In near surface electrical exploration, it is often necessary to estimate the Cole-Cole model parameters according to the measured multi-frequency complex resistivity spectrum of ore and rock samples in advance. Parameter estimation is a nonlinear optimization problem, and the common method is least square fitting. The disadvantage of this method is that it relies on initial value and the result is unstable when data is confronted with noise interference. To further improve the accuracy of parameter estimation, this paper applied artificial neural network (ANN) method to the Cole-Cole model estimation. Firstly, a large number of forward models are generated as samples to train the neural network and when the data fitting error is lower than the error threshold, the training ends. The trained neural network is directly used to efficiently estimate the parameters of vast amounts of new data. The efficiency of the artificial neural network is analyzed by using simulated and measured spectral induced polarization data. The results show that artificial neural network method has a faster computing speed and higher accuracy in Cole-Cole model parameter estimation.
{"title":"Cole-Cole Model Parameter Estimation from Multi-frequency Complex Resistivity Spectrum Based on the Artificial Neural Network","authors":"Weiqiang Liu, Rujun Chen, Liangyong Yang","doi":"10.32389/JEEG20-054","DOIUrl":"https://doi.org/10.32389/JEEG20-054","url":null,"abstract":"In near surface electrical exploration, it is often necessary to estimate the Cole-Cole model parameters according to the measured multi-frequency complex resistivity spectrum of ore and rock samples in advance. Parameter estimation is a nonlinear optimization problem, and the common method is least square fitting. The disadvantage of this method is that it relies on initial value and the result is unstable when data is confronted with noise interference. To further improve the accuracy of parameter estimation, this paper applied artificial neural network (ANN) method to the Cole-Cole model estimation. Firstly, a large number of forward models are generated as samples to train the neural network and when the data fitting error is lower than the error threshold, the training ends. The trained neural network is directly used to efficiently estimate the parameters of vast amounts of new data. The efficiency of the artificial neural network is analyzed by using simulated and measured spectral induced polarization data. The results show that artificial neural network method has a faster computing speed and higher accuracy in Cole-Cole model parameter estimation.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"3 1","pages":"71-77"},"PeriodicalIF":1.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91177967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Shlykov, A. Saraev, S. Agrahari, B. Tezkan, Akarsh Singh
In this paper, we discuss several approaches for a joint inversion of controlled source radiomagnetotelluric (CSRMT) and electrical resistivity tomography (ERT) data observed over anisotropic media. We compare results of 2D isotropic joint inversion with results of a newly developed joint 1D anisotropic inversion algorithm. The developed algorithm involves the full controlled source high frequency forward and inversion formulations without the plane wave assumption. We demonstrate that for measurements on an anisotropic subsurface the isotropic joint inversion cannot fit both datasets properly due to a high anisotropy of shallow horizons of quaternary sands and loams. The joint anisotropic inversion helps to solve this problem and highlights the advantages of a joint inversion of CSRMT and ERT data. We also demonstrate application of the laterally constrain algorithm for the anisotropic inversion. Results of the joint 1D anisotropic inversion of CSRMT and ERT data were successfully compared with existing borehole data.
{"title":"One-dimensional Laterally Constrained Joint Anisotropic Inversion of CSRMT and ERT Data","authors":"A. Shlykov, A. Saraev, S. Agrahari, B. Tezkan, Akarsh Singh","doi":"10.32389/JEEG20-060","DOIUrl":"https://doi.org/10.32389/JEEG20-060","url":null,"abstract":"In this paper, we discuss several approaches for a joint inversion of controlled source radiomagnetotelluric (CSRMT) and electrical resistivity tomography (ERT) data observed over anisotropic media. We compare results of 2D isotropic joint inversion with results of a newly developed joint 1D anisotropic inversion algorithm. The developed algorithm involves the full controlled source high frequency forward and inversion formulations without the plane wave assumption. We demonstrate that for measurements on an anisotropic subsurface the isotropic joint inversion cannot fit both datasets properly due to a high anisotropy of shallow horizons of quaternary sands and loams. The joint anisotropic inversion helps to solve this problem and highlights the advantages of a joint inversion of CSRMT and ERT data. We also demonstrate application of the laterally constrain algorithm for the anisotropic inversion. Results of the joint 1D anisotropic inversion of CSRMT and ERT data were successfully compared with existing borehole data.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"1 1","pages":"35-48"},"PeriodicalIF":1.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89703565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The transient electromagnetic method (TEM) and controlled-source audio-frequency magnetotellurics method (CSAMT) are commonly used in detecting water abundance of rock formation and faults in coal mines. However, these methods show low accuracy, given the multiplicity of their inversion results, especially for areas with minor differences in lithology and electrical property. To improve the accuracy of electromagnetic exploration, a pseudo-2D joint inversion is performed. The objective function of this pseudo-2D joint inversion is established, and the joint inversion process is constrained by resistivity logging data. Afterward, the symmetric successive over-relaxation (SSOR) is used to realize the pseudo-2D joint inversion calculation of TEM and CSAMT with well log constraint. The effectiveness of joint inversion is verified by combining synthetic and field data. Results show that the pseudo-2D joint inversion results of TEM and CSAMT with well log constraint correspond to the actual geological situation. Compared with either TEM or CSAMT, joint inversion has a significantly better capability of reflecting water abundance in rock formation and faults.
