    NASA Astrophysics Data System (ADS)

    Moghadas, D.; André, F.; Slob, E. C.; Vereecken, H.; Lambot, S.

    2010-09-01

    A joint analysis of full-waveform information content in ground penetrating radar (GPR) and electromagnetic induction (EMI) synthetic data was investigated to reconstruct the electrical properties of multilayered media. The GPR and EMI systems operate in zero-offset, off-ground mode and are designed using vector network analyser technology. The inverse problem is formulated in the least-squares sense. We compared four approaches for GPR and EMI data fusion. The two first techniques consisted of defining a single objective function, applying different weighting methods. As a first approach, we weighted the EMI and GPR data using the inverse of the data variance. The ideal point method was also employed as a second weighting scenario. The third approach is the naive Bayesian method and the fourth technique corresponds to GPR-EMI and EMI-GPR sequential inversions. Synthetic GPR and EMI data were generated for the particular case of a two-layered medium. Analysis of the objective function response surfaces from the two first approaches demonstrated the benefit of combining the two sources of information. However, due to the variations of the GPR and EMI model sensitivities with respect to the medium electrical properties, the formulation of an optimal objective function based on the weighting methods is not straightforward. While the Bayesian method relies on assumptions with respect to the statistical distribution of the parameters, it may constitute a relevant alternative for GPR and EMI data fusion. Sequential inversions of different configurations for a two layered medium show that in the case of high conductivity or permittivity for the first layer, the inversion scheme can not fully retrieve the soil hydrogeophysical parameters. But in the case of low permittivity and conductivity for the first layer, GPR-EMI inversion provides proper estimation of values compared to the EMI-GPR inversion.

  8. Ground penetrating radar evaluation of the internal structure of fluvial tufa deposits (Dévanos-Añavieja system, NE Spain): an approach to different scales of heterogeneity

    NASA Astrophysics Data System (ADS)

    Anchuela, Ó. Pueyo; Luzón, A.; Pérez, A.; Muñoz, A.; Mayayo, M. J.; Garbi, H. Gil

    2016-04-01

    The Quaternary Añavieja-Dévanos tufa system is located in the northern sector of the Iberia Chain. It has been previously tackled by means sedimentological studies focused on the available outcrops and some boreholes. They have permitted the proposal of a sedimentary scenario that fits with a pool-barrage fluvial tufa model. However a better knowledge of the characteristics and internal distribution of the usually non-outcropping pool deposits as well as of its relationship with barrage deposits has not been evaluated in detail yet. Palaeoenvironmental studies on tufas are usually biased because tufas are commonly delicate facies exposed to intense erosion during water level fall stages; for this reason outcrops are usually scarce and very often coincide with the most cemented barrage deposits. In order to analyse the internal characteristics of the tufa deposits under study, but also the lateral correlation among different facies, Ground Penetrating Radar (GPR) has been employed both for the evaluation of its applicability in such kind of environments and to improve, if possible, the sedimentary model using geophysical data in sectors without outcrops. A GPR survey including different antennas ranging from 50 to 500 MHz along different sectors and its comparison with natural outcrops has been carried out. GPR results have permitted to deduce clear differences between pool and barrage deposits and to recognise its internal structure and geometrical relationships. The survey also permitted an approach to different scales of heterogeneities in the radarfacies evaluation by using distinct antennas and therefore, reaching different resolutions and penetrations. The resulting integration from different antennas allows three different attenuant and eight reflective radarfacies to be defined permitting a better approach to the real extension of the pool areas. These results have permitted to decipher the horizontal and vertical facies changes and the identification of a

  9. Imaging tropical peatlands in Indonesia using ground-penetrating radar (GPR) and electrical resistivity imaging (ERI): implications for carbon stock estimates and peat soil characterization

    NASA Astrophysics Data System (ADS)

    Comas, X.; Terry, N.; Slater, L.; Warren, M.; Kolka, R.; Kristiyono, A.; Sudiana, N.; Nurjaman, D.; Darusman, T.

    2015-05-01

    Current estimates of carbon (C) storage in peatland systems worldwide indicate that tropical peatlands comprise about 15% of the global peat carbon pool. Such estimates are uncertain due to data gaps regarding organic peat soil thickness, volume and C content. We combined a set of indirect geophysical methods (ground-penetrating radar, GPR, and electrical resistivity imaging, ERI) with direct observations using core sampling and C analysis to determine how geophysical imaging may enhance traditional coring methods for estimating peat thickness and C storage in a tropical peatland system in West Kalimantan, Indonesia. Both GPR and ERI methods demonstrated their capability to estimate peat thickness in tropical peat soils at a spatial resolution not feasible with traditional coring methods. GPR is able to capture peat thickness variability at centimeter-scale vertical resolution, although peat thickness determination was difficult for peat columns exceeding 5 m in the areas studied, due to signal attenuation associated with thick clay-rich transitional horizons at the peat-mineral soil interface. ERI methods were more successful for imaging deeper peatlands with thick organomineral layers between peat and underlying mineral soil. Results obtained using GPR methods indicate less than 3% variation in peat thickness (when compared to coring methods) over low peat-mineral soil interface gradients (i.e., below 0.02°) and show substantial impacts in C storage estimates (i.e., up to 37 MgC ha-1 even for transects showing a difference between GPR and coring estimates of 0.07 m in average peat thickness). The geophysical data also provide information on peat matrix attributes such as thickness of organomineral horizons between peat and underlying substrate, the presence of buried wood, buttressed trees or tip-up pools and soil type. The use of GPR and ERI methods to image peat profiles at high resolution can be used to further constrain quantification of peat C pools and

  10. Characterization of Anomalous Transport in Fractured Rock through the Imaging of Push-Pull Experiments Using Single-Hole Ground Penetrating Radar Reflection Data

    NASA Astrophysics Data System (ADS)

    Shakas, A.; Linde, N.; Baron, L.; Bour, O.; Bochet, O.; Le Borgne, T.

