To appear: Shore & Beach, Vol 72, No. 1, 2004.
portion of the analysis used photographs from the following years: 1940, 1983,
1988, 1995, and 2000. The 1940 data set served as the beginning point for
comparisons with later aerial survey dates. Figure 6 compares the configuration
of barrier island morphology near Fire Island Inlet between 1940 and 2000. Due
to construction of the Democrat Point Jetty, construction of the sand dike and
extensive dredging of inlet shoals the entrance to the inlet entrance has shifted
south by approximately 1,600 ft and narrowed by 200 ft (Figure 6).
Prior to 1939, Democrat Point was rapidly migrating westward, Fire Island
Inlet channel was lengthening, and Oak Beach to the north and the east end of
Cedar Beach were under erosion pressure from strong tidal currents within the
inlet-barrier overlap area (Figure 4). However the west end of Cedar Beach and
Gilgo Beach to the west of the inlet were wide and not directly impacted by
erosion by tidal currents of the overlap zone.
Jetty construction at Democrat Point began in June 1939 and was
completed in April 1941 (Gofseyeff, 1952).
The jetty halted the westward
migration of Fire Island, but soon excess sand began washing around the tip of
the jetty. Spit formation began to occur on the western side of the jetty and Oak
Beach and downdrift areas began to erode at a greater rate than before jetty
placement. The sand dike constructed in 1959 was designed to divert strong
tidal currents away from Oak Beach. As early as January 1960, Cedar Beach
began to experience build-up of sediment around the dike. During the 1960's,
the dike was able to capture some of the sediments that had accumulated
around the jetty and sediment began to fill in a zone extending approximately
10,000 ft to the west of the dike. During the 1970's and 1980's, shoaling around
the dike area continued, and it became evident that the shoal near the dike had
begun to align itself with the rest of the shoreline. However, the massive spit
accretion in the vicinity of Democrat Point Jetty and trapping of sand within the
inlet shoal system had become a considerable problem for navigation and sand
bypassing to Cedar Beach and Gilgo Beach to the west.
Since the 1960's, the sediment-starved downdrift areas of Cedar and
Gilgo Beach have been maintained by a combination of sand buildup around the
6
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