Consensus Report

Drawing Louisiana's New Map: Addressing Land Loss in Coastal Louisiana (2006)

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During the past 50 years, coastal Louisiana has suffered catastrophic land loss due to both natural and human causes, and this loss has increased storm vulnerability and amplified risks to lives, property, and economies--a fact underscored by Hurricanes Katrina and Rita. This report reviews a restoration plan proposed by the U.S. Army Corps of Engineers and the State of Louisiana, finding that, although the individual projects in the study are scientifically sound, there should be more larger-scale projects that provide a comprehensive approach to addressing land loss over such a large area. The report states that restoration efforts should be part of a comprehensive effort to rebuild New Orleans and coastal Louisiana in response to the recent hurricanes. It also recommends that restoration should be guided by a detailed map of the expected future landscape of coastal Louisiana that is developed from agreed upon goals for the region and the nation.

Key Messages

  • A robust regional sediment budget to use deterministic models effectively.
  • At foreseeable rates of land loss, the level of effort described by the LCA Study will likely decrease land loss only in areas adjacent to the specific proposed projects.
  • Coastal Louisiana lies at the nexus between the Gulf of Mexico and the nation's largest watershed (the Mississippi River Basin). The current loss of lands and other environmental problems on and along the delta have many causes, but several of them are the result of the current management of the Mississippi River Basin.
  • Effective management of the efforts proposed in the LCA Study will be a critical factor leading to the overall success of the restoration effort in Louisiana.
  • Efforts to restore significant portions of coastal Louisiana would entail changing the current geographic distribution of land, water, and wetland.
  • Full restoration of past Louisiana wetland cover and function will not be possible.
  • Future efforts must focus more realistically on the location patterns of human settlements relative to project locations, including the option of infrastructure depreciation and abandonment.
  • In addition to lacking fundamental transparency, the project selection process as documented in the LCA Study creates a somewhat inaccurate appearance of legitimacy and rigor. There is insufficient attention to the large knowledge gaps surrounding project benefits measurement, including the somewhat arbitrary weighting of various ecological and physical endpoints of projects.
  • Keeping pace with the relative subsidence rate over the entire delta would require the delivery of sediment-laden waters over long distances, would be extremely costly, and would have an adverse impact on a significant subset of stakeholders.
  • Most of the individual projects proposed in the LCA Study are based on commonly accepted, sound scientific and engineering analyses. However, it is not clear that, in the aggregate, if these projects represent a scientifically sound strategy for addressing coastal erosion at the scale of the affected area.
  • One way to deal efficiently with the change is through comprehensive land-use planning that is coordinated with the planned restoration projects.
  • Since there is a finite availability of water flow and sediment and most of the restoration activities will take decades to provide maximum results, care should be taken to ensure that implementation of an individual project will not preclude other strategies or elements in the future.
  • Stakeholders' near- and long-term responses to gauge their acceptance of the restoration activities.
  • The LCA Study presents sufficient information about the importance of some components of the natural and built environment in coastal Louisiana (e.g., system of deep water ports, oil and gas receiving and transmission facilities, complex and extensive urban landscape, robust commercial fishery) to suggest that substantial economic interests are at stake in coastal Louisiana and that these interests have national significance.
  • The LCA Study proposes the development of process-based models for prediction of coastal response as a central feature of current and future restoration efforts. Modeling will be a key component of the design, operation, and maintenance of the restoration and management of coastal Louisiana.
  • The adaptive management program will play a major role in collecting and synthesizing data and charting new directions as appropriate.
  • The causes of loss and changes in the rate of loss to determine the long-term prospects of maintaining the coastal Louisiana ecosystem and the activities it supports.
  • The economic and societal toll of land loss to frame restoration of coastal Louisiana in terms of national relevance.
  • The geographic variability in the relative role played by natural and anthropogenic causes of land loss to more effectively target the appropriate solutions.
  • The limited understanding of the feasibility of engineered methods of sediment delivery over long distances (such as those employed by the dredging industry) to evaluate the cost and feasibility of projects that do not rely on natural processes to distribute sediment.
  • The natural and anthropogenic processes contributing to net land loss in coastal Louisiana are significant and pervasive, and they have been operating for decades. Achieving no net loss is not a feasible objective because the social, political, and economic impediments are extensive; the sediment supply is limited; and the affected area is large.
  • The relationship between bedload, suspended, and washload transport to understand the factors affecting the vertical sediment concentration profile.
  • The role of growth fault reactivation in land loss to interpret past land loss patterns, to predict future land loss rates and locations, and to design strategies for land creation on the delta.