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Estimation of glacier ice storage in western China constrained by field ground-penetrating radar surveys

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Advances in Climate Change Research 2022年第3期13卷 359-374页

作者： Peng-Bin LIANG Li-De TIAN Institute of International Rivers and Eco-Security Yunnan UniversityKunming 650500China Yunnan Key Laboratory of International Rivers and Transboundary Eco-security Kunming 650091China

Recent decades have witnessed the accelerated retreat of alpine glaciers,which likely portends a decline in the glacial ice melt on which large downstream populations rely for ***,estimating water storage in alpine glaciers is critical for predicting the trend of glacier *** study compiled a rich set of ice thickness observations for glaciers of varying sizes in western *** here presented a first-order assessment of the various errors involved in interpreting ice thickness from ground-penetrating radar(GPR)*** empirical Bayesian kriging(EBK)method was used for ice thickness interpolation and volume *** then established a new volume-scaling law specific to western China glaciers based on these 36 volume-area *** together with the Second Chinese Glacier Inventory(SCGI),we obtain a regional volume estimate of 4451±298 km^(3).By comparison,we believed that this result is the most reliable estimate of the total ice storage in western China and more reliably predicts gross glacier ***,our results show that the method of glacier division can strongly affect the total volume estimation,which previous studies *** emphasizes the need for more surveyed glaciers data and more accurate glacier inventory to improve the evaluation of the climate impact on glacier melting water resources and to help ensure the future survival of these alpine glaciers.

关键词： ground-penetrating radar Glacier thickness survey Glacier volume volume-area scaling law Distributed model Western China

Modeling tree root diameter and biomass by ground-penetrating radar

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Science China Earth Sciences 2011年第5期54卷 711-719页

作者： CUI XiHong CHEN Jin SHEN JinSong CAO Xin CHEN XueHong ZHU XiaoLin State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University Beijing 100875 China State Key Laboratory of Petroleum Resource and Prospecting China University of Petroleum Beijing 102249 China

Roots play a key role in ecosystem functioning as they transfer water and nutrients from soil to plants. Traditional methods for measuring roots are labor-intensive and destructive in nature, which limits quantitative and repeatable assessments in long- term research. ground-penetrating radar （GPR） provides a non-destructive method to measure plant roots. Based on the superiority of GPR with 2 GHz frequency, we developed a new, practical method to estimate root biomass. First, average root matter density was measured by collecting a small number of root samples. Second, under controlled, experimental conditions in a sandy area, a root diameter estimation model base on GPR was developed from which root diameter was estimated. Third, root volume was calculated using the estimated root diameter and assuming the shape of roots to be cylindrical. Finally, root biomass was estimated by averaging root matter density and root volume. Results of this study suggest the following：（1） the density of coarse roots with diameters greater than 0.5 cm is relatively uniform; （2） a new wave shape parameter, AT, extracted from profile data of 2 GHz frequency antenna is independent of root depth, thus enabling the construction of a root diameter estimation model with high accuracy; and （3） results of a field experiment demonstrated the GPR-based method to be feasible and effective in estimating biomass of coarse roots. These findings are helpful for improving GPR-based root diameter and biomass estimation models and suggest the potential of GPR data in studying root systems.

关键词： ground-penetrating radar tree root system root biomass root diameter

Exploring Soil Layers and Water Tables with ground-penetrating radar

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Pedosphere 2004年第3期14卷 273-282页

作者： K.ROTH U.WOLLSCHLAGER CHENGZhu-Hua ZHANGJia-Bao InstituteofEnvironmentalPhysics UniversityofHeidelbergHeidelberg（Germany） InstituteofSoilScience ChineseAcademyofSciencesNanjing210008（China）

ground-penetrating radar (GPR) has been used predominantly for environments with low electrical conductivity like freshwater aquifers, glaciers, or dry sandy soils. The objective of the present study was to explore its application for mapping in subsurface agricultural soils to a depth of several meters. For a loamy sand and a clayey site on the North China Plain, clay inclusions in the sand were detected; the thickness, inclination, and continuity of the confining clay and silt layers was assessed; and a local water table was mapped. Direct sampling (soil coring and profiling) in the top meter and independent measurement of the water table were utilized to confirm the findings. Also, effective estimates of the dielectric number for the site with the dielectric number of moist clayey soils depending strongly on frequency were obtained. Thus, important properties of soils, like the arrangement and type of layers and in particular their continuity and inclination, could be explored with moderate efforts for rather large areas to help find optimal locations for the time-consuming and expensive measurements which would be necessary to detail a model of the subsurface.

