Abstract

       Introduction

            Approach

            Purpose and Scope

            Previous Work

       Simulation of Freshwater-Saltwater Interfaces in Two Dimensions

            Model Design

                 Boundary Conditions

                 Recharge

            Steady-State (Predevelopment) Initial Conditions

                 Heads

                 Interface Positions

            Transient-State Simulations

                 Heads

                 Movement of Interfaces

                      Upper Glacial Aquifer (layer 4)

                      Upper Magothy-Jameco Aquifer (layer 3)

                      Lower Magothy Aquifer (layer 2)

                      Lloyd Aquifer (layer 1)

                      All layers

                 Vertical and Horizontal Velocities

            Sensitivity Analysis

                 Mixing Method

                 Recharge

                      50-Percent Reduction

                      100-Percent Reduction for 3 Years

       Limitations and Assessment of Simulation Results

       Summary and Conclusions

       References Cited

 

       FIGURES

        1. Map of Kings and Queens Counties, N.Y., showing general locations of hypothetical wells, and vertical sections A-A'

          and B-B'

        2. Diagram of idealized ground-water system in a layered coastal environment, showing position of

          freshwater-saltwater interface and transition zone

        3. Diagram of finite difference representation of freshwater-saltwater interface in finite-difference

          cells j-l, j, and j+l along a model row and within a model layer

        4. North-south vertical sections through Brooklyn-Queens aquifer showing generalized aquifer geometry, model layers,

          confining units, pumping wells and locations of simulated predevelopment freshwater-saltwater interfaces in:

          (A) Kings County model

          (B) Queens County model

       5-6. Graphs showing freshwater head under simulated predevelopment conditions and after 10.72

          years of simulated withdrawals from north-shore well W1 and south-shore well cluster W2 or W3:

        5. Kings County: (A) Upper glacial aquifer. (B) Upper Magothy-Jameco aquifer. (C) Lloyd aquifer

        6. Queens County: (A) Upper glacial aquifer. (B) Upper Magothy-Jameco aquifer. (C) Lloyd aquifer

        7. Hydrographs of freshwater head in first inshore cell north of south shore in model layer 4 (upper

                glacial aquifer) of Kings and Queens County models, in response to pumping for 10.72 years at specified

                high, medium, and low rate: (A) Kings County, pumping at W1 and W2. (B) Kings County, pumping at

                W1 and W3. (C) Queens County, pumping at W1 and W2. (D) Queens County, pumping at W1 and W3

 

       TABLES

        1. Hydraulic values used in SHARP ground-water flow models of Brooklyn-Queens aquifer

               system

        2. Number of cells in Kings County SHARP ground-water flow model that converted from freshwater to

               mixed or saltwater, and velocity of interfaces in response to withdrawals from a hypothetical

               north-shore well at W1 and from a cluster of three south-shore wells at W2 or W3:

               A. Kings pumping at W1 and W2

               B. Kings pumping at W1 and W3

        3. Number of cells in Queens County SHARP ground-water flow model that converted from freshwater

               to mixed or saltwater, and velocity of interfaces in response to withdrawals from a hypothetical

               north-shore well at W1 and from a cluster of three south-shore wells at W2 or W3.

               A. Queens pumping at W1 and W2

               B. Queens pumping at W1 and W3

        4. Sensitivity of freshwater-saltwater interface movement, in terms of freshwater cells that convert to

               mixed-water cells, in upper glacial aquifer of SHARP ground-water flow models of Brooklyn-Queens aquifer system, to

               pumping and to a 50-percent reduction in recharge rate

        5. Sensitivity of saltwater-freshwater interface movement, in terms of toe velocity in upper glacial

               aquifer of SHARP ground-water flow models of Brooklyn-Queens aquifer system, to pumping and

               to a 50-percent reduction in recharge rate and to a 3-year period of zero recharge

 

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Abstract

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