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Browsing by Author Van Dam, R.L.

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  • A Comparison of Ground‐Penetrating Radar Early‐Time Signal Approaches for Mapping Changes in Shallow Soil Water Content

    • Authors: Algeo, J.;  Advisor: -;  Participants: Slater, L.; Binley, A.; Van Dam, R.L.; Watts, C. (2018)

  • In this study we performed controlled irrigation experiments using a multifrequency GPR system to compare two statistics used to quantify the ETS: average envelope amplitude (AEA) and carrier frequency amplitude (CFA). Supporting data were provided by direct measurements, electrical resistivity imaging (ERI), and synthetic modeling. In our first experiment, both statistics successfully related the ETS for 250 and 400 MHz GPR data to increasing water content. However, the 400 MHz AEA lost sensitivity at later stages of the irrigation process, whereas the 400 MHz CFA remained sensitive to changes in water content. The 1000 MHz data did not show the expected relationships, possibly due t...
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  • Quantifying Soil Water and Root Dynamics Using a Coupled Hydrogeophysical Inversion

    • Authors: Kuhl, A.S.;  Advisor: -;  Participants: Kendall, A.D.; Van Dam, R.L.; Hyndman, D.W. (2018)

  • In this study, we developed and tested a coupled hydrogeophysical inversion approach that uses electrical resistivity data to estimate soil hydraulic, petrophysical, and root dynamic parameters. This builds on prior research that used either a coupled hydrogeophysical inversion to estimate soil hydraulic parameters only, or a hydrological inversion to estimate root distribution or root water uptake parameters. Our results indicate that under the conditions tested, this approach accurately captures root water dynamics and soil hydraulic parameters. This opens up opportunities to noninvasively image a variety of root distributions and soil systems, better understand the dynamics of RWU ...