GPR data inversion for vegetation layer

In this paper, we developed a vegetation cover model for full-wave inversion of ground-penetrating radar (GPR) data assuming multiple layers with effective electrical properties. Measurements were performed in the laboratory conditions over spelt wheat grown in a sandy soil, using a stepped-frequency continuous-wave GPR system. In order to control the sand surface water content, a water table was fixed at 20 cm depth as well as time domain reflectometry probes at 2 and 20 cm depth were used. Measurements were performed and recorded hourly for about one month and the canopy height was measured daily. The effective electromagnetic properties of the vegetation layer were modeled using a complex refractive index model combined with a single Debye relaxation model. A scattering loss parameter was included in the electromagnetic full-wave GPR model for the vegetation layer. The measurements resulted in a strong link between the scattering losses of the vegetation cover and canopy height (generally, the biomass structure), which is expected to strongly influence the soil moisture values (measured with GPR) in presence of vegetation cover.