Barrier Beaches

Barrier Beaches are narrow and elongate beaches situated parallel to the shoreline. By definition, the beach provides a barrier between the mainland and adjacent nearshore wetland, such as a salt marsh or mudflat and marine waters offshore. Barrier beach systems are comprised of several distinctive topographic elements: the beach and dune complex, (which will be described in detailed below), tidal inlets, and wetlands such as mudflats or salt marsh. Classic barrier beaches occur along the length of the Atlantic Coastal Plain. In contrast to the extensive barrier beach systems of, for instance, the Outer Banks of North Carolina, the beaches in Maine are significantly shorter, framed by the bedrock topography. Ogunquit Beach, Wells Beach and Seawall Beach are fine examples of barrier beaches in Maine. The image below (from Reinson, 1984) shows the various elements of a barrier beach complex.



Beach Zonation
 The profile of the sand beach consists of three zones: (1) the backshore which extends from the high tide limit landward to the dune, (2) the foreshore or the intertidal zone, and (3) the nearshore, which is the low tide level and seaward to the offshore bars. A major element of the backshore is the landward-sloping berm. The berm is generally flat and ends seaward at the berm crest. The berm is the area of the beach most often used for recreation on the beach during low and high tide.


Sand Transport in Barrier Beaches
In a natural barrier beach system the primary process of sediment distribution is longshore transport. In longshore transport, waves breaking on shore carry sand parallel to the coast helping to create the elongate form of the barrier beach. http://pubs.usgs.gov/circ/c1075/change.html. This phenomenon is exhibited in extensive beaches along the Atlantic coastal plain.
Sediment transport in barrier beaches relies heavily on the morphology of the beach and what is referred to as "wave climate" which includes wave height and period (time between waves). These factors can vary seasonally or during storms.
When the natural processes of a beach are impeded by man-made structures or ‘solid stabilization’, the sedimentation processes are disrupted. To learn more about sedimentation patterns of beaches in natural and unnatural settings check out this interactive website by the University of Kentucky.  https://ees.as.uky.edu/sites/default/files/elearning/module14swf.swf

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