{"title":"Research on Pseudo-2D Joint Inversion of TEM and CSAMT Based on Well Log Constraint","authors":"Dong Yi, Cheng Jiu-long, Xu Junjie, Wen Laifu, Chen Tao, Wang Huijie, Chen Zhi, Tian Chuxiao","doi":"10.32389/JEEG20-052","DOIUrl":"https://doi.org/10.32389/JEEG20-052","url":null,"abstract":"The transient electromagnetic method (TEM) and controlled-source audio-frequency magnetotellurics method (CSAMT) are commonly used in detecting water abundance of rock formation and faults in coal mines. However, these methods show low accuracy, given the multiplicity of their inversion results, especially for areas with minor differences in lithology and electrical property. To improve the accuracy of electromagnetic exploration, a pseudo-2D joint inversion is performed. The objective function of this pseudo-2D joint inversion is established, and the joint inversion process is constrained by resistivity logging data. Afterward, the symmetric successive over-relaxation (SSOR) is used to realize the pseudo-2D joint inversion calculation of TEM and CSAMT with well log constraint. The effectiveness of joint inversion is verified by combining synthetic and field data. Results show that the pseudo-2D joint inversion results of TEM and CSAMT with well log constraint correspond to the actual geological situation. Compared with either TEM or CSAMT, joint inversion has a significantly better capability of reflecting water abundance in rock formation and faults.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"15 1","pages":"61-70"},"PeriodicalIF":1.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80109984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Kiernan, D. Jackson, J. Montgomery, J. Anderson, Brannon W. McDonald, K. C. Davis
Karst geology is characterized by the presence of sinkholes and voids, which may pose significant risk to existing infrastructure. Sinkhole formation is often observed near active quarries, where dewatering operations can alter regional groundwater flow patterns leading to subsidence and increased void formation. In these areas, identifying locations which may be susceptible to sinkhole formation requires an ability to map dissolution features within the rock. Traditional geotechnical explorations alone are not well-suited to this effort as they only provide subsurface information at discrete points and therefore may miss voids within the rock. Geophysical methods offer a means to produce continuous profiles of the rock surface and possible locations for voids but interpreting the results of these tests in karstic geology can be challenging. This study uses 2D electrical resistivity and seismic surveys at a site with previous sinkhole activity along an interstate in central Alabama. The site is adjacent to a limestone quarry. Resistivity data is collected using 2D dipole-dipole and strong-gradient arrays. The seismic data is processed using a full waveform inversion (FWI) technique. Subsurface profiles interpreted from the geophysical surveys are then compared to borehole data from previous site investigations. Results from the geophysical surveys are found to be consistent with borehole data regarding variation of bedrock depth and identification of possible sinkhole features. Potential limitations and sources of error pertaining to each survey type are considered.
