DYNAMIC EQUILIBRIUM BEACH PROFILES: FORCES OF OFFSHORE SEDIMENT TRANSPORT IN MARYLAND’S CHESAPEAKE BAY
Bell, Lynda Jean
Sanford, Lawrence P.
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To examine the impact of shoreline erosion on the near shore environment, it is necessary to estimate the quantity and quality of yearly sediment mass that is likely to be added by erosion. Data were collected in 2008 at ten sites along the Maryland shoreline of the Chesapeake Bay and compared to both empirical and theoretical models of offshore profiles. The data collected at each site included a series of three-dimensional bathymetric profiles from offshore transects run at each site, as well as a series of sediment core data that were acquired along each transect. Relationships between grain size, beach type, sediment composition, and strength of eroding sediments were also explored. The results showed that sands dominated offshore surficial sediments at most locations, even though the source sediments were mixtures of sands and muds. The observed offshore profiles were consistent with expectation from ocean beach profile paradigms, with the exception that the steepness proportionality factor was not related to sediment grain size. An adjusted form of the classic Bruun relationship for predicting shoreline retreat was in approximate agreement with long-term observations.