On August 29, 2005, Hurricane Katrina struck eastern Louisiana, Mississippi, and western Alabama killing hundreds of local residents, displacing hundreds of thousands more, and causing an estimated $200 billion in economic damage. Less than four weeks later, Hurricane Rita struck easternmost Texas and western Louisiana. Although the loss of life from Rita was much less than that from Katrina, significant destruction resulted, including the reflooding of some parts of New Orleans damaged during Katrina. The devastation wreaked by Katrina and Rita tragically demonstrated the risks that many coastal areas face from hurricanes and associated flooding. Prior to the storms, the historical and continuing land losses in the coastal regions of Louisiana contributed to widespread concerns regarding the vulnerability of the region to storms and coastal flooding. This report, which focuses on restoration efforts proposed by the U.S. Army Corps of Engineers (USACE) and the State of Louisiana in late 2004, was in the final stages of peer review and was essentially complete when the hurricanes struck. The role that land loss, lack of levee maintenance and improvement, and the large navigation channels (including the Mississippi River Gulf Outlet [MRGO]) played in determining the extent of the damage caused by the hurricanes, and their impact on the national economy, cannot be fully determined at this time. What have become clear are the enormous personal, social, economic, and cultural losses that a major hurricane can bring to the residents of the Gulf Coast and the reverberations of such events nationwide. To the extent that wetlands can offset a significant degree of storm impact, large-scale wetlands restoration projects can be an important component of national efforts to reduce fu-
ture hazards from hurricanes. As more information becomes available about Katrina and Rita, or as reconstruction efforts supersede planned restoration efforts reviewed as part of this study, some of the conclusions of this report may become more significant while others may become moot.
The National Research Council (NRC) recognizes that this report is being released at a time when there may be many more questions than answers. Even so, the report is provided at this difficult time in the hope that its advice on restoring and protecting coastal Louisiana can be considered as part of the nation’s strategy to rebuild the Gulf Coast and reduce the likelihood of future tragedies associated with hurricanes in the region.
EFFORTS TO RESTORE AND PROTECT COASTAL LOUISIANA
Coastal wetlands develop within a fine balance of many geomorphologic and coastal ocean processes. Relative sea level rise, wave action, tidal exchange, river discharges, hurricanes and coastal storms, and the rates of sediment accretion due to sediment deposition and accumulation of organic material play particularly important roles. The interplay of these processes and the wetland’s resilience to natural or anthropogenic perturbations determine its sustainability. Some of the processes of land loss and gain in the Louisiana coastal area are natural and have occurred for centuries. Others are the result of human activities in the wetlands and the watershed of the Mississippi River system.
Annual land loss rates in coastal Louisiana have varied over the last 50 years, declining from a maximum of 100 square kilometers (km2) per yr (39 square miles [mi2] per yr) for the period 1956–1978. Cumulative loss during this 50-year period in Louisiana represents 80 percent of the coastal land loss in the entire United States. Initial efforts to prevent catastrophic land loss were implemented under the federal Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA) in partnership with Louisiana’s efforts through Act 6 (L.A.R.S. 49:213 et seq.). Passed in 1990, CWPPRA called for the development of a comprehensive Louisiana Coastal Wetlands Restoration Plan (P.L. 101-646 §303.b). The first such plan was completed in 1993 and has been in use since that time. In addition, the Louisiana Coastal Wetlands Conservation and Restoration Task Force and the Wetlands Conservation and Restoration Authority prepared a plan for the coast in 1998 entitled Coast 2050: Toward a Sustainable Coastal Louisiana (Coast 2050).
Coast 2050 was developed under a number of federal and state legislative mandates and is the result of recognition by federal, state, and local
agencies that a single plan and coordinated strategy were needed. Coast 2050 was then appended to the 1999 U.S. Army Corps of Engineers 905(b) reconnaissance report. In October 2003, a draft comprehensive study (Louisiana Coastal Area, LA—Ecosystem Restoration: Comprehensive Coastwide Ecosystem Restoration Study [draft LCA Comprehensive Study]) for implementing coastal restoration was released. After reviewing the draft LCA Comprehensive Study, the U.S. Office of Management and Budget requested a near-term approach to focus the scope of work and maintain restoration momentum. The resulting final version of Louisiana Coastal Area (LCA), Louisiana—Ecosystem Restoration Study (LCA Study) was released by USACE in November 2004. As plans for completion of the LCA Study were being finalized, Louisiana’s Office of the Governor requested that the National Academies review the LCA Study’s effectiveness for long-term, comprehensive restoration development and implementation.
THE CURRENT STUDY
The LCA Study and its envisioned successors are unique in many respects, including geographic scope, pervasiveness of the destructive processes involved, complexity of potential impacts to stakeholders, success of preceding efforts to achieve stakeholder consensus, and documentation of earlier planning and restoration efforts. Indeed, the environmental and social challenges confronting coastal Louisiana in the near and distant future are without precedent in North America. Clearly, execution of the LCA Study alone will not achieve its stated goal “to reverse the current trend of degradation of the coastal ecosystem,” although successful completion of some of the projects outlined in the LCA Study will reduce this trend, thereby representing an important step toward the goal of sustaining or expanding wetlands in some local areas. By definition, the activities proposed in the LCA Study were intended to provide a foundation for successful future restoration and protection efforts, including those developed and implemented in response to hurricanes like Katrina and Rita.
The overall approach taken by the NRC’s Committee on the Restoration and Protection of Coastal Louisiana was to examine the LCA Study and all of its components in detail. This examination, supplemented by presentations from key managers, scientists, and engineers in a series of public meetings in Louisiana, served as the basis for evaluating the usefulness of the LCA Study for developing and implementing a long-term comprehensive program consistent with the broad vision articulated in Coast 2050. The committee was charged with addressing four specific sets of questions (shown in italics).
