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@ARTICLE{Weihermller:57158,
      author       = {Weihermüller, L. and Huisman, J. A. and Lambot, S. and
                      Herbst, M. and Vereecken, H.},
      title        = {{M}apping the spatial variation of soil water content at
                      the field scale with different ground penetrating radar
                      techniques},
      journal      = {Journal of hydrology},
      volume       = {340},
      issn         = {0022-1694},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier},
      reportid     = {PreJuSER-57158},
      pages        = {205 - 216},
      year         = {2007},
      note         = {Record converted from VDB: 12.11.2012},
      abstract     = {Two ground penetrating radar (GPR) techniques were used to
                      estimate the shallow soil water content at the field scale.
                      The first technique is based on the ground wave velocity
                      measured with a bistatic impulse radar connected to 450 MHz
                      ground-coupled antennas. The second technique is based on
                      inverse modeling of an off-ground monostatic TEM horn
                      antenna in the 0.8-1.6 GHz frequency range. Data were
                      collected on a 8 by 9 m partially irrigated intensive
                      research plot and along four 148.5 m transects. Time domain
                      reflectometry, capacitance sensors, and volumetric soil
                      samples were used as reference measurements. The aim of the
                      study was to test the applicability of the ground wave
                      method and the off-ground inverse modeling approach at the
                      field scale for a soil with a silt Loam texture. The results
                      for the ground wave technique were difficult to interpret
                      due to the strong attenuation of the GPR signal, which is
                      related to the silt Loam texture at the test site. The root
                      mean square error of the ground wave technique was 0.076
                      m(3) m(-3) when compared to the TDR measurements and 0.102
                      m(3) m(-3) when compared with the volumetric soil samples.
                      The off-ground monostatic GPR measured less within-field
                      soil water content variability than the reference
                      measurements, resulting in a root mean square error of 0.053
                      m(3) m(-3) when compared with the TDR measurements and an
                      error of 0.051 m(3) m(-3) when compared with the volumetric
                      soil samples. The variability between the two GPR
                      measurements was even Larger with a RSME of 0.115 m(3)
                      m(-3). In summary, both GPR methods did not provide adequate
                      spatial information on soil water content variation at the
                      field scale. The main reason for the deviating results of
                      the ground wave method was the poor data quality due to high
                      silt and clay content at the test site. Additional reasons
                      were shallow reflections and the dry upper soil layer that
                      cannot be detected by the ground wave method. In the case of
                      off-ground GPR, the high sensitivity to the dry surface
                      layer is the most likely reason for the observed deviations.
                      The off-ground GPR results might be improved by using a
                      different antenna that allows data acquisition in a lower
                      frequency range. (C) 2007 Elsevier B.V. All rights
                      reserved.},
      keywords     = {J (WoSType)},
      cin          = {ICG-4 / JARA-ENERGY / JARA-SIM},
      ddc          = {690},
      cid          = {I:(DE-Juel1)VDB793 / $I:(DE-82)080011_20140620$ /
                      I:(DE-Juel1)VDB1045},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Engineering, Civil / Geosciences, Multidisciplinary / Water
                      Resources},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000248166500006},
      doi          = {10.1016/j.jhydrol.2007.04.013},
      url          = {https://juser.fz-juelich.de/record/57158},
}