    2014-12-01

    Interpretation of push-pull data is limited by the absence of a clearly defined length scale, information on subsurface heterogeneity, and the assumption that ambient flow is negligible. We address these issues through a series of push-pull experiments with saline and deionized tracers at a granitic experimental research site in Ploemeur, France. The experiments involve different injection fractures, chaser volumes and resting times. Monitoring is performed in a neighboring borehole (~6m away) by single-hole ground penetrating radar (GPR), in both moving and fixed antenna settings. The GPR borehole is isolated from the tracer using a flexible-liner. We clearly image the dominant fractures in which tracer transport takes place and the spatial extent of the tracer plume at different times, which varies from a few meters to more than 10 meters away from the injection point. The differences between time-lapse images are subtle and consistent and in good agreement with the concentration data. We identify fractures in which the tracer is trapped for longer time periods and postulate that these fractures are partly responsible for the observed tailing behavior. By increasing the chasing volume, we see the tracer moving further away from the injection point and occupying different fractures, but our ability to image the tracer retrieval is decreased. By varying the resting time of a given experiment we identify regions of density-driven flow, heterogeneous advection, and ambient flow. Deionized water minimizes density effects, but the response is more quickly attenuated compared with saline tracers. The fixed antenna acquisitions provide data of unprecedented quality that display temporal dynamics in agreement with the concentration data down to very low concentrations. This data set offers very exciting perspectives for coupled hydrogeophysical inversion aimed at understanding anomalous transport in fractured rock formations.

  11. Electrical Resistivity Tomography and Ground Penetrating Radar for locating buried petrified wood sites: a case study in the natural monument of the Petrified Forest of Evros, Greece

    NASA Astrophysics Data System (ADS)

    Vargemezis, George; Diamanti, Nectaria; Tsourlos, Panagiotis; Fikos, Ilias

    2014-05-01

    A geophysical survey was carried out in the Petrified Forest of Evros, the northernmost regional unit of Greece. This collection of petrified wood has an age of approximately 35 million years and it is the oldest in Greece (i.e., older than the well-known Petrified Forest of Lesvos island located in the North Aegean Sea and which is possibly the largest of the petrified forests worldwide). Protection, development and maintenance projects still need to be carried out at the area despite all fears regarding the forest's fate since many petrified logs remain exposed both in weather conditions - leading to erosion - and to the public. This survey was conducted as part of a more extensive framework regarding the development and protection of this natural monument. Geophysical surveying has been chosen as a non-destructive investigation method since the area of application is both a natural ecosystem and part of cultural heritage. Along with electrical resistivity tomography (ERT), ground penetrating radar (GPR) surveys have been carried out for investigating possible locations of buried fossilized tree trunks. The geoelectrical sections derived from ERT data in combination with the GPR profiles provided a broad view of the subsurface. Two and three dimensional subsurface geophysical images of the surveyed area have been constructed, pointing out probable locations of petrified logs. Regarding ERT, petrified trunks have been detected as high resistive bodies, while lower resistivity values were more related to the surrounding geological materials. GPR surveying has also indicated buried petrified log locations. As these two geophysical methods are affected in different ways by the subsurface conditions, the combined use of both techniques enhanced our ability to produce more reliable interpretations of the subsurface. After the completion of the geophysical investigations of this first stage, petrified trunks were revealed after a subsequent excavation at indicated

  12. Estimations of paleochannel geometry and discharge using Ground Penetrating Radar (GPR) on terraces of the Le Sueur River, south-central Minnesota

    NASA Astrophysics Data System (ADS)

    Targos, C. A.; Gran, K. B.

    2014-12-01

    Paleo channels, preserved on terraces via meander cutoffs during an incisional period, record the channel geometry and thus discharge throughout a river's history. We measured paleochannel geometry on terraces throughout the Le Sueur River in south-central Minnesota, to track how channel geometry has changed throughout the last 13,400 years. A rapid drop in base level 13,400 yr B.P. triggered knickpoint migration and valley incision that is ongoing today. Since the 1800's, the area has developed rapidly with an increase in agriculture and the amount of tile drainage, directly impacting river discharge by increasing water input to the river. Five paleochannels were identified on terraces along the Le Sueur River from 1m-resolution lidar data. Ground Penetrating Radar (GPR) was used to obtain a subsurface image across paleo-meanders to estimate the geometry of paleochannels. By measuring the geometry of paleochannels, we can compare the channel geometry and effective discharge at the time the terrace was being carved to today's conditions. Three lines were run across each paleo-channel perpendicular to the historic water flow. Each of the 15 lines were "processed" using the EKKO Project 2 software supplied by Sensors and Software to sharpen the images, making it easier to identify the paleo channel geometry. OSL samples were collected from overbank deposits to determine the time of channel abandonment. Paleo discharge accompanied with depositional ages provide a history of flow conditions on the Le Sueur River. Preliminary results suggest the river channel has widened and increased in depth with time. This implies that the increase in agriculture and tile drainage since the area's development has negatively impacted the Le Sueur River resulting in a change in channel morphometry more conducive to erosion along the bluffs and banks. This increase in erosion has directly impacted the amount of sediment delivered to the rivers from banks and bluffs, increasing the

  13. Locating Desired Source Rocks by Using Shallow Ground Penetrating Radar and Seismic Survey Methods in western Washington, Pacific Northwest of the U.S

    NASA Astrophysics Data System (ADS)

    Cakir, R.; Meng, X.; Butler, Q.; Jenkins, J.; Keck, J.; Walsh, T. J.

