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Restore and protect natural shorelines: Use living shoreline techniques
Adaptation Strategies and Actions
Restore and protect natural shorelines: Use living shoreline techniques
Stabilize and enhance shorelines using natural materials to reduce erosion and flooding and increase habitat value.
What are living shorelines?
Living shorelines refer to a range of “soft armoring” techniques used to stabilize shorelines and protect or enhance natural features. These techniques seek to control erosion and flooding by recreating or enhancing natural shorelines using vegetation and other natural or organic materials. Hybrid techniques combine vegetation, such as marsh plants and submerged aquatic vegetation, with harder materials for added structure and stability, such as oyster shells, biologs (erosion-control products made of natural, biodegradable materials), or rocks. Benefits include provision of erosion control and flood protection while increasing tidal connectivity with minimal disruption to normal coastal processes.5
Learn about the range of living shoreline techniques that can be used to reduce erosion and storm damage and enhance the natural environment.
Why use living shorelines?
Living shorelines are the best shoreline management approach to sustain and protect the environment and coastal communities when used in the right locations with proper design, construction, and maintenance. This natural approach is better than hardened coastal protection measures,12 because living shorelines provide many ecological benefits and can largely avoid the adverse impacts that may result from the use of hardened infrastructure like seawalls and bulkheads.
Living shorelines help to:
- Protect, restore, and enhance shorelines, beaches, and habitat in the littoral zone.7
- Provide continuous habitat (or corridors) between land and water environments for migratory fish and wildlife.
- Protect or create habitat for submerged aquatic vegetation, invertebrates, and other estuarine species.
- Provide food resources and roost sites for waterbirds.
- Support inland habitat migration, helping to minimize or reverse salt marsh habitat loss and degradation.
- Improve water quality through water filtration when native plants are used.
Living shorelines further protect coastal ecosystem services, benefiting human communities by:
- Enhancing and protecting important commercial fisheries and thus local economies.
- Providing critical natural storm defenses by helping to dissipate storm surge and waves and reducing damage from floods, which can further increase real estate values for protected properties.
- Reducing repair and maintenance costs after storm events, since natural systems often have some capacity to self-repair following disturbances.
- Contributing to carbon sequestration and storage (blue carbon), if the approach is vegetation-based.
- Improving water quality.
- Supporting eco-tourism through fishing, hunting, and wildlife viewing activities.
- Enhancing overall coastal resilience.
Living shorelines can be categorized into nonstructural and hybrid shoreline management practices.
Nonstructural methods generally include:
- Vegetation control and management
- Tidal marsh restoration, enhancement, or creation
- Beach fill
- Dune restoration
- Fiber or coir logs (biologs)
Hybrid approaches include:
- Marsh toe revetments
- Offshore breakwaters that may be combined with native vegetation 5
Deciding whether a living shoreline approach is right for a particular site and choosing the most appropriate method to use will depend on many factors, including shoreline location and site characteristics (shoreline slope, water levels, and wave energy). Living shorelines typically work best in areas with relatively lower wave energy. They should be designed within the context of local site conditions and in consultation with all of the various stakeholders involved.11 When planning a living shorelines project, several steps are typically required in the project’s timeframe: site analysis, permit approval and legal compliance, site preparation, installation, monitoring, and maintenance.10
Nonstructural living shoreline techniques
This living shoreline technique includes new plantings, replantings, and maintaining existing vegetation. Living shorelines use predominantly native vegetation. Plantings are used along shorelines in low to moderate wave energy environments with gradual slopes, such as salt marshes, beaches, bays, and other areas. Native grasses can be planted into the tidal and supratidal substrate along shorelines fronted by beaches and mudflats.9 Vegetation helps to dissipate wave energy, stabilize shorelines, and provide fish and wildlife habitat. Plant roots stabilize soils and take up nutrients to improve water quality. Plants may be used alone or in conjunction with coir logs, oyster reefs, or other materials for additional stabilization.
