Net onshore transport order 100 meters
If wave runup exceeds the elevation of the dune, or in the absence of a dune, the beach berm,
the system will be overtopped, transporting sand landward. This is a net change contributing
to the migration of the barrier island landward.
Impacts of the Overwash RegimeBelow are overwash deposits near Rodanthe, North Carolina, after Hurricane Dennis (1999). The sand was transported landward by wave runup overtopping the dune. In both photographs at right, wave runup overtopped the highest part of the system during a storm, resulting in net sand transport landward forming overwash fans.
Refer to the Hurricane Katrina web pages, for photographs and lidar images of hurricane-induced overwash on Dauphin Island, AL.
return to Storm Impact Scale | continue to Inundation Regime