Simulated ground-water flow in the Potomac aquifers, New Castle County, Delaware

Water-Resources Investigations Report 84-4007




Flow in three aquifers of the Potomac Formation in New Castle County, Delaware, was simulated. Results of the calibrated flow model show the maximum transmissivity of the lower aquifer is between 1,000 and 1,500 square feet per day; the middle aquifer, between 3,000 and 3,500 square feet per day; and the upper aquifer, between 5,000 and 6,000 square feet per day. Vertical leakance values for the three confining beds are similar and range 1 x 10 to the (1-8) power per day in downdip areas and .01 per day in subcrop areas. A storage coefficient of 0.00056 was used for each aquifer. A specific storage value of 0.000006 per foot was used for each confining bed. Estimated storage coefficients were not changed during calibration. Changes in water levels resulting from five scenarios of future pumpage were evaluated. Results of these simulations show: (1) the reduction in pumpage at Amoco causing a 120 foot local recovery of heads; (2) water levels generally will change less than 25 feet if there is no change in pumpage; (3) proposed pumpage in western Delaware may cause drawdowns below the tops of the aquifers; and (4) expected increases in pumpage would cause the greatest head decline, about 40 feet, in the lower aquifer at Getty. (USGS)

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Simulated ground-water flow in the Potomac aquifers, New Castle County, Delaware
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Water-Resources Investigations Report
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U.S. Geological Survey,
vii, 85 p. :ill., maps ;28 cm.