Electromagnetic Inversion of GPR Signals and Subsequent Hydrodynamic Inversion to Estimate Effective Vadose Zone Hydraulic Properties

Lambot, Sébastien; Antoine, Michaël; Bosch, I. van den; Slob, Evert; Vanclooster, Marnik

doi:10.2136/vzj2004.1072

Cited by 47 publications

(16 citation statements)

References 56 publications

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“…Waveform inversion methods can theoretically incorporate all the information present in the reflected waveform and thus may provide a tool to reliably and accurately quantify thinlayer parameters. Previous research has demonstrated the efficacy of this approach using GPR reflection data for a variety of subsurface problems, including detecting contaminant infiltration (Kalogeropoulos et al, 2013), measuring soil water content (Lambot et al, 2004;Tran et al, 2012), and quantifying subsurface ε ef and conductivity (σ) (Klotzsche et al, 2010;Busch et al, 2012). However, problems such as the coupled nature of material properties, computing speed, and solution nonuniqueness can hinder the reliability of full-waveform inversion algorithms (Operto et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Reflection waveform inversion of ground-penetrating radar data for characterizing thin and ultrathin layers of nonaqueous phase liquid contaminants in stratified media

Babcock¹,

Bradford

2015

GEOPHYSICS

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Accurately quantifying thin-layer parameters by applying a targeted reflection waveform inversion methodology to ground-penetrating radar (GPR) reflection data may provide a useful tool for near-surface investigation and especially for contaminated site investigation where nonaqueous phase liquid (NAPL) contaminants are present. We implemented a targeted reflection waveform inversion algorithm to quantify thin-layer permittivity, thickness, and conductivity for NAPL thin (≤ 1∕2 dominant wavelength λ) and ultrathin (≤ 1∕8λ) layers using GPR reflection data. The inversion used a nonlinear grid search with a Monte Carlo scheme to initialize starting values to find the global minimum. By taking a targeted approach using a time window around the peak amplitude of the reflection event of interest, our algorithm reduced the complexity in the inverse problem. We tested the inversion on three different synthetic data sets and four field data sets. In all testing, the inversion solved for NAPL-layer properties within 15% of the measured values. This algorithm provides a tool for site managers to prioritize remediation efforts based on quantitative assessments of contaminant quantity and location using GPR.

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Section: Introductionmentioning

confidence: 99%

Reflection waveform inversion of ground-penetrating radar data for characterizing thin and ultrathin layers of nonaqueous phase liquid contaminants in stratified media

Babcock¹,

Bradford

2015

GEOPHYSICS

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“…Table 4.9 summarises studies on the application of ground penetrating radar in predicting soil variables. The papers of Huisman et al (2003) and Lambot et al (2004) on prediction of soil moisture content might be interesting. Results of validation experiments were lacking, however.…”

Section: Ground Penetrating Radarmentioning

confidence: 99%

A selection of sensing techniques for mapping soil hydraulic properties

Knotters

Egmond

Bakker

et al. 2017

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Data on soil hydraulic properties are needed as input for many models, such as models to predict unsaturated water movement and crop growth, and models to predict leaching of nutrients and pesticides to groundwater. The soil physics database of the Netherlands shows several lacunae, and a substantial part of the data were collected more than thirty years ago and thus might not represent actual soil hydraulic conditions. There is a need to fill lacunae in the soil physics dataset, to make the dataset up-to-date and to aggregate soil hydraulic properties observed at point scale to larger spatial units. The relationship between the unsaturated hydraulic conductivity K or the volumetric water content θ and the pressure head h can be described for example by equations such as the Mualem-Van Genuchten equations, the parameter values of which can be predicted from soil properties by using pedo-transfer functions. These soil properties include clay content, loam content, organic matter content and the median grain diameter of the sand fraction (50-2000 µm). Application of proximal sensing techniques in observing soil physics properties in the field might reduce the costs of data collection. The accuracy with which proximal sensing techniques can predict clay content, loam content, organic matter content and the median grain size of the sand fraction (50-2000 µm) needs to be assessed as these are the explanatory variables in the pedo-transfer functions. The aim of this study was to select on-the-go proximal sensing techniques that are able to quantify soil variables that are used in the pedo-transfer functions for prediction of the parameters of the Mualem-Van Genuchten equations. We conclude that near infrared spectrometry, γ-ray spectroscopy and electromagnetic induction methods have a potential in spatial prediction of clay, silt and sand content, and that near infrared spectrometry has a potential in spatial prediction of organic matter content and soil moisture content. The use of pedo-transfer functions requires also the parameters bulk density and median of the sand fraction (M50). Bulk density can be measured by a device called RhoC. However, its performance in predicting bulk density of terrestrial soils has not been validated yet. Most instruments are applied to measure fractions clay, silt and sand. The application of these instruments in the determination of M50 needs to be developed. Possibly the combination of specific surface area and fractions of fine and course sand can give an indication. On the other hand new pedo-transfer functions can be developed neglecting the M50 value while increasing the contribution of other explanatory variables.

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“…Using borehole antennae, one can characterize the subsurface to a substantial depth but of course limited to the space close to borehole locations. By comparison, off-ground GPR data can be acquired on large areas with a high spatial resolution and using only the first reflection amplitude variations or the ground wave, the water content variations from the very near-surface can be estimated (Grote et al, 2003;Lambot et al, 2004a;Lambot et al, 2004b;Lambot et al, 2006). Also, in a quite electrically resistive medium like sand, with no magnetic properties, surface-based GPR data can have a penetration depth of at least 10 wavelengths of the sounding wave (typically 1.5 m of penetration using a 800 MHz antenna).…”

Section: Introductionmentioning

confidence: 99%

Evaluating GroundPenetrating Radar use for water infiltration monitoring

Saintenoy

Schneider

Tucholka

2007

2007 4th International Workshop On, Advanced Ground Penetrating Radar

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Ground-Penetrating Radar (GPR) was tested to monitor water infiltration in sand. Water was injected down an 81 cm long tubed hole, with a piezometer recording the depth of water and a tap valve used to adjust it to 15 cm ± 2 cm above the bottom of the tube. During the 20 minutes of infiltration a GPR system recorded a trace every second with its transmitter and receiver antennae at a fixed offset position on the surface. The signal, enhanced by differential correction, allows for tracing the evolution of top and bottom limits of the water bulb in space and time. Comparison with hydrodynamic model of the infiltration process and simulated radargrams prove that the GPR reflections trace the wetting front and the saturation bulb. A quantified estimation of the evolution of the top border of the wetting zone is provided.

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Electromagnetic Inversion of GPR Signals and Subsequent Hydrodynamic Inversion to Estimate Effective Vadose Zone Hydraulic Properties

Cited by 47 publications

References 56 publications

Reflection waveform inversion of ground-penetrating radar data for characterizing thin and ultrathin layers of nonaqueous phase liquid contaminants in stratified media

Reflection waveform inversion of ground-penetrating radar data for characterizing thin and ultrathin layers of nonaqueous phase liquid contaminants in stratified media

A selection of sensing techniques for mapping soil hydraulic properties

Evaluating GroundPenetrating Radar use for water infiltration monitoring

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