Estimating hydrologic parameters from water table dynamics using coupled hydrologic and ground-penetrating radar inversion

Bradford, John H.; Thoma, Michael; Barrash, Warren

doi:10.1109/icgpr.2014.6970420

Cited by 5 publications

(5 citation statements)

References 7 publications

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“…Among the available geophysical tools, the Ground Penetrating Radar (GPR) is frequently used in geology in particular for shallow prospections requiring high resolution [1][2][3][4]. Over time, GPR has proven useful in soil studies [5], sedimentology [6], in fault and fracture characterization [7][8][9][10], in hydrogeology [11][12][13][14][15][16][17][18][19], and in archeological applications [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

GPR Detection of Fossil Structures in Conductive Media Supported by FDTD Modelling and Attributes Analysis: An Example from Early Pleistocene Marine Clay at Bargiano Site (Central Italy)

et al. 2021

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The application of Ground Penetrating Radar (GPR) prospecting to the search of fossil structures, particularly using advanced techniques like Finite-difference time-domain (FDTD) modelling and GPR attribute analysis, is currently poorly exploited in paleontology. Here, we promote the use of such a GPR workflow at Bargiano (Umbria, central Italy), a unique paleontological site known for the discovery of cetacean skeletons, dolomitized sperm-whale cololites (Ambergrisichnu salleronae), and layered fossil assemblages. The study site is characterized by a very uneven topography shaping highly conductive clayey deposits, representing not exactly ideal conditions for GPR surveying. After generating models encompassing a real topography and variable electrical properties of media, we simulated buried fossil structures at variable depth with different size and geometry, using different operative frequencies. After obtaining information on the characteristics of reflections, investigation depth, and detectability, we provide a comparison with experimental data, also used to compute instantaneous amplitude and phase attributes. Upon depicting a peculiar GPR signature for our targets, we discuss the results in light of ground-truthing performed through trenching. Our workflow allowed us to restrict the excavation areas, extending the surface information in depth in a non-invasive way, and optimizing the field operations, necessary for the preservation of the study site.

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Section: Introductionmentioning

confidence: 99%

GPR Detection of Fossil Structures in Conductive Media Supported by FDTD Modelling and Attributes Analysis: An Example from Early Pleistocene Marine Clay at Bargiano Site (Central Italy)

et al. 2021

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“…Dagenbach et al (2013) showed that this reflection is sensitive to the hydraulic material parameterization model. Bradford et al (2014) measured the transition zone reflection of a drainage pumping test in a fluvial area with a antenna center frequency of 200 MHz and estimated hydraulic material properties. Klenk et al (2015) employed numerical forward simulations and experiments using GPR antennas with higher antenna center frequency (400 and 600 MHz) for a more detailed explanation of the transition zone reflection during imbibition, relaxation, and drainage.…”

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confidence: 99%

Soil hydraulic material properties and subsurface architecture from time-lapse GPR

Jaumann

Roth

2017

Preprint

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Abstract. Quantitative knowledge of effective soil hydraulic material properties is essential to predict soil water movement.ground-penetrating radar (GPR) is a non-invasive and non-destructive geophysical measurement method to monitor the hydraulic processes precisely. Previous studies showed that the GPR signal from a fluctuating groundwater table is sensitive to the soil water characteristic and the hydraulic conductivity function. In this work, we show that this signal is suitable to accurately estimate the subsurface architecture and the associated effective soil hydraulic material properties with inversion 5 methods. Therefore, we parameterize the subsurface architecture, solve the Richards equation, convert the resulting water content to relative permittivity with the complex reflective index model (CRIM), and solve Maxwell's equations numerically. In order to analyze the GPR signal, we implemented a new heuristic event detection and association algorithm. Using events instead of the full wave regularizes the inversion as it allows to focus on the relevant measurement signal. Starting from an ensemble of Latin hypercube drawn initial parameter sets, we sequentially couple the simulated annealing algorithm with the 10 Levenberg-Marquardt algorithm. We apply the method to synthetic as well as measured data from the ASSESS test site and show that the method yields accurate estimates for the soil hydraulic material properties as well as for the subsurface architecture by comparing the results to references derived from time domain reflectometry (TDR) and subsurface architecture ground truth data.

