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Estimation of hydraulic characteristics of the upper glacial and Magothy aquifers at East Meadow, New York, by use of aquifer tests

Water-Resources Investigations Report 87-4211

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Abstract

Drawdown and recovery data from two aquifer tests in central Nassau County, NY were used to calculate aquifer characteristics by several methods to aid in predicting the response of the aquifer system to stress. The first test, on May 12, 1978, entailed pumping the Magothy aquifer for 12 hours; the second on July 30-31, 1985, entailed pumping the upper glacial aquifer for 24 hours. Drawdown and recovery data from both tests were analyzed through analytical solutions and curve-matching procedures, and the resulting hydraulic values were used as initial values in a finite-element radial-flow numerical model to simulate the observed drawdowns and recoveries. Storativity values obtained by all methods were consistent with published estimates; but hydraulic conductivity values were higher than published estimates. The simple analytical solutions and curve-matching procedures gave reasonable values of most terms quickly, but the greatest confidence is in the estimates made with the finite-element model. These estimates for the Magothy aquifer were: horizontal hydraulic conductivity of 100 ft/d; ratio of horizontal to vertical conductivity, 5; and specific storage, 0.0001. Estimates for the upper glacial aquifer were: horizontal hydraulic conductivity, 380 ft/d; ratio of horizontal to vertical hydraulic conductivity, 2.5; and specific yield, 0.15. (USGS)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Estimation of hydraulic characteristics of the upper glacial and Magothy aquifers at East Meadow, New York, by use of aquifer tests
Series title:
Water-Resources Investigations Report
Series number:
87-4211
Edition:
-
Year Published:
1989
Language:
ENGLISH
Publisher:
U.S. Geological Survey ; Books and Open-File Reports Section [distributor],
Description:
vi, 43 p. :ill. ;28 cm.