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@ARTICLE{Kstel:7437,
      author       = {Köstel, J. and Kemna, A. and Javaux, M. and Vanderborght,
                      J. and Vereecken, H.},
      title        = {{Q}uantitative imaging of solute transport in an
                      unsaturated and undisturbed soil monolith with 3-{D} {ERT}
                      and {TDR}},
      journal      = {Water resources research},
      volume       = {44},
      number       = {12},
      issn         = {0043-1397},
      address      = {Washington, DC},
      publisher    = {AGU},
      reportid     = {PreJuSER-7437},
      pages        = {W12411},
      year         = {2008},
      note         = {Record converted from VDB: 12.11.2012},
      abstract     = {Electrical resistivity tomography (ERT) has proved to be a
                      valuable tool for imaging solute transport processes in the
                      subsurface. However, a quantitative interpretation of
                      corresponding ERT results is constrained by a number of
                      factors. One such factor is the nonuniqueness of the ERT
                      inverse problem if no additional constraints are imposed. In
                      the vadose zone, further problems arise from the general
                      ambiguity of the imaged bulk electrical conductivity in
                      terms of water content and solute concentration. In this
                      study we address these issues in detail for a solute tracer
                      experiment conducted in an undisturbed unsaturated soil
                      monolith where the tracer transport was monitored by means
                      of 3-D smoothness-constrained ERT and time domain
                      reflectometry (TDR) measurements. The experimental design
                      allowed the determination of solute tracer concentrations
                      directly from imaged bulk electrical conductivity.
                      Independent TDR data and effluent tracer concentrations
                      provided a "ground truth'' for the ERT-derived apparent
                      convection-dispersion equation transport parameters. The
                      apparent transport velocity calculated from the ERT results
                      was consistent with that based on TDR data and the sampled
                      effluent, independent of the degree of smoothness imposed in
                      the ERT inversion. On the other hand, the apparent
                      dispersivity calculated from the ERT results was larger than
                      that estimated from TDR data but smaller than that estimated
                      from the sampled effluent, with the magnitude of deviations
                      dependent on the degree of smoothing. Importantly, no mass
                      balance problems were observed in the ERT results. We
                      believe that this is largely a consequence of the uniform
                      application of the tracer as a front and of the
                      configuration of the electrode array with respect to the
                      main transport direction. In conclusion, the study
                      demonstrates that ERT can yield unprecedented quantitative
                      information about local- and column-scale solute transport
                      characteristics in natural soils.},
      keywords     = {J (WoSType)},
      cin          = {ICG-4},
      ddc          = {550},
      cid          = {I:(DE-Juel1)VDB793},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Environmental Sciences / Limnology / Water Resources},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000261690900003},
      doi          = {10.1029/2007WR006755},
      url          = {https://juser.fz-juelich.de/record/7437},
}