Trends in Coastal Morphology along the Chenier Plain Shoreline, Louisiana

A. E. Draut
Woods Hole Oceanographic Institution, Department of Geology and Geophysics, Woods Hole, MA

Patterns in coastal morphology were assessed along the area of the Louisiana coast known as the chenier plain, west of Atchafalaya Bay. This section of shoreline is located downdrift of the Atchafalaya river discharge, which carries approximately 84x10⁶ metric tons of suspended sediment annually into the shallow shelf region. Mudflat accretion and progradation have previously been observed along the chenier plain, in contrast to the rapid land loss that characterizes much of the Louisiana coast.

Surveys were conducted from a small boat in March 2001 along 51 km of the chenier plain, extending from Little Constance Lake to northeast of Tigre Point. The coastal characterization survey identified alternating areas of erosion and mudflat accretion along the western chenier plain, pronounced accretion along the eastern chenier plain downdrift of Freshwater Bayou, and apparent erosion east of Freshwater Bayou. Field observations, as well as initial results of isotopic activity analyses (⁷Be, ²¹⁰Pb, ¹³⁷Cs) from shallow-water cores, indicate that accretion and progradation on the eastern chenier plain are enhanced substantially by dredging activity in the Freshwater Bayou channel.

AAPG Search and Discovery Article #90902©2001 AAPG Foundation Grants-in-Aid