Natural and Structural Measures for Shoreline Stabilization

Living Shorelines

Innovative approaches are necessary as This brochure presents a continuum our coastal communities and shorelines of green to gray shoreline stabilization are facing escalating risks from more techniques, highlighting Living Shorelines, powerful storms, accelerated sea-level that help reduce coastal risks and rise, and changing precipitation patterns improve resiliency though an integrated that can result in dramatic economic approach that draws from the full array losses. While the threats of these events of coastal risk reduction measures. may be inevitable, understanding how to adapt to the impact is important as we explore how solutions will ensure the resilience of our coastal communities and shorelines. Coastal Risk Reduction and Living Shorelines

Coastal Risk Reduction SAGE – Systems Approach Coastal systems typically include to Geomorphic Engineering In order to determine the most appropriate both natural habitats and man-made USACE and NOAA recognize the shoreline protection technique, several structural features. The relationships and value of an integrated approach to risk site-specific conditions must be assessed. The following coastal conditions, along with interactions among these features are reduction through the incorporation of important variables in determining coastal other factors, are used to determine the natural and nature-based features in combinations of green and gray solutions vulnerability, reliability, risk and resilience. addition to non-structural and structural for a particular shoreline. Coastal risk reduction can be achieved measures to improve social, economic, through several approaches, which may and ecosystem resilience. To promote Reach: A longshore segment of a shoreline where influences and impacts, such as wind be used in combination with each other. this approach, USACE and NOAA have engaged partners and stakeholders in direction, wave energy, littoral transport, etc. Options for coastal risk reduction include: mutually interact. a community of practice called SAGE, • Natural or nature-based measures: or a Systems Approach to Geomorphic Natural features are created through the Resilience: The ability to avoid, minimize, Engineering. This community of practice withstand, and recover from the effects of action of physical, biological, geologic, provides a forum to discuss science and adversity, whether natural or man made, and chemical processes operating in policy that can support and advance a under all circumstances of use. This nature, and include marshes, dunes systems approach to implementing risk definition also applies to engineering (i), and oyster reefs. Nature-based reduction measures that both sustain ecological (ii), and community resilience (iii). features are created by human design, a healthy environment and create a Fetch: A cross shore distance along open engineering, and construction to mimic resilient shoreline. nature. A living shoreline is an example water over which wind blows to generate of a nature-based feature. SAGE promotes a hybrid engineering waves. For any given shore, there may approach that integrates soft or ‘green’ be several fetch distances depending on predominant wind direction. • Structural measures: Structural natural and nature-based measures, measures include sea walls, groins and with hard or ‘gray’ structural ones at breakwaters. These features reduce Physical conditions: The slope of the landscape scale. These stabilization the foreshore or beach face, a geologic coastal risks by decreasing shoreline solutions include “living shoreline” condition or bathymetry offshore. , wave damage, and flooding. approaches which integrate living • Non-structural measures: Includes components, such as plantings, with Tidal Range: The vertical difference modifications in public policy, structural techniques, such as between high tide and low tide. management practices, regulatory or breakwaters. Storm Surge: The resulting temporary policy and pricing policy (e.g., structure Living Shorelines achieve multiple goals, rise in sea level due to the action of wind acquisitions or relocations, flood such as: stress on the water surface and low proofing of structures, implementing atmospheric pressure created during storms flood warning systems, flood • Stabilizing the shoreline and reducing which can cause coastal flooding. Surge preparedness planning, establishment current rates of shoreline erosion and is the difference from expected tide level. of land use regulations, emergency storm damage; Storm tide is the total water level. response plans). • Providing ecosystem services (such Wave Energy: Wave energy is related to The types of risk reduction measures as habitat for fish and other aquatic wave height and describes the force a wave employed depend upon the geophysical species) and increasing flood storage is likely to have on a shoreline. Different setting, the desired level of risk capacity; and environments will have lower or higher wave energy depending on environmental reduction, objectives, cost, • Maintaining connections between factors like shore orientation, wind, channel reliability, and other factors. land and water ecosystems to width, and bathymetry. Boat wakes can also enhance resilience. generate waves. Low: Limited fetch in a sheltered, shallow or small water body (estuary, river, bay) i.e. < 2 ft. Medium: A range that combines elements of low and high energy (e.g., shallow water with a large fetch or partially sheltered) i.e. 2 - 5 ft. Fetch High: Large fetch, deep water (open ocean). Reach Tidal Range

Storm Tide High Water Level Low Water Level

Storm Surges at Low & High Tide Green - softer Techniques how green or gray Small Waves | Small Fetch | Gentle Slope | Sheltered Coast should your shoreline solution be?

