Understanding Coastal Storm Surge

On average, the United States' densely populated Atlantic and Gulf Coast lie less than 10 feet above mean sea level and are vulnerable to coastal storm surge and associated surge damages. Coastal storm surge is the onshore rush of sea or lake water caused by the high wind and the low pressure centers associated with a landfalling hurricane or other intense storm. In particular, residents of and property within the 100-year coastal flood hazard area are at tremendous risk from this coastal hazard. Storm surge acts like a bulldozer sweeping away everything in its path and flooding low lying areas. The stronger the hurricane the larger the storm surge will be.

The amplitude of the storm surge at any given location is dependent upon the orientation of the coastline with the storm track; the intensity, size, and speed of the storm; and the local bathymetry. The inland reach or inundation caused by a storm surge is influenced by the slope of the continental shelf and shoreline elevation. A shallow sloping coastline will allow the storm surge to inundate coastal communities. Communities developed on a steeper coastline will not see as much surge inundation, although large breaking waves can still present a major problem.

Understanding storm surge is essential in making decisions about coastal development and planning evacuation routes as a hurricane approaches. Modeling is one technique used to evaluate the threat from a potential storm surge as well as to determine areas that need to be evacuated during an intense storm. Several models exist to evaluate storm surge. The animation below represents one example of how modeling is used to evaluate the potential maximum surge for Norfolk, Virginia.

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Hypothetical indundation (resulting from either coastal storm surge or sea level rise) in Norfolk, VA. Credit: NGS, NOAA

Shallow Sloping Coastline

Hypothetical shallow sloping coastline and potential reach of storm surge.
Steep Sloping CoastlineHypothetical steep sloping coastline and potential reach of storm surge.

For more information:

What is the difference between Storm Surge and Storm Tide?

Hurricane Preparedness, Storm Surge

NOAA Climate Storm Surge Education