Overview of coastal restoration in Louisiana

摘要

Erosion and accretion are natural processes in dynamic sedimentary environments (e.g. global coastal systems). Anthropogenic interventions in these systems often create imbalances in these natural processes. The sedimentary environment of coastal Louisiana is a prime example of anthropogenic interventions and challenges associated with consequential imbalances. Large areas of the Mississippi River delta plain in coastal Louisiana are rapidly sinking, similar to other deltas around the world; however, the severity of the phenomena in coastal Louisiana (notwithstanding the human infrastructure which has been superimposed on this delta) makes the situation unique. It is estimated that since the 1930s Louisiana has lost nearly 1.2 million acres (1,875 sq mi) of coastal land. This extreme rate of land loss threatens a range of key national assets and locally important communities, many of which support these national assets. Pipelines, navigation channels, and fisheries as well as centuries-old human settlements and priceless ecosystems are all at risk. Considering the economic, cultural, and historic value of coastal Louisiana to the United States, the loss of these valuable diverse and multifaceted environments is indeed a national disaster in the making. While it is appreciated and understood that these coastal environments are inherently dynamic and subject to ongoing changes, the failure to forestall and redirect present trends of degradational processes foreshadows a serious future risk to the nation. Fortunately, several multipronged efforts are currently operating to develop effective interdisciplinary management strategies that can be applied to the degrading Gulf of Mexico and coastal bay environments, especially in the post-Katrina and post-Deepwater Horizon era. The need for this comprehensive, integrated approach is acute. However, the integration of various coastal restoration features and hurricane protection systems must be such that the ecosystem remains dynamic and functional and is not adversely affected. In addition, ecosystem services, oil and gas activities, and navigation are of national significance and must be preserved. In light of the new challenges facing coastal Louisiana since the 2005 hurricanes, it was only logical that an effort be initiated to develop a comprehensive coastal protection plan that would integrate hurricane protection, conservation, and restoration of coastal areas. These efforts to restore coastal Louisiana encompass the restoration of several key landscape features (i.e. barrier islands, marshes, and ridges) as well as the shorelines. One critical component of protection and restoration in Louisiana, and of the long-term sustainability of the Mississippi River Delta, is efficient management of sediment (both renewable and nonrenewable). As sediment distribution patterns are a reflection of the underlying geology, any effective restoration strategy, to be sustainable, should be based on an understanding of the geological setting.