The environmental and economic consequences of coastal erosion in Louisiana are significant.
Barrier islands fronting the Mississippi River delta plain act as a buffer to reduce the effects of ocean waves and currents on associated estuaries and wetlands. Louisiana’s barrier islands are eroding, however, at a rate of up to 20 meters per year; so fast that, according to recent USGS estimates, several will disappear by the end of the century. As the barrier islands disintegrate, the vast system of sheltered wetlands along Louisiana’s delta plains are exposed to the full force and effects of open marine processes such as wave action, salinity intrusion, storm surge, tidal currents, and sediment transport that combine to accelerate wetlands deterioration.
Human activities during the past century have drastically affected the wetlands.
Natural processes alone are not responsible for the degradation and loss of wetlands in the Mississippi River delta plain. The seasonal flooding that previously provided sediments critical to the healthy growth of wetlands has been virtually eliminated by construction of massive levees that channel the river for nearly 2000 kilometers; sediment carried by the river is now discharged far from the coast, thereby depriving wetlands of vital sediment. In addition, throughout the wetlands, an extensive system of dredged canals and flood-control structures, constructed to facilitate hydrocarbon exploration and production as well as commercial and recreational boat traffic, has enabled salt water from the Gulf of Mexico to intrude brackish and freshwater wetlands. Moreover, forced drainage of the wetlands to accommodate development and agriculture also contribute to wetlands deterioration and loss.
Methods to mitigate wetlands loss are costly and politically sensitive, affecting communities, agriculture, and industry.
A variety of ideas have been put forward as partial solutions to the dramatic loss of barrier islands and wetlands along the Louisiana coast. Most ideas include soft engineering solutions such as coastal restoration through barrier island renourishment. Dredged materials could be distributed onto wetlands. Other ideas include a strategic retreat by creating new navigation channels allowing the delta plains, such as the modern Mississippi River Delta, to erode and proceed through their normal cycles. Such solutions could affect small communities, agricultural interests, and the petroleum industry. Hard engineering solutions, such as building sea walls and breakwaters, are also possible; however, these solutions are not only expensive but have produced mixed results at best.