Frequency influence on the Hilhorst permittivity–conductivity model accuracy

Investigate the influence of electromagnetic frequency modulation on the accuracy of the Hilhorst (2000) linear relationship between bulk dielectric permittivity and bulk electrical conductivity for estimating pore-water electrical conductivity in soils.

Background

Section 2.3 discusses two main approaches to infer pore-water electrical conductivity from bulk measurements: (i) a linear bulk permittivity–bulk conductivity model commonly attributed to Hilhorst (2000) and (ii) models linking bulk conductivity to water content, such as Rhoades et al. (1976). While the Rhoades-type approach is validated for DC conditions, the paper notes that the Hilhorst linear model’s response to frequency changes has not been assessed.

Given that many soil electromagnetic measurements (e.g., TDR, capacitance sensors) operate over varying frequency ranges, understanding how frequency modulation affects the Hilhorst model’s accuracy is essential for reliable salinity estimation across instruments and conditions.

References

Furthermore, while Equation 5 is applicable to DC frequencies, the influence of frequency modulations on the accuracy of Equation 12 has not been evaluated.

— Pedophysics: an open-source python package for soil geophysics  (2403.07473 - Veirana et al., 2024) in Section 2.3 (Soil salinity)