The potential for saltwater intrusion in the Potomac aquifers of the York-James Peninsula, Virginia

Introduction Purpose and scope Approach Location of the study area Acknowledgments Previous studies The Potomac aquifers and confining units Hydrogeologic framework Aquifer and confining-unit properties Ground-water flow and saltwater contamination Potential for saltwater intrusion Definition of saltwater and saltwater intrusion Saltwater in the Virginia Coastal Plain Indicators of saltwater intrusion Simulation of saltwater intrusion in the Potomac aquifers Model grid design, model boundaries, and fluid properties Freshwater sweep Pumping and reversed flow Upward migration of saltwater toward a production well Model uncertainties and limitations Summary References citedFIGURES 1-3.Maps showing: 1. Location of the study area in the Coastal Plain of Virginia 2. Location of the Hampton Roads Planning District in southeastern Virginia 3. The Lee Hall area, Virginia 4. Schematic diagram showing aspects of saltwater intrusion 5. Map showing concentrations of dissolved solids in the Middle Potomac aquifer 6. Graph showing concentrations of dissolved solids in wells at Newport News Park 7. Graph showing water levels in wells at Newport News Park 8. Schematic diagram showing finite-element mesh and boundaries of the Lee Hall Section 9. Map showing water levels measured in the Middle Potomac aquifer, summer 1995 10-17.Sections showing: 10.Simulated concentrations of dissolved solids during freshwater sweep 11.Simulated direction of ground-water flow before pumping began in 1890 12. Simulated direction of ground-water flow in 1940 13.Simulated concentrations of dissolved solids in 1890 and 1940 14.Simulated concentrations of dissolved solids in 1940 and 1960 15.Simulated concentrations of dissolved solids in 1960 and 1997 16.Simulated direction of ground-water flow near a typical production well 17.Simulated concentrations of dissolved solids in 1997, with and without a typical production well TABLES .Horizontal hydraulic conductivities and simulated permeabilities of the Potomac aquifers and confining units 2. Fluid properties assumed for solute-transport simulations I