Measurement and Modeling of the TDR Signal Propagation through Layered Dielectric Media

Reply to discussion of “Soil water content and salinity determination using different dielectric methods in saline gypsiferous soil”

“…Their results clearly demonstrate that arithmetic averaging is the most appropriate method. This is also in line with the findings of Schaap et al (2003), who concluded that the averaging regime is frequency dependent; at lower frequencies, the averaging regime gets closer to arithmetic averaging. Clearly this needs to be considered when comparing TDR and WET sensor results from upward infiltration calibration experiments.…”

Mapping shallow soil moisture profiles at the field scale using full-waveform inversion of ground penetrating radar data

“…A physical decoupling between surface and subsurface soil moisture may occur considering a wet soil subject to fast evaporation or the propagation of a wetting front in a dry soil, especially in coarse materials. In addition, pedogenetic processes and agricultural practices may lead to varying soil moisture conditions, according to the different soil layer properties [Schaap et al, 2003]. Surface soil moisture may therefore fail to reflect the soil moisture conditions in the subsurface that are actually of interest for a lot of processes [Capehart and Carlson, 1997].…”

Dielectric constant time stability of glacial till at a clear-cut site

“…Similar to agricultural fields, the spatial variability of soil θ v at forest sites is influenced by soil texture (Bouten et al, 1992;Hänninen, 1997). Along with soil texture and topographic curvature as a covariant of significance for time stability (Vachaud et al, 1985) other factors, such as soil structure, amount of layers (Chang and Knight, 2001;Schaap et al, 2003), soil particle shape (Coelho et al, 1997), as well as transpiration of forest canopy and vegetation (Bouten et al, 1992;Cienciala et al, 2002;Hupet and Vanclooster, 2002) also contribute to hydrological conditions. Preferential flow occurs through macro-pores of living or decayed root systems (Noguchi et al, 1999), but also subsurface coarse fraction content (stoniness) may have an impact on the hydraulic characteristics of a site.…”