Quantitative Reflection Tomography of <scp>GPR</scp> Data for Soil Water Dynamics Assessment

ABSTRACT Quantitative reflection tomography of common‐offset (CO) and common‐midpoint (CMP) ground penetrating radar (GPR) data offers a robust way to explore soil water dynamics with impressive sand temporal detail. Synthetic modelling illustrated the sensitivity of reflection tomography to changes in water contents and subsurface lithology. The laboratory experiment reinforced the strength of the reflection tomography under realistic conditions of infiltration and redistribution. The combination of tomographic techniques succeeded in imaging not only the propagation of wetting fronts but also the subsequent lateral and vertical variation in soil moisture and providing estimates of volumetric water content by integrating residual reflection redundancy (RRR) minimisation into the inversion procedure; the process delivers superior velocity models and depth‐migrated images. Collectively, this work establishes reflection tomography as a viable, and indeed, highly non‐invasive method for characterising transient hydrological processes, with strong possibilities for soils, hydro geophysics, and environmental monitoring.