Electrical parameter estimation of the soil using GPR and full waveform inversion: a case study in Colombia

Abstract

A method of Full Waveform Inversion on GPR data for the estimation of subsurface electrical properties such as relative permittivity and conductivity is proposed in this paper. The GPR radar antenna used for subsurface data acquisition is a B-scan acquisition and it operates at a center frequency of 400 MHz. B-scan acquisitions are a challenge in the subsurface parameter estimation process due to lack of illumination. In addition, B-scan acquisitions are more sensitive to the starting point in estimating subsurface parameters in comparison to multiple offset acquisitions. However, despite the challenges, this type of acquisition is used because it allows portability in areas of difficult access and quick data collection, reducing processing times and costs. In this work, Full Waveform Inversion with cost function constraints was evaluated to estimate subsurface relative permittivity and conductivity using B-scan acquisitions. The proposed methods were evaluated using data collected in a study area located in Mogotes, Santander, Colombia. From the results obtained, it can be concluded that the use of regularization in the inversion process gives smoother subsurface models, also preserving discontinuities. In addition, the incoherent noise in the data is reduced by Gaussian regularization, allowing a better interpretation of the study area.