Determination of volumetric water content in lossy geophysical media using time domain reflectometry

2002 ◽  
Author(s):  
B. Oswald ◽  
H.R. Benedickter ◽  
W. Bachtold ◽  
H. Fluhler ◽  
P. Marschall
Keyword(s):  
Water Content ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Volumetric Water Content

scholarly journals Application of time domain reflectometry to determination of volumetric water content in rock

1998 ◽  
Vol 34 (10) ◽  
pp. 2623-2631 ◽  
Author(s):  
Toshihiro Sakaki ◽  
Kozo Sugihara ◽  
Tetsuya Adachi ◽  
Kaoru Nishida ◽  
Wei-ren Lin
Keyword(s):  
Water Content ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Volumetric Water Content

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.

scholarly journals Time domain reflectrometry measurements using a movable obstacle for the determination of dielectric profiles

2008 ◽  
Vol 6 ◽  
pp. 1-4
Author(s):  
B. Will ◽  
M. Gerding ◽  
S. Schultz ◽  
B. Schiek
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Time Domain ◽  
Measurement Techniques ◽  
Measurement Data ◽  
Time Domain Reflectometry ◽  
Dielectric Measurement ◽  
Effective Dielectric Constant ◽  
Pulse Delay

Abstract. Microwave techniques for the measurement of the permittivity of soils including the water content of soils and other materials, especially TDR (time domain reflectometry), have become accepted as routine measurement techniques. This summary deals with an advanced use of the TDR principle for the determination of the water content of soil along a probe. The basis of the advanced TDR technique is a waveguide, which is inserted into the soil for obtaining measurements of the effective soil permittivity, from which the water content is estimated, and an obstacle, which can mechanically be moved along the probe and which acts as a reference reflection for the TDR system with an exactly known position. Based on the known mechanical position of the reference reflection, the measured electrical position can be used as a measure for the effective dielectric constant of the environment. Thus, it is possible to determine the effective dielectric constant with a spatial resolution given by the step size of the obstacle displacement. A conventional industrial TDR-system, operating in the baseband, is used for the signal generation and for the evaluation of the pulse delay time of the obstacle reflection. Thus, a cost effective method for the acquisition of the dielectric measurement data is available.

CORRECTING SOIL VOLUMETRIC WATER CONTENTS FROM A DIRECT-READING TIME DOMAIN REFLECTOMETRY INSTRUMENT (IRAMS)

1989 ◽  
Vol 69 (3) ◽  
pp. 701-704 ◽  
Author(s):  
G. C. TOPP ◽  
J. L. B. CULLEY
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Domain ◽  
Computer Software ◽  
Time Domain Reflectometry ◽  
Direct Reading ◽  
Volumetric Soil Water Content ◽  
Linear Correction

Determination of volumetric soil water content (θ) using time domain reflectometry (TDR) is well established. A commercially available instrument (IRAMS) (the IRAMS (Instrument for Reflectometry Analysis of Moisture in Soils) is a trademark registered by Foundation Instruments Inc. of Ottawa) is now available which incorporates computer software, thus providing direct readouts of θ. A field study of the operation of the IRAMS showed that it operates consistently and repeatedly. The IRAMS values were higher but related linearly to those obtained using a TDR cable tester and manual calculations of travel times. A linear correction of the IRAMS readings is proposed and possible causes are suggested for the observed deviations from expected values. Key words: Time domain, reflectometry, soil water content, field

scholarly journals Measurement of Volumetric Water Content by Gravimetric and Time Domain Reflectometry Methods at Field Experiment with Biochar and N Fertilizer

2019 ◽  
Vol 22 (2) ◽  
pp. 61-64 ◽  
Author(s):  
Lucia Toková ◽  
Dušan Igaz ◽  
Elena Aydin
Keyword(s):  
Field Experiment ◽  
Water Content ◽  
Time Domain ◽  
Soil Property ◽  
Time Domain Reflectometry ◽  
Soil Samples ◽  
Volumetric Water Content ◽  
N Fertilizer ◽  
High Concentration ◽  
Indirect Methods

Abstract There are many methods used for soil water content measurement which we can divide into direct gravimetric methods from using soil samples or indirect methods that are based on the measurement of another soil property which is dependent on soil moisture. The paper presents the findings of volumetric water content measurements with gravimetric and time domain reflectometry (TDR) methods. We focused on four variants in the field experiment in Dolná Malanta (Slovakia): control variant (B0+N0), variant with biochar at dose 20 t.ha−1 without N fertilizer (B20+N0), variant with biochar 20 t.ha−1 and N fertilizer 160 kg.ha−1 (B20+N160) and variant with biochar 20 t.ha−1 and N fertilizer 240 kg.ha−1 (B20+N240). TDR is nowadays a well-established dielectric technique to measure volumetric water content; however, its accuracy is influenced by high concentration of salts in soil. In this paper, we evaluated the effect of added N fertilizer on the measuring accuracy of HydroSense II device that is operating under the TDR principle.

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