Characteristics of a ground-water plume derived from artificial recharge with reclaimed wastewater at East Meadow, Long Island, New York
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Water-Resources Investigations Report↗
Geology topics
K. R. Prince
Publications and source records attributed to K. R. Prince.
Analysis of the shallow groundwater flow system near Connetqout Brook, Long Island, New York
Streamflow on Long Island is derived principally from shallow groundwater that flows above the deeper regional flow system. The movement of shallow groundwater was studied during 1975-1982 at Connetquot Brook - an undisturbed stream in Connetquot River State Park - in south-central Long Island. The investigation encompassed: (1) field studies of streamflow, groundwater levels, and age of water as indicated by tritium concentrations, and (2) numerical simulation of the shallow flow system to evaluate the hydraulic factors that influence groundwater flow near and beneath the stream. Analysis of water-level data indicates that groundwater flow is essentially horizontal throughout the drainage basin except near and beneath the stream, where it moves upward diagonally and discharges into the streambank at three sites were 1-2 ft higher than stream stage in the and in wells driven into the streambank at three sites were 1-2 ft higher than stream stage in the first 5 ft of penetration. Increases in head, which were detected to depths of 30 ft beneath the streambed, indicate upward movement of water above that depth. Water samples from selected wells were analyzed for tritium concentration to determine the relative age of water to locate the bottom boundary of the shallow flow system. Tritium concentrations indicate that the lower boundary is from 45 to 100 ft below the water table. A two-dimensional cross-sectional flow model of the shallow flow system indicated that: (1) stream width and streambed hydraulic conductivity influence heads mostly within about 50 ft of the stream; (2) the thickness of the shallow flow system influences heads more distant from the stream but has a negligible effect near the stream; and (3) the quantity of water entering the system as recharge from precipitation influences the heads throughout the area. Field measurements of hydraulic head indicate the shallow flow system to extend to about 30 ft below the stream channel. Results of the sensitivity analysis indicate that the thickness of the shallow system has a negligible effect on head distribution beneath the stream.
New York↗
Estimation of hydraulic characteristics of the upper glacial and Magothy aquifers at East Meadow, New York, by use of aquifer tests
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)
Water-Resources Investigations Report↗
Ground-water resource assessment of the Montauk area, Long Island, New York
The water resources of the Montauk area were investigated from October 1980 through September 1983 to assess the availability of fresh groundwater. The principal aquifer, which consists of fine- to coarse-grained stratified glacial drift, is the sole source of freshwater. The freshwater/saltwater interface lies as much as 150 ft below sea level, but the till unit and the marine-clay unit limit the thickness of the zone from which freshwater may easily be withdrawn to < 100 ft in most places. Precipitation, the sole source of freshwater in the Montauk area , averages about 42 in/yr. Direct runoff is approximately 1 in/yr, and evapotranspiration about 20 in/yr; the remaining 21 inches is the net recharge to the principal aquifer. The horizontal hydraulic conductivity, as calculated from specific-capacity data, ranges from 130 to 350 ft/d. Analysis of an aquifer pumping test indicates that horizontal hydraulic conductivity of the principal aquifer is approximately 275 ft/d and the vertical hydraulic conductivity is approximately 90 ft/d; the storage coefficient ranges from 1.1 x .001 to 2.2 x .001. A numerical two-dimensional flow model that simulates the areal flow of fresh- and saltwater was developed to evaluate the effects of the present level of groundwater development and the potential effects of increased future withdrawals. Model results indicate that the principal aquifer is capable of producing several times more than the 0.6 mil gal/d now being withdrawn for public supply. Examination of well design and pumping rates, and analysis of analog-model studies of saltwater upconing to wells, indicate that the peak pumping rate of public supply wells exceeds the limit necessary to avoid contamination from saltwater. With proper well design and distribution of pumping stress, the aquifer system would be capable of supplying enough water to meet the needs of the population projected through 1995.
New York↗
Potentiometric surfaces of the upper glacial and Magothy aquifers and selected streamflow statistics, 1943-72, on Long Island, New York
A brief text describes the two major aquifers and the discharge pattern of major streams on Long Island. Four water-table maps for the years 1943, 1959, 1966, and 1972, an average water-table map for the period 1943-72 supplemented by five well hydrographs representing Kings, Queens, western Nassau, eastern Nassau, and Suffolk Counties, and three potentiometric- surface maps of the Magothy aquifer for the years 1959, 1966, and 1972 are included. A statistical summary of stream discharge presents average annual discharges, annual average discharges, and average 7-day, 10-year low-flow discharges for major streams.
Open-File Report↗