Numerical Simulation of Sediment Pathways at an Idealized Inlet and EBB Shoal
ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
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Bypassing at inlets can occur across the ebb shoal, through tidal exchange, and by episodic collapse of shoals. To examine ebb-shoal and tidal exchange bypassing in a systematic way, we investigated sediment pathways at an idealized inlet with a coupled tide, wave, and sediment transport-morphology change numerical modeling system. The idealized inlet, ebb shoal, and channel were devised to test the coupled modeling system and isolate sediment transport pathways driven by wave and tidal forcing. The inlet, channel, ebb shoal, and bay dimensions approximate those of Shinnecock Inlet, New York. Five simulations consisting of tide forcing, wave forcing fair-weather and storm, and combined tide and wave forcing were conducted. Patterns of calculated morphology change followed those found in nature. Simulations with waves impounded sand against the updrift jetty and eroded the bottom in the nearshore area on the downdrift side of the inlet. Wave breaking on the ebb shoal primarily moved material updrift, but also flattened the shoal by eroding the top and depositing material around its perimeter. For the forcing conditions examined, waves were the dominant transport mechanism. Tidal currents modified the morphology change primarily at the inlet entrance and on the updrift side of the ebb shoal by opposing the current during the flood tide.
- Hydrology, Limnology and Potamology