Geomorphic Evolution of a Rapidly Deteriorating Barrier Island System with Multiple Sediment Sources:Eastern Isles Dernieres, Louisiana, 1887 to 2006

摘要

The Isles Dernieres barrier island system in south-central Louisiana is a dynamic coastal system comprised of Raccoon, Whiskey, Trinity, and East islands, from west to east (Fig. 1). This system has deteriorated rapidly since the late 1800s-the seaward shoreline has retreated landward 11 m/yr (36 ft/yr) and the overall land area has decreased by 78 percent (McBride and Byrnes, 1997). The eastern Isles Dernieres (i.e., Trinity and East islands) are unique in that sediment input to the system is sourced from the erosional headland, as described by the barrier island development model in Penland et al. (1988), as well as sediment bypassing Cat Island Pass to the east (Jaffe et al., 1989,1997). This longshore-sourced sediment affects the islands' geomorphology and helps to replace sediment lost by erosion. This study aims to document both the geomorphic implications of this secondary sediment source as well as the effects on the barrier island development model for the Mississippi River delta plain described in Penland et al. (1988).