ENGINEERED BARRIER ISLANDS: LIFELESS PILES OF SAND

Barrier islands are dynamic features of unconsolidated sand that require sea-level rise, a good supply of sand, wave energy and a modest tidal amplitude for their existance. Barrier islands are capable of landward migration in response to sea-level rise and/or a reduction in sand supply. The current global sea-level rise is causing island thinning by erosion on both sides of many of the world's 2,100 barrier islands; a process that will facilitate true island migration by overwash in the near future. These islands have become favored haunts for heavy development, especially in the western world. Such development has completely altered the unique surficial geomorphology and ecology of many islands as manicured lawns replace dunes, and condominiums replace maritime forests. The impacts, however, are more far reaching than landscape aesthetics. Once buildings are ensconced on an island most societies attempt to protect them by stabilizing the shoreline. Stabilization is carried out by shore hardening and beach nourishment. Cross-island processes, essential to island migration, cease. Island evolutionary processes are completely frustrated by humans. As sea level continues to rise, the equilibrium position of the shoreline continues to retreat in a landward direction although the actual shoreline remains static. If century-old armoring is removed, many islands would disappear. And if stabilization continues in the context of a rising sea level, maintenance of beaches and buildings on barrier islands will become economically untenable, and recreational barrier islands will likely be abandoned in favor of protection of major coastal cities. If long-term viability (2 to 4 generations) of the islands is a priority, then efforts should be made to keep the islands alive. To do this, human development processes must evolve as barrier island processes evolve. Cross-island overwash, shoreline retreat, and barrier island migration must be allowed to continue in one form or another. Current assumptions, prevalent in coastal management circles, that barrier islands can be maintained in place with viable recreational beaches overlook long-term coastal processes combined with sea-level rise.