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Electromagnetic Determination of Soil Water Content Using TDR: I. Applications to Wetting Fronts and Steep Gradients
Author(s) -
Topp G. C.,
Davis J. L.,
Annan A. P.
Publication year - 1982
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1982.03615995004600040002x
Subject(s) - reflectometry , soil water , wetting , water content , soil science , dielectric , environmental science , time domain , materials science , geology , geotechnical engineering , composite material , optoelectronics , computer science , computer vision
The time‐domain reflectometry (TDR) technique has been demonstrated to be a viable method for determining soil water content in uniformly wet soils. The TDR response in nonuniformly wet soils was examined herein both theroetically and experimentally. An extensive set of experiments was carried out in a controlled laboratory test facility which permitted synthesis of steep water content gradients and wetting fronts. The water content measured by the TDR technique has been found to be the same as the average water content to within 0.01 cm 3 cm −3 in extremely nonuniform conditions. This result is quite surprising at first but is readily explained by the nature of the dielectric constant and water content relationship. The TDR technique has also been found useful in detecting and monitoring the progression of wetting front advance through a soil.