Hydrogeologic framework of the Virginia coastal plain
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Virginia↗
Geology topics
J. F. Harsh
Publications and source records attributed to J. F. Harsh.
Potentiometric-surface map for the Cretaceous aquifer, Virginia coastal plain, 1978
The Atlantic Coastal Plain of Virginia includes 9,600 square miles--all or part of 40 counties east of the Fall Line. The undifferentiated Cretaceous sediments underlying this area are the most productive and extensive source of ground water, from which large withdrawals have been made over the past 40 years. In 1978, withdrawals exceeded 100 million gallons per day. To determine the effect of continued withdrawals, annual synoptic water levels for 1978 were used to prepare a map showing the approximate configuration of the potentiometric surface. (USGS)
Virginia↗
Quality and movement of ground water in Otter Creek - Dry Creek basin, Cortland County, New York
A steady increase in the chloride and nitrate content of water in a sand and gravel aquifer of glacial origin in the Cortland, N.Y., area prompted a study to obtain data on the extent and source of these constituents. Chloride concentration in the upper part of the aquifer increased generally from 2 mg/liter in 1930 to 20 mg/liter in 1976, and nitrate concentration (as nitrogen) in the upper part of the aquifer increased from 1 mg/liter in 1930 to an average of 4 mg/liter in 1976. Although the ground water is normally very hard, its quality generally meets State standards for source waters used for drinking. Road salting and farming seem to be the primary cause of chloride increases, although septic systems may be a major source locally. Farm-animal waste, sewage systems, and fertilizers are the major contributors of nitrate to ground water. Flow in the aquifer system in the Otter Creek-Dry Creek basin was simulated with a digital-computer model. The model was calibrated by comparing measured water levels in the aquifer with those determined by the model. The major sources of recharge are from precipitation and seepage from losing reaches of the streams. (Woodard-USGS)
New York↗
Digital-model simulation of the glacial-outwash aquifer, Otter Creek-Dry Creek basin, Cortland County, New York
The city of Cortland, New York, and surrounding areas obtain water from the highly productive glacial-outwash aquifer underlying the Otter Creek-Dry Creek basin. Pumpage from the aquifer in 1976 was approximately 6.3 million gallons per day and is expected to increase as a result of population growth and urbanization. A digital ground-water model that uses a finite-difference approximation technique to solve partial differential equations of flow through a porous medium was used to simulate the movement of water within the aquifer. The model was calibrated to equilibrium conditions by comparing water levels measured in the aquifer in March 1976 with those computed by the model. Then, from the simulated water-level surface for March, a transient-condition run was made to simulate the surface as measured in September 1976. Computed water levels presented as contours are generally in close agreement with potentiometric-surface maps prepared from field measurements of March and September 1976.
New York↗