Coastal Hazards Overlay District Guide: Creating More Resilient Communities
The Coastal Hazards Overlay Guidebook from North Carolina State University, published January 2025, provides a framework to help design and integrate a coastal hazards overlay district into existing local codes and standards in order to guide resilience efforts and requirements within geographically defined areas. An overlay district applies additional regulations to a geographic area with underlying zoning standards. Multiple overlays may be added to a base zoning code to address particular land use concerns. The guide provides recommendations specific to creating coastal hazard overlays and is intended primarily for local government officials who would be responsible for designing and overseeing the use of an overlay district, such as planners, attorneys, or other city staff. This guidebook offers flexibility by proposing a range of resilience-building land use strategies that can be combined to make a locally-specific set of requirements for overlay districts.
Guidebook Components
An overlay district applies two or more complementary data sources (such as sea-level rise modelling and future coastal development plans) to map and establish standards based on local risk. These maps can be used to create categories (low, medium, and high) of hazardous conditions to guide development and planning. The Coastal Hazards Overlay District Guidebook presents this method for shoreline, tidal, and riverine conditions, though overlay districts can be used to address risks related to other environmental conditions as well. The guide features:
- Guidelines on Coastal Hazard Overlay District development
- Terms and definitions
- Design standards and techniques
- Case studies
- Recommendations
- Graphics illustrating strategies
Other resources within the guide include process diagrams, checklists, matrices of design strategies, and over 50 design and planning techniques.
Strategies and Recommendations
The coastal hazards overlay concept aims to put forward community planning and design guidelines that encourage resilience to coastal hazards. The guide outlines risk-reduction strategies for coastal communities that can be combined for various conditions. The strategies are divided into community-led relocation, avoid, protect, accommodate, and hybrid categories. One particularly relevant consideration for how these strategies may be combined is the type of zoning – use-based (Euclidian) or form-based. Use-based zoning classifies districts based on their allowable uses, such as residential or commercial developments. Form-based zoning defines zones based on their physical components (e.g., building sizes and heights) and is related to the New Urbanism concept.
As an example of the coastal hazard overlay application, the guidebook details a case study on the Flood Resilience Overlay District (FROD) from Boston, MA’s comprehensive plan. The FROD combines current flood risks (the currently-defined 100-year floodplain) and future flood risks (the projected 100-year floodplain in 2070 with 40 inches of sea-level rise). These combined layers are used to identify priority neighborhoods, such as Charlestown. The Charlestown plan incorporated the FROD data to determine appropriate strategies to address current and future flood risk, such as dry and wet floodproofing, protecting critical infrastructure, and elevating buildings above the Base Flood Elevation.
As in the Boston example, the authors suggest that these strategies can be combined after assessing current and future hazards, defining the overlay district goals and boundaries, and studying existing policies, plans, and programs. Once the overlay district is adopted and implemented, it should be regularly monitored and updated. Other case studies feature examples from Carmel by-the-Sea, CA, Christchurch, NZ, Moreton Bay, AUS, Hampton, VA, Miami/Dade County, FL, Newtok, AK, Norfolk, VA, Pass Christian, MS, Port Aransas, TX, Tillamook, OR, and Washington, DC.
Guidebook Development
The Guidebook was developed by researchers at North Carolina State University in partnership with Unabridged Architecture, Mississippi State Gulf Coast Community Design Studio, the Center for Applied Transect Studies, and DPZ CoDESIGN. The work was sponsored by the Department of Homeland Security Office of University Programs and FEMA. A previous academic article in Landscape Journal by the Guidebook authors, titled “New Urbanism and the Hazard Transect Overlay District: Improving the Integration of Disaster Resilience and Design in Coastal Areas” (Smith, Anderson and Perkes, 2021), outlined the ideas that are implemented within the guide. The Guidebook ground-truths the overlay method in three pilot communities in the Gulf Coast (Biloxi, MS, Pass Christian, MS, and Mobile, AL), and compares the outcomes to a community in New Zealand. The pilot communities went through planning workshops with the research team to gather information on local environmental, social, and political conditions that would impact implementation of the districts.
Publication Date: January 2025
Authors or Affiliated Users:
- Gavin Smith
- Chitali Biswas
Related Organizations:
- North Carolina State University
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Resource Types:
- Best practice
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