Living shoreline

Vegetation Edging Sills Only Only Photo Credit: Maryland Department of Natural Resources - Shoreline Conservation Service - Shoreline Resources Natural of Department Maryland Credit: Photo Estuary Delaware for Partnership Credit: Photo Conservation Service - Shoreline Resources Natural of Department Maryland Credit: Photo

Roots hold soil in place to reduce Structure to hold the toe of existing Parallel to existing or vegetated Large volume of sand added from erosion. Provides a buffer to upland or vegetated slope in place. Protects shoreline, reduces wave energy outside source to an eroding beach. areas and breaks small waves. against shoreline erosion. and prevents erosion. A gapped Widens the beach and moves the approach would allow habitat shoreline seaward. Suitable For Suitable For connectivity, greater tidal exchange, Suitable For Low wave energy environments. Most areas except high wave energy and better waterfront access. environments. Low-lying oceanfront areas with Material Options Suitable For existing sources of sand and Vegetation* Base with • Native plants* Most areas except high wave energy sediment. Material Options environments. Benefits Material Options (low wave only, temporary) Vegetation* Base with • Dissipates wave energy • “Snow“ fencing • Sand Material Options • Slows inland water transfer • Erosion control blankets Benefits • Increases natural storm • tubes • Stone water infiltration • Living reef (oyster/mussel) • Sand breakwaters • Expands usable beach area • Provides habitat and • Rock baskets • Living reef (oyster/mussel) • Lower environmental impact ecosystem services • Rock gabion baskets than hard structures Benefits • Minimal impact to natural • Flexible strategy Benefits community and ecosystem • Dissipates wave energy • Redesigned with relative ease processes • Slows inland water transfer • Provides habitat and • Provides habitat and • Maintains aquatic/terrestrial • Provides habitat and ecosystem services ecosystem services interface and connectivity ecosystem services • Dissipates wave energy Disadvantages • Flood water storage • Increases natural storm • Slows inland water transfer water infiltration • Provides habitat and • Requires continual sand resources Disadvantages • Toe protection helps prevent ecosystem services for renourishment • No storm surge edge loss • Increases natural storm • No high water protection reduction ability water infiltration • Appropriate in limited situations Disadvantages • No high water protection • Toe protection helps prevent • Possible impacts to regional • Appropriate in limited situations • No high water protection wetland edge loss sediment transport • Uncertainty of successful • Uncertainty of successful Disadvantages vegetation growth and vegetation growth and competition with invasive competition with invasive • Require more land area • No high water protection • Uncertainty of successful vegetation growth and competition with invasive

* Native plants and materials must be appropriate for current salinity and site conditions.

Initial Construction: Initial Construction: Initial Construction: Initial Construction: Operations & Maintenance: Operations & Maintenance: Operations & Maintenance: Operations & Maintenance:

Initial Construction: = up to $1000 per linear foot, = $1001 - $2000 per linear foot, = $2001 - $5000 per linear foot, = $5001 - $10,000 per linear foot Operations and Maintenance (yearly for a 50 year project life): = up to $100 per linear foot, = $101 - $500 per linear foot, = over $500 per linear foot Green - softer Techniques how green or gray Gray - Harder Techniques Small Waves | Small Fetch | Gentle Slope | Sheltered Coast should your shoreline solution be? Large Waves | Large Fetch | Steep Slope | Open Coast

Living shoreline Coastal Structure

Beach Nourishment Beach Nourishment Groin Only & Vegetation on Dune Photo Credit: USACE New York District Public Affairs District Public York New USACE Credit: Photo Affairs District Public York New USACE Credit: Photo Affairs District Public York New USACE Credit: Photo