{"title":"Characterization of a Karst Site using Electrical Resistivity Tomography and Seismic Full Waveform Inversion","authors":"M. Kiernan, D. Jackson, J. Montgomery, J. Anderson, Brannon W. McDonald, K. C. Davis","doi":"10.32389/JEEG20-045","DOIUrl":"https://doi.org/10.32389/JEEG20-045","url":null,"abstract":"Karst geology is characterized by the presence of sinkholes and voids, which may pose significant risk to existing infrastructure. Sinkhole formation is often observed near active quarries, where dewatering operations can alter regional groundwater flow patterns leading to subsidence and increased void formation. In these areas, identifying locations which may be susceptible to sinkhole formation requires an ability to map dissolution features within the rock. Traditional geotechnical explorations alone are not well-suited to this effort as they only provide subsurface information at discrete points and therefore may miss voids within the rock. Geophysical methods offer a means to produce continuous profiles of the rock surface and possible locations for voids but interpreting the results of these tests in karstic geology can be challenging. This study uses 2D electrical resistivity and seismic surveys at a site with previous sinkhole activity along an interstate in central Alabama. The site is adjacent to a limestone quarry. Resistivity data is collected using 2D dipole-dipole and strong-gradient arrays. The seismic data is processed using a full waveform inversion (FWI) technique. Subsurface profiles interpreted from the geophysical surveys are then compared to borehole data from previous site investigations. Results from the geophysical surveys are found to be consistent with borehole data regarding variation of bedrock depth and identification of possible sinkhole features. Potential limitations and sources of error pertaining to each survey type are considered.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"160 1","pages":"1-11"},"PeriodicalIF":1.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90330413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Red-bed basins with rich hydrocarbon source rocks are widely distributed in south China, such as Banshi Basin in southern Jiangxi, which may have very good prospects for oil and gas exploration. However, due to poor ground conditions, and complex geological structures, seismic exploration and conventional electromagnetic methods cannot provide useful information for hydrocarbon evaluation. This study uses the wide field electromagnetic (WFEM) method to investigate the distribution and geoelectric characteristics of the target stratum of a red-bed basin in Jiangxi province, China. The inversion results demonstrate that the WFEM method could quickly delineate the favorable area and determine the location of the parametric well, confirming that the WFEM method is an effective geophysical exploration method for evaluating hydrocarbon resources in red-bed basins.
{"title":"Application of the Wide Field Electromagnetic Method for Oil and Gas Exploration in a Red-bed Basin of South China","authors":"Diquan Li, Qiao Zhang","doi":"10.32389/JEEG20-041","DOIUrl":"https://doi.org/10.32389/JEEG20-041","url":null,"abstract":"Red-bed basins with rich hydrocarbon source rocks are widely distributed in south China, such as Banshi Basin in southern Jiangxi, which may have very good prospects for oil and gas exploration. However, due to poor ground conditions, and complex geological structures, seismic exploration and conventional electromagnetic methods cannot provide useful information for hydrocarbon evaluation. This study uses the wide field electromagnetic (WFEM) method to investigate the distribution and geoelectric characteristics of the target stratum of a red-bed basin in Jiangxi province, China. The inversion results demonstrate that the WFEM method could quickly delineate the favorable area and determine the location of the parametric well, confirming that the WFEM method is an effective geophysical exploration method for evaluating hydrocarbon resources in red-bed basins.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"8 1","pages":"25-34"},"PeriodicalIF":1.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78043269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The boom-type roadheader is the main equipment for realizing the mechanization of coal drifting in coal mines, and it is an indispensable production equipment in major coal-producing countries. Substantial vibrations are generated during the operation of a roadheader; these vibrations carry substantial energy and, thus, can be regarded as a potential source and used for seismic advance detection purposes in mine drifts. Compared with a conventional exploration source, a roadheader source produces a complex continuous random signal. The shape of a seismic wavelet is uncertain and its duration is relatively long; thus, it must be processed into a conventional pulse signal before it can be used for subsequent processing and analysis. Therefore, based on the advantages of seismic interferometry in random signal processing, two seismic interference techniques, namely, deconvolution and cross-correlation, are introduced for constructing a compound interference algorithm. On the basis of a theoretically derived formula, a random signal impulse processing experiment is conducted using field-acquired source signals from a roadheader; this approach resolves the problem that cross-correlation alone cannot yield ideal results. Hence, a feasible algorithm for the impulse processing of a random signal, namely, the compound interference algorithm, is proposed. The algorithm deconvolves each seismic trace to obtain the reference trace and other receiver traces after compressing the wavelet. Then, the reference trace and each receiver trace are cross-correlated, and the wavelet time delay information of each correlated wavelet pulse, namely, the wavelet time delay information of the receiver trace relative to the reference trace, is obtained. Accordingly, the direct wave and reflected waves are recognized. To evaluate the performance of the algorithm, an algorithm application experiment is conducted for another group of random source signals that were collected by a roadheader under different coal drift conditions. Again, the algorithm processing results are consistent with the single-shot record characteristics of an explosive source. Consequently, the proposed algorithm can satisfy the requirements for engineering exploration and analysis. A comprehensive analysis further demonstrates that the compound interference algorithm is both feasible and effective and that the processed seismic signals can be used for subsequent processing and interpretation.
