Efficient Deconvolution of Ground-Penetrating Radar Data

Schmelzbach, Cédric; Huber, Emanuel

doi:10.1109/tgrs.2015.2419235

Cited by 30 publications

(18 citation statements)

References 55 publications

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“…Two geophysical methods have regularly been used for studying the glacier's hydrological systems, seismology (active and passive) and radar. Ground-penetrating-radar (GPR) has been used to detect englacial drainage systems in cold ice (Moorman and Michel, 2000;Stuart, 2003;Catania et al, 2008;Catania and Neumann, 2010;Schaap et al, 2019;Hansen et al, 2020) and temperate ice (Arcone and Yankielun, 2000;Hart et al, 2015). There exist only a small number of studies that investigate seasonal changes within the englacial hydrological network, and all of these have been undertaken on coldice glaciers.…”

Section: Introductionmentioning

confidence: 99%

“…Such studies have been conducted with an impulse ice-penetrating radar system within a cold-ice environment (Macgregor et al, 2011;Christianson et al, 2016); however no such analysis has been performed using a commercial GPR within a temperate ice environment or to characterise an englacial conduit network. In order to extract the reflectivity from a commercial GPR system, an inversion workflow can be implemented (Schmelzbach et al, 2012). Within a glaciological environment such an inversion workflow can provide constraints on temporal and spatial changes in glacier hydrology.…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, by performing GPR measurements across subsequent melt seasons, we can verify whether these englacial networks were reactivated after the winter period in a similar location or whether they close down and become inactive the following melt season. We detect these seasonal and annual changes by extracting the GPR reflection strength (reflectivity) using a GPR impedance inversion scheme (Schmelzbach et al, 2012). The spatial extent of the reflectivity patterns allows potential englacial flow paths to be imaged.…”

Section: Introductionmentioning

confidence: 99%

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Monitoring the seasonal changes of an englacial conduit network using repeated ground-penetrating radar measurements

et al. 2020

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Abstract. Englacial conduits act as water pathways to feed surface meltwater into the subglacial drainage system. A change of meltwater into the subglacial drainage system can alter the glacier's dynamics. Between 2012 and 2019, repeated 25 MHz ground-penetrating radar (GPR) surveys were carried out over an active englacial conduit network within the ablation area of the temperate Rhonegletscher, Switzerland. In 2012, 2016, and 2017 GPR measurements were carried out only once a year, and an englacial conduit was detected in 2017. In 2018 and 2019 the repetition survey rate was increased to monitor seasonal variations in the detected englacial conduit. The resulting GPR data were processed using an impedance inversion workflow to compute GPR reflection coefficients and layer impedances, which are indicative of the conduit's infill material. The spatial and temporal evolution of the reflection coefficients also provided insights into the morphology of the Rhonegletscher's englacial conduit network. During the summer melt seasons, we observed an active, water-filled, sediment-transporting englacial conduit network that yielded large negative GPR reflection coefficients (<-0.2). The GPR surveys conducted during the summer provided evidence that the englacial conduit was 15–20 m±6 m wide, ∼0.4m±0.35m thick, ∼250m±6m long with a shallow inclination (2∘), and having a sinusoidal shape from the GPR data. We speculate that extensional hydraulic fracturing is responsible for the formation of the conduit as a result of the conduit network geometry observed and from borehole observations. Synthetic GPR waveform modelling using a thin water-filled conduit showed that a conduit thickness larger than 0.4 m (0.3× minimum wavelength) thick can be correctly identified using 25 MHz GPR data. During the winter periods, the englacial conduit no longer transports water and either physically closed or became very thin (<0.1 m), thereby producing small negative reflection coefficients that are caused by either sediments lying within the closed conduit or water within the very thin conduit. Furthermore, the englacial conduit reactivated during the following melt season at an identical position as in the previous year.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Monitoring the seasonal changes of an englacial conduit network using repeated ground-penetrating radar measurements

et al. 2020

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“…An outline of the GPR CO processing is described in Table 2. It consists of the following major steps: (1-6) pre-processing by assigning the GNSS data with the GPR data, setting time zero and the record length, interpolating clipped data, bandpass filtering to remove noise, trace binning to account for varying walking speeds, elevation static correction, (7) deterministic 120 amplitude correction to compensate for the amplitude decay due to gemoetrical spreading, absorption and transmission losses, (8) GPR deconvolution to remove the GPR source wavelet and increase the vertical resolution (Schmelzbach and Huber, 2015), (9) an amplitude preserving migration to re-position the reflections in their correct location and to increase the horizontal resolution, (10) identifying an amplitude matching scalar in order to match the amplitudes across all GPR surveys, (11)(12)(13) sparse-spike deconvolution to recover the reflectivity (Sacchi, 1997) and to calibrate the reflectivity and stretch the reflectivity 125 to depth below glacier surface. In order to calibrate the reflectivity, ground truth data were used.…”

