TABLE 11-1 Storm-Surge Tidal Elevation Affecting the South Carolina Coast (1893-1979).

Storm Date

Area

Maximum Storm Tide (ft)

27-28 August 1893

St. Helena, Hilton Head

20

13 October 1893

Georgetown

13

25-26 September 1894

Charleston

10

2 October 1898

lower coast

14

27-28 August 1911

Charleston, Beaufort

12

11-15 August 1940

entire coast

13

17 September 1945

Parris Island

9

15 October 1947

Parris Island

9-12

15 October 1954

upper coast (Hazel)

17-18

9 July 1959

Bull Bay (Cindy)

10

29 September 1959

lower coast (Gracie)

8-9

4-5 September 1979

Charleston (David)

8-9

this relatively undeveloped area. In South Carolina a typical 100-year return rate storm surge is in the range of 13 to 15 ft (see FEMA Flood Insurance Rate Maps), certainly qualifying Hurricane Hugo as such an event. Little wave data was available, but offshore deep-water readings at NOAA (NDBC) stations indicated a maximum height of 28 ft (Meindl, written communication, 1990).

The average elevation of the low country in coastal South Carolina is about 10 ft above MSL. The outer barrier islands have lower average elevations, 5 ft or less, near the bayside. This means that most of the barrier surface, except for a few high spots, was totally under water during the height of the storm surge. The mainland in this area is all part of the low-lying coastal plain, which gently slopes up to an elevation of approximately 20 ft near U.S. Route 17 (see Figure 11-1). Driftlines of debris and floatables were found across this road just north of Bull Bay, indicating the landward extent of saltwater flooding. Actually, the best data acquired by FEMA for the determination of surge heights for the plotting of isolines across the flooded area were the many houses on the developed barrier islands and inland mainland area. Inside water marks are considered good sources of water elevation information, as the buildings act as stilling wells. There is an extensive amount of information on



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement