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The dependence of the electrical conductivity measured by time domain reflectometry on the water content of a sand
Author(s) -
Ferré P. A.,
Redman J. D.,
Rudolph D. L.,
Kachanoski R. G.
Publication year - 1998
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/98wr00218
Subject(s) - reflectometry , calibration , conductivity , materials science , electrical resistivity and conductivity , time domain , water content , soil science , analytical chemistry (journal) , environmental science , geotechnical engineering , remote sensing , geology , chemistry , electrical engineering , chromatography , physics , engineering , computer science , quantum mechanics , computer vision
We present paired measurements of the water content and electrical conductivity collected in a laboratory column packed with a homogeneous, clean sand over a wide range of water content and pore water electrical conductivity (EC) conditions. The EC was determined using the method of Nadler et al. [1991] from waveforms collected with two‐rod time domain reflectometry (TDR) probes with and without baluns and with three‐rod probes without baluns. Following Heimovaara et al. [1995], we calibrated the probes in saline solutions to account for the series resistance of the cable and connectors. The calibrated EC shows a nonlinear dependence on the water content that is well described by a simple power relationship [ Archie , 1942]. Recognizing that calibration in saline solutions is impractical for some TDR probes, we demonstrate that the EC response can be calibrated directly using the results of drainage events, incorporating only a separate calibration of the cable resistance. None of the probe designs shows any clear advantage for EC measurement.