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@ARTICLE{Sucre:17434,
      author       = {Sucre, O. and Pohlmeier, A. and Miniére, A. and Blümich,
                      B.},
      title        = {{L}ow-field {NMR} logging sensor for measuring hydraulic
                      parameters of model soils},
      journal      = {Journal of hydrology},
      volume       = {406},
      issn         = {0022-1694},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier},
      reportid     = {PreJuSER-17434},
      year         = {2011},
      note         = {Funding from the German Research Council (DFG) framed
                      within the interdisciplinary project TRANSREGIO 32
                      (Interdisciplinary Collaborative Research Center, 2010) is
                      gratefully acknowledged. The insightful comments of the
                      referees were also of great help. OS expresses his gratitude
                      to the German Service of Academic Exchange (DAAD) for his
                      Ph.D. Grant and to K. Kupferschlager and M. Adams for the
                      provided technical support.},
      abstract     = {Knowing the exact hydraulic parameters of soils is very
                      important for improving water management in agriculture and
                      for the refinement of climate models. Up to now, however,
                      the investigation of such parameters has required applying
                      two techniques simultaneously which is time-consuming and
                      invasive. Thus, the objective of this current study is to
                      present only one technique, i.e., a new non-invasive method
                      to measure hydraulic parameters of model soils by using
                      low-field nuclear magnetic resonance (NMR). Hereby, two
                      model clay or sandy soils were respectively filled in a 2
                      m-long acetate column having an integrated PVC tube. After
                      the soils were completely saturated with water, a low-field
                      NMR sensor was moved up and down in the PVC tube to
                      quantitatively measure along the whole column the initial
                      water content of each soil sample. Thereafter, both columns
                      were allowed to drain. Meanwhile, the NMR sensor was set at
                      a certain depth to measure the water content of that soil
                      slice. Once the hydraulic equilibrium was reached in each of
                      the two columns, a final moisture profile was taken along
                      the whole column. Three curves were subsequently generated
                      accordingly: (1) the initial moisture profile, (2) the
                      evolution curve of the moisture depletion at that particular
                      depth, and (3) the final moisture profile. All three curves
                      were then inverse analyzed using a MATLAB code over
                      numerical data produced with the van Genuchten-Mualem model.
                      Hereby, a set of values (alpha, n, theta(r) and theta(s))
                      was found for the hydraulic parameters for the soils under
                      research. Additionally, the complete decaying NMR signal
                      could be analyzed through Inverse Laplace Transformation and
                      averaged on the 1/T-2 space. Through measurement of the
                      decay in pure water, the effect on the relaxation caused by
                      the sample could be estimated from the obtained spectra. The
                      migration of the sample-related average < 1/T-2,T-Sample >
                      with decreasing saturation speaks for a enhancement of the
                      surface relaxation as the soil dries, in concordance with
                      results found by other authors. In conclusion, this
                      low-field mobile NMR technique has proven itself to be a
                      fast and a non-invasive mean to investigate the hydraulic
                      behavior of soils and to explore microscopical aspect of the
                      water retained in them. In the future, the sensor should
                      allow easy soil moisture measurements on-field. (C) 2011
                      Elsevier B.V. All rights reserved.},
      keywords     = {J (WoSType)},
      cin          = {IBG-3},
      ddc          = {690},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Engineering, Civil / Geosciences, Multidisciplinary / Water
                      Resources},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000294518500003},
      doi          = {10.1016/j.jhydrol.2011.05.045},
      url          = {https://juser.fz-juelich.de/record/17434},
}