City of Tybee Island, Georgia, Sea-Level Rise Adaptation Plan

Tybee Island is a barrier island located 18 miles away from Savannah, Georgia - accessible only by a single causeway. The Tybee Island Sea-Level Rise Adaptation Plan identifies how more frequent coastal flooding and sea-level rise could impact low-lying infrastructure on the island; and provides a synthesis of the public engagement processes, technical research, and sea-level rise adaptation strategies. The City of Tybee Island partnered with Georgia Sea Grant, the University of Georgia, and Stetson University to develop this sea-level rise adaptation plan.

According to the plan, some of the island’s most visible sea-level rise impacts over the next 50 years include:

Flooding of city well houses - in which drinking water and waste disposal could be limited or unavailable.

Tidal backup of storm water drainage systems in low-lying areas of Tybee Island, resulting in periodic saltwater flooding of neighborhood roads and yards.

Tidal flooding of US Highway 80, the only access to Tybee Island. Flooding is known to restrict accessibility to Tybee Island and poses clear risks to public safety, particularly through loss of emergency vehicle access and blockage of the City’s sole evacuation route.

Based upon the specific sea-level rise vulnerabilities facing the island, five potential local adaptation actions were selected by the community for consideration. (Cost-benefit analysis were conducted for these options which are detailed in the final chapter).

  1. Elevation of Municipal Well Pumps:  Elevating the first floor of the City’s well houses and electronic components to three feet above the 100-year floodplain.
  2. Elevation of US Highway 80: Elevating the US 80 causeway between Wilmington Island and Tybee Island to three feet above current grade.
  3. Stormwater Retrofits: Retrofits of low-lying stormwater infrastructure to prevent flooding from tidewater backflow.
  4. Building a Seawall: Construction of a back-island seawall, at a height of three feet over the current nuisance tidal flooding level, to prevent bank overflow in low-lying areas.
  5. Enhanced Beach Nourishment: Increased frequency of beach renourishment relative to increased sea-level rise out to 2060

To facilitate local decision-making, the project team developed a series of analyses to assess the relative benefits and costs of the selected adaptation options. Chapter 5 summarizes the technical approaches used to develop these benefit-cost analyses, and provides detailed results for each strategy.

In April 2016, the City Council unanimously voted to accept the report and is working to implement its recommendations.  The report also helped the City garner additional points under FEMA's Community Rating System (a subprogram of the National Flood Insurance Program that rewards communities that actively work to reduce their flood risks) and city flood insurance policyholders will enjoy a 25% discount on their flood insurance premiums as a result of the City's efforts to prepare for sea-level rise. 

The Tybee Island Sea-Level Rise Plan was included as a case study for sea-level rise adaptation by the U.S. Climate Resilience Toolkit. Also a recipient of NOAA Sea Grant’s 2014 National Superior Outreach Programming Award, the project has reached over 4,000 citizens, students, government officials, and scientists in its development.

 

 

Publication Date: April 17, 2016

Authors or Affiliated Users:

  • Jason M. Evans
  • Jill Gambill
  • Robin J. McDowell
  • P. Warwick Prichard
  • Charles S. Hopkinson

Related Organizations:

  • City of Tybee Island, Georgia

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  • Adaptation plan

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