5.5 national average

7.6 state MARSH RESILIENCE SCALE average

1 2 3 4 5 6 7 8 9 10 9.0 reserve average

Exceedingly good current conditions at North-Inlet combine with reasonable vulnerability and MARSH RESILIENCE AT adaptation potential scores to give an overall resilience that is better than the state, Southeast THE LANDSCAPE SCALE region and national average. Management recommendations: Very good How does the North-Inlet Winyah marsh resilience is mitigated by small areas in Bay Research Reserve compare? which future migration may take place. High current condition marshes will naturally self- sustain into the future if barriers to inland migration can be removed or made more permeable.

Current conditions Vulnerability Adaptive capacity Marsh resilience depends largely Marshes are more vulnerable to Marshes with more space and fewer on current composition and sea level rise when more of their barriers to migration have a greater exposure to stressors such as vegetation is lower in the tidal capacity to survive sea level rise. development and agriculture. frame and they have soils that are likely to erode. The capacity for tidal marshes in and The current condition of tidal marshes in around the North Inlet-Winyah Bay and around the North Inlet-Winyah Bay Tidal marshes in and around the North Reserve to adapt to future sea level rise Reserve are far better than the rest of the Inlet-Winyah Bay Reserve are slightly is slightly higher than marshes nation, and quite a bit better than South more vulnerable than marshes throughout the nation, but not quite as Carolina and the Southeast region. This throughout South Carolina, but less good as marshes in the rest of South area is characterized by very high vulnerable than marshes throughout the Carolina and the Southeast. This area amounts of marsh core to edge, high Southeast and the nation. Soils are less has fairly complex shorelines and a high amounts of surrounding natural land erodible than other areas, the tidal range degree of potential marsh cover, and very low amounts of is fairly high, but the amount of marsh connectedness, but potential marsh surrounding agriculture. vegetation below the mean higher high migration space is limited. water levels is significantly greater than marshes in most other areas.

TOTAL TOTAL TOTAL (1 TO 10) (-10 TO -1) (1 TO 10) National average 5.65 National average -5.21 National average 5.65 Southeast 7.08 Southeast -4.58 Southeast 6.98 State of South Carolina 7.36 State of South Carolina -3.58 State of South Carolina 7.41 North Inlet Winyah Bay 9.50 North Inlet Winyah Bay -4.50 North Inlet Winyah Bay 6.50

CURRENT CONDITIONS | VULNERABILITY | ADAPTIVE CAPACITY

– LESS RESILIENT MORE RESILIENT + ABOUT THIS PROJECT

What do we mean by tidal marsh resilience? SCIENCE & TOOLS FOR COASTAL COMMUNITIES NATIONWIDE Tidal marshes buffer against storm surge, reduce erosion, fortify upland property, and—together with other wetlands—provide an estimated $23.2 billion in storm protection annually. Marshes also How can I use this information? improve water quality, create habitat for fish and wildlife, provide opportunities for outdoor recreation, and boost local economies. To find the detailed scores and supporting data for the marshes in your Reserve or state, visit the Digital Coast. Being able to These coastal ecosystems are characterized by hypoxic and compare the vulnerability, current condition, and adaptation saline soil conditions with plant communities that are largely potential of individual marshes across the country allows users driven by precipitation and flooding regimes. Small changes in to conduct comparative studies, analyze how watershed and these regimes—for example, in inundation duration—can have marsh level conditions impact vulnerability, and develop large impacts on marsh composition. The ability of marshes consistent approaches to ensuring tidal wetlands can adapt to to resist or recover from such changes is an indication of their sea level rise. The scores are derived from consistent data over resilience. Sea level rise is a significant, long-term disruption broad geographies, making them useful for screening large that affects most tidal marshes. In this assessment, resilience areas for marshes with particular characteristics, targeting is an integrative measure of a marsh’s capacity to persist as fieldwork and monitoring, and strengthening experimental rates of sea level rise accelerate into the future. design. Because they take future conditions into consideration, they can be used to identify marsh restoration and migration pathway conservation opportunities that are cost effective and Where do the scores and maps come from? sustainable for the long term. The results can be used to assess the degree to which site-specific data represents other marshes Rankings for tidal marsh resilience to sea level rise at the in the state or region and to prioritize sites for new Reserves or landscape scale were calculated using GIS-based metrics new components of existing Reserves. Used in tandem with of current marsh condition, vulnerability to sea level rise, other NERRS-based marsh assessment tools, these rankings and potential for adaptation. The assessment protocol used provide an integrated continuum of assessment to inform efforts standardized comparisons over consistent watershed areas to study, restore, or protect tidal marshes at the local, state, (HUC 12) along all coastal areas that contained salt marshes. regional, and national scales. • Current marsh conditions included measures of a marsh’s core area compared to its exposed and unvegetated edges and the What should I keep in mind? surrounding impervious, agricultural, and natural land cover. More edges, especially if not vegetated, expose more of the This assessment is based on data from the coastal areas of marsh to potential erosion. Impervious and agricultural cover the lower 48 United States. It does not include the Great Lakes. can contribute to runoff and pollutants that degrade marsh The results are regional in scope and should be used as conditions, while increased natural cover mitigates those screening level information at the local scale. The team has created a framework to perform similar assessments using effects. Based on NOAA’s Coastal Change Analysis Program more detailed local data and information. With high resolution (C-CAP) 2011 land cover data. data, the same protocol can be implemented at the local level to • Vulnerability included soil erodibility, total tidal range, and the inform site specific decision making and support long term percentage of marsh below mean high water and mean sea marsh resilience strategies. level. Marshes are more vulnerable to sea level rise when more of their vegetation is lower in the tidal frame, especially when that frame is not large. Erosion of marsh soils could WHERE CAN I LEARN MORE? increase with more frequent inundation. Based on NOAA Sea This user-friendly report includes more information about Level Rise viewer elevation data and NRCS SSURGO soils. this assessment, its methods, and its results. Project partners include the National Estuarine Research • Adaptive capacity included shoreline sinuosity and armoring Reserve System, National Oceanic and Atmospheric (hardening), available space for migration, and future marsh Administration’s Office for Coastal Management, the connectedness. The more complex, (sinuous) a shoreline, the University of New Hampshire, and the National Estuarine more protection it provides, while a hardened shoreline impedes Research Reserve Association. migration. The more connected a marsh is, the higher its RACHEL STEVENS, Stewardship Coordinator adaptive capacity. By combining elevation with projected sea Great Bay National Estuarine Research Reserve level rise scenarios, we estimate available space for migration. [email protected] | (603) 778-0015 Based on NOAA C-CAP and elevation data combined with Environmental Sensitivity Index (ESI) shoreline data. SUZANNE SHULL, GIS Specialist Padilla Bay National Estuarine Research Reserve [email protected] | (360) 428-1092