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Dakota Aquifer Program--Geologic Framework

Regionalized Classification and its Application to the Dakota Aquifer, Hodgeman County, Kansas

by Ricardo A. Olea and Geoffrey C. Bohling

Original published as KGS Open-file Report 96-22, June 1996.


Regionalized classification is a numerical technique for the partition of a portion of the planet into volumes that are as internally homogeneous as possible and as different as possible from each other. The method works at its best when there are measurements of the same attributes at all control points evenly scattered around the area of interest.

Application of the procedure employing four cumulative thickness measurements in 231 wells in south-central Hodgeman county leads to the following findings concerning the heterogeneity of the amount of shale in the Dakota aquifer:

  1. Delineation of thick basal sand deposits in the Dakota Formation suggest sedimentation along fluvial system draining the area to the northwest.
  2. A thicker than normal and elongated accumulation of sand suggests the existence of a WNW channel during Cheyenne time.
  3. Most favorable deposition of sands in mid-Dakota Formation was erratic and concentrated in the flanks of flood plains.
  4. There is an extensive northwest-southeast band where deposition of sands was never favorable.
  5. Continuous favorable condition throughout the entire genesis of the Dakota aquifer is haphazard and sporadic.
All findings are in agreement with previous general notions about the geology of the aquifer in Hodgeman county in particular and the state in general.

Table of Contents



Ward's Method

Discriminant Analysis

Allocation by Extension

The Dakota Aquifer Program Study

Well clustering by the Ward's method

Discriminant analysis

Mapping of group membership probabilities

Regionalized classification maps



Appendix--Dakota aquifer sampling used in the regionalized classification

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Updated Sept. 16, 1996.
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