    2015-12-01

    The Washington State Department of Natural Resources (WADNR) manages 2.1 million acres of forested state trust lands in Washington. WADNR sells timber and other agricultural products to help fund local services and the construction of institutions such as public schools and universities. Quality of rocks used as a surface on the roads built to access the timber is the essential and selecting appropriate rock quarry locations is challenging. Traditional borehole drilling methods only provide information from discrete locations. The study was conducted in the Capitol Forest area of western Washington. In our previous study, we suggested that a combination of P-wave seismic and ground penetrating radar (GPR) can be a rapid, comprehensive and cost effective alternative for identifying desired rock sources. In this study, we further improved upon that method and accomplished the following: 1) rock quality at a relatively fine resolution was distinguished and 2) the spatial variability of the rock was identified. Both 450 MHz and 80 MHz GPR antennas were used to obtain high resolution radargrams in the near-surface zone with 5m maximum penetration depth and lower resolution radargrams in the deeper subsurface zone with about 20m maximum penetration depth. We then correlated the GPR radargrams with P-wave velocities using the refraction survey data as well as S-wave velocities, estimated using Multi-Channel Analysis of Surface Waves (MASW) survey data. Additionally, nearby test pits and boreholes (maximum depth = 15 meters) were used to confirm the geophysical measurements. Our study results demonstrate that the combination of GPR, using the two antennas, and seismic surveys provides very useful subsurface information regarding quality and spatial distribution of the rocks beneath the overburden. Subsurface images gathered from these combined geophysical methods do assist quarry operators to rapidly locate the desired rock sources.

  14. Classification of freshwater ice conditions on the Alaskan Arctic Coastal Plain using ground penetrating radar and TerraSAR-X satellite data

    USGS Publications Warehouse

    Jones, Benjamin M.; Gusmeroli, Alessio; Arp, Christopher D.; Strozzi, Tazio; Grosse, Guido; Gaglioti, Benjamin V.; Whitman, Matthew S.

    2013-01-01

    Arctic freshwater ecosystems have responded rapidly to climatic changes over the last half century. Lakes and rivers are experiencing a thinning of the seasonal ice cover, which may increase potential over-wintering freshwater habitat, winter water supply for industrial withdrawal, and permafrost degradation. Here, we combined the use of ground penetrating radar (GPR) and high-resolution (HR) spotlight TerraSAR-X (TSX) satellite data (1.25 m resolution) to identify and characterize floating ice and grounded ice conditions in lakes, ponds, beaded stream pools, and an alluvial river channel. Classified ice conditions from the GPR and the TSX data showed excellent agreement: 90.6% for a predominantly floating ice lake, 99.7% for a grounded ice lake, 79.0% for a beaded stream course, and 92.1% for the alluvial river channel. A GIS-based analysis of 890 surface water features larger than 0.01 ha showed that 42% of the total surface water area potentially provided over-wintering habitat during the 2012/2013 winter. Lakes accounted for 89% of this area, whereas the alluvial river channel accounted for 10% and ponds and beaded stream pools each accounted for <1%. Identification of smaller landscape features such as beaded stream pools may be important because of their distribution and role in connecting other water bodies on the landscape. These findings advance techniques for detecting and knowledge associated with potential winter habitat distribution for fish and invertebrates at the local scale in a region of the Arctic with increasing stressors related to climate and land use change.

  15. Ground penetrating radar evaluation of the internal structure of fluvial tufa deposits (Dévanos-Añavieja system, NE Spain): an approach to different scales of heterogeneity

    NASA Astrophysics Data System (ADS)

    Pueyo Anchuela, Ó.; Luzón, A.; Pérez, A.; Muñoz, A.; Mayayo, M. J.; Gil Garbi, H.

    2016-07-01

    The Quaternary Añavieja-Dévanos tufa system is located in the northern sector of the Iberian Chain. It has been previously tackled by means sedimentological studies focused on the available outcrops and some boreholes. They have permitted the proposal of a sedimentary scenario that fits with a pool-barrage fluvial tufa model. However a better knowledge of the characteristics and internal distribution of the usually non-outcropping pool deposits as well as of its relationship with barrage deposits has not been evaluated in detail yet. Palaeoenvironmental studies on tufas are usually biased because tufas are commonly delicate facies exposed to intense erosion during water level fall stages; for this reason outcrops are usually scarce and very often coincide with the most cemented barrage deposits. In order to analyse the internal characteristics of the tufa deposits under study, but also the lateral correlation among different facies, ground penetrating radar (GPR) has been employed both for the evaluation of its applicability in such kind of environments and to improve, if possible, the sedimentary model using geophysical data in sectors without outcrops. A GPR survey including different antennas ranging from 50 to 500 MHz along different sectors and its comparison with natural outcrops has been carried out. GPR results have permitted to deduce clear differences between pool and barrage deposits and to recognise its internal structure and geometrical relationships. The survey also permitted an approach to different scales of heterogeneities in the radarfacies evaluation by using distinct antennas and therefore, reaching different resolutions and penetrations. The resulting integration from different antennas allows three different attenuant and eight reflective radarfacies to be defined permitting a better approach to the real extension of the pool areas. These results have permitted to decipher the horizontal and vertical facies changes and the identification of

  16. Joint estimation of soil moisture profile and hydraulic parameters by ground-penetrating radar data assimilation with maximum likelihood ensemble filter

    NASA Astrophysics Data System (ADS)

