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AI-GEOSTATS: Data on varying support sizes.

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  • Noemi Barabas
    Dear list members, I have a problem concering a three dimensional data set of sediment cores. The cores have been sampled by dividing them into sections of
    Message 1 of 2 , Jan 15, 2002
      Dear list members,

      I have a problem concering a three dimensional data set of sediment cores.

      The cores have been sampled by dividing them into sections of varying
      length, and each sample represents the depth-averaged concentration over
      that length. Thus, resolution varies within cores as well as from core to
      core. The data set is of the measured concentrations at discrete
      locations (x,y,z (corresponding of the mid-depth of the core section)).

      I would like to do 3-D kriging, but need to address the following issues:
      1. concentrations WITHIN the cores are reestimated such that
      the average remains constant,
      2. how do I use data with varying support sizes in the estimation
      at a point of a set support size (defined by a regular
      estimation grid) located OUTSIDE of the cores?

      Has this problem been addressed by anybody, is there a reference or two
      where I might check?

      Thank you very much!

      Noemi

      Noemi Barabas

      PhD Candidate
      The University of Michigan
      Dept. Civil and Environmental Engineering
      1351 Beal Avenue (13 EWRE)
      Ann Arbor, MI 48109-2125
      Phone: (734) 615-5905




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    • Isobel Clark
      Dear Noemi The handling of different support in a kriging system goes all the way back to Matheron s work in the 60 s. In fact, that is probably why it caught
      Message 2 of 2 , Jan 16, 2002
        Dear Noemi

        The handling of different support in a kriging system
        goes all the way back to Matheron's work in the 60's.
        In fact, that is probably why it caught on in mining
        so well. The length of drillcore can be handled quite
        simply, once you have a 'point' semi-variogram model.

        There is a whole chapter on this in my old book,
        Practical Geostatistics (1979) which can be downloaded
        free from the Web at:

        http://uk.geocities.com/drisobelclark/practica.html

        The details on handling different support are also
        discussed in my 1977 paper "Practical kriging in three
        dimensions", Computers and Geosciences, Vol 3, pp.173-
        180 which can be downloaded via my 'briefcase' at
        http://uk.geocities.com/drisobelclark/briefcase.html.

        Your biggest problem is that most (sic) software does
        not deal with this problem, but assumes all samples to
        be of equivalent support.

        Please feel free to contact me if you have any
        detailed questions
        Isobel Clark


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