Developing a Coastal Resilience Assessment for the Cape Fear River Basin
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Posted byRachel Gregg
Coastal communities are highly vulnerable to storm surge, coastal erosion, flooding, and impaired water quality from sea level rise and increased frequency and severity of storms. To understand potential exposure to these hazards across the coastal landscape, the University of North Carolina- Asheville’s National Environmental Modeling and Analysis Center (NEMAC) teamed with the National Fish and Wildlife Foundation (NFWF) to develop a coastal resilience assessment framework. The resulting framework identifies areas with the greatest potential to boost community resilience to climate change while also improving fish and wildlife habitats. The pilot area for the tool’s development focused on the Cape Fear River Basin in North Carolina, and has since been refined for use in all U.S. coastal states, territories, and commonwealths, making it a national model for understanding hazard exposure in coastal watersheds.
NEMAC and NFWF partnered to develop a tool that could be applied at the watershed level for planning for sea level rise, storm surge, and flooding impacts. The Coastal Resilience Evaluation and Siting Tool (CREST) identifies areas that may achieve the dual goals of increasing community and ecosystem resilience to climate change. Using nationwide standardized datasets, the tool integrates spatial analyses and modeling to identify areas of exposure to severe storm and flooding events. Communities can use the tool as a first step in developing a risk or vulnerability assessment to prioritize effective adaptation planning. NEMAC developed a rapid prototype for the Cape Fear River Basin watershed with input from experts and modelers within the watershed. Based on the success of the Cape Fear prototype, NEMAC and NFWF developed a national model for coastal watershed resilience planning.
In developing CREST, NEMAC focused on the concept of exposure as defined by the presence of a community asset impacted by a threat. To identify places where assets are most exposed to sea level rise and flooding hazards, two models were created—a Threat Index and a Community Asset Index. Datasets for the models were selected considering factors that might affect a community’s capacity to respond and adjust to a threat or stressor. Inputs for the Threat Index included sea level rise and storm surge scenarios (National Oceanic and Atmospheric Administration climate models); flood-prone areas (Federal Emergency Management Agency flood maps); and soils with poor drainage potential, soils with high erodibility potential, areas of low slope, and land subsidence data (U.S. Geological Survey datasets). Community assets included residents, buildings, and infrastructure. For example, in the Cape Fear River Basin, the data for the Community Asset Index included population density, impervious surfaces, and critical facilities and infrastructure, such as dams and water treatment facilities. To incorporate local knowledge on community assets, particularly infrastructure such as dams, NEMAC ran watershed workshops to gather local knowledge about asset types and locations. The most exposed areas are defined as those with the highest presence of threats and the highest presence of valued community assets.
These indices have since been refined to create the Regional Coastal Resilience Assessment methodology, developed by NEMAC, NFWF, and NOAA. These assessments use a Community Exposure Index (a combination of the Threat Index and Community Asset Index) and a Fish and Wildlife Index to identify Resilience Hubs or areas where nature-based solutions can best be implemented to protect human communities and natural habitats. The CREST website displays the results of the Regional Coastal Resilience Assessments to help users identify potential locations for nature-based projects.
Outcomes and Conclusions
CREST was originally designed for NFWF staff to determine priorities for funding coastal resilience projects to benefit human communities and protect critical fish and wildlife habitat. As the tool was first developed, the overall project goal was building resilience across the landscape. Given interest by coastal communities, the tool has been refined to also help planners and decision-makers consider parcel-level exposure to hazards. CREST is not intended to supplant, but rather complement, ongoing state and community-level coastal restoration and protection projects. CREST can now be used by conservation organizations and municipalities to identify areas where they can achieve multiple community resilience and conservation outcomes and maximize return on investment in climate adaptation projects. Moving forward, there is a need to: (1) increase usability for additional stakeholders, including state agencies, municipalities, and conservation organizations, and (2) refine the process of cumulative exposure assessment to break out single hazard impacts in specific areas based on community needs (e.g., AccelAdapt Tool).
Through this process, NEMAC has learned that communities and individuals do not have to buy into the underlying causes of coastal climate impacts to agree on the need to take action, and not all communities are ready to act even when they have been given all the relevant exposure information. In some instances, communities are surprised at the results. For example, communities may have initially thought that sea level rise posed the greatest and most imminent threat, but through the CREST process, they learned that flooding from heavy precipitation events may affect a greater number of assets within an earlier timeframe.
Sims, S.A. and R.M. Gregg. (2021). Developing a Coastal Resilience Assessment for the Cape Fear River Basin [Case study of a project of National Environmental Modeling and Analysis Center, UNC Asheville]. Product of EcoAdapt’s State of Adaptation Program. Retrieved from CAKE: https://www.cakex.org/case-studies/developing-coastal-resilience-assessment-cape-fear-river-basin (Last updated October 2021)