James Irving

Ground-penetrating radar (GPR) is a popular technique for characterizing the distribution of water content in the subsurface. The reason for this is the strong electromagnetic (EM) wave velocity contrast that exists between water and earth materials. With both surface-based and borehole GPR methods, however, there are a number of factors that limit the resolution of the subsurface velocity estimates (and therefore water content estimates) that we can obtain using current data collection and processing methodologies. The goal of my Ph.D. thesis was to address some of these issues and develop improved methods for characterization of subsurface EM wave velocity from crosshole and surface-based GPR data. At Stanford, I was involved in the following research projects:

• efficient modeling of antenna transmission and reception for crosshole GPR
• investigation of the effects of antenna length on crosshole GPR tomography
• strategies for improving crosshole GPR tomography at close borehole spacings
• significance of saturation-related anisotropy in GPR data
• combined crosshole and surface-based GPR tomography
• GPR diffraction velocity analysis (with Paul Sava in SEP)

At the beginning of my Ph.D. at Stanford, I also wrote some basic finite-difference time-domain (FDTD) codes in MATLAB for modeling borehole and surface-based GPR to help with my research. This work has been published in the journal Computers & Geosciences. Click here (pdf file) to download the final version of the paper. The codes are available to the public here (zip file).

During my M.Sc. at the University of British Columbia, I looked at the estimation and removal of dispersion from GPR data. Click here to download the publication related to this research.