TY - JOUR
T1 - Mapping soil layers using electrical resistivity tomography and validation
T2 - Sandbox experiments
AU - Xu, Dong
AU - Sun, Ronglin
AU - Yeh, Tian Chyi Jim
AU - Wang, Yu Li
AU - Momayez, Moe
AU - Hao, Yonghong
AU - Lee, Cheng Haw
AU - Hu, Xiangyun
N1 - Funding Information:
This research was supported by the China Scholarship Council (Grant 201706410014), the National Natural Science Foundation of China (Grant 41630317, 41474055); the Fundamental Research Funds for the for the Central Universities, China University of Geosciences, China (Grant CUGCJ1707) and the National Key R&D Program of China (Grant 2016YFC0600201-7).
Funding Information:
This research was supported by the China Scholarship Council (Grant 201706410014 ), the National Natural Science Foundation of China (Grant 41630317 , 41474055 ); the Fundamental Research Funds for the for the Central Universities, China University of Geosciences, China (Grant CUGCJ1707 ) and the National Key R&D Program of China (Grant 2016YFC0600201-7 ).
Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2019/8
Y1 - 2019/8
N2 - Knowledge of the geologic structure at a field site is a useful piece of information for hydrologic modeling since it can serve as more site-specific prior information about the hydraulic parameter patterns at the site than generic spatial statistics. Widely accepted electrical resistivity tomography (ERT) survey for mapping subsurface anomalies could be a viable tool for acquiring this information. However, their ability to delineate geologic structures has not been thoroughly investigated. In this study, two-dimensional ERT numerical experiments were first conducted to study the effects of boundary conditions on the dipole-dipole and pole-pole array configurations. An ERT setup subsequently was implemented in a sandbox consisting of complex layers of different sands. A continuous copper wire was installed along the sides of the sandbox to impose potential boundaries. Using data collected with the pole-pole array in the sandbox under different degrees of drainage and the Successive Linear Estimator (SLE) algorithm, we show that ERT yields electrical conductivity estimates of complex layer structures with small uncertainties. In addition, using SLE with physically meaningful correlation scales as prior information can lead to an electrical conductivity field that is consistent with visually observed layer structures. The correlation scale concept also was demonstrated to provide guidance to the design of the electrode spacing in the surveys. Moreover, the estimated field was validated by predicting electrical potential fields from two independent ERT surveys using electrodes at different locations. Results of this study suggest that the combination of ERT and SLE is a viable geophysical survey tool for mapping geologic layer structures. Research Significance: This study develops a method to implement prescribed potential boundaries for enhancing the pole-pole ERT survey, illustrates the importance of correlation scales and develops an approach for validating ERT results.
AB - Knowledge of the geologic structure at a field site is a useful piece of information for hydrologic modeling since it can serve as more site-specific prior information about the hydraulic parameter patterns at the site than generic spatial statistics. Widely accepted electrical resistivity tomography (ERT) survey for mapping subsurface anomalies could be a viable tool for acquiring this information. However, their ability to delineate geologic structures has not been thoroughly investigated. In this study, two-dimensional ERT numerical experiments were first conducted to study the effects of boundary conditions on the dipole-dipole and pole-pole array configurations. An ERT setup subsequently was implemented in a sandbox consisting of complex layers of different sands. A continuous copper wire was installed along the sides of the sandbox to impose potential boundaries. Using data collected with the pole-pole array in the sandbox under different degrees of drainage and the Successive Linear Estimator (SLE) algorithm, we show that ERT yields electrical conductivity estimates of complex layer structures with small uncertainties. In addition, using SLE with physically meaningful correlation scales as prior information can lead to an electrical conductivity field that is consistent with visually observed layer structures. The correlation scale concept also was demonstrated to provide guidance to the design of the electrode spacing in the surveys. Moreover, the estimated field was validated by predicting electrical potential fields from two independent ERT surveys using electrodes at different locations. Results of this study suggest that the combination of ERT and SLE is a viable geophysical survey tool for mapping geologic layer structures. Research Significance: This study develops a method to implement prescribed potential boundaries for enhancing the pole-pole ERT survey, illustrates the importance of correlation scales and develops an approach for validating ERT results.
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U2 - 10.1016/j.jhydrol.2019.05.036
DO - 10.1016/j.jhydrol.2019.05.036
M3 - Article
AN - SCOPUS:85066444120
VL - 575
SP - 523
EP - 536
JO - Journal of Hydrology
JF - Journal of Hydrology
SN - 0022-1694
ER -