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Summary The U.S. Army Corps of Engineers released the Louisiana Coastal Protection and Restoration (LACPR) draft final technical report in March, 2009 (USACE, 2009). The Corps of Engineers conducted this planning study in response to federal legislation passed in November 2005. Public Law 109-103 directed the Corps to âconduct a comprehen- sive hurricane protection analysis and design at full federal expense to develop and present a full range of flood control, coastal restoration, and hurricane protection measures to provide â. . . protection for a storm surge equivalent to a Category 5 hurricane within the project areaâ and with the provision that â. . . the analysis will be conducted in close co- ordination with the State of Louisiana and its appropriate agenciesâ (P.L. 109-103; emphasis added). The following is the second and final report from the National Re- search Council (NRC) Committee on the Review of the Louisiana Coastal Protection and Restoration (LACPR) Program. The committeeâs first report was released in 2008. The committee was charged to review two draft reports from the LACPR team and to assess âthe hurricane risk reduction framework, alternatives for flood control, storm protection, coastal restoration, and risk analysisâ (the committeeâs full statement of task is listed in Appendix A). This report presents this committeeâs re- view and advice for improvements of the LACPR March 2009 draft final technical report. The proposed comprehensive hurricane protection planning for southern Louisiana entails implementation of a variety of structural, non- structural, and coastal restoration measures. Examples of structural measures include levees and floodwalls; examples of nonstructural measures include flood insurance and buyouts; examples of coastal resto- ration measures include the creation or enhancement of wetlands or bar- rier islands. Evaluating various combinations of these measures, and identifying a preferred plan or course of action, represents considerable technical and other challenges due to the complex natural environment of 1
2 Second Review of LACPR Draft Report coastal Louisiana and the tremendous power of land-falling hurricanes that beset the Gulf of Mexico. Coastal Louisiana covers a vast areal extent and consists of a variety of physiographic features such as estuaries, wetlands, rivers, urban areas, and flood control structures. Furthermore, this is a dynamic landscape that is subject to ongoing sea level rise and future changes in climate. Not only will environmental conditions in this vast region change over time, but social and demographic conditions will change and initiatives such as nonstructural measures for reducing flood risk reduction (e.g., rates of flood insurance purchases; elevating buildings in vulnerable ar- eas; and adoption of zoning measures) will change and evolve in unfore- seen ways. LACPR projects thus should be designed with some capacity to adapt to future, changing conditions. At the same time, it is important that the Corps of Engineers utilize the best technical advice and professional judgment to identify priority protection and restoration alternatives and actions. The Corps of Engi- neers is the federal governmentâs expert on hydrology and hurricane pro- tection issues in this region and, with this project, the U.S. Congress re- quested the Corpsâ expertise and recommendations regarding future hur- ricane protection analysis and design. Despite being given authority from the U.S. Congress for this project over three years ago, the LACPR draft final technical report does not offer a comprehensive long-term plan for structural, nonstructural, and restoration measures across coastal Louisiana, nor does it suggest any initial, high-priority steps that might be implemented in the short term. Instead, a variety of different types of structural and nonstructural op- tions are presented, with no priorities for implementation. The lack of a comprehensive long-term hurricane protection and coastal restoration plan, and the lack of advice on initial high- priority steps and projects, represent substantial shortcomings of the LACPR draft final technical report. Comprehensive and effective hurricane protection and restoration in coastal Louisiana will entail cooperation among several entities, but es- pecially between the Corps of Engineers and the State of Louisiana (as called for in the federal legislation). The Corps and the State of Louisi- ana have issued separate reports on hurricane protection and coastal res- toration with what appears to be only limited efforts to synchronize them. Closer cooperation and collaboration between the Corps and the state will be essential for financing, technical planning and project implemen- tation, monitoring, and adaptation.
Summary 3 To help promote cooperative federal-state hurricane protection and restoration, the Corps of Engineers and the State of Louisiana should initiate joint deliberations immediately to agree upon a long-term com- prehensive planâincluding structural, nonstructural, and restoration pro- jectsâand also identify a small number of high-priority projects for ini- tial implementation. It will be important that this cooperative effort not be a lengthy and expensive planning exercise; rather, it should draw upon the voluminous existing research and data on project alternatives derived in the course of the LACPR study, along with previous studies by the Corps, the State of Louisiana, and others. These deliberations should include discussion of the long-term sustainability of project alternatives given past trends and future projections of Louisiana wetland losses ow- ing to erosion and relative sea level rise. Before the end of 2009, the Corps of Engineers and the State of Louisiana should agree on the elements of a single comprehensive plan for long-term hurricane protection and coastal restoration. As part of that plan, the Corps and the state should agree on a number of high-priority projects for immediate implementation. Other key findings and recommendations from this report include: â¢ There is a need for more detailed description of sediment avail- ability, including better justification for the assumption that the current shoreline can be maintained in place. The LACPR team should complete a sediment budget for coastal Louisiana and provide better explanation of potential costs and environmental impacts of dredging alternatives. â¢ There should be a more explicit acknowledgement of ongoing and future coastal erosion trends and their implications for restoration priorities. Rather than focusing energy and resources into trying to maintain the current configuration of southern Louisianaâs eroding coastline, the LACPR team is encouraged to focus its protection and restoration plans on high-priority projects. â¢ The LACPR report should provide a better and more quantitative explanation of the scientific uncertainty associated with projections of marsh and wetlands restoration (including diversions), surge attenuation by wetlands, numerical modeling efforts, and the implications of Mississippi River diversions. â¢ The high level of uncertainty of the effects of proposed river di- versions suggests the need for careful monitoring and evaluation of existing diversions. It also suggests the importance of an
4 Second Review of LACPR Draft Report adaptive strategy that can adjust to and build upon new informa- tion as more is learned about the responses of these coastal wet- lands systems to human interventions. â¢ Storm surge protection for the City of New Orleans should be designed for a hurricane storm surge event with an expected return interval of 400 to 1,000 years. â¢ The LACPR team should perform a quantitative risk assessment of the structural protection systems that includes the probability of system failure of the various components including floodwalls, levees, ring levees, and floodgates. â¢ The LACPR team (and the Corps) should take a more aggressive leadership role in promoting a variety of nonstructural measures that are important to reducing flood risks in coastal Louisiana. Examples of these nonstructural measures include limiting development in flood-prone areas and stronger public education efforts regarding flooding risk in different sections of New Orleans. â¢ Multi-Criteria Decision Analysis is a potentially useful approach to evaluate projects with important environmental, social, and cultural impacts; however, flaws in the application of these methods to the LACPR study have prevented any convincing results. As applied, the methods do not support the identification of a preferred alternative for any of the planning areas. Furthermore, they do not support the rankings of alternative plans as presented in the LACPR report. â¢ The LACPR team should more specifically identify and explain the trade-offs between commercial navigation and river diversions for coastal restoration. â¢ It is encouraging that the LACPR draft final technical report describes the importance of preventing induced development. The report, however, does not adequately demonstrate how these principles will be a prominent part of hurricane protection and coastal restoration actions. Discouraging development in particularly vulnerable areas, whether or not they are protected by levees, is a fundamental principle of flood risk management and reduction. The LACPR should strengthen its cooperation with state and local entities to ensure that the prevention of induced development is accorded a more prominent and meaningful role in future plans. â¢ The multiple authorizations that govern ecosystem restoration
Summary 5 and hurricane protection in southern Louisiana represent a piecemeal approach and may hinder integrated, adaptive restora- tion and protection improvements across the region.