Wind affects barrier coasts both directly, through sand transport, and indirectly, due to storm waves and surges.
On sandy barrier beaches, wind moves dried sand grains into ridges and hills, particularly if onshore winds predominate. Vegetation is critical to dune formation because sand-tolerant grasses trap grains and hold dunes together with their roots. Dunes serve a vital role in protecting inland areas from storm surges and wave attack. As a result, many communities require that buildings be erected behind the dunes or a certain distance (a setback) from an established coastline. If dunes are cut for roads or walkways, they become particularly vulnerable to erosion.
Dunes and storm surges—two wind-driven factors—contribute to the process of overwash, which extends a barrier landward. During storms with elevated water levels, storm surge and waves overtopping the dunes carry sand into the bay or lagoon behind the barrier, which results in the landward migration of the barrier over time.
Storm surges and waves, along with high winds, also breach barriers to create new inlets. Inlets are critical to navigation, and the flood-tidal shoals that form at inlets aid in new salt marsh formation on the bay side of barriers. Because of these direct and indirect impacts, wind is a very important factor in barrier morphology.