ERDC/CHL CHETN-II-44
September 2001
Comparison of Shoreline Change Rates:
Jones Beach Island, New York
14
West
12
Linear Trend Estimate (1835-1991)
Fire
10
Island
Post Inlet Rate (1941-1991)
Inlet
8
Jones Inlet
6
4
2
0
110
100
90
80
70
60
50
40
30
20
10
0
-2
-4
-6
-8
Transect Number
Figure 7. Shoreline change rates, Jones Beach Island, NY
Standing and Random Longshore Sand Waves:
Mecox Bay
Gravens (1999) documented undulations in the shoreline
(Figure 9) of Fire Island, Long Island, NY, that are fixed in
space, which might be thought of as standing waves, as
opposed to translatory LSWs (type 15). He developed a
methodology for describing their dynamics through an
independent-wave analysis, from which a root-mean-
square deviation in shoreline position at a fixed location
alongshore can be calculated. Gravens (1999) gave
recommendations to account for shoreline undulations in
beach-fill design. Understanding of the temporal and
spatial behavior of these in a beach-fill design allows
planners to make a decision to mediate or to wait and
accept the temporary recession. Increasing the volume of
the dune as a safeguard and/or placement of a sacrificial
berm in a fill are possible remediation measures. The
cause of shoreline undulations is unknown, but it is
hypothesized that seasonal wave direction and propagation
over irregular bathymetry may play a role.
Figure 8. Longshore sand waves west
of Mecox Bay, Long Island, NY (Photo-
graph courtesy of First Coastal Corp.)
12
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