This title appears in the Scientific Report :
2023
Including the Effects of Borehole Fillings and Finite-Length Antenna Models in 2.5D Crosshole Ground Penetrating Radar Full-Waveform Inversion
Including the Effects of Borehole Fillings and Finite-Length Antenna Models in 2.5D Crosshole Ground Penetrating Radar Full-Waveform Inversion
In the past years, the critical zone has been massively used for water supply, agricultural production, and waste storage purposes. In order to assess and understand the related environmental risks, a spatially high-resolved characterization of the critical zone is required for assessing the impact...
Saved in:
Personal Name(s): | Hoven, Dominik (Corresponding author) |
---|---|
Warren, Craig / van der Kruk, Jan / Vereecken, Harry / Klotzsche, Anja | |
Contributing Institute: |
Agrosphäre; IBG-3 |
Imprint: |
2023
|
Conference: | American Geophysical Union Fall Meeting 2023, San Francisco (USA), 2023-12-11 - 2023-12-15 |
Document Type: |
Conference Presentation |
Research Program: |
Agro-biogeosystems: controls, feedbacks and impact |
Publikationsportal JuSER |
In the past years, the critical zone has been massively used for water supply, agricultural production, and waste storage purposes. In order to assess and understand the related environmental risks, a spatially high-resolved characterization of the critical zone is required for assessing the impact of small-scale heterogeneities on flow and transport processes. Crosshole ground penetrating radar (GPR) full-waveform inversion (FWI) has often been used for more detailed and high-resolution characterization of permittivity and electrical conductivity of the subsurface. Generally, to provide reliable results for crosshole GPR data, a good ray coverage with a large number of angles is required. Although it is common to measure higher angles (more than 45° from horizontal) in the field, these data often cannot be used in standard inversion approaches as the signal-to-noise ratio is poor, and deviations of the travel time occur because of borehole filling effects. Additionally, for the 2D FWI a 3D to 2D filter needs to be applied to the data to account for the different radiation and propagation patterns in 3D and 2D, which causes problems especially for data related to high contrast zones. Here, we present a novel time domain 2.5 GPR FWI coupled with the 3D forward solver gprMax, which is able to incorporate 3D radiation and propagation, borehole fillings and borehole antennas. The recent version of gprMax is able to use subgrids which allow localized areas of finer spatial resolution within the main finite-difference time-domain mesh. We have used subgrids to efficiently model water-filled boreholes and finite-length antennas to make the forward model in our 2.5D FWI as close to reality as possible. To investigate the improved 2.5D FWI, we create a realistic synthetic model and quantify the impact of higher angles on vertical resolution, by adding objects with stronger contrasts. Using this model, we analyzed the improvements in reconstruction of the synthetic model, starting from the regular 2D FWI up to a 2.5D FWI incorporating boreholes and finite-length antenna models. Furthermore, we provide advice on using the 2.5D FWI, regarding rising computational time, the selection of starting models and other inversion parameters. |