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Multiple-Aquifer Characterization from Single Borehole Extensometer Records

Ground Water

By:
and
DOI: 10.1111/j.1745-6584.2004.tb02449.x

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Abstract

Measurement and analysis of aquifer-system compaction have been used to characterize aquifer and confining unit properties when other techniques such as flow modeling have been ineffective at adequately quantifying storage properties or matching historical water levels in environments experiencing land subsidence. In the southeastern coastal plain of Virginia, high-sensitivity borehole pipe extensometers were used to measure 24.2 mm of total compaction at Franklin from 1979 through 1995 (1.5 mm/year) and 50.2 mm of total compaction at Suffolk from 1982 through 1995 (3.7 mm/year). Analysis of the extensometer data reveals that the small rates of aquifer-system compaction appear to be correlated with withdrawals of water from confined aquifers. One-dimensional vertical compaction modeling indicates measured compaction is the result of nonrecoverable hydrodynamic consolidation of the fine-grained confining units and interbeds, as well as recoverable compaction and expansion of coarse-grained aquifer units. The calibrated modeling results indicate that nonrecoverable specific storage values decrease with depth and range from 1.5 x 10-5/m for aquifer units to 1.5 x 10-4/m for confining units and interbeds. The aquifer and Potomac system recoverable specific storage values were all estimated to be 4.5 x 10-6/m, while the confining units and interbeds had values of 6.0 x 10-6/m. The calibrated vertical hydraulic conductivity values of the confining units and interbeds ranged from 6.6 x 10-4 m/year to 2.0 x 10-3 m/year. These parameter values will be useful in future management and modeling of ground water in the Virginia Coastal Plain.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Multiple-Aquifer Characterization from Single Borehole Extensometer Records
Series title:
Ground Water
DOI:
10.1111/j.1745-6584.2004.tb02449.x
Volume
42
Issue:
1
Year Published:
2004
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Ground Water
First page:
45
Last page:
58