    Tran, Anh Phuong; Vanclooster, Marnik; Zupanski, Milija; Lambot, Sébastien

    2014-04-01

    Ground-Penetrating Radar (GPR) has recently become a powerful geophysical technique to characterize soil moisture at the field scale. We developed a data assimilation scheme to simultaneously estimate the vertical soil moisture profile and hydraulic parameters from time-lapse GPR measurements. The assimilation scheme includes a soil hydrodynamic model to simulate the soil moisture dynamics, a full-wave electromagnetic wave propagation model, and petrophysical relationship to link the state variable with the GPR data and a maximum likelihood ensemble assimilation algorithm. The hydraulic parameters are estimated jointly with the soil moisture using a state augmentation technique. The approach allows for the direct assimilation of GPR data, thus maximizing the use of the information. The proposed approach was validated by numerical experiments assuming wrong initial conditions and hydraulic parameters. The synthetic soil moisture profiles were generated by the Hydrus-1D model, which then were used by the electromagnetic model and petrophysical relationship to create "observed" GPR data. The results show that the data assimilation significantly improves the accuracy of the hydrodynamic model prediction. Compared with the surface soil moisture assimilation, the GPR data assimilation better estimates the soil moisture profile and hydraulic parameters. The results also show that the estimated soil moisture profile in the loamy sand and silt soils converge to the "true" state more rapidly than in the clay one. Of the three unknown parameters of the Mualem-van Genuchten model, the estimation of n is more accurate than that of α and Ks. The approach shows a great promise to use GPR measurements for the soil moisture profile and hydraulic parameter estimation at the field scale.

  17. Sedimentological and geophysical studies of clastic reservoir analogs: Methods, applications and developments of ground-penetrating radar for determination of reservoir geometries in near-surface settings. Final report

    SciTech Connect

    McMechan, G.A.; Soegaard, K.

    1998-05-25

    An integrated sedimentologic and GPR investigation has been carried out on a fluvial channel sandstone in the mid-Cretaceous Ferron Sandstone at Coyote Basin along the southwestern flank of the San Rafael Uplift in east-central Utah. This near-surface study, which covers a area of 40 {times} 16.5 meters to a depth of 15 meters, integrates detailed stratigraphic data from outcrop sections and facies maps with multi-frequency 3-D GPR surveys. The objectives of this investigation are two-fold: (1) to develop new ground-penetrating radar (GPR) technology for imaging shallow subsurface sandstone bodies, and (2) to construct an empirical three-dimensional sandstone reservoir model suitable for hydrocarbon flow-simulation by imaging near-surface sandstone reservoir analogs with the use of GPR. The sedimentological data base consists of a geologic map of the survey area and a detailed facies map of the cliff face immediately adjacent to the survey area. Five vertical sections were measured along the cliff face adjacent to the survey area. In addition, four wells were cored within the survey area from which logs were recorded. In the sections and well logs primary sedimentary structures were documented along with textural information and permeability data. Gamma-ray profiles were also obtained for all sections and core logs. The sedimentologic and stratigraphic information serves as the basis from which much of the processing and interpretation of the GPR data was made. Three 3-D GPR data sets were collected over the survey area at frequencies of 50 MHZ, 100 MHZ, and 200 MHZ.

  18. Inference of multi-Gaussian property fields by probabilistic inversion of crosshole ground penetrating radar data using an improved dimensionality reduction

    NASA Astrophysics Data System (ADS)

    Hunziker, Jürg; Laloy, Eric; Linde, Niklas

    2016-04-01

    Deterministic inversion procedures can often explain field data, but they only deliver one final subsurface model that depends on the initial model and regularization constraints. This leads to poor insights about the uncertainties associated with the inferred model properties. In contrast, probabilistic inversions can provide an ensemble of model realizations that accurately span the range of possible models that honor the available calibration data and prior information allowing a quantitative description of model uncertainties. We reconsider the problem of inferring the dielectric permittivity (directly related to radar velocity) structure of the subsurface by inversion of first-arrival travel times from crosshole ground penetrating radar (GPR) measurements. We rely on the DREAM_(ZS) algorithm that is a state-of-the-art Markov chain Monte Carlo (MCMC) algorithm. Such algorithms need several orders of magnitude more forward simulations than deterministic algorithms and often become infeasible in high parameter dimensions. To enable high-resolution imaging with MCMC, we use a recently proposed dimensionality reduction approach that allows reproducing 2D multi-Gaussian fields with far fewer parameters than a classical grid discretization. We consider herein a dimensionality reduction from 5000 to 257 unknowns. The first 250 parameters correspond to a spectral representation of random and uncorrelated spatial fluctuations while the remaining seven geostatistical parameters are (1) the standard deviation of the data error, (2) the mean and (3) the variance of the relative electric permittivity, (4) the integral scale along the major axis of anisotropy, (5) the anisotropy angle, (6) the ratio of the integral scale along the minor axis of anisotropy to the integral scale along the major axis of anisotropy and (7) the shape parameter of the Matérn function. The latter essentially defines the type of covariance function (e.g., exponential, Whittle, Gaussian). We present

  19. Computational modeling of on-contact antennas for the detection and localization of anti-personnel landmines via ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Hines, Margery Jeanne

