Barrier Islands

A barrier island is a long, thin, sandy stretch of land oriented parallel to the mainland coast, which protects the coast from the full force of powerful storm waves. Between the barrier island and the mainland is a lagoon or bay. Barrier islands are dynamic systems that migrate under the influence of changing sea levels, storms, waves, tides, and longshore currents. Approximately 2,100 barrier islands are known to exist around the world. In the United States, barrier islands occur along gently sloping sandy coastlines such as those along the Gulf Coast and the Atlantic Coast as far north as Long Island, New York. They are, in contrast, absent along the generally steep and rocky Pacific Coast. Some of the better known barrier islands along the coast of the United States are Padre Island, Texas, the world's longest barrier island; Sanibel and Captiva Islands, Florida; Cape Hatteras, North Carolina; and Assateague Island, Maryland.

Residential and recreational development on barrier islands has become a contentious issue in recent years. Although the islands serve as buffers against the sea by constantly shifting and changing their locations, the owners of homes, stores, and hotels on barrier islands often try to stabilize the shifting sand to protect their property. This is accomplished by beach hardening (the construction of engineered barriers) or beach nourishment (the continual replacement of sand that has been washed away during storms). In either case, the result is an interruption of the natural processes that formed the islands. Construction that prevents the naturally occurring erosion of sand from the seaward side of a barrier island, for example, may result in erosion problems when the landward side is consequently starved of sand. Beach nourishment projects typically require ever increasing amounts of sand to maintain a static beachfront, and are therefore economically viable for only short periods of time. Although coastal management activities have long been directed towards beach hardening and nourishment, current scientific thinking suggests that the islands are more appropriately viewed as geologically transient features rather than permanent shorelines suitable for development.