{"title":"Impulse Processing Algorithm for Random Source Signals of Roadheaders That Is Based on Compound Interferometry","authors":"Shenglin Li, Pingsong Zhang, Chaoqiang Xi","doi":"10.32389/JEEG20-026","DOIUrl":"https://doi.org/10.32389/JEEG20-026","url":null,"abstract":"The boom-type roadheader is the main equipment for realizing the mechanization of coal drifting in coal mines, and it is an indispensable production equipment in major coal-producing countries. Substantial vibrations are generated during the operation of a roadheader; these vibrations carry substantial energy and, thus, can be regarded as a potential source and used for seismic advance detection purposes in mine drifts. Compared with a conventional exploration source, a roadheader source produces a complex continuous random signal. The shape of a seismic wavelet is uncertain and its duration is relatively long; thus, it must be processed into a conventional pulse signal before it can be used for subsequent processing and analysis. Therefore, based on the advantages of seismic interferometry in random signal processing, two seismic interference techniques, namely, deconvolution and cross-correlation, are introduced for constructing a compound interference algorithm. On the basis of a theoretically derived formula, a random signal impulse processing experiment is conducted using field-acquired source signals from a roadheader; this approach resolves the problem that cross-correlation alone cannot yield ideal results. Hence, a feasible algorithm for the impulse processing of a random signal, namely, the compound interference algorithm, is proposed. The algorithm deconvolves each seismic trace to obtain the reference trace and other receiver traces after compressing the wavelet. Then, the reference trace and each receiver trace are cross-correlated, and the wavelet time delay information of each correlated wavelet pulse, namely, the wavelet time delay information of the receiver trace relative to the reference trace, is obtained. Accordingly, the direct wave and reflected waves are recognized. To evaluate the performance of the algorithm, an algorithm application experiment is conducted for another group of random source signals that were collected by a roadheader under different coal drift conditions. Again, the algorithm processing results are consistent with the single-shot record characteristics of an explosive source. Consequently, the proposed algorithm can satisfy the requirements for engineering exploration and analysis. A comprehensive analysis further demonstrates that the compound interference algorithm is both feasible and effective and that the processed seismic signals can be used for subsequent processing and interpretation.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"13 1","pages":"13-24"},"PeriodicalIF":1.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87529694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaoyue Cao, Xin Huang, C. Yin, Liangjun Yan, Bo Zhang
The conventional 3D magnetotelluric (MT) forward modeling and inversions generally assume an isotropic earth model. However, wrong results can be obtained when using an isotropic model to interpret the data influenced by the anisotropy. To effectively model and recover the earth structures including anisotropy, we develop a 3D MT inversion framework for a triaxial anisotropic model. We use the unstructured finite-element method for our forward modeling. This offers more possibility to simulate more complex underground geology and topography. To solve the inverse modeling problem, we use a limited-memory quasi-Newton algorithm (L-BFGS) with a parallel direct solver for optimization that avoids the explicit calculation of the Hessian matrix and saves the memory and computational time. We validate our algorithm via numerical experiments on both synthetic data and MT survey data from the US Array project.
