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@PHDTHESIS{Klotzsche:139929,
      author       = {Klotzsche, Anja},
      title        = {{F}ull-waveform inversion of crosshole {GPR} data for
                      hydrogeological applications},
      volume       = {193},
      school       = {RWTH Aachen},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH, Zentralbibliothek, Verlag},
      reportid     = {FZJ-2013-05898},
      isbn         = {978-3-89336-915-7},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {X. 164 S.},
      year         = {2013},
      note         = {Dissertation, RWTH Aachen, 2013},
      abstract     = {High resolution and precise characterization of aquifers is
                      needed to improve the understanding of flow and solute
                      transport processes. Decimeter-scale and high
                      contraststructures caused by changes in the porosity or clay
                      content can have a dominant effect on hydraulic processes
                      within an aquifer. Such heterogeneities or layering in
                      aquifers can be related to preferential flow paths or
                      impermeable clay lenses and can act as electromagnetic
                      low-velocity waveguides. Crosshole ground penetrating radar
                      is able to provide shallow subsurface electrical properties,
                      viz. dielectric permittivity and electrical conductivity,
                      and has proven a powerful tool to map and characterize
                      aquifers due to the method’s high resolution and
                      sensitivity to porosity and soil water content. Ray-based
                      methods, which incorporate only a small part of the measured
                      signal in the inversion, such as first-arrival travel times
                      and first-cycle amplitudes, are not able to detect such
                      layers. In contrast, the crosshole GPR full-waveform
                      inversion, which considers the entire waveform or
                      significant parts thereof, is able to resolve sub-wavelength
                      high resolution images and can detect high contrast layers.
                      Recently, a novel 2D time-domain vectorial full-waveform
                      crosshole radar inversion was introduced that significantly
                      improves the model resolution compared to standard ray-based
                      techniques. This GPR full-waveform inversion is modified by
                      allowing an optimized acquisition setup that significantly
                      reduces the acquisition time and computational costs. The
                      improved algorithm is employed to invert crosshole GPR data
                      acquired within a gravel aquifer in the Thur valley,
                      Switzerland, using the ray-based results as starting models.
                      Compared to the ray-based inversion, the results from the
                      full-waveform inversion show images with significantly
                      higher resolution. The simulated traces of the final model,
                      obtained by the full-waveform inversion, fit the observed
                      traces very well in the lower part of the section and
                      reasonably well in the upper part of the section. By
                      incorporating the vadose zone and the water table in the
                      starting models and inversion domain, we are able to improve
                      the initial results and resolve unprecedented sub-wavelength
                      high resolution images for permittivity and conductivity in
                      the entire inversion domain including a high permittivity
                      layer between 5 m - 6 m depth. This high permittivity layer
                      acts as an electromagnetic low-velocity waveguide and is
                      caused by an increased porosity indicating a [...]},
      keywords     = {Dissertation (GND)},
      cin          = {IBG-3},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {246 - Modelling and Monitoring Terrestrial Systems: Methods
                      and Technologies (POF2-246)},
      pid          = {G:(DE-HGF)POF2-246},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/139929},
}