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F. J. Spitz

Publications and source records attributed to F. J. Spitz.

4 recordsLinked to original sources
USGS1996

Evaluation of saltwater intrusion and travel time in the Atlantic City 800-foot sand, Cape May County, New Jersey, 1992, by use of a coupled-model approach and flow-path analysis

Regional and subregional ground-water-flow models were coupled, and the output was analyzed by a particle-tracking method. The results were then used to assess the effects of ground-water withdrawals on the flow of saltwater in the Atlantic City 800-foot sand in Cape May County, New Jersey, and to estimate the travel time from areas in which the chloride concentration of the ground water exceeds 250 milligrams per liter to the county's nearest public supply wells. First, a quasi-three-dimensional finite-difference computer model of freshwater and saltwater flow that simulated regional ground-water flow through the unconsolidated materials underlying the New Jersey Coastal Plain was used to estimate flow at the boundaries of the subregional study area. The results of the regional simulation were used as input to a second quasi-three-dimensional finite-difference model that was used to simulate flow in the subregion, the Atlantic City 800-foot sand in Cape May County. The results of the simulation of flow in the subregion were analyzed by a semianalytical particle-tracking method to estimate ground-water flow paths and travel time of ground water from areas in which chloride concentrations exceed 250 milligrams per liter to public supply wells located at Stone Harbor, New Jersey. Ground-water withdrawals from the Atlantic City 800-foot sand were assumed to be equal to those reported for 1991. Results of the analysis indicate that the time required for saltwater to reach the public supply wells is on the order of hundreds of years. These results, however, are based on the assumptions that the aquifer is homogeneous. The presence of zones of high permeability in the aquifer could reduce the predicted travel times of the saltwater from its present location to the supply wells. Travel times also could be reduced if ground-water withdrawals increase.

New Jersey↗
USGS1996

Hydrologic feasibility of water-supply-development alternatives in Cape May County, New Jersey

Increasing public-supply withdrawals in Cape May County, New Jersey associated with increasing residential and seasonal tourist populations have led to regionally lowered ground-water levels, a reversal of ground-water flow directions toward onshore, and landward encroachment of saltwater in the shallow aquifer system. The three aquifers composing the shallow system are, in order of increasing depth, the unconfined Holly Beach water-bearing zone and the confined estuarine sand and Cohansey aquifers. The changes to the ground-water system have been greatest in the confined aquifers near the three major well fields on the Cape May peninsula. Formerly productive water-supply wells have been abandoned because of saltwater contamination. Concern about anthropogenic contamination has prevented shifting of withdrawals to the unconfined aquifer. Surface- water sources have also been little used. Further development on the peninsula involving increased water demand will exacerbate the current saltwater-encroachment problems. The purpose of this study was to test the feasibility of possible water-supply-development alternatives by use of predictive ground-water flow simulations. The alternatives involve (1) injection of tertiary- treated wastewater to replenish aquifer storage and create a hydraulic barrier to saltwater encroachment, (2) withdrawal of brackish water in order to create a hydraulic barrier, (3) conjunctive use of ground water and surface water, enabling the reduction of ground-water withdrawals, and (4) redistribution of withdrawals inland to the unconfined aquifer. Results of these simulations can potentially be used in the design of a water-supply-development strategy that preserves supply and a monitoring program that ensures early warning of saltwater encroachment, thereby allowing sufficient time for development of an alternative supply. The water-supply- development alternatives were evaluated by comparison of results of predictive simulations made with a previously calibrated ground-water flow model of the shallow aquifer system. The quasi-three-dimensional sharp-interface model was calibrated to 1988 annual average hydrologic conditions. The planning period for the predictive simulations is 1989-2049. For the planning period, total public-supply withdrawals were increased 100 percent over average 1983-88 withdrawals. Results of a baseline simulation involving only the increased withdrawals were compared to each of the simulated alternatives, which also include the withdrawals. Hydraulic heads, saltwater- freshwater interface movement, and ground-water flows were compared. Simulation results indicate that the barrier-injection or barrier-withdrawal scheme could be useful in managing the water supply for a specific location. The conjunctive- use scheme would provide a marginal regional hydrologic benefit. Redistribution of withdrawals appears to be the only regional alternative that would result in recovery of ground-water levels and would substantially slow saltwater encroachment; however, anthropogenic land-surface contamination of the unconfined aquifer would have to be considered if the redistribution alternative is acted upon.

Water-Resources Investigations Report↗