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“…Many full waveform inversion approaches directly use the resulting Green's function (e.g., Lambot et al, 2009;Busch et al, 2012;Jadoon et al, 2012) in the cost function. Using the full antenna signal may lead to many local minima prohibiting a reliable identification of the global minimum (e.g., Bradford et al, 2014). In contrast, filtering the radargram with convolution approaches to determine travel time and amplitude of a limited number of events leads to better convergence and may even allow the application of efficient locally convergent algorithms (e.g., Buchner et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…Also simultaneous GPR measurements during the infiltration process are difficult, because the antenna coupling to the subsurface is influenced by the changing water content close to the surface. Fluctuating groundwater table experiments (e.g., Bradford et al, 2014;Léger et al, 2015) require intermediate timescales (hours to days) and provide information about the material properties close to the groundwater table. These experiments are typically limited to fluvial or coastal areas or are induced artificially in test sites.…”

Section: Introductionmentioning

confidence: 99%

“…Dagenbach et al (2013) showed that this reflection is sensitive to the hydraulic material parameterization model. Bradford et al (2014) measured the transition zone reflection of a drainage pumping test in a fluvial area with an antenna center frequency of 200 MHz and estimated hydraulic material properties. Klenk et al (2015) employed numerical forward simulations and experiments using GPR antennas with higher antenna center frequency (400 and 600 MHz) for a more-detailed explanation of the transition zone reflection during imbibition, equilibration, and drainage.…”

Section: Introductionmentioning

confidence: 99%

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Soil hydraulic material properties and layered architecture from time-lapse GPR

Jaumann

Roth

2018

Hydrol. Earth Syst. Sci.

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Abstract. Quantitative knowledge of the subsurface material distribution and its effective soil hydraulic material properties is essential to predict soil water movement. Groundpenetrating radar (GPR) is a noninvasive and nondestructive geophysical measurement method that is suitable to monitor hydraulic processes. Previous studies showed that the GPR signal from a fluctuating groundwater table is sensitive to the soil water characteristic and the hydraulic conductivity function. In this work, we show that the GPR signal originating from both the subsurface architecture and the fluctuating groundwater table is suitable to estimate the position of layers within the subsurface architecture together with the associated effective soil hydraulic material properties with inversion methods. To that end, we parameterize the subsurface architecture, solve the Richards equation, convert the resulting water content to relative permittivity with the complex refractive index model (CRIM), and solve Maxwell's equations numerically. In order to analyze the GPR signal, we implemented a new heuristic algorithm that detects relevant signals in the radargram (events) and extracts the corresponding signal travel time and amplitude. This algorithm is applied to simulated as well as measured radargrams and the detected events are associated automatically. Using events instead of the full wave regularizes the inversion focussing on the relevant measurement signal. For optimization, we use a global-local approach with preconditioning. Starting from an ensemble of initial parameter sets drawn with a Latin hypercube algorithm, we sequentially couple a simulated annealing algorithm with a Levenberg-Marquardt algorithm. The method is applied to synthetic as well as measured data from the ASSESS test site. We show that the method yields reasonable estimates for the position of the layers as well as for the soil hydraulic material properties by comparing the results to references derived from ground truth data as well as from time domain reflectometry (TDR).

show abstract

Estimating hydrologic parameters from water table dynamics using coupled hydrologic and ground-penetrating radar inversion

Cited by 5 publications

References 7 publications

GPR Detection of Fossil Structures in Conductive Media Supported by FDTD Modelling and Attributes Analysis: An Example from Early Pleistocene Marine Clay at Bargiano Site (Central Italy)

GPR Detection of Fossil Structures in Conductive Media Supported by FDTD Modelling and Attributes Analysis: An Example from Early Pleistocene Marine Clay at Bargiano Site (Central Italy)

Soil hydraulic material properties and subsurface architecture from time-lapse GPR

Soil hydraulic material properties and layered architecture from time-lapse GPR

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