{"title":"3D MT Anisotropic Inversion Based on Unstructured Finite-element Method","authors":"Xiaoyue Cao, Xin Huang, C. Yin, Liangjun Yan, Bo Zhang","doi":"10.32389/JEEG20-006","DOIUrl":"https://doi.org/10.32389/JEEG20-006","url":null,"abstract":"The conventional 3D magnetotelluric (MT) forward modeling and inversions generally assume an isotropic earth model. However, wrong results can be obtained when using an isotropic model to interpret the data influenced by the anisotropy. To effectively model and recover the earth structures including anisotropy, we develop a 3D MT inversion framework for a triaxial anisotropic model. We use the unstructured finite-element method for our forward modeling. This offers more possibility to simulate more complex underground geology and topography. To solve the inverse modeling problem, we use a limited-memory quasi-Newton algorithm (L-BFGS) with a parallel direct solver for optimization that avoids the explicit calculation of the Hessian matrix and saves the memory and computational time. We validate our algorithm via numerical experiments on both synthetic data and MT survey data from the US Array project.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"37 1","pages":"49-60"},"PeriodicalIF":1.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89344554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abandoned wells may act as conduits for the contamination of groundwater by oil field brines and other pollutants. The steel casings of abandoned wells eventually develop leaks, which if not properly plugged, can allow pollutants to reach freshwater aquifers that supply drinking water. Resistivity surveys were conducted in the vicinity of five abandoned oil wells in order to characterize the near-surface geology and to determine the effects of the steel casings and potential leakage. The arrays consisted of dipole-dipole (DD) and inverse Schlumberger (SLB) arrays. The effects from steel cased wells can manifest as low resistivity anomalies in the vicinity of the casings, depending on proximity of the line to the well, well location along the line, and the specific array used. These features appear as vertical, circular, elliptical, and bell-like anomalies. However, in some instances with the SLB array, the data appear not to be affected by the presence of steel casings. This observation is significant because resistivity surveys utilizing the SLB array can provide reliable information on near-surface geology next to abandoned wells, and horizontal and vertical extension of brine impacted areas due to leaking abandoned oil wells. The DD array, on the other hand, is better at locating potentially hidden abandoned wells but interpreting subsurface structure or contamination with the array is more difficult.
{"title":"Electrical Resistivity Imaging near Abandoned Steel Oil Wells: Five Case Studies, USA","authors":"M. Saribudak, D. Rucker, Allan Haas","doi":"10.32389/jeeg20-048","DOIUrl":"https://doi.org/10.32389/jeeg20-048","url":null,"abstract":"Abandoned wells may act as conduits for the contamination of groundwater by oil field brines and other pollutants. The steel casings of abandoned wells eventually develop leaks, which if not properly plugged, can allow pollutants to reach freshwater aquifers that supply drinking water. Resistivity surveys were conducted in the vicinity of five abandoned oil wells in order to characterize the near-surface geology and to determine the effects of the steel casings and potential leakage. The arrays consisted of dipole-dipole (DD) and inverse Schlumberger (SLB) arrays. The effects from steel cased wells can manifest as low resistivity anomalies in the vicinity of the casings, depending on proximity of the line to the well, well location along the line, and the specific array used. These features appear as vertical, circular, elliptical, and bell-like anomalies. However, in some instances with the SLB array, the data appear not to be affected by the presence of steel casings. This observation is significant because resistivity surveys utilizing the SLB array can provide reliable information on near-surface geology next to abandoned wells, and horizontal and vertical extension of brine impacted areas due to leaking abandoned oil wells. The DD array, on the other hand, is better at locating potentially hidden abandoned wells but interpreting subsurface structure or contamination with the array is more difficult.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"115 1","pages":"545-556"},"PeriodicalIF":1.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85265016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The fluxes between groundwater and surface water play a significant role in quantifying water balance along stream reaches to continent scales. Changes in these dynamics are occurring due to aquifer depletion, where pre-development baseflow conditions have transitioned to losing conditions. This problem is studied along the Arkansas River in Western Kansas across a stream reach that transitions from near steady state to losing conditions, and contributes focused recharge to a depleting Ogallala Aquifer. Existing hydrologic data illustrates the lack of understanding they provide related to the control of fluxes exerted by alluvial deposits. Electrical resistivity imaging (ERI) surveys were conducted along this river transect to elucidate the dynamic hydrologic connection existing between the Arkansas River and underlying Arkansas Alluvial and Ogallala Aquifers. Temporal changes in ERI profiles are associated with the transient hydrologic conditions below the water-sediment interface, and complement the hydrogeologic interpretations of the individual ERI profiles. Additionally, fine grained soil inclusions may become revealed by temporal changes in resistivity due to differences in their water holding capacity relative to that of a surrounding matrix of coarser grained soil across changes in recharge. These findings corroborate the role of river-aquifer connectivity and riverbed heterogeneity on localized recharge through embedded assemblages of fine and coarse grained soils.
