Virginia CZM Program: 2017 Coastal Grant Project Description and Final Summary

Project Task:VA CZM logo

82 

Grantee:

 Virginia Institute of Marine Science

Project Title:

Living Shoreline Sea Level Resiliency:  Performance and Adaptive Management of Existing Sites 

Project Description:

The goal of this project is monitoring effectiveness of nature based resilience projects such as those that use living shoreline management strategies. Living shoreline strategies can effectively control shoreline erosion while providing water quality benefits and maintaining natural habitat and coastal processes. These ecosystem-based management systems have been the preferred alternative for stabilizing tidal shorelines in the Commonwealth of Virginia since 2011. However, a recent analysis has shown that between 2011 and 2016 only 24% of the permits granted for shore protection were considered living shorelines (ASMFC, 2016). These types of systems may be relatively new to many landowners and some managers who may not be convinced about the long-term effectiveness of the systems for shore protection, their maintenance, and the main reason they are being constructed.Research has been performed on the effectiveness of created marsh habitats, but studies on the long-term effectiveness of the structures for shore protection in Chesapeake Bay from a design and construction perspective are relatively few.

The Coastal Zone Management program, through NOAA grants, has funded several projects that have reviewed design considerations and monitored systems for effectiveness. These studies presented data regarding the construction and performance of three living shoreline projects that were built between 1999 and 2003 in Maryland (Hardaway et al., 2009) and were the basis for the “Living Shoreline Design Guidelines for Shore Protection in Virginia’s Estuarine Environments” and the contractor training classes (Hardaway et al., 2010). The present project seeks to build upon and expand monitoring protocols at living shoreline systems for determining effectiveness of shore protection and habitat creation and stability through time using a detailed site assessment and survey. In addition, referencing the latest research results of migration and accretion of marshes in Chesapeake Bay, the project will seek to determine what elements make these successful over the short and longer terms.

A second goal of the present project is to determine the coastal habitat response of created wetlands and beaches at living shorelines in the face of sea-level rise. Using a detailed elevation survey of each site and the U.S. Army Corps of Engineers climate change adaptation sea-level rise scenarios, we will model how the whole system may respond to these changes in water level through time. Typically, shore protection structures are built in front of eroding banks that input sediment to Chesapeake Bay and provide limited subtidal habitat. Systems that are constructed in front of eroding upland banks have a ”backstop” up which these created intertidal habitats may not be able to migrate as sea level rises. This affects their long-term performance. The collected data will be used to project impacts of sea level rise through time on the structures, the upland banks, and created marshes and beaches to determine adaptive management strategies for these sites.These adaptive management strategies could be in the form of strategically adding rock and sand to the existing cross-section to address increased future water levels and to maintain the living shoreline benefits through time.

This project will use site-specific shore protection and habitat effectiveness for both medium and high energy sites as well as low and high upland banks to develop guidelines for managers, contractors, and homeowners to adapt existing and future living shoreline projects to sea level rise.Living shorelines can reduce sediment input as well as provide both subtidal, intertidal, and pore space habitats for diverse estuarine fauna and their predators.Determining how resilient these systems will be in the face of climate change requires understanding how these systems functioned in the past.

Federal Funding:

$40,000 

Project Contact:

Scott Hardaway, Jr, 804.684.7277; hardaway@vims.edu  

Project Status:

10/1/2017 - 9/30/2018; Project Completed  

Final Product:

Living Shoreline Sea-Level Resiliency: Performance and Adaptive Management of Existing Sites (PDF)  

Project Summary:

The goal of this project was to monitor the effectiveness of rock sills as a nature-based shore protection strategy and to determine their coastal resiliency in the face of sea-level rise.  Living shoreline strategies can effectively control shoreline erosion while providing water quality benefits and maintaining natural habitat and coastal processes. Research has been performed on the effectiveness of created marsh habitats, but studies on the long-term effectiveness of the structures for shore protection in Chesapeake Bay from a design and construction perspective are relatively few.

Four sites were assessed and surveyed: Captain Sinclair’s Recreational Area constructed in 2016, Occohannock on the Bay constructed in 2013, St. Mary’s City in 2002, and Jefferson Patterson Park & Museum in 1999.  Captain Sinclair fronts a low marsh and St. Mary’s and Jefferson Patterson have high banks.  The Occohannock living shoreline fronts both low upland and had a high bank that was graded during construction.  All four systems presently are providing shore protection to the upland and a stable marsh habitat.

Using an intermediate and high rate of sea-level rise, as determined by the Corps of Engineers, adaptive management strategies were modeled on the shore protection system at each site.  By 2050, at an intermediate rate of sea-level rise, if the marsh is able to maintain itself, it will migrate landward at Captain Sinclair, but the sill will become mostly submerged.  It will still provide wave attenuation to the site.  No adaptive management is suggested for this site because raising the rock height will not maintain the marsh behind it.  The entire system is very low.

At Occohannock, the sill will become mostly submerged by 2050.  The marsh will move landward and just landward of the sill will become non-vegetated wetland.  Depending on the actual rate of sea level rise, rock may be warranted to protect the base of the bank from storm waves that may impact under elevated water levels.  At the present time, the marsh at St. Mary’s is keeping up with sea level rise.  However, if the rate increases, the marsh may struggle to survive.  In addition, as the structure is submerged, erosion may impact the bank which presently is protected.  One adaptive management option is to proportionally add rock and sand to the entire system to start over at a higher elevation. At Jefferson Patterson, an intermediate rate of sea level rise will leave a wide swath of non-vegetated wetlands behind the structures, and the sills would be submerged at high water.  Adding rock to the system will provide protection to the base of bank under elevated water levels.  Sand could be added, but it would be costly and may not be necessary.  It would depend on the ability of the marsh to keep up with sea level rise. 

Disclaimer: This project summary provides the federal dollars initially awarded to the grantee. Due to underexpenditure or reprogramming of grant funds, this figure may change. For more information on the allocation of coastal grant funds, please contact Laura McKay, Virginia Coastal Program Manager, at 804.698.4323 or email:Laura.McKay@deq.virginia.gov

A more detailed Scope of Work for this project is available. Please direct your request for a copy to Virginia.Witmer@deq.virginia.gov or April.Bahen@deq.virginia.gov.

 

 

footer divider
footer divider
footer divider
Virginia Department of
Environmental Quality
P.O. Box 1105
Richmond, VA 23218
(804) 698-4000


Some resources on this website require Adobe Reader and Flash Player, Microsoft Word, PowerPoint or Excel. If you wish to receive this content in an accessible format pursuant to Section 508 of the federal Rehabilitation Act of 1973, as amended (29 U.S.C. § 794 (d)), please call 800-592-5482. In addition, this website includes hyperlinks to websites neither controlled nor sponsored by DEQ or the Commonwealth of Virginia. Links may open in a new window. If you wish to receive content from a website which is neither controlled nor sponsored by DEQ or the Commonwealth, please contact the host of that website directly.

Privacy Statement | Terms Of Use | WAI Compliance | Contact Us