Carolina Environmental Diversity Explorations
Small sand volume barrier islands · By Dirk Frankenberg
Small and large sand volume barrier islands
On this field trip, we'll visit Masonboro Island and North Topsail Beach. Click to see a larger map. (Satellite image from NASA with map drawn over top. More about the photograph)
Barrier islands are the dominant geographic feature of sandy coastlines, but recurring storm damage on some demonstrates that different barrier islands present very different levels of risk to residential development. One of the best indicators of development risk is island sand volume. Some barrier islands have substantial dunes behind the beach as well as a sequence of large dunes and sandy ridges between the beach and the back-barrier salt marsh. Others have sand only on the beach and in a narrow, flat area behind it (the berm) and nothing but a few small dunes between the beach and the back-barrier salt marsh. Residential developments on islands with small sand volumes are far more likely to be destroyed or damaged by storms than are islands with high sand volumes.
Thanks to recent research at North Carolina universities, we now understand some of the reasons that different islands have such different sand volumes and risk characteristics. Two virtual field trips in this series will summarize some of that research and take you to islands along our southern coast that represent high and low ends of the sand volume spectrum. One of each pair has been developed, the other has not been. This trip takes you to two small sand volume islands, the undeveloped Masonboro Island and the residentially developed North Topsail Beach on Topsail Island. The next trip in this collection takes you to the high sand volume pair, the residentially developed Bogue Bank and undeveloped Bear Island. Both virtual trips are based on descriptions of these islands in the author’s 1997 book entitled The Nature of North Carolina’s Southern Coast: Barrier Islands, Coastal Waters and Wetlands. This book provides directions to the islands covered in both trips, should you want to see their sand volume differences and development risks for yourself.