    Ground-penetrating radar (GPR) is a mature technology which has developed into a popular tool for subsurface imaging; however its application in landmine detection is still in its infancy. Landmines are typically buried in dispersive soils below a rough surface where the effectiveness of conventional air-coupled GPR is limited. By utilizing ground-contact antennas the signal penetration is dramatically improved and data analysis is simplified. In order to canvas an area while achieving ground-contact with the antennas, this research proposes that the antennas be mounted to the bottom of the feet of a walking robotic platform developed by Square One Systems Design, called the Tri-Sphere Multi-Mode Mobility Platform. Using three antennas in both the transmitting and receiving modes, three unique bistatic GPR traces can be obtained from which a novel anti-personnel landmine detection and localization method is proposed. For each GPR trace, the target reflection is enhanced using circular polarization and is extracted using background removal. The full-path travel times are then determined by correlating the target reflections with a reference signal. These travel times are used to geometrically determine the target position to a single subsurface scattering point, which is identified as the potential target location. This detection method is fully autonomous, thereby allowing the robot to canvas a large amount of area and mark potential threats without any human interaction. Using a 3-dimensional finite-difference time domain model, GPR data is simulated for sixteen statistically different rough surfaces, nine different target locations, and two target casings, amounting to 288 unique simulations. The soil modeled is 10% wet Bosnian soil, which is both lossy and dispersive. For comparison, the various simulations are analyzed with both the exact simulated background response and the statistically approximated background response. Ultimately, using the approximated

  20. Microgravimetric and ground penetrating radar geophysical methods to map the shallow karstic cavities network in a coastal area (Marina Di Capilungo, Lecce, Italy)

    NASA Astrophysics Data System (ADS)

    Leucci, Giovanni; De Giorgi, Lara

    2010-06-01

    The coastal area Marina di Capilungo located ~50km south-west of Lecce (Italy) is one of the sites at greatest geological risk in the Salento peninsula. In the past few decades, Marina di Capilungo has been affected by a series of subsidence events, which have led in some cases to the partial collapse of buildings and road surfaces. These events had both social repercussions, causing alarm and emergency situations, and economic ones in terms of the funds for restoration. With the aim of mapping the subsurface karstic features, and so to assess the dimensions of the phenomena in order to prevent and/or limit the ground subsidence events, integrated geophysical surveys were undertaken in an area of ~70000m2 at Marina di Capilungo. Large volume voids such as karstic cavities are excellent targets for microgravity surveys. The absent mass of the void creates a quantifiable disturbance in the earth's gravitational field, with the magnitude of the disturbance directly proportional to the volume of the void. Smaller shallow voids can be detected using ground-penetrating radar (GPR). Microgravimetric and GPR geophysical methods were therefore used. An accurate interpretation was obtained using small station spacing and accurate geophysical data processing. The interpretation was facilitated by combining the modelling of the data with the geological and topographic information for explored caves. The GPR method can complement the microgravimetric technique in determining cavity depths and in verifying the presence of off-line features and numerous areas of small cavities, which may be difficult to be resolved with only microgravimetric data. However, the microgravimetric can complement GPR in delineating with accuracy the shallow cavities in a wide area where GPR measurements are difficult. Furthermore, microgravity surveys in an urban environment require effective and accurate consideration of the effects given by infrastructures, such as buildings, as well as those given

  1. Airborne laser scan measurements of winter snow accumulation in high alpine catchments - hydrological implications and verification by ground penetrating radar at glacier surface

    NASA Astrophysics Data System (ADS)

    Helfricht, K.; Keuschnig, M.; Heilig, A.; Mayer, C.; Kuhn, M.

    2012-04-01

    hydrological modeling. Due to ice dynamic processes, elevation changes observed by ALS at glacier surface can locally deviate from real snow depths. To account for these processes, two field campaigns were conducted along with the ALS flights to determine the snow depths utilizing ground penetrating radar (GPR), snow probing and snow pits. Geo-referenced GPR profiles were calibrated to measurements of snow depth at the snow pit locations and by snow probing data. Hence, the GPR measurements are a continuous source of snow depths along defined tracks. These data were compared to ALS obtained snow depths. Differences caused by ice dynamic processes are mainly located at higher glacier elevations. Close to the glacier tongue, variations between elevation changes of ALS and GPR determined snow depths are much smaller and irregularly distributed around zero.

  2. Probing the Architecture of the Weathering Zone in a Tropical System in the Rio Icacos Watershed (Puerto Rico) With Drilling and Ground Penetrating Radar (GPR)

    NASA Astrophysics Data System (ADS)

    Orlando, J.; Comas, X.; Mount, G. J.; Brantley, S. L.

    2012-12-01

    Weathering processes in rapidly eroding systems such as humid tropical environments are complex and not well understood. The interface between weathered material (regolith) and non-weathered material (bedrock) is particularly important in these systems as it influences water infiltration and groundwater flow paths and movement. Furthermore, the spatial distribution of this interface is highly heterogeneous and difficult to image with conventional techniques such as direct coring and drilling. In this work we present results from a preliminary geophysical study in the Luquillo Critical Zone Observatory (LCZO) located in the rain forest in the Luquillo Mountains of northeastern Puerto Rico. The Luquillo Mountains are composed of volcaniclastic rocks which have been uplifted and metamorphosed by the Tertiary Rio Blanco quartz diorite intrusion. The Rio Blanco quartz diorite weathers spheroidally, creating corestones of relatively unweathered material that are surrounded by weathered rinds. A number of boreholes were drilled near the top of the Rio Icacos watershed, where the corestones are thought to be in the primary stages of formation, to constrain the regolith/bedrock interface and to provide an understanding of the depth to which corestones form. The depth of the water table was also a target goal in the project. Drilling reveals that corestones are forming in place, separated by fractures, even to depths of 10s of meters below ground surface. One borehole was drilled to a depth of about 25 meters and intersected up to 7 bedrock blocks (inferred to be incipient corestones) and the water table was measured at about 15 meters. Ground Penetrating Radar surveys were conducted in the same location to determine if GPR images variable thicknesses of saprolite overlying corestones. GPR common offset measurements and common midpoint surveys with 50, 100, and 200 MHz antenna frequencies were combined with borehole drillings in order to constrain geophysical results. We

  3. High-resolution ground-penetrating radar monitoring of soil moisture dynamics: Field results, interpretation, and comparison with unsaturated flow model

    NASA Astrophysics Data System (ADS)

    Steelman, Colby M.; Endres, Anthony L.; Jones, Jon P.

