Remotely Estimation of the Soil Hydraulic Properties by Using Full-Waveform Hydrogeophysical Inversion of the Time-Lapse GPR Data (original) (raw)

2009

Abstract

Recently, ground-penetrating radar (GPR) is increasingly being used to provide quantitative information of the subsurface distributions and hydrological properties. We used integrated hydrogeophysical inversion of time-lapse, proximal ground penetrating radar (GPR) data to remotely estimate the unsaturated soil hydraulic properties. The radar system is based on international standard vector network analyzer technology and a full-waveform model is used to describe wave propagation in the antenna-air-soil system, including antenna-soil interactions. Hydrodynamic modeling was based on a one-dimensional solution of Richard’s equation and was used to constrain the inverse electromagnetic problem in reconstructing vertical water content profiles. As a result, the estimated parameters reduce to the soil hydraulic properties, thereby strongly reducing the dimensionality of the inverse problem. The approach is tested in controlled laboratory conditions for a variable infiltration event in a homogeneous sandy soil. In total, sixteen GPR observations were made with uneven time steps, to catch most of the observed water dynamics. Results were compared with TDR and ground truth measurements. Finally, we tested the approach in real field conditions at one location. TDR probes were installed at four different depths to infer the dynamics of vertical water content profile and used as a reference method for comparsion. The results suggest that the proposed method is promising for characterizing the shallow subsurface hydraulic properties at the field scale with a high spatial resolution.

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