Study Objective
The stability in location and in cross-sectional channel area of coastal inlets is of
central interest for the operation and maintenance of navigation channels, as well as for
understanding the interaction of inlets and beaches. The control of coarse sediment
(gravel) on inlet morphology and hydrodynamics is also of scientific and engineering
interest. In an effort to improve understanding of tidal inlet stability, this study was
undertaken at two Long Island, NY, north shore inlets, Mattituck Inlet and Goldsmith
Inlet.
The study covers review of the literature, compilation and analysis of historic New
York District survey records, site visits, short-term measurements of water level and
current, bathymetric surveys, sediment sampling, bathymetry change and aerial
photography analysis, mathematical analysis, and numerical modeling. In support of this
study, a bathymetric survey of both inlets was made in October 2002, together with
limited measurements of the water level and current. The acquired process data, together
with previous measurements, modeling, and morphologic analysis, allow examination of
the stability of the subject inlets.
Figure 1-7. Goldsmith Inlet with view northeast into Long Island Sound, showing
substantial gravel and cobble, 22 March 2003
The objective of this study is to improve understanding of the factors that contribute
to the stability of channel cross-sectional area and location and orientation for small inlets
that may in part be controlled by the presence of coarse sediment. The morphology and
morphology change at Mattituck Inlet and Goldsmith Inlet are explored through
comparisons of channel cross sections and beach profiles and by generating topographic
difference maps for Mattituck Inlet. Morphologic analysis identifies areas of erosion and
deposition, while yielding information on sediment bypassing and ebb and flood shoal
formation. Waves and currents combine to form the longshore current, the predominant
mechanism of coastal sediment transport. Numerical modeling of the tidal
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Chapter 1 Introduction
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