New Jersey Water Science Center
Great Falls of the Passaic River at Paterson, N.J.
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Project Title: Allocation Analysis
The general objective of this program is to annually determine the effects of proposed or planned withdrawals in 2 to 4 previously studied areas of New Jersey where complexities of hydrogeology and/or pumping plans make water-allocation permit evaluations by NJDEP difficult. The effects of withdrawals in these areas will be evaluated by updating and utilizing groundwater models used in previous water-supply investigations. This program will accomplish several objectives:
Statement of Problem
Development of water supply is a dynamic condition, and demand areas may shift, or quality or quantity concerns may change in a former study area. This program will address the need of the N.J. Department of Environmental Protection (NJDEP) to understand the possible effects of proposed or planned withdrawals within these previously studied areas. This program will update the relevant models so that new simulations which incorporate recent shifts or changes in development can be used to quantify the effects of such development. The U.S. Geological Survey (USGS) has used results from groundwater-flow models as the principal approach to understanding and predicting the effects of water-supply development. The location of these groundwater-flow models are shown in figure 1. A short description of each of these models is given in table 1. The areas of the models range from 2.3 to 9,000 square miles, cover a diverse geologic range, and are in various states of calibration. Some of the models are from older projects, calibrated to hydrologic conditions up through the 1970's. Of the 29 groundwater flow models listed in table 1, 18 are archived (computer files and operational software are available), and 11 are not archived (no availabe computer files). New advanced techniques to analyze groundwater-flow systems or interpret model results are being developed over time. Models used in previously completed studies do not reflect the advantages of these new techniques until necessary updates to the model code or to the model input or output are made. Further, advanced understanding of the geohydrology of a previously studied area from the time of the study completion requires updates to system representation to take full advantage of new advanced analytical techniques.
Strategy and Approach
The priority of areas to be evaluated will be determined by the NJDEP. The model or models to be used for a new study of an area and the cost and time constraints of possible model improvements will be evaluated by the USGS. The USGS will also evaluate the ability of new and advanced techniques to improve model results and the effect and value of updating the model representation of the area's geohydrology. The model or models will be updated as needed and used to evaluate the effects of proposed or planned withdrawals within the study area. Generally, the modeling analysis will be documented through correspondance and presentations at meetings. Where water-allocation permit evaluations are controversial, data and findings will be documented with a short USGS report.