ERDC/CHL CHETN-II-44
September 2001
a) April 1983
b) April 1995
Figure 9. Shoreline undulation at Fire Island, Long Island, NY (Gravens 1999)
Isolation of Beach from Longshore Transport Inputs: Beaches located between the
downdrift jetty of an inlet and the attachment bar may become isolated from significant sediment
inputs. As depicted in Figure 10, sand from the predominant transport direction will bypass the
beach and continue downdrift, whereas the large attachment bar will tend to act as a groin and
block sand from reaching the beach during transport reversals. At the beach, sand can move
alongshore and toward the attachment bar or toward the jetty. Offshore transport during storms
and loss of material into the navigation channel by a rip current near the jetty also removes sand.
The beach thus tends to lose more sand than it can gain. A solution is placement of composite
structures to hold the local beach (Hanson and Kraus 2001).
Figure 10. West side of Shinnecock Inlet, Long Island, NY,
26 October 1996
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