A Case Study of Ebb Tidal Delta Equilibrium: Ocean City, Marylandby Steven G. Underwood, US Army Engineers Waterways, Experiment Station, United States,
Fred J. Anders, US Army Engineers Waterways, Experiment Station, United States,
Abstract: The inlet at Ocean City, Maryland was created by hurricane surge breaching of Fenwick Island Spit in 1933. Inlet stabilization was completed in 1934-1935. The inlet jetties have been held responsible for pronounced alteration of adjacent shorelines. Historically, rates of erosion along the Delmarva coastline averaged approximately 0.6 meters per year. Since jetty construction, erosion rates in excess of 10 meters per year have occurred on the downdrift shoreline of northern Assateague Island. Historical bathymetric charts depicting the shoreline prior to ebb tidal shoal formation immediately after jetty stabilization, and at periodic intervals to present day have been examined. Comparison of sediment samples from the ebb delta and updrift native beaches shows a uniformity of grain size. Core data were also used to evaluate delta thickness for calculation of shoal volume. The data suggest volume of the ebb tidal delta increased rapidly after jetty construction but has gradually tapered to present day as a state of equilibrium is approached. Natural sand bypassing could resume and slow northern Assateague Island's erosional rate to the historical rate of 0.6 meters per year.
Subject Headings: Ocean engineering | Tides | Case studies | Urban areas | Equilibrium | Islands | Shoreline | Jetties | Erosion | Inlets (waterway) | North America | Maryland | United States
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