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@ARTICLE{HendricksFranssen:16634,
      author       = {Hendricks Franssen, H.J. and Kaiser, H.P. and Kuhlmann, U.
                      and Bauser, G. and Stauffer, F. and Müller, R. and
                      Kinzelbach, W.},
      title        = {{O}perational real-time modeling with ensemble {K}alman
                      filter of variably saturated subsurface flow including
                      stream-aquifer interaction and parameter updating},
      journal      = {Water resources research},
      volume       = {47},
      issn         = {0043-1397},
      address      = {Washington, DC},
      publisher    = {AGU},
      reportid     = {PreJuSER-16634},
      pages        = {W02532},
      year         = {2011},
      note         = {The study was performed within the project "Real-Time
                      Control of a Well-Field Using a Groundwater Model," a
                      cooperation between ETH Zurich, Zurich Water Supply, and TK
                      Consult Zurich. This project is funded by the Swiss
                      Innovation Promotion Agency CTI under contract 7608.2
                      EPRP-IW.},
      abstract     = {Urban groundwater is frequently contaminated, and the exact
                      location of the pollution spots is often unknown.
                      Intelligent monitoring of the temporal variations in
                      groundwater flow in such an area assists in selectively
                      extracting groundwater of drinking water quality. Here an
                      example from the city of Zurich (Switzerland) is shown. The
                      monitoring strategy consists of using the ensemble Kalman
                      filter (EnKF) for optimally combining online observations
                      and online models for the real-time characterization of
                      groundwater flow. We conducted numerical simulation
                      experiments for the period January 2004 to December 2007
                      with a 3-D finite element model for variably saturated
                      groundwater flow. It was found that the daily assimilation
                      of piezometric head data with EnKF results in a better
                      characterization of piezometric heads than does a model
                      which is inversely calibrated with historical data but not
                      updated in real time. The positive impact of model updating
                      with observations can still be observed 10 days after the
                      update. These simulations also suggest that parameters
                      (hydraulic conductivity and leakage) are successfully
                      updated: 1 and 10 day piezometric head predictions are
                      better with than without updating of parameters. Additional
                      experiments with a synthetic model for the same site, in
                      which the only difference is that certain parameter values
                      are selected as the unknown "true" conditions, show that
                      EnKF also successfully updates unknown parameters. However,
                      this is only the case if spatially distributed hydraulic
                      conductivities and leakage coefficients are jointly updated
                      and if a damping parameter is used. The mean absolute error
                      of estimated log leakage coefficients decreased by up to
                      $63\%;$ for log hydraulic conductivity a decrease of up to
                      $27\%$ was observed. From January 2009 the method has been
                      operational at the Water Works Zurich and showed a
                      remarkable performance until present (October 2010).},
      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 / Limnology / Water Resources},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000287819100003},
      doi          = {10.1029/2010WR009480},
      url          = {https://juser.fz-juelich.de/record/16634},
}