This summer I had the chance to participate in a DAAD Rise Pro internship, which, I would highly suggest to anybody who would be interested in exploring research in another country -I put the link at the end of this blog entry. I was an intern at the Forschungzentrum Jülich, under the supervision of Professor Jan Van der Kruk and his post-doctoral student, Anja Klötzsche. Prof Van der Kruk is well-known in the field of hydrogeophysics, and from the little I have gathered, works alot with ground penetrating radar whether it be for surface or borehole measurements.
Therefore, the project I worked on this summer covered between borehole GPR measurements in a rhizotron facility. The final goal of the project is to be able to model the soil water content in the rhizotron in time. The first thing I learned was what a rhizotron is, which is basically a trench with horizontal boreholes. The horizontal boreholes are what made things complicated since GPR measurements are mostly done between vertical boreholes. Therefore, there is not much literature on horizontal borehole GPR measurements, especially concerning the interaction between the direct wave and the air-refracted waves. To get a better idea of this interaction, we decided to model our measurements using GPRmax. This powerful tool is based on a finite-difference time domain modeling of electromagnetic wave propagation. It is fairly easy to use, since it only requires that you know the geometry and electro-magnetic propreties of the environment you want to simulate, your source wave, and your transmitter and receptor positions and localizations. Once these parameters are known, running GPRmax will allow you to predict the wave you will record at the receiver. GPRmax is free to se and an added bonus is that the GPRmax team has recently updated their page: http://www.gprmax.com/index.shtml . You can find the executables and the very well-down user’s manual there. Good luck to all your EM wave modellers!
Link to the german exchange program: https://www.daad.de/rise/en/