ABSTRACT

The Mississippi River delta and chenier plains in Louisiana are experiencing catastrophic coastal land loss rates exceeding 100 km²/yr. Louisiana's coastal zone contains 40 percent of the U. S. wetlands and 80 percent of the Nation's loss occurs here. The origin and stability of these coastal environments is tied to the sediments discharged by the Mississippi River throught the delta cycle process. Sediments accumulate in well-defined delta complexes at approximately 800-1000 year intervals followed by abandonment and barrier island formation. The delta-cycle process, that bulds new delta complexes, barrier islands, and cheniers is curently stopped by flood and navigation control structures. These structures harness the flow of the Mississippi River within a massive levee system, channeling most of the sediments off the continental shelf. Deprived of sediments and subsiding rapidly, Louisiana's wetlands are vanishing. Researchers have long recognized the catastrophic coastal land loss conditions occurring and speculated on the causes. The chronic problem of wetland loss is well documented, but poorly understood. Over the last decade, two schools of thought have developed in the coastal research community concerning the relative roles of the causal factors driving the extreme rates of land loss and change. One school of thought emphasizes the natural processes of the delta cycle process and human activities are ranked as secondary in importance. In contrast, the other school of thought places primary importance on human activities and of secondary importance are the natural processes. A review of previous coastal land loss research indicates the only way to accurately determine the relative roles of different types and processes of land loss is to develop a classification suitable for quantitatively mapping the spatial distribution and contribution of each geomorphic loss type to the total amount of land loss in a given interval of time.