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Tales of the Coast
Coastal Dynamics

Dune Formation

Sand dunes are common features along sandy coastlines around the world. The only climatic zones lacking extensive coastal dunes are the frozen Arctic and Antarctic

The normally dry backshore of sandy beaches may be the most common source of dune sands. A flat or low-relief area inland of the coastline is needed to accommodate the dunes, and there must be predominant onshore or alongshore winds for at least part of the year.

The presence of vegetation or other obstructions to the wind results in sand being trapped and leads to the creation of sand dunes. In areas where there is sufficient sand and the beach is wide, dunes can be encouraged to develop naturally by planting dune grass or other vegetation or by installing sand fences to trap the landward-blowing sand. Dunes can be constructed artificially by beach nourishment, grading existing sand available on the dry beach, or "beach scraping" (removing sand from below the high-water line during low tide and using it to construct a protective dune).

A line of dunes can provide protection from flooding due to high water levels and wave overtopping. Dunes can also reduce wave damage in developed landward areas by causing waves to break as they propagate over the dunes. Sand stored in dunes is also available as a sacrificial contribution to the increased longshore and offshore sand transport during storms. Dunes, by contributing their volume to the sand in transport, reduce the landward movement of the shoreline in storm events.

Dunes on North Carolina Shore
Source: National Oceanic & Atmospheric Adminstration

Dune Formation

Dunes Serve Multiple Valuable Purposes: Dunes are important as recreational areas, as habitat for various species of birds, as shore protection, and as temporary sources and sinks of sand in the coastal environment. Although they are found along many sandy coasts, dunes are finite resources and they need to be protected and preserved.