Long Island Sound waves

Work done by the wind blowing over the surface of Long Island Sound is used to generate waves, to set the surface layer of water in motion. 

Fig. 2. Maximum horizontal particle speed at the bottom in water of depth

The part of the bottom of Long Island Sound that is expected to be directly affected by wind-raised waves is generally that on the shoreward... 

Waves cause significant water velocities over the bottom of Long Island Sound within a wave-affected zone that is confined to a shoreside area where the water depth is less than 18 m. Wind-driven currents occur only in the upper third of the water column throughout the deep water of the Sound. The tide is the dominant source of power for bottom pro-... 

Erosion of the shore under attack of waves is sufficiently rapid at many places around Long Island Sound to be a matter of concern in the management of shoreside property. The nature of the materials which constitute the Long Island Sound shoreline is summarized in Table II. Silt-clay material that may be released upon erosion is present in the stratified drift, the interglacial deposits, and end moraines. End moraines account for only 17% of the erodible shoreline and this percentage has... 

The specific dissipation due to wave power is strongly dependent on water depth and, therefore, will have sharply defined bounds in most estuaries. It Is determined by the depth, the available fetch, and the intensity of the winds having sufficient duration to raise a fully developed sea. For Long Island Sound the wave-dominated zone is that in water shallower than 18 m this constitutes 54% of the total area of the Sound. Within the wave-dominated zone the particle motion due to waves at the water surface is more effective in exciting sediment from the bottom than other causes of water movement. Large quantities of sediment may be set in motion by the waves and relatively small currents can then effect substantial transport of the material so excited. An example of an estuary in which wave-excited sediment is an important fraction of the total sediment available for estuarine processes is the Tay, where wave erosion followed by overland flow on bare mudflats exposed on the ebb of the tide results in large sediment concentrations in the water of the estuary (Buller et al., 1975). 

Long Island Sound wind-driven water movements of local origin do not influence the water flow over the deeper parts where the deposits of muddy sediment are located. Their effects in the wave-affected zone have not been investigated. 

Salt marshes are a common feature of the Long Island Sound coast. Where they remain protected from wave erosion their surface is an index of high tide. If coastal submergence occurs over time, as has been the case in New England for at least the last 100 years, the protected marsh grows upward to maintain its surface at high tide and provides a record of previous environmental conditions. The surface of a marsh is exposed to the atmosphere most of the time. The highest point of the tidal cycle immerses the surface only about 5% of the time. 

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