Consensus Report

Each report is produced by a committee of experts selected by the Academy to address a particular statement of task and is subject to a rigorous, independent peer review; while the reports represent views of the committee, they also are endorsed by the Academy. Learn more on our expert consensus reports.

In response to the destruction caused by hurricanes Katrina and Rita, the U.S. Congress requested that the U.S. Army Corps of Engineers to produce a comprehensive technical report for future protection and design against Category 5 hurricanes in southern Louisiana. Entitled "Louisiana Coastal Protection and Restoration Technical Report," the Corps' draft technical report offer many alternatives for the restoration of wetlands, future design of levees and floodwalls, and nonstructural measures to provide hurricane protection. This National Research Council (NRC) report reviews the Corps' draft report and provides recommendations on how it can be improved. The Corps is commended for integrating and providing new approaches in this complex ecological and geological environment. However, the draft report does not identify projects of higher priority and greater benefits, and there are significant weaknesses in each of the report's three main sections. Most notably, the National Research Council report finds that the Corps' draft report lacks evidence that the sediment resources necessary to maintain the current coastal configuration, given the current and future rates of subsidence, degradation, and sea level rise, will be available.

Key Messages

  • Given the considerable economic, cultural, and other values of the City of New Orleans, and a congressional mandate to produce a design for Category 5 protection, the LACPR report should focus on producing designs and plans based on storms with return intervals associated with Category 5 storms.
  • In its future reports, the LACPR team is encouraged to present an integrated set of measures that can limit future development in low-lying, flood prone areas.
  • Some sections of the LACPR draft technical report especially those that consider future redevelopment scenarios and increases in population growth are written with a limited appreciation of the fact that the region�s coastal areas are experiencing rapid rates of degradation and subsidence and are in fact disappearing. These scenarios of redevelopment thus may be inconsistent with the report�s stated objectives of reducing risks to public health and safety, and reducing damages from catastrophic storm inundation.
  • The LACPR draft report gives insufficient attention to the need to counter the phenomenon of induced development behind levees and to preventing the future development of high-hazard areas not protected by levees.
  • The LACPR draft report provides little discussion of the details of the federal-state-local cooperation that will be necessary to fully implement nonstructural measures of the integrated Multiple Lines of Defense Strategy proposed in the technical report.
  • The LACPR draft technical report properly includes discussion of many of these nonstructural strategies, and the LACPR team should be credited for evaluating such measures.
  • The LACPR report should consistently refer to relative levels of protection from hurricanes and storm surge, and make it clear that absolute protection is not possible.
  • The kind of MCDM approach taken in the LACPR draft report generally is a feasible and appropriate way to rank the kinds of alternative plans under consideration.
  • The lack of some prioritization of alternatives based upon their relative merits in terms of cost and restoration and risk reduction potential constitutes a weakness within the draft technical report.
  • The process of plan evaluation should be better documented within the LACPR report.
  • The report lacks a systematic analysis of the obstacles that limit local government, households, and businesses from adopting these nonstructural measures, and it fails to identify an adequate suite of remedies that could help address these obstacles.
  • The use of a probabilistic framework to evaluate storm surge within the LACPR draft technical report is a more comprehensive and sophisticated approach to evaluating plan elements than by use of the Saffir-Simpson Hurricane Scale.