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@ARTICLE{Bechtold:21587,
      author       = {Bechtold, M. and Vanderborght, J. and Weihermüller, L. and
                      Herbst, M. and Günther, T. and Ippisch, O. and Kasteel, R.
                      and Vereecken, H.},
      title        = {{U}pward transport in a three-dimensional heterogeneous
                      laboratory soil under evaporation conditions},
      journal      = {Vadose zone journal},
      volume       = {11},
      number       = {2},
      issn         = {1539-1663},
      address      = {Madison, Wis.},
      publisher    = {SSSA},
      reportid     = {PreJuSER-21587},
      year         = {2012},
      note         = {This study was funded by the network EOS
                      (www.netzwerk-eos.dlr.de). We are grateful for the help of
                      Robert Schroder, Odilia Esser, Anke Langen, and many more
                      during the construction of the experimental setup. We thank
                      Mathieu Javaux for providing the MATLAB library for
                      convection-dispersion analytical solutions (CASlib),
                      Johannes Koestel for making his MATLAB code for the ERT
                      error estimation available, and Horst Hardelauf for support
                      in coupling PARTRACE with the finite-volume flow model. We
                      thank Niklas Linde for several useful comments.},
      abstract     = {Upward water flow induced by evaporation can cause soil
                      salinization and transport of contaminants to the soil
                      surface and influences the migration of solutes to the
                      groundwater. In this study, we used electrical resistivity
                      tomography (ERT) to obtain time-lapse images of an
                      upward-flow tracer experiment under evaporation conditions
                      in a three-dimensional, spatially correlated heterogeneous
                      laboratory soil composed of three different materials
                      (coarse-, medium-, and fine-grained sands). The tracer
                      experiment was performed during 40 d of quasi-steady-state,
                      upward-flow conditions. Monitored transport was compared
                      with three-dimensional numerical simulation based on the
                      Richards and advection-dispersion equations. The ERT-derived
                      and modeled solute transport correlated well in the lower
                      part of the laboratory soil, while deviations increased
                      toward the surface. Inversion of synthetic ERT data
                      indicated that deviations cannot be explained by ERT data
                      and inversion errors only, but also errors of the flow and
                      transport model must be invoked. The classical
                      potential/actual evaporation (E-pot/E-a) concept
                      underestimated the experimental evaporation, as locally E-a
                      exceeded E-pot, which was determined as the maximum
                      evaporation from an insulated free water table minus soil
                      heat flux. Increasing the potential evaporation rate
                      uniformly in the model, so that wet high-evaporation zones
                      can compensate for lower evaporation from dry zones,
                      increased the correlation between experiment and model.
                      Despite the remaining deviations, experiment and model
                      showed a consistent and systematic pattern of preferential
                      upward transport pathways. Close above the water table, most
                      of the transport occurred in the coarse material, while with
                      increasing height, transport was dominated by the finer
                      materials. This study is an experimental benchmark for
                      three-dimensional flow and transport models using simplified
                      evaporation boundary conditions and for ERT to monitor
                      upward transport.},
      keywords     = {J (WoSType)},
      cin          = {IBG-3},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Environmental Sciences / Soil Science / Water Resources},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000306830700005},
      doi          = {10.2136/vzj2011.0066},
      url          = {https://juser.fz-juelich.de/record/21587},
}