A natural barrier to the destructive forces of wind and waves, sand dunes are our first line of defense against coastal storms and beach erosion.  They absorb the impact of storm surge and high waves, preventing or delaying flooding of inland areas and damage to inland structures.  They are also sand storage areas that supply sand to eroded beaches during storms and buffer windblown sand and salt spray.

Due to the high energy 'washing' effect of ocean and bay waves, soil, as we are accustomed to thinking of it, is converted to clean, relatively coarse mineral fragments (sand). The deposit of sand along the shore is subjected to the high winds common the area where the sea meets the land, and is blown in every direction throughout the year. Where vegetation can get a foothold in the dry, unfertile sand, the windblown sand grains get batted down to the base of the plant and the sand surface incrementally rises, one grain at a time. Over days, weeks and years, depending upon how hard the wind blows, dunes rise up out of the flat beach. Beach grass has adapted to being buried by the sand and it makes its way to the new surface as it gets buried. In time of large ocean storms waves crash into the dunes and the sand is re-supplied to the beach on front, which has been eroded in the early stages of the storm. The relationship of the beach and dune is an important symbiosis. One which we respect and shape our beach management program around.

Increased development and recreational use of the barrier beach threatens the stability of our dunes.  Structures built too close to the shoreline are inhibiting the landward movement of the dune in response to sea level rise resulting in a decrease in the dune width.  Driving and walking on the dunes in areas not designated for such use, causes deterioration of beach grass and other vegetation that helps to trap and hold the sand in place.  Although beach grass is a hardy plant, amazingly tolerant to high salinity conditions, direct sun, extreme heat, lack of fertile soil and a fluctuating water supply, it can not survive being trampled by vehicle or man. As part of its resistance to salinity and drying conditions the plant has developed a thick brittle stalk which unfortunately snaps easily when trampled or driven upon. The passage of only a few people over the dune at the same point will kill a strip of grass.  Without vegetation, the dune is exposed to wind erosion resulting in blowouts or breaches.  These low spots not only create a weak spot in the dune but, become channels for floodwaters to move inland during storm events.  As a result, inland areas become more vulnerable during coastal storms.  Protecting dunes helps prevent loss of life and property during storms and protects the sand supply that slows shoreline erosion.