关键词： ground-penetrating radar soil layers water table

ground-penetrating radar imaging of railroad subgrade and subsoil strata

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Ground-penetrating radar imaging of railroad subgrade and su...

Reverse-Time Migration from Rugged Topography to Image ground-penetrating radar Data in Complex Environments

The 2nd International Conference on Environmental and Engineering Geophysics

作者： Shikun Deng Hanming Gu Zhijun Zhou Chaobin Hu Institute of Geophysics and Geomatics China University of Geosciences Wuhan 430074 China

＜正＞ground-penetrating radar （GPR） investigations of the railroad subgrade and subsoil strata were carried out on two different railroad lines. One survey carried out on the Hanshou section of Shimen to Changsha single-track railroad line aimed to delineate the cavities and loose zones in railroad subgrade and subsoil strata. This section of railroad is about 2 km long and mostly located in a valley in lower hilly land. The cavities and loose zones to be mapped in this area developed in subgrade and subsoil strata below the railroad with about 2 to 10 m depth. Data were acquired with 50 MHz antenna and three 2 km long survey lines parallel to the rail were deployed, one of them along the central axis of the rail track, and two others along the railroad shoulders. The processed GPR profiles give good indications of the cavities and loose zones in the railroad subgrade and subsoil strata. Another survey carried on the Xianning section of the Beijing to Guangzhou double-track electrified railroad line, where a collapse occurred. It aimed to investigate the geological cause of the formation of a occurred collapse and to delineate the scope of potential collapses. The corroboration of GPR results by digging slope pits from the railroad shoulder to below the rail track and drillings between the tracks demonstrated the power and utility of the high-resolution GPR method as an aid for railroad maintenance. GPR data provided very useful information for grouting and reinforcing processing of the railroad subgrade.

关键词： ground-penetrating radar railroad geological hazards subgrade subsoil strata

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Engineering 2018年第5期4卷 661-666页

作者： John H. Bradford Janna Privette David Wilkins Richard Ford Department of Geosciences Boise State University Boise ID 83725-1535 USA Department of Geosciences Weber State University Ogden UT 84408-2507 USA

In ground-penetrating radar （GPR） imaging, it is common for the depth of investigation to be on the same order as the variability in surface topography, In such cases, migration fails when it is carried out from a datum after the application of elevation statics, We introduce a reverse-time migration （RTM） algorithm based on the second-order decoupled form of Maxwell＇s equations, which requires computation of only the electric field, The wavefield extrapolation is computed directly from the acquisition surface without the need for datuming, In a synthetic case study, the algorithm significantly improves image accuracy over a processing sequence in which migration is performed after elevation statics, In addition, we acquired a field dataset at the Coral Pink Sand Dunes （CPSD） in Utah, USA, The data were acquired over rugged topography and have the complex internal stratigraphy of multiply eroded, modern, and ancient eolian deposits, The RTM algorithm significantly improves radar depth images in this challenging environment,

关键词： ground-penetrating radar Reverse-time migration Sand dune Amplitude analysis

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

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Applied Geophysics 2015年第4期12卷 615-625,630页

作者：曾昭发陈雄李静陈玲娜鹿琪刘凤山吉林大学地球探测科学与技术学院长春130026 美国特拉华州立大学应用数学研究中心多佛19901

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.

关键词： ground-penetrating radar impedance inversion tapering function stochasticmedium

ground penetrating radar (GPR) Identification Method for Agricultural Soil Stratification in a Typical Mollisols Area of Northeast China

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Chinese Geographical Science 2023年第4期33卷 664-678页

作者： RUAN Weimin LIU Baojiang LIU Huanjun DONG Hang SUI Yueyu Northeast Institute of Geography and Agroecology Chinese Academy of SciencesChangchun 130102China University of Chinese Academy of Sciences Beijing 100049China

