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Hazard Information

NCCOHAZ has identified three major hazards - Storm Surge, Inlet Opening, and Shoreline Erosion - that have the potential to cause extensive damage to human and natural systems along the North Carolina coastline. Theses hazards often are be caused by episodic extreme events such as hurricanes, tropical storms, and mid-latitude cyclones (nor'easters). Sea level rise is an on-going longer term process that amplifies the potential for storm surge, inlet opening, and shoreline erosion.

1. Storm Surge

NOAA's Hurricane Preparedness web site defines storm surge as "simply water that is pushed toward the shore by the force of the winds swirling around the storm. This advancing surge combines with the normal tides to create the hurricane storm tide, which can increase the mean water level 15 feet or more. In addition, wind driven waves are superimposed on the storm tide. This rise in water level can cause severe flooding in coastal areas, particularly when the storm tide coincides with the normal high tides. Because much of the United State's densely populated Atlantic and Gulf Coast coastlines lie less than 10 feet above mean sea level, the danger from storm tides is tremendous." For More information on storm surge see this NOAA Storm Surge site.

Below is an image of storm surge impacts from Hurricane Katrina.


2. Inlet Opening

Inlets can open during severe storms and fragment narrow barrier islands. Inlet opening is especially pertinent for the Outer Banks of North Carolina due to narrow island widths and low elevations. New and suddenly formed inlets pose real challenges to the region's economy due to it heavy dependence on tourist inflows which are channeled down Highway 12, the only road providing access to southern Outer Banks destinations such as Rodanthe, Buxton, Frisco, and Hatteras. It also can disrupt daily lives of permanent residents and cut off local populations from needed services. For example, a new inlet resulting from Hurricane Isabel in 2003 temporarily prevented school children in Hatteras from attending the region's only high school located in Buxton just a few miles away along Highway 12. Fortunately, a fleet of boats from the local commercial and recreational fishing communities lent a hand to transport both students and other residents around the breach until the highway was repaired.

Below is an image of the inlet formed by Hurricane Isabel in 2003. See maps of Inlet Opening Potential and Previously Formed Inlets.


3. Shorline Erosion

Shoreline erosion (or beach erosion) occurs when waves and currents remove sand from the beach system. Shoreline erosion can be characterized as either: (a) seasonal, (b) chronic, or (c) acute. Seasonal erosion along North Carolina's coast is most active during the winter months when higher energy waves impact the shoreline and transport sand offshore depositing it into sand bars. Gentler waves that prevail during the summer season transport sand located offshore back onto the beach. Chronic erosion occurs simultaneously with seasonal erosion and is linked to sea level rise. Given that sea level rise is a slow and ongoing process that occurs over decadal time scales and longer, this type of erosion can be considered chronic. Extreme storm events cause acute erosion. These are short duration events like hurricanes or nor'easters that can remove large volumes of sand resulting in shoreline erosion on the order of tens of feet within just a few hours.

Below is an image suggesting shoreline erosion caused by Hurricane Dennis' impact along the Outer Banks in 1999. See maps of Coastal Erosion.