{"title":"Characterizing Riverbed Heterogeneity across Shifts in River Discharge through Temporal Changes in Electrical Resistivity","authors":"W. Koehn, S. Tucker-Kulesza, D. R. Steward","doi":"10.32389/jeeg20-049","DOIUrl":"https://doi.org/10.32389/jeeg20-049","url":null,"abstract":"The fluxes between groundwater and surface water play a significant role in quantifying water balance along stream reaches to continent scales. Changes in these dynamics are occurring due to aquifer depletion, where pre-development baseflow conditions have transitioned to losing conditions. This problem is studied along the Arkansas River in Western Kansas across a stream reach that transitions from near steady state to losing conditions, and contributes focused recharge to a depleting Ogallala Aquifer. Existing hydrologic data illustrates the lack of understanding they provide related to the control of fluxes exerted by alluvial deposits. Electrical resistivity imaging (ERI) surveys were conducted along this river transect to elucidate the dynamic hydrologic connection existing between the Arkansas River and underlying Arkansas Alluvial and Ogallala Aquifers. Temporal changes in ERI profiles are associated with the transient hydrologic conditions below the water-sediment interface, and complement the hydrogeologic interpretations of the individual ERI profiles. Additionally, fine grained soil inclusions may become revealed by temporal changes in resistivity due to differences in their water holding capacity relative to that of a surrounding matrix of coarser grained soil across changes in recharge. These findings corroborate the role of river-aquifer connectivity and riverbed heterogeneity on localized recharge through embedded assemblages of fine and coarse grained soils.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"34 1","pages":"581-587"},"PeriodicalIF":1.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85379982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Nie, Junfeng Shen, Pengfei Zhou, Liu Zhengyu, Pang Yonghao, Wei Zhou, Andong Chen
In Southeast China, the presence of boulders significantly threatens subway construction projects. Undetected boulders could negatively impact the efficiency and safety of subway construction methods that use shield and tunnel-boring machines. Therefore, boulder detection is a necessary step before construction begins. Recently, the cross-hole electrical resistivity tomography (ERT) method has gained attention as a potential boulder-detection approach in subway construction projects. However, in this method, the detection effect of each electrode configuration still needs to be assessed. In this study, a full-scale physical model test was conducted to determine the optimal electrode configuration for the cross-hole ERT method. Additionally, a sensitivity analysis of three types of electrode configurations, namely, bipole–bipole, dipole–dipole, and pole–tripole, was conducted. The results showed that the detection ability of the bipole–bipole electrode configuration was satisfactory, with very good boulder-detection resolution and sensitivity. Conversely, the resolution of the dipole–dipole electrode configuration, with relatively low signal strength, decreased as boulder distribution became more complex. Although the pole–tripole electrode configuration showed acceptable resolution, the boulder-detection results had many artifacts. Thus, the full-scale physical model test was conducted to thoroughly investigate the cross-hole ERT electrode configurations and determine the influence of boulder distribution on the measurements, with a view on achieving a more efficient application of this method in the field.
{"title":"Cross-hole ERT Configuration Assessment for Boulder Detection: A Full-scale Physical Model Test","authors":"L. Nie, Junfeng Shen, Pengfei Zhou, Liu Zhengyu, Pang Yonghao, Wei Zhou, Andong Chen","doi":"10.32389/jeeg20-018","DOIUrl":"https://doi.org/10.32389/jeeg20-018","url":null,"abstract":"In Southeast China, the presence of boulders significantly threatens subway construction projects. Undetected boulders could negatively impact the efficiency and safety of subway construction methods that use shield and tunnel-boring machines. Therefore, boulder detection is a necessary step before construction begins. Recently, the cross-hole electrical resistivity tomography (ERT) method has gained attention as a potential boulder-detection approach in subway construction projects. However, in this method, the detection effect of each electrode configuration still needs to be assessed. In this study, a full-scale physical model test was conducted to determine the optimal electrode configuration for the cross-hole ERT method. Additionally, a sensitivity analysis of three types of electrode configurations, namely, bipole–bipole, dipole–dipole, and pole–tripole, was conducted. The results showed that the detection ability of the bipole–bipole electrode configuration was satisfactory, with very good boulder-detection resolution and sensitivity. Conversely, the resolution of the dipole–dipole electrode configuration, with relatively low signal strength, decreased as boulder distribution became more complex. Although the pole–tripole electrode configuration showed acceptable resolution, the boulder-detection results had many artifacts. Thus, the full-scale physical model test was conducted to thoroughly investigate the cross-hole ERT electrode configurations and determine the influence of boulder distribution on the measurements, with a view on achieving a more efficient application of this method in the field.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"20 1","pages":"569-579"},"PeriodicalIF":1.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75623190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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