In order to achieve a rapid and accurate identification of soil stratification information and accelerate the development of smart agriculture,this paper conducted soil stratification experiments on agricultural soils in the Mollisols area of Northeast China using ground penetrating radar(GPR)and obtained different types of soil with frequencies of 500 MHz,250 MHz,and 100 MHz *** soil profile data were obtained for 500 MHz,250 MHz,and 100 MHz antennas,and the dielectric properties of each type of soil were *** the image processing procedure,wavelet analysis was first used to decompose the pre-processed radar signal and reconstruct the high-frequency information to obtain the reconstructed signal containing the stratification ***,the reconstructed signal is taken as an envelope to enhance the stratification *** Hilbert transform is applied to the envelope signal to find the time-domain variation of the instantaneous frequency and determine the time-domain location of the ***,the dielectric constant of each soil horizon is used to obtain the propagation velocity of the electromagnetic wave at the corresponding position to obtain the stratification position of each soil *** research results show that the 500 MHz radar antenna can accurately delineate Ap/Ah,horizon and the absolute accuracy of the stratification is within 5 *** effect on the soil stratification below the tillage horizon is not apparent,and the absolute accuracy of the 250 MHz and 100 MHz radar antennas on the stratification is within 9 *** overwhelming majority of the overall calculation errors are kept to within 15%.Based on the three central frequency antennas,the soil horizon detection rate reaches 93.3%,which can achieve accurate stratification of soil profiles within 1 *** experimental and image processing methods used are practical and feasible;however,the GPR will show a missed detection for soil horizons with only s

关键词： soil stratification ground-penetrating radar profiling wavelet analysis envelope signal Northeast China

Reverse-Time Prestack Depth Migration of GPR Data from Topography for Amplitude Reconstruction in Complex Environments

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Journal of Earth Science 2015年第6期26卷 791-798页

作者： John H.Bradford Center for Geophysical Investigation of the Shallow Subsurface Boise State University

With increased computational power, reverse-time prestack depth migration（RT-PSDM） has become a preferred imaging tool in seismic exploration, yet its use has remained relatively limited in ground-penetrating radar（GPR） applications. Complex topography alters the wavefield kinematics making for a challenging imaging problem. Model simulations show that topographic variation can substantially distort reflection amplitudes due to irregular wavefield spreading, attenuation anomalies due to irregular path lengths, and 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. Here, I use a full wave-equation RT-PSDM algorithm to image GPR data in the presence of large topographic variability relative to the depth of investigation. The source and receiver wavefields are propagated directly from the topographic surface and this approach inherently corrects for irregular kinematics, spreading and attenuation. The results show that when GPR data are acquired in areas of extreme topography, RT-PSDM can accurately reconstruct reflector geometry as well as reflection amplitude.

关键词： reverse-time prestack depth migration ground-penetrating radar topography wavefield reflector geometry reflection amplitude.

GPR Wave Propagation Model in a Complex Geoelectric Structure Using Conformal First-Order Symplectic Euler Algorithm

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Computers, Materials & Continua 2019年第8期61卷 793-816页

作者： Man Yang Hongyuan Fang Juan Zhang Fuming Wang Jianwei Lei Heyang Jia College of Water Conservancy&Environmental Engineering Zhengzhou UniversityZhengzhou450001China National Local Joint Engineering Laboratory of Major Infrastructure Testing and Rehabilitation Technology Zhengzhou450001China Collaborative Innovation Center of Water Conservancy and Transportation Infrastructure Safety Zhengzhou450001China CCCC First Highway Consultants Co. LTDShanxi ProvinceXi’an710065China

Possessing advantages such as high computing efficiency and ease of programming,the Symplectic Euler algorithm can be applied to construct a groundpenetrating radar(GPR)wave propagation numerical model for complex geoelectric ***,the Symplectic Euler algorithm is still a difference algorithm,and for a complicated boundary,ladder grids are needed to perform an approximation process,which results in a certain amount of ***,grids that are too dense will seriously decrease computing *** paper proposes a conformal Symplectic Euler algorithm based on the conformal grid technique,amends the electric/magnetic fieldupdating equations of the Symplectic Euler algorithm by introducing the effective dielectric constant and effective permeability coefficient,and reduces the computing error caused by the ladder approximation of rectangular ***,three surface boundary models(the underground circular void model,the undulating stratum model,and actual measurement model)are *** comparing reflection waveforms simulated by the traditional Symplectic Euler algorithm,the conformal Symplectic Euler algorithm and the conformal finite difference time domain(CFDTD),the conformal Symplectic Euler algorithm achieves almost the same level of accuracy as the CFDTD method,but the conformal Symplectic Euler algorithm improves the computational efficiency compared with the CFDTD method *** the dielectric constants of the two materials vary greatly,the conformal Symplectic Euler algorithm can reduce the pseudo-waves almost by 80% compared with the traditional Symplectic Euler algorithm on average.

关键词： Symplectic Euler algorithm conformal grid complex geoelectric model ground-penetrating radar pseudo-reflection wave