Carolina Environmental Diversity Explorations
Hurricanes on sandy shorelines · By Dirk Frankenberg
Hurricane storm surges
Figure 2 illustrates just how high hurricane storm surges can get along the gently sloping shorefaces of the southeastern United States. The photograph is of an exhibit at the North Carolina Aquarium at Fort Fisher. The exhibit stands 6.5 feet above mean sea level, and the wavy lines across it record the height of known hurricane storm surges. At the top is the line for Hurricane Camille, which came ashore in Mississippi in 1969 with a surge 25 feet above sea level. The next wavy line records the same information for Hurricane Hugo at McClellanville, South Carolina, in l989 with a 20-foot surge.
The exhibit can’t show it, but these huge surges rose up in less than six hours as the storms made landfall. Storm surges of the magnitude shown on this exhibit occur only in places where the offshore sea floor is shallow and gently sloping. Such geometry gives the oncoming storm surge no place to go but up. In places where offshore waters are deep, the storm surge can drain back to sea along the seafloor rather than rise up to the heights shown in the exhibit.