Detection of Tracer Plumes Using Full‐Waveform Inversion of Time‐Lapse Ground Penetrating Radar Data: A Numerical Study in a High‐Resolution Aquifer Model

Imaging subsurface small-scale features and monitoring transport of tracer plumes at a fine resolution is interest to characterize processes in aquifers. Full-waveform inversion (FWI) crosshole ground penetrating radar (GPR) measurements enables aquifer characterization decimeter-scale resolution. The method produces images both relative dielectric permittivity (εr) bulk electrical conductivity (σb) that can be related hydraulic properties distributions. To test the potential time-lapse GPR FWI for imaging plumes, we conducted numerical experiment by injecting saline water, desalinated ethanol heterogeneous aquifer. tracers only changed σb, whereas εr σb. Tracer concentrations were retrieved from inverted σb models using information about petrophysical parameters. could recover preferential paths ∼0.2 m width, while derived structures are smoother. 50 data sets demonstrated derive spatially resolved breakthrough curves image plane between boreholes. Thus, high-resolution with produce high contrast against background has great