    2012-09-01

    Surface ground-penetrating radar (GPR) techniques have been used by a number of previous researchers to characterize soil moisture content in the vadose zone. However, limited temporal sampling and low resolution near the surface in these studies greatly impedes the quantitative analysis of vertical soil moisture distribution and its associated dynamics within the shallow subsurface. To further examine the capacity of surface GPR, we have undertaken an extensive 26 month field study using concurrent high-frequency (i.e., 900 MHz) reflection profiling and common-midpoint (CMP) soundings to quantitatively monitor soil moisture distribution and dynamics within the shallow vadose zone. This unprecedented data set allowed us to assess the concurrent use of these techniques over two contrasting annual cycles of soil conditions. Reflection profiles provided high-resolution traveltime data between four stratigraphic reflection events while cumulative results of the CMP sounding data set produced precise depth estimates for those reflecting interfaces, which were used to convert interval-traveltime data into soil moisture. The downward propagation of major infiltration episodes associated with seasonal and transient events are well resolved by the GPR data. The use of CMP soundings permitted the determination of direct ground wave velocities, which provided high-resolution information along the air-soil interface. This improved resolution enabled better characterization of short-duration wetting/drying and freezing/thawing processes, and permitted better evaluation of the nature of the coupling between shallow and deep moisture conditions. The nature of transient infiltration pulses, evapotranspiration episodes, and deep drainage patterns observed in the GPR data series were further examined by comparing them with a vertical soil moisture flow simulation based on the variably saturated model, HYDRUS-1D. Using laboratory-derived soil hydraulic property information from soil

  4. Deciphering Deposits: Using Ground Penetrating Radar and Numerical Modeling to Characterize the Emplacement Mechanisms and Associated Energetics of Scoria Cone Eruption and Construction

    NASA Astrophysics Data System (ADS)

    Courtland, Leah M.

    Our understanding of tephra depositional processes is significantly improved by high-resolution ground-penetrating radar (GPR) data collected at Cerro Negro volcano, Nicaragua. The data reveal three depositional regimes: (1) a near-vent region on the cone itself, where 10 GPR radargrams collected on the western flank show quantifiable differences between facies formed from low energy normal Strombolian and higher energy violent Strombolian processes, indicating imaging of scoria cone deposits may be useful in distinguishing eruptive style in older cones where the proximal to distal tephra blanket has eroded away; (2) a proximal zone in which horizons identified in crosswind profiles collected at distances of 700 and 1,000 m from the vent exhibit Gaussian distributions with a high degree of statistical confidence, with tephra thickness decreasing exponentially downwind from the cone base (350 m) to ~ 1,200 m from the vent, and where particles fall from a height of less than ~2 km; and (3) a medial zone, in which particles fall from ~4 to 7 km and the deposit is thicker than expected based on thinning trends observed in the proximal zone of the deposit, indicating a transition from sedimentation dominated by fallout from plume margins to that dominated by fallout from the buoyant eruption cloud. Horizons identified in a crosswind profile at 1600 m from vent exhibit Gaussian distributions, again with high degrees of statistical confidence. True diffusion coefficients are calculated from Gaussian fits of crosswind profiles and do not show any statistical variation between zones (2) and (3). Data display thinning trends that agree with the morphology predicted by the advection-diffusion equation to a high degree of statistical confidence, validating the use of this class of models in tephra forecasting. One such model, the Tephra2 model, is reformulated for student use. A strategy is presented for utilizing this research-caliber model to introduce university

  5. Characterizing targets and backgrounds for 3D laser radars

    NASA Astrophysics Data System (ADS)

    Steinvall, Ove K.; Larsson, Hakan; Gustafsson, Frank; Chevalier, Tomas R.; Persson, Asa; Klasen, Lena M.

    2004-12-01

    Exciting development is taking place in 3 D sensing laser radars. Scanning systems are well established for mapping from airborne and ground sensors. 3 D sensing focal plane arrays (FPAs) enable a full range and intensity image can be captured in one laser shot. Gated viewing systems also produces 3 D target information. Many applications for 3 D laser radars are found in robotics, rapid terrain visualization, augmented vision, reconnaissance and target recognition, weapon guidance including aim point selection and others. The net centric warfare will demand high resolution geo-data for a common description of the environment. At FOI we have a measurement program to collect data relevant for 3 D laser radars using airborne and tripod mounted equipment for data collection. Data collection spans from single pixel waveform collection (1 D) over 2 D using range gated imaging to full 3 D imaging using scanning systems. This paper will describe 3 D laser data from different campaigns with emphasis on range distribution and reflections properties for targets and background during different seasonal conditions. Example of the use of the data for system modeling, performance prediction and algorithm development will be given. Different metrics to characterize the data set will also be discussed.

  6. The 3D laser radar vision processor system

    NASA Technical Reports Server (NTRS)

    Sebok, T. M.

    1990-01-01

    Loral Defense Systems (LDS) developed a 3D Laser Radar Vision Processor system capable of detecting, classifying, and identifying small mobile targets as well as larger fixed targets using three dimensional laser radar imagery for use with a robotic type system. This processor system is designed to interface with the NASA Johnson Space Center in-house Extra Vehicular Activity (EVA) Retriever robot program and provide to it needed information so it can fetch and grasp targets in a space-type scenario.

