Relations Between Dielectric Permittivity and Volumetric Water Content of Living Soil

2021 ◽  
Author(s):  
Agnieszka Szyplowska ◽  
Hironobu Saito ◽  
Shin Yagihara ◽  
Kahori Furuhata ◽  
Justyna Szerement ◽  
...  
Keyword(s):  
Dielectric Permittivity ◽  
Water Content ◽  
Volumetric Water Content

Measuring duff moisture content in the field using a portable meter sensitive to dielectric permittivity

2004 ◽  
Vol 13 (3) ◽  
pp. 343 ◽  
Author(s):  
P. R. Robichaud ◽  
D. S. Gasvoda ◽  
R. D. Hungerford ◽  
J. Bilskie ◽  
L. E. Ashmun ◽  
...  
Keyword(s):  
Dielectric Permittivity ◽  
Water Content ◽  
Forest Cover ◽  
Volumetric Water Content ◽  
Moisture Meter ◽  
Sample Chamber ◽  
Frequency Domain Reflectometry ◽  
Forest Cover Types ◽  
Gravimetric Water Content ◽  
Best Fit

Duff water content is an important consideration for fire managers when determining favourable timing for prescribed fire ignition. The duff consumption during burning depends largely on the duff water content at the time of ignition. A portable duff moisture meter was developed for real-time water content measurements of non-homogenous material such as forest duff. Using circuitry developed from time and frequency domain reflectometry (TDR and FDR) technologies, this sensor measures a change in frequency that is responsive to the dielectric permittivity of the duff material placed in a sample chamber and compressed. Duff samples from four forest cover types—Douglas fir, larch, lodgepole pine and spruce/alpine fir—were used to calibrate the frequency output to volumetric water content. A second-order polynomial (R2 = 0.97) provides the best fit of the data to volumetric water content. The accuracy of the duff moisture meter is ±1.5% at 30% volumetric water content and ±4% at 60% volumetric water content. The volumetric water content can readily be converted to gravimetric water content, which is used more frequently by fire managers and as an input to predictive models of duff consumption.

Water content as a function of apparent dielectric permittivity in a Fibric Limnic Humisol

2008 ◽  
Vol 88 (1) ◽  
pp. 79-84 ◽  
Author(s):  
S F Lange ◽  
S E Allaire ◽  
V. Juneau
Keyword(s):  
Dielectric Permittivity ◽  
Water Content ◽  
Organic Matter Content ◽  
Organic Soil ◽  
Matter Content ◽  
Time Domain Reflectometry ◽  
Volumetric Water Content ◽  
Wide Range ◽  
Intact Soil Cores ◽  
Intact Soil

Volumetric water content (θv) was estimated from time domain reflectometry (TDR) measurementsof apparent dielectric permittivity (Ka) in an organic soil (Humisol). The goals of this study were: (i) to test the accuracy of existing θv-Ka relationships in this soil and if found insufficient (ii) to develop alternative θv-Ka relationships for this organic soil. The Ka values were measured over a wide range of θv in intact soil cores taken from three horizons (Ohp, Of, Oco). Empirical θv-Ka relationships found in the literature for organic porous media could not accurately describe the θv-Ka relationships of any horizon of this Humisol, probably because of the its very large organic matter content (> 75%) of this soil. New θv-Ka relationships for each horizon were consequently developed. Key words: Organic soil, TDR, coprogenic soil, volumetric water content, apparent dielectric permittivity

Using time domain reflectometry in triaxial testing

2000 ◽  
Vol 37 (6) ◽  
pp. 1325-1331
Author(s):  
J LH Grozic ◽  
M E Lefebvre ◽  
P K Robertson ◽  
N R Morgenstern
Keyword(s):  
Cyclic Loading ◽  
Water Content ◽  
Time Domain ◽  
Void Ratio ◽  
Time Domain Reflectometry ◽  
Volumetric Water Content ◽  
Degree Of Saturation ◽  
Triaxial Testing ◽  
Empirical Correlations ◽  
Static And Cyclic Loading

Time domain reflectometry (TDR) can be used to determine the volumetric water content of soils. This note describes the utilization of a TDR miniprobe in triaxial testing. The TDR performance was examined with a series of tests that not only proved its reliability but also resulted in two empirical correlations. Using these correlations, the degree of saturation and volumetric water content during triaxial testing could be determined. The TDR was then put to use in a laboratory program designed to investigate the response of loose gassy sand under static and cyclic loading. Because of the TDR measurements it was possible to determine the degree of saturation and void ratio of the gassy specimens. The TDR miniprobe proved to be accurate, simple to use, and inexpensive to build.Key words: time domain reflectometry, TDR, triaxial testing, gassy, unsaturated.

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