Drone-mounted GPR surveying: flight-height considerations for diffraction-based velocity analysis

This is a Preprint and has not been peer reviewed. This is version 1 of this Preprint.

Downloads

Download Preprint

Authors

Adam Booth, Tiffany Koylass

Abstract

Recent studies highlight the potential of the drone platform for ground penetrating radar (GPR) surveying. Most guidance for optimising drone flight-heights is based on maximising the image quality of target responses, but no study yet considers the impact on diffraction travel-times. Strong GPR velocity contrasts across the air-ground interface introduce significant refraction effects that distort diffraction hyperbolae and introduce errors into diffraction-based velocity analysis. The severity of these errors is explored with synthetic GPR responses, using ray- and finite-difference approaches, and a real GPR dataset acquired over a sequence of diffracting features buried up to 1 m in the ground. Throughout, GPR antennas with 1000 MHz centre-frequency are raised from the ground to heights < 0.9 m (0-3 times the wavelength in air). Velocity estimates are within +10% of modelled values (spanning 0.07-0.13 m/ns) if the antenna height is within ½ wavelength of the ground surface. Greater heights reduce diffraction curvature, damaging velocity precision and masking diffractions against a background of subhorizontal reflectivity. Real GPR data highlight further problems of the drone-based platform, with data dominated by reverberations in the air-gap and reduced spatial resolution of wavelets at target depth. We suggest that a drone-based platform is unsuitable for diffraction-based velocity analysis, and any future drone surveys are benchmarked against ground-coupled datasets.

DOI

https://doi.org/10.31223/X5GS5K

Subjects

Earth Sciences, Geophysics and Seismology, Other Earth Sciences

Keywords

drone, diffraction, GPR, ground penetrating radar, velocity analysis

Dates

Published: 2021-09-06 18:13

License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
None

Data Availability (Reason not available):
https://doi.org/10.6084/m9.figshare.16573025.v1

Add a Comment

You must log in to post a comment.


Comments

There are no comments or no comments have been made public for this article.