A common type of living shoreline approach is planting marsh grasses in existing substrate to create or enhance marsh fringes (areas of marsh vegetation found between open water and upland areas that can range from several feet to several miles wide).9 Plantings of appropriate species in marsh substrate can help create marsh and preserve habitat for fish, mollusks, crustaceans, and birds. Fringing marshes created through a living shoreline approach have been shown to perform many of the same ecosystem services that more extensive marshes provide, including wave dispersion, fish and invertebrate habitat, sediment trapping, and filtration.3
Marsh enhancement refers to the restoration or creation of tidal marsh, which is appropriate along shorelines with low wave energy. Marsh restoration entails adding marsh plants to barren or eroding areas or replanting vegetation in areas damaged by storms. Marsh creation refers to building marsh where it didn’t exist previously, which can require bank grading of non-vegetated intertidal areas.5 All techniques that increase marsh habitat contribute to coastal storm protection by reducing waves and stabilizing sediments.16 The dense marsh vegetation and shallow water act to slow and reduce storm surge or slow its arrival time landward of the wetland.17,18
Beach enhancement includes beach nourishment and dune restoration techniques. Beach nourishment is the addition of sand to a beach to raise its elevation and/or increase its width to enhance its ability to buffer upland areas from wave action.5 Dune restoration is the process of planting appropriate dune plants to reshape and stabilize a dune, which can further help buffer inland areas from wave action and inundation. The success of beach nourishment projects depends on the compatibility of new sand with the native beach materials (i.e., matching grain size and density and planting native plant species). Beach enhancement is typically used to prevent shoreline erosion or to enhance beach areas that have been eroded.
Biologs (e.g., coir or fiber logs)
Bioengineered natural coastal buffers combine plantings with erosion-control products made of natural, biodegradable materials, such as fiber or coir logs and fiber blankets. These logs are made of compact fiber wrapped in a netting to hold the fiber in place. The biodegradable logs are placed closely along shorelines, typically staked into place to prevent being moved by waves and currents, and will naturally assimilate into the surrounding habitat over time (usually between 6 and 24 months depending on the density and type of fiber used).8 They are used to temporarily contain soil or sand fill and protect the shoreline until planted sites establish root systems and become stabilized. This technique is most effective for salt marsh restoration and protection in the face of storms and sea level rise. It is best in sites that are relatively protected from boat wakes and waves. Other considerations when using biologs include constructing the logs to hold up to wave energy and tidal elevations, as well as ensuring marsh grasses are at an optimal height above water.
Sills, groins, and revetments
Marsh restoration can be combined with hard structures for added stabilization in areas that experience higher wave energy. These ‘hybrid’ techniques may consist mostly of natural shorelines but will have added structural components, such as marsh toe revetments, marsh sills, or groins.
Marsh toe-revetments are freestanding, low-profile structures typically made of stone and placed at the eroding edge of a marsh near the mean low water elevation.4 These can be used along a natural marsh that has eroding edges or where upland bank erosion is present.
Marsh sills are similar low-profile structures placed near the mean low water elevation and close to the shore. They are generally made of stone, rock, or timber sheet piles. Sills are typically used to create marsh where they do not already exist or to protect beaches from wave action. They trap sediment behind or landward of the structure to help establish new marsh or rebuild existing marsh. Sills can also create foraging areas for fish as well as hard substrate that can be beneficial to algae, shellfish, and other invertebrates.9,14 A drawback to using a sill system is that it can reduce or divert sediments from adjacent shore areas.
Groins are similar to sills except groins are placed perpendicular to the shoreline, rather than parallel. Groins are also made mostly of stone and used to trap sand that moves along the beach to increase sediment over time and protect beaches from erosion. One drawback is they can disrupt longshore sediment transport and adversely affect downdrift shorelines.5
Breakwaters are large, gapped stone structures that are strategically placed offshore of a sandy beach in moderate to high wave energy environments. These systems provide shoreline protection by intercepting incoming waves and creating more stable beaches. Because breakwaters can disrupt longshore sediment transport and adversely affect downdrift beaches, they are often used in conjunction with beach nourishment and dune enhancement.5 Breakwaters are generally made of timber, stone, concrete, or rocks.
Biogenic reefs are natural breakwaters that can dissipate wave energy and promote sediment deposition shoreward of the reef. Examples include oyster reefs, coral reefs, and shellfish beds.1,6 Biogenic reefs can provide additional ecosystem services, including:
- Production of fish and invertebrates with commercial, recreational, and ecological significance;
- Water quality improvement;
- Nutrient cycling; and
- Stabilization of adjacent shorelines and habitats.2
Breakwater oyster reefs located seaward of armored shorelines have also been shown to mitigate fish and shellfish habitat loss caused by hardened structures.13
Target Species, Species Groups, Habitats and Stressors
1. Baggett, L.P., S.P. Powers, R.D. Brumbaugh, L.D. Coen, B.M. DeAngelis, J.K. Greene, B.T. Hancock, S.M. Morlock, B.L. Allen, D.L. Breitburg, D. Bushek, J.H. Grabowski, R.E. Grizzle, E.D. Grosholz, M.K. La Peyre, M.W. Luckenback, et al., 2015: Guidelines for evaluating performance of oyster habitat restoration. Restor Ecol, 23 (6), 737-745.