  7. Application of ground-penetrating radar, digital optical borehole images, and cores for characterization of porosity hydraulic conductivity and paleokarst in the Biscayne aquifer, southeastern Florida, USA

    USGS Publications Warehouse

    Cunningham, K.J.

    2004-01-01

    This paper presents examples of ground-penetrating radar (GPR) data from two study sites in southeastern Florida where karstic Pleistocene platform carbonates that comprise the unconfined Biscayne aquifer were imaged. Important features shown on resultant GPR profiles include: (1) upward and lateral qualitative interpretative distribution of porosity and hydraulic conductivity; (2) paleotopographic relief on karstic subaerial exposure surfaces; and (3) vertical stacking of chronostratigraphic high-frequency cycles (HFCs). These characteristics were verified by comparison to rock properties observed and measured in core samples, and identified in digital optical borehole images. Results demonstrate that an empirical relation exists between measured whole-core porosity and hydraulic conductivity, observed porosity on digital optical borehole images, formation conductivity, and GPR reflection amplitudes-as porosity and hydraulic conductivity determined from core and borehole images increases, formation conductivity increases, and GPR reflection amplitude decreases. This relation allows for qualitative interpretation of the vertical and lateral distribution of porosity and hydraulic conductivity within HFCs. Two subtidal HFCs in the uppermost Biscayne aquifer have significantly unique populations of whole-core porosity values and vertical hydraulic conductivity values. Porosity measurements from one cycle has a median value about two to three times greater than the values from the other HFC, and median values of vertical hydraulic-conductivity about three orders of magnitude higher than the other HFC. The HFC with the higher porosity and hydraulic conductivity values is shown as a discrete package of relatively low-amplitude reflections, whereas the HFC characterized by lower porosity and hydraulic-conductivity measurements is expressed by higher amplitude reflections. Porosity and hydraulic-conductivity values measured from whole-core samples, and vuggy porosity

  8. Accumulation Rate Variability and Winter Mass Balance Estimates using High Frequency Ground-Penetrating Radar and Snow Pit Stratigraphy on the Juneau Icefield, Alaska

    NASA Astrophysics Data System (ADS)

    Braddock, S. S.; Boucher, A. L.; Sandler, H. C.; McNeil, C.; Campbell, S. W.; Kreutz, K. J.

    2012-12-01

    In July 2012, 200 km of 400 MHz ground-penetrating radar (GPR) profiles were collected across the Juneau Icefield, Alaska. The goal was to determine if spatial accumulation rate variability and winter mass balance estimates could be improved by linking stratigraphic features between yearly-excavated snow pits through GPR. Profiles were collected along the centerline and cross sections of the main branch, northwest, and Southwest branch of the Taku Glacier as well as the Mathes, Llewellyn, and Demorest Glaciers. Over 650 km^2 of area and 1000 m of elevation range were covered during this pilot project linking sixteen snow pits with GPR data across the icefield. The field work was conducted as part of the Juneau Icefield Research Program (JIRP) with hopes of continuing this method in future years if first year results show promise. As an annually operated field research and education program, JIRP creates a unique opportunity to provide significant future contributions to Alaska mass balance records if the program is continued. Signal penetration reached ≤ 25 m with maximum depths reached at higher elevations of the icefield. Conversely, minimal penetration occurred in wetter regions at lower elevations, likely caused by volume scattering from free water within the firn and ice. Ice lenses and the annual layer located in mass balance snow pits correlated well with continuous stratigraphy imaged in GPR profiles suggesting that the lenses are relatively uninterrupted across the icefield and that GPR may be an appropriate tool for extrapolating point mass balance pit depths in this part of Alaska. The Northwest and Southwest Branches of the Taku Glacier show a strong stratigraphic thinning gradient, west to east; the main trunk of the Taku Glacier which originates from the Mathes-Llewellyn ice divide showed a similar thinning from the divide to the ELA. The thinning displayed by all three glacier systems matches a typical gradient from accumulation zone to ELA

  9. Analysis of Approximations and Aperture Distortion for 3D Migration of Bistatic Radar Data with the Two-Step Approach

    NASA Astrophysics Data System (ADS)

    Zanzi, Luigi; Lualdi, Maurizio

    2010-12-01

    The two-step approach is a fast algorithm for 3D migration originally introduced to process zero-offset seismic data. Its application to monostatic GPR (Ground Penetrating Radar) data is straightforward. A direct extension of the algorithm for the application to bistatic radar data is possible provided that the TX-RX azimuth is constant. As for the zero-offset case, the two-step operator is exactly equivalent to the one-step 3D operator for a constant velocity medium and is an approximation of the one-step 3D operator for a medium where the velocity varies vertically. Two methods are explored for handling a heterogeneous medium; both are suitable for the application of the two-step approach, and they are compared in terms of accuracy of the final 3D operator. The aperture of the two-step operator is discussed, and a solution is proposed to optimize its shape. The analysis is of interest for any NDT application where the medium is expected to be heterogeneous, or where the antenna is not in direct contact with the medium (e.g., NDT of artworks, humanitarian demining, radar with air-launched antennas).