Large volume of sand added from Helps anchor sand and provide a Offshore structures intended to Perpendicular, projecting from outside source to an eroding beach. buffer to protect inland area from break waves, reducing the force shoreline. Intercept water flow Widens the beach and moves the waves, flooding and erosion. of wave action and encourages and sand moving parallel to the shoreline seaward. sediment accretion. Can be floating shoreline to prevent beach erosion Suitable For or fixed to the ocean floor, attached and break waves. Retain sand Suitable For Low-lying oceanfront areas with to shore or not, and continuous or placed on beach. segmented. A gapped approach Low-lying oceanfront areas with existing sources of sand and Suitable For existing sources of sand and sediment. would allow habitat connectivity, greater tidal exchange, and better sediment. Coordination with beach Material Options waterfront access. nourishment. Material Options Suitable For Sand with vegetation Material Options • Sand Can also strengthen Most areas except high wave energy dunes with: • Concrete/stone rubbleƗ Benefits environments often in conjunction • Geotextile tubes with marinas. • Timber • Expands usable beach area • Rocky core • Metal sheet piles • Lower environmental impact Material Options Benefits Benefits than hard structures • Grout-filled fabric bags • Wood • Flexible strategy • Expands usable beach area • Armorstone • RockƗ • Protection from wave forces • Redesigned with relative ease • Lower environmental impact • Pre-cast concrete blocks • Methods and materials are • Provides habitat and • Flexible strategy • Living reef (oyster/mussel) adaptable ecosystem services • Redesigned with relative ease if low wave environment • Can be combined with beach • Vegetation strengthens dunes nourishment projects to extend Disadvantages Benefits and increases their resilience to their life • Reduces wave force and height • Requires continual sand resources storm events Disadvantages for renourishment • Provides habitat and • Stabilizes wetland • No high water protection ecosystem services • Can function like reef • Erosion of adjacent sites • Appropriate in limited situations • Economical in shallow areas • Can be detrimental to shoreline Disadvantages • Possible impacts to regional • Limited storm surge flood level ecosystem (e.g. replaces native reduction sediment transport • Requires continual sand resources substrate with rock and reduces for renourishment Disadvantages natural habitat availability) • No high water protection • No high water protection • Expensive in deep water • Appropriate in limited situations • Can reduce water circulation • Possible impacts to regional (minimized if floating breakwater is sediment transport applied) • Can create navigational hazard • Require more land area • Uncertainty of successful vegetation growth and competition with invasive • No high water protection Ɨ Rock/stone needs to be appropriately sized for site specific wave energy. • Can reduce water circulation • Can create navigation hazard

Gray can be greener: e.g., ‘Living Breakwater’ using oysters to colonize rocks or ‘Greenwall/Biowall’ using vegetation, alternative forms and materials

Initial Construction: Initial Construction: Initial Construction: Initial Construction: Operations & Maintenance: Operations & Maintenance: Operations & Maintenance: Operations & Maintenance:

Initial Construction: = up to $1000 per linear foot, = $1001 - $2000 per linear foot, = $2001 - $5000 per linear foot, = $5001 - $10,000 per linear foot Operations and Maintenance (yearly for a 50 year project life): = up to $100 per linear foot, = $101 - $500 per linear foot, = over $500 per linear foot how green or gray Gray - Harder Techniques should your shoreline solution be? Large Waves | Large Fetch | Steep Slope | Open Coast

Coastal Structure

Groin Bulkhead Photo Credit: USACE New York District Public Affairs District Public York New USACE Credit: Photo Conservation Service - Shoreline Resources Natural of Department Maryland Credit: Photo Resources Natural and Environment of Department Carolina North Credit: Photo Affairs District Public York New USACE Credit: Photo

Perpendicular, projecting from Lays over the slope of a shoreline. Parallel to the shoreline, vertical Parallel to shoreline, vertical or shoreline. Intercept water flow Protects slope from erosion and retaining wall. Intended to hold sloped wall. Soil on one side of wall and sand moving parallel to the waves. soil in place and allow for a stable is the same elevation as water on the shoreline to prevent beach erosion shoreline. other. Absorbs and limits impacts of Suitable For and break waves. Retain sand large waves and directs flow away Suitable For placed on beach. Sites with pre-existing hardened from land. shoreline structures. High energy settings and sites with Suitable For Suitable For pre-existing hardened shoreline Material Options Coordination with beach structures. Accommodates working Areas highly vulnerable to storm nourishment. • Stone rubbleƗ water fronts (eg: docking for ships surge and wave forces. • Concrete blocks and ferries). Material Options Material Options • Cast concrete slabs Ɨ Material Options • Concrete/stone rubble • Sand/concrete filled bags • Stone • Timber • Rock-filled gabion basket • Steel sheet piles • Rock • Metal sheet piles • Timber • Concrete Benefits Benefits • Concrete • Steel/vinyl sheets • Mitigates wave action • Composite carbon fibers • Steel sheet piles • Protection from wave forces • Little maintenance • Benefits • Methods and materials are • Indefinite lifespan Benefits adaptable • Minimizes adjacent site impact • Prevents storm surge flooding • Can be combined with beach • Moderates wave action • Resists strong wave forces Disadvantages nourishment projects to extend • Manages tide level fluctuation • Shoreline stabilization behind their life • No major flood protection • Long lifespan structure Disadvantages • Require more land area • Simple repair • Low maintenance costs • Loss of intertidal habitat • Less space intensive horizontally Disadvantages • Erosion of adjacent sites • Erosion of adjacent than other techniques (e.g. • Can be detrimental to shoreline unreinforced sites • No major flood protection vegetation only) ecosystem (e.g. replaces native • Require more land area • Erosion of seaward seabed Disadvantages substrate with rock and reduces • No high water protection • Erosion of adjacent natural habitat availability) • Prevents upland from being a unreinforced sites • Erosion of seaward seabed • No high water protection sediment source to the system • Loss of intertidal habitat • Disrupt sediment transport leading • May be damaged from to beach erosion overtopping oceanfront • Higher up-front costs storm waves • Visually obstructive • Prevents upland from being a • Loss of sediment source to the system • Prevents upland from being a • Induces wave reflection sediment source to the system • May be damaged from overtopping oceanfront storm waves Ɨ Rock/stone needs to be appropriately sized for site specific wave energy.

