W&M ScholarWorks Reports 3-2015 Fairfax County Shoreline Management Plan C. Scott Hardaway Jr. Virginia Institute of Marine Science Donna A. Milligan Virginia Institute of Marine Science Christine A. Wilcox Virginia Institute of Marine Science Marcia Berman Virginia Institute of Marine Science Tamia Rudnicky Virginia Institute of Marine Science See next page for additional authors Follow this and additional works at: https://scholarworks.wm.edu/reports Part of the Environmental Monitoring Commons, Natural Resources Management and Policy Commons, and the Water Resource Management Commons Recommended Citation Hardaway, C., Milligan, D. A., Wilcox, C. A., Berman, M., Rudnicky, T., Nunez, K., & Killeen, S. (2015) Fairfax County Shoreline Management Plan. Virginia Institute of Marine Science, William & Mary. https://doi.org/ 10.21220/V5RM72 This Report is brought to you for free and open access by W&M ScholarWorks. It has been accepted for inclusion in Reports by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. Authors C. Scott Hardaway Jr., Donna A. Milligan, Christine A. Wilcox, Marcia Berman, Tamia Rudnicky, Karinna Nunez, and Sharon Killeen This report is available at W&M ScholarWorks: https://scholarworks.wm.edu/reports/589 Fairfax County Shoreline Management Plan Prepared for Fairfax County and Virginia Coastal Zone Management Program Virginia Institute of Marine Science College of William & Mary Gloucester Point, Virginia March 2015 Fairfax County Shoreline Management Plan Prepared for Fairfax County and Virginia Coastal Zone Management Program Shoreline Studies Program Center for Coastal Resources Management C. Scott Hardaway, Jr. Marcia Berman Donna A. Milligan Tamia Rudnicky Christine A. Wilcox Karinna Nunez Sharon Killeen Virginia Institute of Marine Science College of William & Mary Gloucester Point, Virginia This project was funded by the Virginia Coastal Zone Management Program at the Department of Environmental Quality through Grant #NA13NOS4190135 of the U.S. Department of Commerce, National Oceanic and Atmospheric Administration, under the Coastal Zone Management Act of 1972, as amended. The views expressed herein are those of the authors and do not necessarily reflect the views of theU.S. Department of Commerce, NOAA, or any of its subagencies. March 2015 Fairfax County Table of Contents 1 Introduction ........................................................................................................................ 1 2 Coastal Setting ................................................................................................................... 3 2.1 Geology/Geomorphology ............................................................................................. 3 2.1.1 Geology ............................................................................................................... 3 2.1.2 Shore Morphology ............................................................................................... 3 2.2 Coastal Hydrodynamics ............................................................................................... 8 2.2.1 Wave Climate ..................................................................................................... 8 2.2.2 Sea-Level Rise .................................................................................................... 9 2.2.3 Shore Erosion .....................................................................................................10 3 Shoreline Best Management Practices ...............................................................................11 3.1 Implications of Traditional Erosion Control Treatments ................................................11 3.2 Shoreline Best Management Practices – The Living Shoreline Alternative ...................11 3.3 Non-Structural Design Considerations .........................................................................12 3.4 Structural Design Considerations .................................................................................14 3.4.1 Sills .....................................................................................................................14 3.4.2 Breakwaters ........................................................................................................15 4 Methods .............................................................................................................................17 4.1 Shore Status Assessment ...........................................................................................17 4.2 Geospatial Shoreline Management Model ..................................................................17 5 Shoreline Management for Fairfax County ........................................................................ 20 5.1 Shoreline Management Model (SMM) Results ........................................................... 20 5.2 Shore Segments of Concern /Interest ......................................................................... 22 5.2.1 (Area of Interest#1) Mason Neck Headland Breakwater System ......................... 22 5.2.2 (Area of Interest #2) Turnout on GWP Low Sill ................................................... 22 5.2.3 (Area of Interest#3) Turn out on GWP Medium Sill...............................................23 6 Summary and Links to Additional Resources ..................................................................... 24 7 References .........................................................................................................................25 Appendix 1: Shoreline Management Model Graphic .................................................................27 Appendix 2: Glossary of Shoreline Best Management Practices ............................................... 29 Appendix 3: Guidance for Structural Design and Construction in Fairfax County .......................31 Shoreline Management Plan List of Figures Figure 1-1. Location of Fairfax County within the Chesapeake Bay estuarine system. The location of the National Oceanic and Atmospheric Administration tide gage is shown. ...........................................................................................................1 Figure 2-1. Geology of Fairfax County (Mixon et al., 1989). ................................................................3 Figure 2-2. Topographic sheet of Reach 1 in Fairfax County. ............................................................. 4 Figure 2-3. Topographic sheet of Reach 2 in Fairfax County. ............................................................. 4 Figure 2-4. Topographic sheet of Reach 3 in Fairfax County. .............................................................. 4 Figure 2-5. Broad, fringing tidal fresh water marshes along Belmont Bay. ........................................ 4 Figure 2-6. Shore protection along eroding banks of Belmont Bay. ....................................................5 Figure 2-7. Eroding banks along Belmont Bay. ..................................................................................5 Figure 2-8. Gabion structures that are acting as breakwaters along Mason Neck State Park. From Bing Maps. .............................................................................................................5 Figure 2-9. One attached and three detached breakwaters along Mason Neck north of High Point. As the sandy bank erodes, the breakwaters likely will become attached. From Bing Maps. ............................................................................................ 6 Figure 2-10. Broad, shallow marsh along the Potomac River between High Point and Hallowing Point. ............................................................................................................. 6 Figure 2-11. The shorelines along this section of shoreline in Reach 2 along the Potomac River has been graded and protected at the base. ................................................................... 6 Figure 2-12. Along the Gunston Cove shoreline, the high upland bank is mostly in a natural state and is erosional. ..................................................................................................... 6 Figure 2-13. Development and shore protection along Dogue Creek. ..................................................7 Figure 2-14. Ferry Point differs from other points in Fairfax in that it is developed and protected with a large revetment. ...................................................................................7 Figure 2-15. The high bank at Mount Vernon has been graded and the shoreline protected with a stone block seawall. ..............................................................................................7 Figure 2-16. The fixed entrance to Little Hunting Creek. ......................................................................7 Figure 2-17. The George Washington Memorial Parkway runs along the shoreline in Reach 3. ............ 8 Figure 2-18. Development along Reach 3. .......................................................................................... 8 Figure 2-19. Dyke Marsh with wooded upland and occasional treed islands. ....................................... 8 Figure 2-20. Wave climate map for the Potomac River (from Basco and Shin, 1993). .......................... 9 Fairfax County Figure 3-1. One example of forest management. The edge of the bank is kept free of tree and shrub growth to reduce bank loss from tree fall. ......................................................12