ERDC/CHL CHETN-II-47
March 2004
Figure 14. Location of three hot spots at Folly Beach, SC, fill project (courtesy of Paul Gayes,
Coastal Carolina University)
A second hot spot was located around the Holiday Inn in the center of the island. The hotel seawall
encroached seaward of the adjacent shoreline and the design berm width wrapped seaward around
the two-block-long seawall. As the fill readjusted to the coastal processes, fill material in front of the
seawall was removed. The cause of this "perceived" hot spot was infrastructure encroachment on the
active beach.
A third hot spot was associated with the area of fill located just north of Stono Inlet at the south end
of the island. This downdrift terminal end of the project lost fill sand due to both inlet processes and
end effects. Sand from the beach is suspected to be transported into the inlet flood and ebb shoal area
and then downcoast by the net southerly transport.
The behavior of the fill was measured by change in beach contours and their movement relative to
the pre-fill conditions. An examination of sidescan survey data indicated complex nearshore geology
(Figure 15). Data and interpretation on this project was also provided by Paul T. Gayes, Center for
Marine and Wetland Studies, Coastal Carolina University. Over time, the bathymetric contours
moved offshore indicating seaward transport of sand over the project area. A longshore transport
drift reversal is indicated at the north end of the island toward Lighthouse Inlet. Consequently, the
"washout" area acts as a source of sand to both the north and south beaches and also to the offshore.
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