Sediment Transport off Northeast Florida Outside the Surf Zone during Hurricanes

The highly active Atlantic Ocean hurricane seasons of 2004 and 2005 produced unique morphological changes outside of the surf zone. This paper focuses on two northeast Florida areas — St. Johns County and Volusia County. These morphological changes, as determined by bathymetric surveys, revealed net sediment accretion in greater than 30-foot water depths after the 2004 storms just offshore of the St. Johns County Shore Protection Project and net sediment erosion on sand shoals located in 60-foot water depths, about seven miles offshore of Volusia County after the 2005 storms. Analyses of beach profiles and borrow area survey data revealed significant sediment transport at large depths, greater than those associated with typical wave conditions. Application of depth of closure and near bottom velocity methods showed wave conditions in 2004 and 2005 capable of sediment transport at these large depths.