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Intricacies in the interpretation of vertical radar profiling caused by borehole effects

Rossi, M. LU ; Cassiani, G.; Vignoli, G.; Irving, J.; Deiana, R. and Binley, A. (2017) 23rd European Meeting of Environmental and Engineering Geophysics In 23rd European Meeting of Environmental and Engineering Geophysics
Abstract

Estimation of hydraulic parameters of the vadose zone is a relevant issue in hydrological characterization and flow model calibration. Two borehole Ground Penetrating Radar (GPR) techniques are discussed: Zero-Offset Profiling (ZOP) and Vertical Radar Profiling (VRP). The field case is representative of a very common situation in vadose zone characterization: Above the water table, the permittivity inside the air-filled borehole is significantly smaller than in the embedding soil. In this case, if the first-arrivals are picked and the corresponding inversions are performed without a careful analysis, the recovered dielectric relative permittivity (år) profiles are in large disagreement. The presented analysis of VRP synthetic and real... (More)

Estimation of hydraulic parameters of the vadose zone is a relevant issue in hydrological characterization and flow model calibration. Two borehole Ground Penetrating Radar (GPR) techniques are discussed: Zero-Offset Profiling (ZOP) and Vertical Radar Profiling (VRP). The field case is representative of a very common situation in vadose zone characterization: Above the water table, the permittivity inside the air-filled borehole is significantly smaller than in the embedding soil. In this case, if the first-arrivals are picked and the corresponding inversions are performed without a careful analysis, the recovered dielectric relative permittivity (år) profiles are in large disagreement. The presented analysis of VRP synthetic and real datasets clarifies that the presence of the air-filled borehole may alter the propagation of electromagnetic waves, invalidating the comparison among VRP and ZOP first-arrivals. Once the borehole effects are accounted, the comparison between the ZOP and VRP år-profiles is more reasonable and reveals the different resolution of these techniques, focusing on the information that can be inferred for hydrological characterizations. Thus, VRP surveys in vadose zone must be accurately interpreted, as the electromagnetic waves may propagate via "guided" modes along the borehole.

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Chapter in Book/Report/Conference proceeding
publication status
published
subject
in
23rd European Meeting of Environmental and Engineering Geophysics
publisher
European Association of Geoscientists and Engineers, EAGE
conference name
23rd European Meeting of Environmental and Engineering Geophysics
external identifiers
  • scopus:85039844792
ISBN
9789462822238
DOI
10.3997/2214-4609.201702088
language
English
LU publication?
yes
id
3b658942-891b-412f-913a-aca70c2a6181
date added to LUP
2018-01-10 08:56:21
date last changed
2018-01-10 10:02:14
@inproceedings{3b658942-891b-412f-913a-aca70c2a6181,
  abstract     = {<p>Estimation of hydraulic parameters of the vadose zone is a relevant issue in hydrological characterization and flow model calibration. Two borehole Ground Penetrating Radar (GPR) techniques are discussed: Zero-Offset Profiling (ZOP) and Vertical Radar Profiling (VRP). The field case is representative of a very common situation in vadose zone characterization: Above the water table, the permittivity inside the air-filled borehole is significantly smaller than in the embedding soil. In this case, if the first-arrivals are picked and the corresponding inversions are performed without a careful analysis, the recovered dielectric relative permittivity (år) profiles are in large disagreement. The presented analysis of VRP synthetic and real datasets clarifies that the presence of the air-filled borehole may alter the propagation of electromagnetic waves, invalidating the comparison among VRP and ZOP first-arrivals. Once the borehole effects are accounted, the comparison between the ZOP and VRP år-profiles is more reasonable and reveals the different resolution of these techniques, focusing on the information that can be inferred for hydrological characterizations. Thus, VRP surveys in vadose zone must be accurately interpreted, as the electromagnetic waves may propagate via "guided" modes along the borehole.</p>},
  author       = {Rossi, M. and Cassiani, G. and Vignoli, G. and Irving, J. and Deiana, R. and Binley, A.},
  booktitle    = {23rd European Meeting of Environmental and Engineering Geophysics},
  isbn         = {9789462822238},
  language     = {eng},
  publisher    = {European Association of Geoscientists and Engineers, EAGE},
  title        = {Intricacies in the interpretation of vertical radar profiling caused by borehole effects},
  url          = {http://dx.doi.org/10.3997/2214-4609.201702088},
  year         = {2017},
}