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AI-GEOSTATS: 3D-kriging with soil data

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  • Markus Boehm
    Dear all, how should soil data (~3300 profiles, ~150m average horizontal distance, all about 1 meter deep with different thickness of horizons representing
    Message 1 of 3 , Jun 7, 2001
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      Dear all,

      how should soil data (~3300 profiles, ~150m average horizontal distance,
      all about 1 meter deep with different thickness of horizons representing
      type of soil, humus contents, ...) be kriged?

      I need all information of the different horizons to calculate the somewhat
      like ground water infiltration rate.

      Does it make sense to use 3D-kriging methods? I think then there should a
      modification of the z-coordinate be made. I mean stretching of the
      z-coordinate. Does anyone know how to deal with the problem or some useful
      textbook?

      Or would you prefer to do 2D-kriging for a number of depths (10cm,
      20cm,...), so there's no need to modify the z-coordinate?


      Regards,
      Markus


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    • Med Bennett
      ... I would compute a vertical or downhole variogram to see if there if any significant spatial correlation in that direction. If so, you should attempt to
      Message 2 of 3 , Jun 7, 2001
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        At 01:03 PM 6/7/01 +0200, Markus Boehm wrote:
        >Dear all,
        >
        >how should soil data (~3300 profiles, ~150m average horizontal distance,
        >all about 1 meter deep with different thickness of horizons representing
        >type of soil, humus contents, ...) be kriged?
        >
        >I need all information of the different horizons to calculate the somewhat
        >like ground water infiltration rate.
        >
        >Does it make sense to use 3D-kriging methods? I think then there should a
        >modification of the z-coordinate be made. I mean stretching of the
        >z-coordinate. Does anyone know how to deal with the problem or some useful
        >textbook?
        >
        >Or would you prefer to do 2D-kriging for a number of depths (10cm,
        >20cm,...), so there's no need to modify the z-coordinate?
        >
        >
        >Regards,
        >Markus


        I would compute a vertical or "downhole" variogram to see if there if any
        significant spatial correlation in that direction. If so, you should
        attempt to use a 3D kriging method, as it would be wasteful not to use that
        information. You will have to use a very high value for anisotropy in the
        Z direction (on the order of 1000 probably) or else leave the depth units
        as cm and the horizontal units in m.


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      • Markus Boehm
        Dear List, sorry that you had to wait for this summary. I post the answers that I received in this Mail with the corresponding names and email addresses. The
        Message 3 of 3 , Jun 21, 2001
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          Dear List,

          sorry that you had to wait for this summary.

          I post the answers that I received in this Mail with the corresponding
          names and email addresses. The answers were help for us to decide to do
          kriging in 2-dimensional layers. However, so far do not have final results
          but it seems to work fine this way.
          Thanks to


          Rudi Dutter <R.Dutter@...>:
          (...
          I was involved in a geochemical analysis project at the peninsula Kola
          where we
          had less data than you have, and also a much smaller amount of values in
          the
          z-direction. Nevertheless the results are documented in
          C. Reiman et al. (1998): Environmental Geochemical Atlas of the Central
          Barents
          Region. Norges geologiske undersokelse (NGU), Geological Survey of Norway.

          We experienced with kriging in 2-dimensional layers, and the results are
          published. Only afterwards we started investigating the relations between
          the
          empirical structures between the layers. This seems to be very
          interesting,
          however, no result is published.

          I believe that 3d-kriging does not bring much, however, the comparisons
          between
          the structures of the layers are very challencing.
          ...)



          Denis Marcotte <Denis.Marcotte@...>:
          (...
          It is probably better to treat this kind of data as 2D, soil type by soil
          type. You can krige the thickness of each soil type and also the measured
          variables; this will allow you to reconstruct vertical sections
          everywhere. The data probably shows a complicated trend along the vertical
          profile which complicates seriously the 3D study.
          ...)



          Med Bennett <mbennett@...>:
          (...
          I would compute a vertical or "downhole" variogram to see if there if any
          significant spatial correlation in that direction. If so, you should
          attempt to use a 3D kriging method, as it would be wasteful not to use
          that
          information. You will have to use a very high value for anisotropy in the
          Z direction (on the order of 1000 probably) or else leave the depth units
          as cm and the horizontal units in m.
          ...)



          "Nel, Fanie" <fnel@...>:
          (...
          I would suggest that you only krig within a horizon , not across horizons.
          This assumes that the variables behave diffrently in each horizon. You
          will
          also have to estimate the width of each horizon.

          If a variable shows a different variograms vertically and horizontally you
          should do 3D kriging.
          ...)



          I hope there all who wrote to me listed above (there is some chaos in my
          Mailbox these days).

          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          Markus Böhm
          Groner Landstr. 45
          D-37081 Goettingen

          fon: +49 (0)551 / 5317388
          fax: +49 (0)180 / 01212 5 109 12 817
          mail: 1) mboehm@...-goettingen
          2) boehm.m@...
          url: http://www.stud.uni-goettingen.de/~mboehm

          On Thu, 7 Jun 2001, Markus Boehm wrote:

          > Dear all,
          >
          > how should soil data (~3300 profiles, ~150m average horizontal distance,
          > all about 1 meter deep with different thickness of horizons representing
          > type of soil, humus contents, ...) be kriged?
          >
          > I need all information of the different horizons to calculate the somewhat
          > like ground water infiltration rate.
          >
          > Does it make sense to use 3D-kriging methods? I think then there should a
          > modification of the z-coordinate be made. I mean stretching of the
          > z-coordinate. Does anyone know how to deal with the problem or some useful
          > textbook?
          >
          > Or would you prefer to do 2D-kriging for a number of depths (10cm,
          > 20cm,...), so there's no need to modify the z-coordinate?
          >
          >
          > Regards,
          > Markus
          >
          >
          > --
          > * To post a message to the list, send it to ai-geostats@...
          > * As a general service to the users, please remember to post a summary of any useful responses to your questions.
          > * To unsubscribe, send an email to majordomo@... with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list
          > * Support to the list is provided at http://www.ai-geostats.org
          >


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