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Effect of grid size on digital simulation of ground-water flow in the southern High Plains of Texas and New Mexico

Water-Resources Investigations Report 87-4085

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Abstract

Three models of the aquifer in the southern High Plains were compared to determine the effect of grid size on simulated water levels. The first model, calibrated prior to this study, had 10-mi grid spacing. The mean difference between the simulated and measured pre-development water levels in this model was +0.28 ft with a standard deviation of 25.8 ft. The second model, calibrated during this study independently of the first model, had 5-mi grid spacing. The mean difference between the simulated and measured pre-development water levels was -0.01 ft with a standard deviation of 44.4 ft. For 1980 water levels, the mean difference was +8.22 ft with a standard deviation of 27.9 ft. The results from the first and second models were compared. The standard deviation of the differences in simulated water levels was 19.0 ft for the pre-development period and 21.8 ft for 1980. There appeared to be no hydrologic significance to the pattern of the differences. A third model, constructed by aggregating the data from the second model, had 10-mi grid spacing. The mean difference in simulated pre-development water levels between the second and third models was +0.86 ft with a standard deviation of 8.9 ft. For the 1980 water levels, the mean difference between the models was +0.39 ft with a standard deviation of 4.4 ft. The study found that the same hydrologic conclusions would have been reached had 5-mi grid spacing or 10-mi grid spacing been used. It was further concluded that the difference in simulated water levels between models with 5-mi grid spacing or 10-mi grid spacing was five to six times smaller than the differences between the simulated and measured water levels. (Author 's abstract)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Effect of grid size on digital simulation of ground-water flow in the southern High Plains of Texas and New Mexico
Series title:
Water-Resources Investigations Report
Series number:
87-4085
Edition:
-
Year Published:
1987
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
iv, 31 p. :ill., maps ;28 cm.