1. Simulation of groundwater response to development: CENTRAL PASSAIC RIVER BASIN, NJ Fatoumata Barry 1,2, Duke Ophori 1, Jeffrey L. Hoffman 2 and Robert Canace 2 1 Department of Earth & Environment Studies, Montclair State University, Upper Montclair, NJ 07043 2 New Jersey Department of Environmental Protection P.O. Box 427, Trenton, NJ 08625

2. 2 Issues Increased demand of water Due to population growth Decline of water levels Due to increase withdrawals Decreased recharge Due to urban development Contamination Have limited withdrawal in some areas

3. 3 Objectives Develop a regional GW flow model to simulate: flow paths contaminants paths contaminants source protection areas around wells Delineate regional discharge and recharge areas

4. 4 Study Area Hackensack – Passaic River Basin

5. 5 Model Design Conceptualization Sandstone, Siltstone Basalt Silt, Clay (Semi-confining Unit) BEDROCK (LAYER 3) SURFACIAL Sand and Gravel LAYER 1 Layer 1 Layer 2 Layer 3 Sand and Gravel (LAYER 2)

6. 6 Model Design - Boundaries Lateral: Western edge: Ramapo Fault (Granite on West side of fault) Northern, Southern and Eastern edge: Crest of the 2 nd Watchung Mountain Vertical: Top: Surface water Rivers, lakes, wetlands Bottom: Bedrock

7. Data Input

8. 8 Input Data Sets Aquifer Parameters: specified for each grid cell within each layer Hydraulic Conductivity Transmissivity Storage coefficients Initial water levels Botton and Top elevations Vertical leakance to account for the hydraulic connection between adjacent layers. Pumping Wells Observation Wells Recharge values River Data

9. 9 Flow Simulation Modeling was done using the MODFLOW and MODPATH codes in the GMS package

10. Simulation Results

11. 11 Steady State Calibration Surface and Heads of Unconfined Sand and Gravel comparison Layer 1 Surface Elevation

12. 12 1990 Computed and Observed Water Level Original Calibrated

13. Interpretation

14. 14 Prepumpage (1898) versus Recent (1995) Wetlands in unconfined sand and gravel 18981995

15. 15 Unconfined Sand and Gravel Discharge Areas 18981995

16. 16 Semi-confined Sand and Gravel Discharge Areas 1898 1995

17. 17 Decline of Water Levels between 1898 and 1995

18. 18 Hanover Twp - Heads and Flow vectors 1929 -1974

19. 19 Hanover Twp - Heads and Flow vectors 1979 -1995

20. 20 East Hanover, Parsippany Twps - Capture Zones Analysis

21. 21 Conclusion Benefit from the model Wetlands reduced from prepumping to pumping conditions Discharge areas reduced after pumping started Temporal flow patterns easily visualized Decline of groundwater levels can be visualized Analytical and Numerical Capture zones compared Analytical capture zones found to be conservative

22. Questions and Comments Thank you