EXAMINING THE PHYSICAL AND ECONOMIC IMPACTS OF SEA-LEVEL RISE AT THE COMMUNITY LEVEL: HILTON HEAD ISLAND, SC

Hilton Head Island is a centerpiece of the South Carolina beach-based tourism industry which stands to suffer significant losses to infrastructure and ecosystems unless long-term adaptive planning is implemented. Significant challenges to enacting proactive legislation exist, such as imperceptions by the public, lack of a sense of urgency, and lack of high-quality, science-based projections of likely impacted areas. By combining high quality LIDAR based elevation data with parcel data provided by the county, a framework for action can be built.

A 5 ft resolution DEM based on a 2002 LIDAR flight of Beaufort County was used to derive 1 ft contour lines relative to NAVD88. Because MHW at Hilton Head is 3.75 ft, the 6 ft contour interval was used to estimate a sea-level rise scenario of 2.25 ft. Most projections for future sea level indicate that we will experience a rise of at least 2.25 ft by the end of the century. To highlight areas impacted, areas below 6 ft in elevation were overlain with both Beaufort County parcel data and 30 m resolution LandSat landcover data. Problem areas in the road network and impacted buildings were also identified.

Results estimate that 22% of Hilton Head Island will be inundated with water more than half the time given 2.25 ft of rise in sea level. One hundred percent of land parcels owned by the Town of Hilton Head (>900 acres) will be impacted and represent a wide variety of municipal services and infrastructure types. The largest land cover classes in areas of loss were dry mixed forest/woodland (1655 acres) and marsh/emergent wetland (1182 acres). Over 500 acres of urban lands were impacted by a 2.25 ft sea-level rise.