Gray can be greener: e.g., ‘Living Breakwater’ using oysters to colonize rocks or ‘Greenwall/Biowall’ using vegetation, alternative forms and materials

Initial Construction: Initial Construction: Initial Construction: Initial Construction: Operations & Maintenance: Operations & Maintenance: Operations & Maintenance: Operations & Maintenance: Is a Living Shoreline a Good Fit for What I Need? How To Find Out More

Living Shorelines achieve multiple goals such as: If you have a Living Shorelines permitting • Stabilizing the shoreline and reducing current rates of shoreline question, contact your state’s office of erosion and storm damage Environmental Protection, Conservation or Natural Resources, your coastal zone • Providing ecosystem services, such as habitat for fish and other manager such as your state’s Department aquatic species and increasing flood storage capacity of State, as well as your local U.S. Army • Maintaining connections between land and water ecosystems Corps of Engineers (USACE) district office. to enhance resilience If you would like science or engineering Site-specific conditions will influence your choice of shoreline protection technique advice, or to talk to people who have (ex: wave energy level, fetch lengths, rate and pattern of erosion, etc). Here are some experience studying or constructing additional factors to keep in mind as you consider Living Shorelines. living shorelines, reach out to some of the following: your local universities, your City’s Department of Planning What are the benefits? and Department of Parks, Sea Grant • Erosion control and shore stabilization. • Complemented natural shoreline Chapter, Littoral Society, The Nature • Restored and enhanced habitat which dynamics & movement; increased Conservancy, The Trust for Public Land, supports fish and wildlife populations. resilience and absorption of wave The Environmental Protection Agency energy, storm surge and floodwaters; (EPA), National Oceanic and Atmospheric • Increased property values. and an adaptive tool for preparation of Administration (NOAA), USACE, • Enhanced community enjoyment. sea level rise. engineering firms and other organizations that focus on your local waterfront. • Opportunities for education. • Improved water quality from settling or trapping sediment (e.g. once These and other websites are good • Improved public access to waterfront established, a marsh can filter surface references to learn more about Living through recreational activities such water runoff or oysters can provide Shorelines: as fishing, boating and birding. coastal water filtration). Can be used to satisfy zoning and SAGE permitting requirement for waterfront www.SAGEcoast.org development projects. NOAA Restoration www.habitat.noaa.gov/livingshorelines

What are some challenges? USACE Engineer Research Development • Uncertainty in risk because of lack • In urban environments, there is limited Center, Engineering with Nature of experience of techniques. land (bulkheads may seem like the el.erdc.usace.army.mil/ewn • Public funds are often tied to only option), a variety of upland uses (industrial past use may have left legacy USACE North Atlantic Division, National government permit compliance. Planning Center of Expertise for Coastal Storm contaminants) and high velocity waters. • Permitting processes can be lengthy Damage Reduction www.nad.usace.army.mil/About/ and challenging. The existing regulatory • The overall sediment system needs to be taken into account to NationalCentersofExpertise/CoastalStorm process is centered on traditional “gray” DamageReduction(Planning).aspx or “hard” techniques. Regulators and protect neighboring properties from experiencing starved down drift project sponsors alike are learning how Virginia Institute of Marine Science (VIMS) to design living shorelines projects. shorelines or other consequences Center for Coastal Resources Management Talk with someone about your state’s as a result of a project. ccrm.vims.edu/livingshorelines/index.html permitting process or to hear about • Lack of public awareness of Coasts, Oceans, Ports & Rivers their experiences. performance and benefits of Institute (CORPI) • It takes time to develop and test new living shorelines. www.mycopri.org/livingshorelines shoreline protection methods. • Not all techniques have the same level The Nature Conservancy of performance or success monitoring. • There may be land ownership www.nature.org/ourinitiatives/habitats/ constraints. Consider where federal Less practiced techniques may require oceanscoasts/howwework/helping-oceans- and state jurisdiction for the water body more monitoring. adapt-to-climate-change.xml starts and ends.

What INFLUENCES cost? • The materials chosen for the project • Sometimes it’s possible to install the influence cost. project yourself, other times you will • Including green techniques can need help from a professional. be cheaper than traditional • Long term maintenance is required as gray techniques. any landscape project (e.g. replanting may be needed after a storm).

Developed with support and funding from SAGE, NOAA and USACE; February 2015