WSP06275

• File Number: 8449.800
• Description: Denver Basin and South Platte River Basin Technical Study
• State: CO
• Basin: South Platte
• Date: 11/15/1985
• Author: SEO
• Title: Denver Basin Ground Water Model Report Technical Appendix C
• Water Supply Pro - Doc Type: Publication

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DATA INPUT & VERIFICATION

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Data files' representing aquifer parameters were developed for the
Laramie-Fox Hills, the Lower Arapahoe, the Upper Arapahoe, the Denver, the
Lower Dawson, and the Upper Dawson Aquifers.

A rectilinear grid system with 120 rows and 84 columns was selected for
input of aquifer parameters. Each grid in the system represents a square
mile and the assumption was made that sections of land correspond to the
grids in the system. The grid system is shown on Figure 6.

Values for the elevations of the aquifer bases,. the elevations of
aquifer tops and thicknesses of water yieloing materials were read for the
center of each section from Figures lA, 18, 1C, 10, 1E, 2A, 2B, 2C, 3A, 38,
3D, 3E, 3F, 4A, 48, and 4C and entered directly into the computer from the
keyboard. Similarly, values for hydraulic conductivity of water yielding
materials were coded from maps adopted from Hydrologic Atlas HA-659. The
values coded for conductivities are shown in Figures 7, 8, 9 and 10. In and
near the aquifer outcrops, the elevations of the potentiometric surfaces
were also coded. Hydrologic Atlases HA-647 and HA-546 were used for the
potent i ometric surfaces of the Arapahoe and Denver aqu Hers respectively,
The potent iometri c surface of the Larami e-Fox Hi 11 s aquifer was taken from
Figure 38. Figure 11 was used for the potentiometric surface of the Dawson
aquifers. Figure 11 was adopted from Hydrologic Atlas HA-643 and reflects
refinements based on water levels measured by the Division of Water
Resources personnel.

A set of values for a particular aquifer parameter can be referred to
as a two-dimensional array, Each valve in a t\\'0-dimensiona1 array has row
and column index numbers which relate the value to the appropriate grid
location in the grid system shown on Figure 5. Any section for which a
value for an aquifer parameter was not coded or for which the aquifer was
absent is repre~ented in the array with. a zero (0).

A computer program named "D2Df'I was developed to facilitate data .entry
and to check the accuracies of data entry. The program required the user to
specify a maximum and a minimum value to be accepted into an array. Any
value entered from the keyboard less than the minimum value or greater than
the maximum value was rejected. For example, if values for an aquifer
surface should fall between 4000' and 6000' and the computer operator
incorrectly entered 5000' as 500' or 50,000', the incorrect value would be
rejected and a message to that effect would appear on th~ computer monitor.
After arrays were coded, "D2DF" was used to generate contour maps of the
arrays. Figure 12 represents an example of such a map. The lines of equal

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