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@ARTICLE{Couvreur:22887,
      author       = {Couvreur, V. and Vanderborght, J. and Javaux, M.},
      title        = {{A} simple three-dimensional macroscopic root water uptake
                      model based on the hydraulic architecture approach},
      journal      = {Hydrology and earth system sciences},
      volume       = {16},
      issn         = {1027-5606},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {PreJuSER-22887},
      pages        = {2957 - 2971},
      year         = {2012},
      note         = {V.C. is supported by the "Fonds National de la Recherche
                      Scientifique" (FNRS) of Belgium as a Research Fellow. The
                      authors thank this funding agency for its financial support.
                      We also thank Sjoerd van der Zee for his valuable comments,
                      which helped to improve the final version of this
                      manuscript.},
      abstract     = {Many hydrological models including root water uptake (RWU)
                      do not consider the dimension of root system hydraulic
                      architecture (HA) because explicitly solving water flow in
                      such a complex system is too time consuming. However, they
                      might lack process understanding when basing RWU and plant
                      water stress predictions on functions of variables such as
                      the root length density distribution. On the basis of
                      analytical solutions of water flow in a simple HA, we
                      developed an "implicit" model of the root system HA for
                      simulation of RWU distribution (sink term of Richards'
                      equation) and plant water stress in three-dimensional soil
                      water flow models. The new model has three macroscopic
                      parameters defined at the soil element scale, or at the
                      plant scale, rather than for each segment of the root system
                      architecture: the standard sink fraction distribution SSF,
                      the root system equivalent conductance K-rs and the
                      compensatory RWU conductance K-comp. It clearly decouples
                      the process of water stress from compensatory RWU, and its
                      structure is appropriate for hydraulic lift simulation. As
                      compared to a model explicitly solving water flow in a
                      realistic maize root system HA, the implicit model showed to
                      be accurate for predicting RWU distribution and plant collar
                      water potential, with one single set of parameters, in
                      dissimilar water dynamics scenarios. For these scenarios,
                      the computing time of the implicit model was a factor 28 to
                      214 shorter than that of the explicit one. We also provide a
                      new expression for the effective soil water potential sensed
                      by plants in soils with a heterogeneous water potential
                      distribution, which emerged from the implicit model
                      equations. With the proposed implicit model of the root
                      system HA, new concepts are brought which open avenues
                      towards simple and mechanistic RWU models and water stress
                      functions operational for field scale water dynamics
                      simulation.},
      keywords     = {J (WoSType)},
      cin          = {IBG-3},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Geosciences, Multidisciplinary / Water Resources},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000308245800039},
      doi          = {10.5194/hess-16-2957-2012},
      url          = {https://juser.fz-juelich.de/record/22887},
}