Introduction to subsurface radar

Daniels, David J.; Gunton, D.J.; Scott, Howard F.

doi:10.1049/ip-f-1.1988.0038

Cited by 207 publications

(122 citation statements)

References 11 publications

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“…Surface-based GPR is a geophysical method based on the transmission and reflection of high frequency (1 MHz to 1 GHz) EM energy that is seeing wider use for shallow subsurface characterization (Daniels et al 1988;Davis and Annan 1989). In the typical surface-based GPR survey, data are acquired by transmitting an EM energy pulse into the subsurface and recording reflected energy at the surface with a receiver antenna.…”

Section: Surface-based Ground Penetrating Radarmentioning

confidence: 99%

Vadose Zone Transport Field Study: Summary Report

Ward¹,

Conrad²,

Daily³

et al. 2006

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SummaryA series of field studies were conducted at the Hanford Site, near Richland, Washington, from FY 2000 through FY 2003 at two different locations to develop data sets to test models of flow and transport in the vadose zone. The field studies were also done to investigate advanced monitoring techniques for evaluating flow-and-transport mechanisms and delineating contaminant plumes in the vadose zone at the Hanford Site. The studies were conducted as part of the Groundwater/Vadose Zone Integration Project Science and Technology Project, now known as the Remediation and Closure Science Project, managed by the Pacific Northwest National Laboratory (PNNL) and supported by the U.S. Department of Energy, Richland Operations Office. This report summarizes the key findings from the field studies and demonstrates how data collected from these studies are being used to improve conceptual models and develop numerical models of flow and transport in Hanford's vadose zone. Results from the field studies and associated analysis have appeared in more than 46 publications generated over the past 4 years. These publications include test plans and status reports in addition to numerous technical notes and papers.Two major field campaigns were performed, one at a well injection test site and a second at a clastic dike test site. Both field studies have resulted in field-scale transport parameters for Hanford conditions, which are useful for improving predictions of subsurface flow and transport at the Hanford Site. In addition, advanced geophysical methods, including high resolution electrical resistivity measurements, were successfully tested and are now being deployed at Hanford for subsurface investigations and tank retrieval detection. The most useful information gained from these studies has been a better understanding of flow and transport in the vadose zone, and this has been specifically related to the impact of small-scale stratigraphic features (e.g., sediment layering) on water flow and contaminant transport. Conceptual models have been developed that take into account the lateral spreading of water and contaminants observed in the field studies. Numerical models of unsaturated flow and transport have been revised to account for lateral spreading of subsurface contaminant plumes.The key results from these studies include: 1) Greater understanding of the complexity of plume migration in the vadose zone at Hanford. Finescale geologic heterogeneities, including grain fabric and lamination, were observed to have a strong effect on the large-scale behavior of contaminant plumes, primarily through increased lateral spreading resulting from anisotropy.2) Observations of anion exclusion in Hanford sediments. Anion exclusion is a mechanism by which negatively charged ions are repelled from the surfaces of negatively charged soil particles, thereby increasing their velocity. Thus, the travel time of ions like pertechnetate, the stable form of 99 Tc found in oxidized environments, may decrease over that of unsaturated water f...

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Section: Surface-based Ground Penetrating Radarmentioning

confidence: 99%

Vadose Zone Transport Field Study: Summary Report

Ward¹,

Conrad²,

Daily³

et al. 2006

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“…Detailed discussions of the fundamental principles of GPR can be found in the publications by Daniels et al [1988] and Davis and Annan [1989]. A single radar trace can be approximated by the convolution of the source EM pulse (or wavelet) with a series of reflection coefficients, defined at each subsurface interface as:…”

Section: Geostatistical Analysis Of Radar Reflection Imagesmentioning

confidence: 99%

The effect of vertical measurement resolution on the correlation structure of a ground penetrating radar reflection image

Knight

Tercier

Irving

2004

Geophysical Research Letters

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[1] Geostatistical analysis of a ground penetrating radar reflection image can be used to quantify the maximum correlation direction and the range of horizontal and subhorizontal radar reflections. A review of previous work, and an analysis of a photograph of layered sediments, suggest that the vertical resolution of a radar image strongly affects its lateral correlation structure. Numerical modeling was used to generate synthetic radar sections and investigate the effect of the vertical resolution of the radar measurement on the link between the correlation structure of the radar reflections and the true correlation structure of subsurface water content. The horizontal range of the radar reflections decreased as the vertical resolution improved, closely matching that of the water content when the vertical resolution was approximately equal to the vertical range of the water content.

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“…Information about the sub-surface can be extracted from the amplitude and time delay of these reflections. There are many applications that use GPR for sub-surface detection tasks such as archaeology, pipe and cable detection, geological profiling, buried landmine detection [5], snow thickness estimation and pavement evaluation [6].…”

Section: Introductionmentioning

confidence: 99%

Near-surface Interface Detection for Coal Mining Applications using Bispectral Features and GPR

Strange

Ralston

Chandran

2005

Subsurf Sens Technol Appl

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The use of ground penetrating radar (GPR) for detecting the presence of near-surface interfaces is a scenario of special interest to the underground coal mining industry. The problem is difficult to solve in practice because the radar echo from the near-surface interface is often dominated by unwanted components such as antenna crosstalk and ringing, ground-bounce effects, clutter, and severe attenuation. These nuisance components are also highly sensitive to subtle variations in ground conditions, rendering the application of standard signal pre-processing techniques such as background subtraction largely ineffective in the unsupervised case. As a solution to this detection problem, we develop a novel pattern recognition-based algorithm which utilizes a neural network to classify features derived from the bispectrum of 1D early time radar data. The binary classifier is used to decide between two key cases, namely whether an interface is within, for example, 5 cm of the surface or not. This go/no-go detection capability is highly valuable for underground coal mining operations, such as longwall mining, where the need to leave a remnant coal section is essential for geological stability. The classifier was trained and tested using real GPR data with ground truth measurements. The real data was acquired from a testbed with coalclay, coal-shale and shale-clay interfaces, which represents a test mine site. We show that, unlike traditional second order correlation based methods such as matched filtering which can fail even in known conditions, the new method reliably allows the detection of interfaces using GPR to be applied in the near-surface region. In this work, we are not addressing the problem of depth estimation, rather confining ourselves to detecting an interface within a particular depth range. KEY WORDSGPR, bispectrum, interface detection, horizon control, coal mining.

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Introduction to subsurface radar

Cited by 207 publications

References 11 publications

Vadose Zone Transport Field Study: Summary Report

Vadose Zone Transport Field Study: Summary Report

The effect of vertical measurement resolution on the correlation structure of a ground penetrating radar reflection image

Near-surface Interface Detection for Coal Mining Applications using Bispectral Features and GPR

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