Section: Gpr Data Processingmentioning

confidence: 99%

Monitoring the seasonal changes of an englacial conduit network using repeated ground penetrating radar measurements

Church¹,

Grab²,

Schmelzbach³

et al. 2020

Preprint

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Between 2012 and 2019, repeated 25 MHz ground penetrating radar (GPR) surveys were carried out over an active englacial conduit network within the ablation area of the temperate Rhonegletscher, Switzerland. In 2018 and 2019 the repetition survey rate was increased to monitor seasonal variations. The resulting GPR data were processed using an impedance inversion workflow to compute GPR reflection coefficients and layer impedances, which are indicative of the conduit's infill material. The spatial and temporal evolution of the reflection coefficients also provided insights into the morphology of the 5 Rhonegletscher's englacial conduit network. During the summer melt seasons, we observed an active, water-filled, sedimenttransporting englacial conduit network that yielded large negative GPR reflection coefficients (<-0.2). For all the GPR surveys conducted during the summer, the englacial conduit was 15-20 m wide,~0.4 m thick,~250 m long with a shallow inclination (2°) and having a sinusoidal shape. We speculate that such a geometry is likely the result of extensional hydraulic fracturing.Synthetic GPR waveform modelling using a thin water-filled conduit showed that a conduit thickness larger than 0.4 m (0.3 10 × minimum wavelength) thick can be correctly identified using 25 MHz GPR data. During the winter periods, the englacial conduit shuts down and either physically closed or becomes very thin (<0.1 m), thereby producing small negative reflection coefficients that are caused by either sediments lying within the closed conduit or water within the very thin conduit. Furthermore, the englacial conduit reactivated during the following melt season at an identical position as in the previous year.

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“…Construction of a perfectly migrated GPR section (following the method developed by Irving et al, 2010) by convolution of the propagated wavelet with a Primary Reflectivity Section. The propagated wavelet is estimated from field data processing step 5 (according to the method by Schmelzbach and Huber, 2015). The Primary Reflectivity Section is derived from the previously obtained velocity model.…”

Section: From Aquifer Porosity Models To Gpr Reflection Sectionsmentioning

confidence: 99%

Reduction of conceptual model uncertainty using ground-penetrating radar profiles: Field-demonstration for a braided-river aquifer

Pirot

Huber

Irving

et al. 2019

Journal of Hydrology

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Hydrogeological flow and transport strongly depend on the connectivity of subsurface properties. Uncertainty concerning the underlying geological setting, due to a lack of field data and prior knowledge, calls for an evaluation of alternative geological conceptual models. To reduce the computational costs associated with inversions (parameter estimation for a given conceptual model), it is beneficial to rank and discard unlikely conceptual models prior to inversion. Here, we demonstrate an approach based on a quantitative comparison of groundpenetrating radar (GPR) sections obtained from field data with corresponding simulation results arising from various geological scenarios. The comparison is based on three global distance measures related to wavelet decomposition, multiple-point histograms, and connectivity that capture geometrical characteristics of geophysical reflection images. Using field data from the Tagliamento braided river system, Italy, we demonstrate that seven out of nine considered geological scenarios can be discarded as they produce GPR sections that are incompatible with those observed in the field. The retained scenarios reproduce important features such as cross-stratified deposits and irregular property interfaces. The most convenient distance measure of those considered is the one based on wavelet-decomposition. Direct analysis of the distances is the most intuitive and fastest way to compare scenarios.

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Efficient Deconvolution of Ground-Penetrating Radar Data

Cited by 30 publications

References 55 publications

Monitoring the seasonal changes of an englacial conduit network using repeated ground-penetrating radar measurements

Monitoring the seasonal changes of an englacial conduit network using repeated ground-penetrating radar measurements

Monitoring the seasonal changes of an englacial conduit network using repeated ground penetrating radar measurements

Reduction of conceptual model uncertainty using ground-penetrating radar profiles: Field-demonstration for a braided-river aquifer

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