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Table 1. Summary of Net Longshore Sediment Transport Estimates (thousands m /yr)
Location
Previous Studies
This Study
Regional
Democra
Taney
RPI
Kana
Impound-
(1961a,b) (1983) (1995)
Sediment
t Pt.
ment at Jetty
Budget
Growth
(1940 to
(1955 to 1979)
(~ 1979 to
(1870 to
1954)
1995)
1938)
a
c
c
West of Montauk Pt.
76.5
72.6
58
-
-
94+40
(8 km)
East of Shinnecock
-
233
219
-
-
115+40
Inlet (approx 2-3 km)
West of Shinnecock
-
187
104
-
-
45+40
Inlet (approx 2-3 km)
West of Groin Field
-
99
-85
-
-
-1+40
b
East of Moriches Inlet
230
140
45
-
-
29+40
(approx 2-3 km)
West of Moriches Inlet -
123
76
-
-
52+40
(approx 2-3 km)
e
e
East of Fire Island
-
106
150
-
159 to
172+40
Inlet (approx 14.1 km)
238
d
East of Fire Island
122 to
306
467
-
-
194+40
b
Inlet (approx 2-3 km)
460 ;
b
f
344
240
360
385
-
176+40
Fire Island East Jetty
" est"
b
a
Estimated.
b
Assumed net LST.
c
Profile data unavailable; based on Leatherman and Joneja (1980) shoreline position data.
d
Net LST rate was assumed based on impoundment; all other cells derived from this value.
e
Based on interpolation across cell 153A (see RPI 1983, Kana 1995).
f
Considered a high estimate of the net LST.
Taney (1961a,b). Taney presents one of the earliest studies discussing littoral transport
processes for the south shore of Long Island, providing geomorphic support for the
predominant east-to-west net LST direction. However, he mentions a reversal in the net LST
immediately west of Fire Island Inlet, along Gilgo Beach, due to tidal currents and wave
refraction on the shoal at the mouth of the inlet. He emphasizes that the littoral drift rate
varies with distance alongshore. LST rate estimates are presented based on the migration of
inlets prior to stabilization, impoundment at jetties east of the inlets after stabilization, and
consideration of inlet dredging records (Table 1). The first method is considered more
accurate, due to the fact that the second method cannot account for the quantity of sediment
that bypasses the inlet or is lost to the flood or ebb shoals. Taney concludes, "the present rate
of littoral drift is much greater than can be derived from this source" (the Montauk Point
bluffs). "Streams do not contribute sediments to the system." "Therefore, the great
difference between the estimates of the amount of sediments moving and that supplied by the
bluff unit of the headlands section would indicate that a source of beach material in addition
to the bluffs is required. It appears that the only remaining sources of supply of littoral
materials are the existing beaches, and possibly a small portion of the nearshore bottom."
RPI (1983). RPI formulated a regional sediment budget based on profile data from June
1955 to December 1979 to represent "typical" long-term conditions for the study area. In the
alongshore direction, 25 fixed compartments were established based on the availability of
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Rosati et al.
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