2. Baggett, L.P., S.P. Powers, R. Brumbaugh, L.D. Coen, B. DeAngelis, J. Greene, B. Hancock, and S. Morlock, 2014: Oyster habitat restoration monitoring and assessment handbook. The Nature Conservancy, Arlington, VA, USA, 96 p.
3. Bilkovic, D.M., M. Mitchell, P. Mason, and K. Duhring. 2016. The Role of Living Shorelines as Estuarine Habitat Conservation Strategies. Coastal Management, 44 (3), 161-174.
4. Center for Coastal Resources Management [CCRM]. 2016. Living Shorelines. Virginia Institute of Marine Science. Accessed online January 2017. Online at: http://ccrm.vims.edu/livingshorelines/index.html.
5. Duhring, K.A. 2006. Overview of Living Shoreline Design Options for Erosion Protection on Tidal Shorelines. In Erdle, S.Y., J.L.D. Davis, and K.G. Sellner, eds. (2008). Management, Policy, Science and Engineering of Nonstructural Erosion Control in the Chesapeake Bay: Proceedings of the 2006 Living Shoreline Summit. Tools and Decision-Making: Facilitating and Encouraging Living Shoreline Implementation. CRC Publ. No. 08-164, Gloucester Point, VA, 136p.
6. Grabowski, J.H., R.D. Brumbaugh, R.F. Conrad, A.G. Keeler, J.J. Opaluch, C.H. Peterson, M.F. Piehler, S.P. Powers, and A.R. Smyth, 2012: Economic Valuation of Ecosystem Services? Provided by Oyster Reefs. BioScience, 62 (10), 900-909. DOI: 10.1525/bio.2012.62.10.10.
7. Jacobus, S. 2016. NJDEP Living Shorelines Program. Office of Coastal and Land Use Planning. Presentation for the “Nature-Based Solutions to Enhance Coastal Resilience” Workshop, National Wildlife Federation, June 28, 2016.
8. Massachusetts Coastal Zone Management. 2017. StormSmart Properties Fact Sheet 5: Bioengineering - Natural Fiber Blankets on Coastal Banks. Accessed March 2017. Online at: http://www.mass.gov/eea/agencies/czm/program-areas/stormsmart-coasts/sto....
9. National Research Council. 2007. Mitigating Shore Erosion Along Sheltered Coasts. National Academies Press, Washington, DC. http://www.nap.edu/catalog/11764.html.
10. National Oceanic and Atmospheric Administration [NOAA] Restoration Center. 2016. Living Shoreline Planning and Implementation. Accessed January 2017. Online at: http://www.habitat.noaa.gov/restoration/techniques/lsimplementation.html.
11. National Oceanic and Atmospheric Administration [NOAA]. 2015. Guidance for Considering the Use of Living Shorelines. NOAA Living Shorelines Workgroup. 36 p.
12. Restore America’s Estuaries [RAE]. 2015. Living Shorelines: From Barriers to Opportunities. Arlington, VA.
13. Scyphers S.B., S.P. Powers, K.L. Heck Jr, D. Byron, 2011: Oyster Reefs as Natural Breakwaters Mitigate Shoreline Loss and Facilitate Fisheries. PLoS ONE, 6 (8): e22396. DOI: 10.1371/journal.pone.0022396.
14. Seitz, R.D., R.N. Lipcius, N.H. Olmstead, M.S. Seebo, and D.M. Lambert, 2006. Influence of shallow-water habitats and shoreline development on abundance, biomass, and diversity of benthic prey and predators in Chesapeake Bay. Marine Ecology Progress Series, 326, 11-27.
15. Systems Approach to Geomorphic Engineering [SAGE]. 2015. Natural and structural measures for shoreline stabilization brochure. Accessed March 1, 2017. http://sagecoast.org/docs/SAGE_LivingShorelineBrochure_Print.pdf.
16. US Army Corps of Engineers [USACE]. 2013. Coastal Risk Reduction and Resilience. CWTS 2013-3. Washington, DC: Directorate of Civil Works, US Army Corps of Engineers.
17. Wamsley, T.V. 2009. Interaction of Hurricanes and Natural Coastal Features: Implications for Storm Damage Reduction. Doctoral Thesis, Water Resources Engineering, Lund University. LUTVDG/TVVR-1049.
18. Wamsley, T.V., M.A. Cialone, J.M. Smith, and B.A. Ebersole. 2009. Influence of landscape restoration and degradation on storm surge and waves in southern Louisiana. Journal of Natural Hazards, 51 (1): 207–224.
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