4D ground-penetrating radar during a plot scale dye tracer experiment

• Published in: Journal of applied geophysics Vol. 118; pp. 139 - 144
• Main Authors: Allroggen, Niklas, van Schaik, N. Loes M.B., Tronicke, Jens
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-07-2015
• Subjects: Brilliant blue; Ground penetrating radar; Time-lapse imaging; Brilliant blue; Time-lapse imaging; Ground penetrating radar
• ISSN: 0926-9851; 1879-1859
• DOI: 10.1016/j.jappgeo.2015.04.016

Flow phenomena in the unsaturated zone are highly variable in time and space. Thus, it is challenging to measure and monitor such processes under field conditions. Here, we present a new setup and interpretation approach for combining a dye tracer experiment with a 4D ground-penetrating radar (GPR) survey. Therefore, we designed a rainfall experiment during which we measured three surface-based 3D GPR surveys using a pair of 500MHz antennas. Such a survey setup requires accurate acquisition and processing techniques to extract time-lapse information supporting the interpretation of selected cross-sections photographed after excavating the site. Our results reveal patterns of traveltime changes in the measured GPR data, which are associated with soil moisture changes. As distinct horizons are present at our site, such changes can be quantified and transferred into changes in total soil moisture content. Our soil moisture estimates are similar to the amount of infiltrated water, which confirms our experimental approach and makes us confident for further developing this strategy, especially, with respect to improving the temporal and spatial resolution.
•We present a combined dye tracer and GPR experiment on the plot scale.•We image subsurface soil moisture patterns by travel-time changes between horizons.•Our method provides insights into the temporal evolution of infiltration patterns.