  10. The science case for the EISCAT_3D radar

    NASA Astrophysics Data System (ADS)

    McCrea, Ian; Aikio, Anita; Alfonsi, Lucilla; Belova, Evgenia; Buchert, Stephan; Clilverd, Mark; Engler, Norbert; Gustavsson, Björn; Heinselman, Craig; Kero, Johan; Kosch, Mike; Lamy, Hervé; Leyser, Thomas; Ogawa, Yasunobu; Oksavik, Kjellmar; Pellinen-Wannberg, Asta; Pitout, Frederic; Rapp, Markus; Stanislawska, Iwona; Vierinen, Juha

    2015-12-01

    The EISCAT (European Incoherent SCATer) Scientific Association has provided versatile incoherent scatter (IS) radar facilities on the mainland of northern Scandinavia (the EISCAT UHF and VHF radar systems) and on Svalbard (the electronically scanning radar ESR (EISCAT Svalbard Radar) for studies of the high-latitude ionised upper atmosphere (the ionosphere). The mainland radars were constructed about 30 years ago, based on technological solutions of that time. The science drivers of today, however, require a more flexible instrument, which allows measurements to be made from the troposphere to the topside ionosphere and gives the measured parameters in three dimensions, not just along a single radar beam. The possibility for continuous operation is also an essential feature. To facilitatefuture science work with a world-leading IS radar facility, planning of a new radar system started first with an EU-funded Design Study (2005-2009) and has continued with a follow-up EU FP7 EISCAT_3D Preparatory Phase project (2010-2014). The radar facility will be realised by using phased arrays, and a key aspect is the use of advanced software and data processing techniques. This type of software radar will act as a pathfinder for other facilities worldwide. The new radar facility will enable the EISCAT_3D science community to address new, significant science questions as well as to serve society, which is increasingly dependent on space-based technology and issues related to space weather. The location of the radar within the auroral oval and at the edge of the stratospheric polar vortex is also ideal for studies of the long-term variability in the atmosphere and global change. This paper is a summary of the EISCAT_3D science case, which was prepared as part of the EU-funded Preparatory Phase project for the new facility. Three science working groups, drawn from the EISCAT user community, participated in preparing this document. In addition to these working group members, who

  11. The lost church of Montemurro (Basilicata, Italy): Ground Penetrating Radar and Electrical Resistivity Tomography for detecting its buried remains in S. Maria Square.

    NASA Astrophysics Data System (ADS)

    Bavusi, Massimo; Giocoli, Alessandro; de Martino, Gregory; Loperte, Antonio; Lapenna, Vincenzo

    2010-05-01

    Montemurro is a little centre town located in the Agri Valley (Basilicata Region, Italy) which was affected by two catastrophic events: in the 1842 a very large landslide has damaged great part of the centre and in the 1857 the town was destroyed completely by the "Great Neapolitan Earthquake" (Mallet, 1862), a seismic event having epicenter in the Agri Valley (Cello et al., 2003; Bavusi et al., 2004). Signs of those tragic events can be still found in the fabric of the city. One of these is certainly S. Maria square, a place suspected to house a church before the disastrous events of 1842. This suspicion is supported by a series of evidences: a historical drawing, dating back to before 1842, shows a church in position compatible with the location of the square; in aerial view S. Maria square appears as tear in the fabric of the city; the tales of the erderlies of Montemurro speak about an ancient missing church in the town. Then, in the attempt to resolve the doubt about the presence of the church, a geophysical survey was planned in S. Maria Square with the aim to detect some buried masonry structures related to the church. In this work we selected two active techniques such as the Ground Penetrating Radar (GPR) and the Electrical Resistivity Tomography (ERT). Sixty parallel GPR profiles 0.5 m spaced were gathered in S. Maria Square and in a contiguous street by using a GSSI SIR3000 system with a central frequency antenna of 200 MHz. Processed radargrams showed numerous reflectors and heterogeneities in the subsoil related to manmade objects. Then, a laborious data processing (Nuzzo et al., 2002) allowed to obtain several time-slices showing noticeable reflections compatible with masonry structures. Moreover, two ERT profiles were carried out by using an IRIS Syscal R2 system equipped with a multielectrode cable. The first ERT profile 86 m long and having 44 electrodes 2 m spaced allowed to investigate up to 9 m of depth. The second, overlapped on the previous

  12. What comes in must not come out - proglacial lake sedimentation patterns and trapping efficiency derived from ground penetrating radar and echo sounding

    NASA Astrophysics Data System (ADS)

    Otto, Jan-Christoph; Etzlsdorfer, Jürgen; Buckel, Johannes; Keuschnig, Markus; Griesebner, Gerald; Kum, Georg; Wiesenegger, Hans

    2016-04-01

    Since the late 1990s a proglacial lake developed following the retreat of the Obersulzbachkees glacier in the Austrian Alps. The lake formed behind a bedrock ridge at an altitude of 2,200 m covering an area of 152,000 m². Since its formation the lake is monitored by the local authorities that operate two runoff monitoring stations at the lake outlet stream. In a previous study sediment output from the lake was recorded during two years (2010/11). This study seeks to investigate sedimentation patterns and storage volumes in the lake using two different geophysical methods. The aim of the project is to assess sediment input and discuss the lake's impact on the fluvial sediment transport system of the valley. The study is part of the FUTURELAKE project that seeks to model the formation of new glacier lakes and their possible future evolution in the Austria Alps. We investigated lake morphology and lake sedimentation using ground penetrating radar (GPR) and echo sounding data from measurements in 2009 and 2015/16. GPR data was collected in winter on the frozen lake surface and in summer from a boat using different antenna frequencies (100/200 MHz). Lake morphology is best described as a bowl shaped hollow with a maximum length of 650 and a width of 460 m. The bowl has a flat bottom and asymmetrically shaped sides along the length axis with a steeper slope of more than 50° inclination towards the lake outlet and a gentler slope following an extended shallow shore area towards the glacier. The maximum depth of the lake decreased from 42.5 m to 35.6 m depicting lake sedimentation between 2009 and 2015. Two tributaries enter the lake from the south draining two parts of the decomposing Obersulzbachkees glacier. Sediment input from these creeks is responsible for delta formation at this end of the lake. Two other tributaries enter the lake on the longer sides from opposite directions (east and west) both draining other separated parts of the glacier ensemble. Sediment