Simulation of Ground-Water Discharge to Biscayne Bay, Southeastern Florida
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Simulation of Ground-Water Discharge to Biscayne Bay, Southeastern Florida U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY Prepared as part of the U.S. GEOLOGICAL SURVEY PLACE-BASED STUDIES PROGRAM and in cooperation with the U.S. ARMY CORPS OF ENGINEERS Rainfall Surface water in Everglades Biscayne Evapotranspiration Recharge Bay Submarine ground-water Canal Canal discharge Water table Water table Lateral BISCAYNE boundary AQUIFER flow Freshwater Municipal Municipal well field well field Brackish water Seawater Water-Resources Investigations Report 00-4251 Simulation of Ground-Water Discharge to Biscayne Bay, Southeastern Florida By Christian D. Langevin U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 00-4251 Prepared as part of the U.S. GEOLOGICAL SURVEY Place-Based Studies Program and in cooperation with the U.S. ARMY CORPS OF ENGINEERS Tallahassee, Florida 2001 U.S. DEPARTMENT OF THE INTERIOR GALE A. NORTON, Secretary U.S. GEOLOGICAL SURVEY CHARLES G. GROAT, Director Use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Geological Survey. For additional information Copies of this report can be write to: purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Branch of Information Services Suite 3015 Box 25286 227 N. Bronough Street Denver, CO 80225-0286 Tallahassee, FL 32301 888-ASK-USGS Additional information about water resources in Florida is available on the World Wide Web at http://fl.water.usgs.gov CONTENTS Abstract.................................................................................................................................................................................. 1 Introduction ........................................................................................................................................................................... 2 Purpose and Scope....................................................................................................................................................... 2 Methods of Field Investigation.................................................................................................................................... 2 Previous Studies........................................................................................................................................................... 5 Acknowledgments ....................................................................................................................................................... 6 Hydrogeology of Southeastern Florida.................................................................................................................................. 6 Hydrostratigraphy ........................................................................................................................................................ 7 Aquifer Properties........................................................................................................................................................ 8 Water-Budget Components.......................................................................................................................................... 10 Rainfall, Evapotranspiration, and Runoff .......................................................................................................... 10 Surface-Water/Ground-Water Interaction ......................................................................................................... 10 Ground-Water Withdrawals............................................................................................................................... 13 Freshwater-Saltwater Transition Zone......................................................................................................................... 14 Simulation of Ground-Water Discharge to Biscayne Bay..................................................................................................... 22 Governing Equations ................................................................................................................................................... 24 SEAWAT Simulation Code.......................................................................................................................................... 26 Cross-Sectional Ground-Water Flow Models.............................................................................................................. 27 Model Design..................................................................................................................................................... 27 Model Calibration and Simulation Results........................................................................................................ 29 Sensitivity Analysis ........................................................................................................................................... 33 Regional-Scale Ground-Water Flow Model ................................................................................................................ 34 Spatial and Temporal Discretization..................................................................................................................35 Assignment of Aquifer Parameters.................................................................................................................... 35 Boundary Conditions ......................................................................................................................................... 38 Biscayne Bay............................................................................................................................................ 38 Inland Model Domain Boundaries........................................................................................................... 38 Lower Model Boundary........................................................................................................................... 39 Internal Hydrologic Stresses.............................................................................................................................. 39 Canals....................................................................................................................................................... 39 Ponded Surface Water.............................................................................................................................. 40 Recharge and Runoff ............................................................................................................................... 40 Evapotranspiration ................................................................................................................................... 40 Municipal Well Fields.............................................................................................................................. 42 Initial Conditions ............................................................................................................................................... 42 Calibration Procedure and Model Results ......................................................................................................... 42 Comparison of Simulated and Observed Heads ...................................................................................... 42 Comparison of Simulated and Observed Canal Baseflow....................................................................... 43 Net Recharge............................................................................................................................................ 51 Saltwater Interface ................................................................................................................................... 51 Ground-Water Flow to Biscayne Bay...................................................................................................... 54 Sensitivity Analysis ........................................................................................................................................... 56 Model Limitations ....................................................................................................................................................... 59 Conclusions ........................................................................................................................................................................... 60 References Cited.................................................................................................................................................................... 61 Appendix I: Lithologic Descriptions of Selected Cores as Determined for this Study......................................................... 67 Appendix II: Field Data Collected as Part of this Study ....................................................................................................... 85 Appendix III: Monitoring Stations Used in this Study.......................................................................................................... 101 Appendix IV: Verification of the SEAWAT Code ................................................................................................................. 121 Contents III PLATES 1. Sections showing sensitivity analysis results for the Coconut Grove model.................................................. pocket 2. Sections showing sensitivity analysis results for the Deering