Maryland Coastal Resiliency Assessment
The Maryland Department of Natural Resources recognizes that the presence of natural features such as marshes and coastal forests can reduce the impact of inundation and erosion on the state’s coastal communities. These habitats dampen waves, stabilize sediment, and absorb water, thereby providing residents with more time to select and implement other adaptation strategies. To better understand the resiliency benefits of existing natural features, the Department partnered with The Nature Conservancy to conduct a Coastal Resiliency Assessment. The Assessment evaluates shoreline hazards, investigates coastal community flood risk, and identifies where coastal habitats are providing the greatest protection to residents.
In October 2012, Hurricane Sandy made landfall on the East Coast. The resulting storm surge devastated coastal populations from North Carolina through Maine, with more than $41 million in damages estimated throughout Maryland. Although Maryland was not the most hard-hit among those states affected, much debate surrounded the impacts of the next hurricane, tropical storm, or Nor’easter, especially since sea level rise is expected to exacerbate flooding and erosion impacts.
The Maryland Department of Natural Resources (DNR) is invested in understanding the state’s vulnerability to coastal hazards and acting to mitigate impacts to people, natural resources, public lands, and investments. In fact, the Department has the lead role among state agencies in advancing the scientific understanding of Maryland’s vulnerability to climate change, and in advocating for sound planning to avoid or minimize anticipated impacts. Furthermore, Maryland is a signatory to the 2014 Chesapeake Bay Watershed Agreement, which established a Climate Resiliency Goal to increase the resilience of the Chesapeake Bay watershed, including its living resources, habitats, public infrastructure, and communities, in order to withstand adverse impacts from changing environmental and climate conditions. One means of meeting this goal is through the pursuit, design, and construction of restoration and protection projects.
While DNR utilizes various tools to target restoration and protection based on ecological, water quality, and other criteria, these tools do not consider the risk-reduction benefits of natural features for nearby coastal communities. DNR partnered with The Nature Conservancy to develop the Statewide Coastal Resiliency Assessment to fill this information gap and facilitate proactive natural solutions to enhance the resilience of its coastal communities. Funding for this project was provided by the National Oceanic and Atmospheric Administration’s Office for Coastal Management through DNR’s Chesapeake & Coastal Service. Along with The Nature Conservancy, DNR worked closely with the Natural Capital Project, U.S. Army Corps of Engineers, and a group of state, federal and non-profit partners to develop the assessment. Work is now underway to disseminate the results and train partners on how to apply Maryland’s resiliency data to programs, projects, and natural resource conservation and enhancement efforts.
Maryland’s Coastal Resiliency Assessment was completed to evaluate the risk reduction benefits of existing natural features and identify areas where conservation and restoration will enhance the resiliency of coastal communities. The project team was composed of staff from The Nature Conservancy and DNR’s Chesapeake & Coastal Service, and was informed by a steering committee consisting of 25 staff from three state agencies, two federal agencies, and three non-profit organizations. The steering committee met quarterly to inform model development and ensure that products of the assessment were applicable and relevant to current decision-making processes. An additional 29 advisors provided guidance on particular model components and feedback on draft results.
The Assessment consisted of a natural features analysis and a community flood risk analysis, both of which were used to identify priority shoreline areas for conservation and restoration activities.
To conduct the natural features analysis, the project team applied the InVEST Coastal Vulnerability Model developed by Natural Capital Project to Maryland’s coastline at a 250-meter scale. The model evaluated relative exposure to coastal hazard impacts (i.e. inundation and erosion) and the relative role habitats play in reducing said exposure. Maryland habitats of interest included coastal forests, tidal wetlands and marshes, oyster reefs, submerged aquatic vegetation, and dunes. To evaluate natural feature complexes that extend inland, the project team also modified The Nature Conservancy’s Marsh Protection Potential Index framework to rank existing marshes by their ability to protect people from coastal hazards.
To conduct the community flood risk analysis, the project team modified and applied a risk framework developed by the Army Corps of Engineers for the 2015 North Atlantic Coast Comprehensive Study. The analysis ranked residential land use from low to high risk at a 30-meter scale across the study area. Population density, social vulnerability, and probability of exposure to a flood event were considered in risk rankings.
Priority Shoreline Areas were identified where habitats play a high role in hazard reduction and are adjacent to community flood risk areas. Coastal habitats were found to play a significant role along 22% of Maryland’s shoreline, with coastal forests and tidal marshes providing the most benefit in terms of risk reduction.
Outcomes and Conclusions
The Assessment resulted in the creation of five data layers to inform resiliency focused projects, which are available on Maryland’s Coastal Atlas - the state's coastal data viewing platform.
- The Shoreline Hazard Index identifies high, moderate, and low hazard shorelines based on six physical and shoreline characteristics.
- The Habitat Role in Hazard Reduction data identifies where shorelines play a high, moderate, low, or nonexistent role in hazard reduction.
- The Community Flood Risk Areas identify and rank residential areas from low to high risk. The metrics of population density, age, income, language proficiency, and probability of exposure were used to evaluate the ability of a community to prepare for, respond to, and recover from a coastal hazard event.
- The Priority Shoreline Areas identify where habitats have the potential to play a high or moderate role in risk reduction for coastal communities.
- The Marsh Protection Potential Index ranks the potential of existing marshes to protect coastal communities based on marsh size, proximity to hazards, proximity to residential areas, proximity to other coastal habitats, and the likelihood that the marsh will persist into the year 2100.
These resiliency data layers are being integrated into decision-making at DNR so that risk reduction is considered when evaluating parcels for conservation or restoration opportunities. DNR also offers trainings on the use and application of these products to other state agencies and partners.
Some of the key findings include:
- Coastal habitats can reduce flooding and erosion impacts, with forests and wetlands playing the greatest roles. These areas significantly protect 22% of Maryland’s shoreline.
- Marshes play a particularly important role in risk-reduction along the Tangier Sound in Somerset County, and the Assawoman Bay and Isle of Wight Bay shorelines in Worcester County.
- The majority of high-risk exposure occurs along the Lower Eastern Shore (Dorchester, Somerset, and Worcester counties).
- Shoreline hardening, transportation infrastructure, and development prevents habitat from playing a role in protection, most notably on the Western Shore. Hybrid approaches, such as living shorelines that incorporate structural components, may be more appropriate in these areas.
Carlozo, N. 2016. Maryland Coastal Resiliency Assessment. Ed. Rachel M. Gregg [Case study on a project of the Maryland Department of Natural Resources]. Retrieved from CAKE: http://www.cakex.org/case-studies/maryland-coastal-resiliency-assessment (Last updated October 2016)