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@ARTICLE{Mboh:22938,
      author       = {Mboh, C.M. and Huisman, J.A. and Zimmermann, E. and
                      Vereecken, H.},
      title        = {{C}oupled {H}ydrogeophysical {I}nversion of {S}treaming
                      {P}otential {S}ignals for {U}nsaturated {S}oil {H}ydraulic
                      {P}roperties},
      journal      = {Vadose zone journal},
      volume       = {11},
      number       = {2},
      issn         = {1539-1663},
      address      = {Madison, Wis.},
      publisher    = {SSSA},
      reportid     = {PreJuSER-22938},
      year         = {2012},
      note         = {C.M. Mboh and J. A. Huisman gratefully acknowledge support
                      by Grants HU1312/2-1 and HU1312/2-2 of the Deutsche
                      Forschungsgemeinschaft.},
      abstract     = {Streaming potential (SPs) is the electric potential
                      generated by fluid flow in a charged porous medium. The SPs
                      signals are related to pore water velocity, bulk electrical
                      conductivity, pore water charge excess, and soil porosity.
                      While several studies have estimated hydraulic properties of
                      the saturated zone from SPs, there have been fewer attempts
                      to infer unsaturated hydraulic properties from SPs. From
                      numerical and laboratory experiments in which infiltration
                      and subsequent drainage was monitored with nonpolarizable
                      Ag/AgCl electrodes and tensiometers, we showed that it is
                      feasible to estimate three key Mualemvan Genuchten hydraulic
                      parameters (fitting parameters alpha and n and saturated
                      hydraulic conductivity K-s) and Archie's saturation exponent
                      (n(a)) using a coupled hydrogeophysical inversion approach.
                      In addition to a reasonably good estimate of n(a), coupled
                      hydrogeophysical inversion of actual SPs measurements during
                      drainage provided estimates of alpha, n, and K-s that were
                      comparable to those obtained from an independent inversion
                      of the tensiometric data (matric heads). We concluded that
                      coupled hydrogeophysical inversion of time-lapse SPs signals
                      is a promising method for hydraulic characterization of the
                      vadose zone. Accurate modeling of SPs signals is essential
                      for reliable inversion results, but there is still debate
                      about the appropriate model for the voltage coupling
                      coefficient at partial saturation. Our experimental data
                      showed a nonlinear and monotonic decrease in the absolute
                      voltage coupling coefficient with decreasing saturation. A
                      comparison of several available models with our experimental
                      data showed that models that consider the relative
                      permeability and the relative electrical conductivity in
                      addition to the saturated coupling coefficient and water
                      saturation were most appropriate.},
      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:000306830700017},
      doi          = {10.2136/vzj2011.0115},
      url          = {https://juser.fz-juelich.de/record/22938},
}