York County Shoreline Management Plan Prepared for York County, Virginia and Virginia Coastal Zone Management Program Virginia Institute of Marine Science College of William & Mary Gloucester Point, Virginia January 2014 York County Shoreline Management Plan Prepared for York County, Virginia 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 Environ- mental Quality through Grant #NA12NOS4190168 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. January 2014 York County Table of Contents 1 Introduction ........................................................................................................................ 1 2 Coastal Setting ................................................................................................................... 2 2.1 Geology/Geomorphology ............................................................................................. 2 2.1.1 Geology ............................................................................................................... 2 2.1.2 Shore Morphology ............................................................................................... 3 2.2 Coastal Hydrodynamics ............................................................................................... 5 2.2.1 Wave Climate ..................................................................................................... 5 2.2.2 Sea-Level Rise .....................................................................................................7 2.2.3 Shore Erosion .......................................................................................................7 3 Shoreline Best Management Practices ................................................................................ 8 3.1 Implications of Traditional Erosion Control Treatments ................................................. 8 3.2 Shoreline Best Management Practices – The Living Shoreline Alternative .................... 8 3.3 Non-Structural Design Considerations .......................................................................... 8 3.4 Structural Design Considerations .................................................................................11 3.4.1 Sills .....................................................................................................................11 3.4.2 Breakwaters ........................................................................................................12 4 Methods .............................................................................................................................14 4.1 Shore Status Assessment ...........................................................................................14 4.2 Geospatial Shoreline Management Model ..................................................................14 5 Shoreline Management for York County .............................................................................17 5.1 Shoreline Management Model (SMM) Results ............................................................17 5.2 Shore Segments of Concern /Interest ......................................................................... 19 5.2.1 Bay Tree Beach Road: Chesapeake Bay (Area of Concern) ................................. 19 5.2.2 Penniman Spit: York River (Area of Interest) ..................................................... 20 6 Summary and Links to Additional Resources ......................................................................23 7 References ........................................................................................................................ 24 Appendix 1: Shoreline Management Model Flow Diagram ....................................................... 26 Appendix 2: Glossary of Shoreline Best Management Practices ............................................... 28 Appendix 3: Guidance for Structural Design and Construction in York County ......................... 30 Shoreline Management Plan List of Figures Figure 1-1. Location of York County within the Chesapeake Bay estuarine system. The location of National Oceanic and Atmospheric Administration tide gauges also are shown. ....................................................................................................1 Figure 2-1. Geology of the upriver section of York County on the York River (Mixon et al., 1989) overlain on a USGS topographic map. .............................................. 2 Figure 2-2. Geology of the downriver section of York County and it’s Chesapeake Bay shoreline (Mixon et al., 1989) overlain on a USGS topographic map. .............................. 2 Figure 2-3. Eroding banks, marsh fringe, and shore protection structures along the York River between Queens Creek and Skimino Creek. Several of the structures have been effective maintaining a marsh behind it thereby reducing direct wave impact to the upland bank and slowing erosion. .............................3 Figure 2-4. Upland bank with revetment, an eroding high bank along the National Park Service’s Colonial Parkway. ......................................................................................3 Figure 2-5. Yorktown breakwaters and beach nourishment project. Photo date 17 Oct 2010. ........... 4 Figure 2-6. The shoreline between Yorktown and Wormley Creek generally has high banks that are hardened with stone revetments. Photo date 24 Jul 2013. .................................. 4 Figure 2-7. Steep, vegetated banks with narrow fringe marsh in Wormley Creek. ............................ 4 Figure 2-8. Low upland bank in a residential area that has a rock revetment for shore protection behind a fringe marsh. ...................................................................................5 Figure 2-9. Low upland bank in a low-energy residential area that has a rock revetment for shore protection. ........................................................................................................5 Figure 2-10. Predicted wave heights that would result from a 35 mph wind during a possible 2-yr event. (From Basco and Shin, 1993). Wave heights and period (in parentheses) are shown. ............................................................................................ 6 Figure 2-11. Map of the FEMA floodplains for the 100 year and 500 year events (York County, 2013). ........................................................................................................7 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. ................................................ 9 Figure 3-2. Maintaining and enhancing the riparian and marsh buffers can maintain a stable coastal slope. ..................................................................................................... 9 Figure 3-3. Bank grading in Westmoreland County reduces steepness and will improve growing conditions for vegetation stabilization. ............................................................. 9 Figure 3-4. This low-energy site had minor bank grading, sand added, and Spartina alterniflora planted. This photo shows the site after 24 years. ........................................10 York County Figure 3-5. Sand fill with stone sills and marsh plantings at Poplar Grove, Mathews County, Virginia after six years and the cross-section used for construction (From Hardaway et al., 2010). .......................................................................................11 Figure 3-6. Longwood University’s Hull Springs Farm four years after construction and the cross-section used for construction (from Hardaway et al., 2010). ............................11 Figure 3-7. High sills built along Westmoreland State Park’s high energy, high bank shoreline. The material that slumps from the bank will be caught behind the sills and stabilize the base of the bank by protecting it from wave attack. A more recent photo shows that the slump material is starting to become vegetated. ...............12 Figure 3-8. Photo taken at Yorktown during a spring storm. The low coast was easily overwashed. .................................................................................................................. 13 Figure 3-9. The breakwaters at Yorktown provide a wide recreational beach as well as storm erosion protection for the business district. These structures were phased in beginning in 1994. 2011 Virginia Base Mapping Program Image. ................... 13 Figure 3-10. Headland breakwaters at the confluence of Cabin Creek and the Poquoson River. These structures were built relatively closely-space to provide a recreational beach as well as to protect the upland. Left: A 2011 Virginia Base Mapping Program image shortly after installation. Right: Photo taken in July 2013. Planted beach grasses have thrived at the site. .............................................................. 13 Figure 5-1. Portal