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Hydrogeology and simulation of water flow in strata above Bearpaw Shale and equivalents of eastern Montana and northeastern Wyoming

Water-Resources Investigations Report 85-4281

By:
and

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Abstract

The Powder River, Bull Mountains, and Williston basins of Montana and Wyoming were investigated to understand the geohydrology and subsurface water flow. Rocks were separated into: Fox Hills-lower Hell Creek aquifer (layer 1), upper Hell Creek confining layer (layer 2), Tullock aquifer (layer 3), Lebo confining layer (layer 4), and Tongue River aquifer (layer 5). Aquifer transmissivities were estimated from ratios of sand and shale and adjusted for kinematic viscosity and compaction. Vertical hydraulic conductance per unit area between layers was estimated. Potentiometric surface maps were drawn from limited data. A three-dimensional finite-difference model was used for simulation. Five stages of simulation decreased and standard error of estimate for hydraulic head from 135 to 110 feet for 739 observation nodes. The resulting mean transmissivities for layers 1-5 were 443, 191, 374, 217, and 721 sq ft/d. The corresponding mean vertical hydraulic conductances per unit area between the layers were simulated; they ranged from 0.000140 to 0.0000150. Mean annual recharge across the study area was about 0.26 percent of average annual precipitation. Large volumes of interlayer flow indicate the vertical flow may be significant. (USGS)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Hydrogeology and simulation of water flow in strata above Bearpaw Shale and equivalents of eastern Montana and northeastern Wyoming
Series title:
Water-Resources Investigations Report
Series number:
85-4281
Edition:
-
Year Published:
1986
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
v, 72 p. :ill., maps ;28 cm.