ated flooding. Coastal Louisiana, however, faces many unique challenges, which are the subject of this report and the proposed efforts it reviews.

The Mississippi River Delta and its associated wetlands helped to shape Louisiana’s culture and economy. In addition to being a land of natural beauty and bounty, it is also home to a rich diversity of peoples. While the unique culture of New Orleans and the bayous has been the traditional magnet drawing millions of tourists to the delta, a growing appreciation for the complex wetland systems of the area is attracting increasing numbers of tourists in search of the nature and history of the area. The long, slow mingling of freshwater and saltwater that takes place between the uplands and the Gulf of Mexico has produced a rich mosaic of wetland habitats that support rare and endangered species; great flocks of waterfowl; and commercially exploited populations of furbearers, fish, shrimp, crawfish, oysters, and crabs.

Even in the aftermath of Hurricanes Katrina and Rita, Louisiana will remain a center for oil and natural gas production, transportation, and refining, and its marine fisheries are among the most valuable in the nation. The access it provides to the Mississippi River Basin also makes it a hub for shipping and navigation. The committee recognizes that this report is being released at a time when there may be many more questions than answers. Even so, the report is provided at this difficult time in the hope that its advice on restoring and protecting coastal Louisiana can be considered as part of the nation’s strategy to rebuild the Gulf Coast and reduce the likelihood of future tragedies, such as Katrina and Rita.


Coastal deposition along the southern edge of the North American continent has been taking place for tens of millions of years. However, the modern Mississippi River Delta as recognized today began to form when, at the end of the last ice age, the drainage of the mid-continent became integrated, creating the Mississippi River itself. Like other coastal deltas, the Mississippi River Delta plain is the product of sediment deposition and accumulation where waters of the river empty into the coastal ocean. During the late Wisconsian glaciation’s peak roughly 22,000 years ago, sea level was 91–106 meters (m) (300–350 feet [ft]) lower than present. When the late Wisconsian glaciers began melting 4,000 years later, an era of sea level rise known as the Holocene transgression began, and with it came dramatic changes in the basin’s hydrologic character. As the Mississippi River Basin eroded, the Mississippi River changed from a system of braided streams carrying coarse-grained sediments to a sinuous, meandering, interconnected system that carried relatively fine grain clay, silt, and sand, similar in some respects to that known today.

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement