Loading ...
Sorry, an error occurred while loading the content.
 

GEOSTATS: Variograms with multiple sills

Expand Messages
  • Syed.R.Syed@EXXON.sprint.com
    Lisa Dent s questions on variograms with multiple sills refer: 1) Variograms stabilizing and then fluctuating up again could mean one of several things, most
    Message 1 of 1 , Apr 27, 1997
      Lisa Dent's questions on variograms with multiple sills refer:

      1) Variograms stabilizing and then fluctuating up again could mean
      one of several things, most notably:

      (a) a trend in the data (or drift)
      (b) not enough samples at the larger lags (rule of thumb is to cut
      off at half the maximum lag distance).

      2) Assuming it is because of a trend, try to figure out why. I assume
      that for a stream, nutrient concentrations would not be abrupt
      isolated patches, but rather something more gradual, as the stream
      cuts more of the mainland to reach maturity over time. There is also
      a big contrast between upsteam area where there is no flood plain and
      further downstream where it starts to meander. Intuitively then, there
      should be a trend here somewhere although I am no stream expert.

      3) Re (2), the moral here is there is no substitute for a subjective,
      intuitive understanding onf the problem domain before using geostatistics
      to complement that understanding. The tools shouldn't be used as a
      black box. I would read up on 'stream science' if there is such a thing
      before trying to infer 'patches' of nutrient concentrations. Good luck.

      Regards, Syed

      --
      *To post a message to the list, send it to ai-geostats@....
      *As a general service to list users, please remember to post a summary
      of any useful responses to your questions.
      *To unsubscribe, send email to majordomo@... with no subject and
      "unsubscribe ai-geostats" in the message body.
      DO NOT SEND Subscribe/Unsubscribe requests to the list!
    Your message has been successfully submitted and would be delivered to recipients shortly.