You are being redirected because this document is part of your ASTM Compass® subscription.
    This document is part of your ASTM Compass® subscription.

    Volume 41, Issue 2 (March 2018)

    Evaluation of the Performance of TDR and Capacitance Techniques for Soil Moisture Measurement

    (Received 19 September 2016; accepted 24 July 2017)

    Published Online: 2018

    CODEN: GTJODJ

      Format Pages Price  
    PDF (1.44 MB) 15 $25   ADD TO CART

    Cite this document

    X Add email address send
    X
      .RIS For RefWorks, EndNote, ProCite, Reference Manager, Zoteo, and many others.   .DOCX For Microsoft Word



    Abstract

    Though researchers have employed various techniques (gravimetric, electromagnetic, neutron scattering, heat pulse, microwave, and optical remote sensing techniques) for soil moisture measurement, dielectric-based techniques (Time Domain Reflectometry [TDR] and capacitance technique [CT]) have gained much more popularity, mainly due to revolutionary developments in the fields of electronics and data communication systems. However, the suitability and relative performance of these techniques for moisture measurement of soils is a point of debate. Hence, in order to address this issue, extensive studies were conducted on soils of entirely different characteristics, compacted at various compaction states (dry densities and water contents) by employing TDR and capacitance probes. Subsequently, the dielectric constant of the soil and its bulk electrical conductivity were obtained using these probes and compared against each other and those computed from Topp’s equation, which is a well-established relationship between the dielectric constant of the soil and its volumetric moisture content. An attempt was also made to correlate Ka values obtained from the dielectric techniques and Topp’s equation with those of the Time Propagation (TP) Mixing model, which incorporates the properties of the soil matrix as well. It has been observed that the Ka-TDR matches well with the Ka-Topp and Ka-TP, while the best match has been observed between Ka-TDR and Ka-Topp as compared to the Ka-CT. As such, the study demonstrates clearly that Topp’s equation, which ignores the soil-specific parameters, is capable of determining the soil moisture content appropriately. This study proposes an empirical equation that relates dielectric constants obtained from Topp’s equation to those obtained from TDR, CT, and the TP Mixing model. Such a relationship can be further utilized for estimating the volumetric soil moisture content.

    Author Information:

    Susha Lekshmi, S. U.
    Department of Civil Engineering, Indian Institute of Technology Bombay, Powai, Mumbai

    Singh, D. N.
    Department of Civil Engineering, Indian Institute of Technology Bombay, Powai, Mumbai

    Tarantino, Alessandro
    Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow,

    Baghini, M. S.
    Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai


    Stock #: GTJ20160240

    ISSN:0149-6115

    DOI: 10.1520/GTJ20160240

    Author
    Title Evaluation of the Performance of TDR and Capacitance Techniques for Soil Moisture Measurement
    Symposium ,
    Committee D18