One grain at a time: How Gulf Coast Barrier Islands Rebuild after storms

Formed by Wind. Land that is formed by wind is called aeolian after the greek god of wind, Aeolous. It's a beautiful word for a landscape process that sculpts sand into fantastic forms, pronounced 'ae-ohh-lee-an'. In Greek mythology, Aeolus lives in the stratosphere pursing his lips and directing his exhales downward at people, animals, land. The drawings of the mythical Aeolus are comical, yet the hurricane experience is otherworldly, directional like Aeolus is depicted with his massively powerful lungs gusting, huffing, and billowing.  Satellite imagery shows us that hurricanes are well-organized systems of clouds and air masses and not a mythical source of wrath from the sky. But, I can say from experience that Hurricanes feel mythically powerful when you watch trees crash down on houses, roof shingles peel off, and water rise over an entire island and pull it back, wiped clean.

Sand Fences and Sea Oats. I have experienced many Florida hurricanes and witnessed barrier islands flattened by storm surge when decades of wind-built dunes are swept away in half a day. Water pours over the islands and washes out the sand- the Aeolian processes erased. A barrier island after a major storm is thin, fragile, just a scarce white crust with water pooling on all sides.  Each day the island shifts, rebuilds, settles, and starts the slow meticulous accretion of the dunes a few grains at a time. Wind gusts over and around tufts of sea oats. The process is quickened with sand fence installation and native dune vegetation planting. Sand fences are a common sight in Florida, to the untrained eye they are idle fence posts. In reality, they are agents of change; critical catalysts in the accumulation of island sand that actively reform the island. A well-developed island protects the main land as the name implies 'barrier island' from storm surge and wind damage. Barrier islands are the first line of protection during a storm, making their erosion an economic concern. Dune building happens on the timescale of decades- certainly within the scope of a human life. Sand fences are placed perpendicular to the direction of wind, as seen in the photo below. 

 

The naturally-present active agent in rebuilding dunes is pioneer vegetation. It is a Florida state law that sea oats- Uniola paniculata- can not be harvested, cut, disturbed, or otherwise removed from any area where they grow because the root system of the plant holds sand in place. Pioneer vegetation includes a number of uniquely adapted dune plants that spread with above ground rhizomes to catch sand particles and build the dunes over time, as described in one of my favorite books on coastal plants:

"Immediately landward of the beach above the highest tides, pioneer dune areas are colonized by low herbs (e.g. sea-rockets, sand atriplex, seaside evening primrose) that become established in the organic debris deposited by wind and waves. As sand accumulates around these plants, the dune feature increases in height, forming the primary, or fore dune. Fore dunes increase in size when low, tough, rhizomatous plants- such as sea-oats or bitter panicum- trap and stabilize the shifting sands." -Common Coastal Plants in Florida: A Guide to Planting and Maintenance ed. By Michael R. Barnett and David W. Crewz