Q: Are the strategies outlined in the LCA Study based on sound scientific and engineering analyses, and are they appropriate to achieve the goals articulated in the plan? What other approaches might be considered? Are adequate measures of success articulated in the LCA Study?
Taken individually, the majority of the projects proposed in the LCA Study are based on commonly accepted, sound scientific and engineering analyses. It is not clear, however, that in the aggregate, whether or not these projects represent a scientifically sound strategy for addressing coastal erosion at the scale of the affected area. Thus, 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. As stated in numerous USACE policy statements and recommended in past NRC reports, planning and implementation of water resources projects (including those involving environmental restoration) should be undertaken within the context of the larger system. A group of projects within a given watershed or coastal system may interact at a variety of scales to produce either beneficial or deleterious effects. Cost-effectiveness analyses discussed in the LCA Study and in supporting documents reflect an effort to identify least-cost alternatives but do not appear to reflect a system-wide effort to maximize beneficial synergies among various projects. The selection of any suite of individual projects in future efforts to restore coastal Louisiana should include a clear effort to maximize the beneficial, synergistic effects of individual projects to minimize or reverse future land loss. Further, because there is a finite availability of water flow and sediment and many of the proposed projects must function for decades to deliver maximum benefit, care should be taken to ensure that implementation of an individual project does not preclude other strategies or elements that are being considered for the future. To achieve this, the development of an explicit map of the expected future landscape of coastal Louisiana should be a priority as the implementation of the LCA Study moves ahead.
The approaches advanced in the LCA Study focus largely on proven engineering and other methods to address land loss at the local scale. In general, individual projects appear to be based on commonly accepted, sound scientific and engineering analyses. The emplacement of 61 kilometers [km]) (38 miles [mi]) of revetment along the banks of MRGO as one of the five major wetland restoration projects proposed in the LCA Study, however, does not appear to be consistent with the study’s stated goals. Despite an estimated cost of $108.3 million,1 this project is expected
to reduce land loss by only 0.5 km2 per yr (0.2 mi2 per yr) over the next 50 years. (Louisiana is projected to lose an average of 26.7 km2 per yr [10.3 mi2 per yr] over the next 50 years.) Although the location of the land loss may make it more significant, the need for and potential value of this project are directly related to the outcome of a study being conducted by USACE, scheduled for completion in FY 2005, to evaluate the potential decommissioning of MRGO for deep draft navigation. In addition to questions regarding the appropriateness of this particular project, its selection casts doubt on the rigor of the ranking and selection process. The selection of the restoration efforts of MRGO as one of the five major projects to be carried out as part of the LCA Study should be reconsidered in light of the limitations of expected benefits and the results of ongoing studies on the decommissioning of MRGO for deep draft navigation. If a decision is made to decommission MRGO, various options could be considered, including complete closure, that would significantly reduce the need to strengthen the levees along its route. If partial closure is chosen, perhaps maintaining MRGO for shallow draft vessels, some of the work along the outlet may still be required. Restoration efforts requiring planning would be more fully informed once a final decision has been made.
Conflicting stakeholder interests represent one of the greatest barriers to robust coastal restoration efforts in Louisiana. A dominant human-related component of land loss is the constraint on the river system imposed by spoil banks and levees, but these features also provide benefits to a range of stakeholders. By minimizing the cost of dredging and reducing uncontrolled flooding in inhabited and agricultural areas, these features support important local economic activities. Many of Louisiana’s inhabited areas are located on natural levees formed by deposition on the floodplain during major floods. Valuable agricultural land was originally maintained at an elevation above water level through flood-derived sedimentation but is now protected by levees, which preclude new sediment introduction. Obviously, the prospects are low that sediment-rich water will be intentionally allowed to flood broad expanses of urban and agricultural land to maintain elevation with the pace of relative sea level rise.
As discussed above, locating individual projects in an effort to maximize positive synergistic effects will tend to concentrate efforts into selected areas within coastal Louisiana. Although distributing individual projects, and the benefits associated with them, across the entire region may be less contentious, such an approach will either drive up the total cost or reduce the likelihood of success for a given amount of effort and expenditure. Successfully implementing a project selection strategy that maximizes synergistic effects of individual projects will require greater popular support for a comprehensive plan both from within the state and
at the national level. Such support will likely come about only through greater public involvement in the decision-making process of a comprehensive plan. Louisiana’s restoration goals should be better defined and more clearly communicated to the public. This means that maps of the region and projected land-use patterns with and without various restoration projects should be circulated. Without a clarified definition of the temporal and spatial dimensions of “restoration,” unrealistic expectations and disappointments are likely. The projections can be revised as additional data become available and a better understanding is developed through the adaptive management program and the science plan.
Although some inhabited areas will require relocation in order to carry out some proposed wetland restoration efforts, it will be difficult to persuade those affected by local relative sea level rise to abandon their property without a program of financial compensation and a social plan to maintain the cultural integrity of the affected communities. It is important that decisions involving relocation and compensation following Hurricanes Katrina and Rita, or in response to future events, be made in such a manner as to minimize the likelihood of additional relocation or disruption in response to future restoration efforts. The appropriate decisions and responses after major storms have to reflect a broad consensus about the future nature of coastal Louisiana and may have to include managed retreat. Managed retreat and various restoration strategies should include early and active stakeholder participation and concurrence. Relocation could occur either gradually with a few families at a time or at a much higher rate in areas severely affected by Katrina and Rita or future events. This is not intended to preclude reoccupation of the many areas affected by the recent hurricanes or similar events in the future. Rather, this approach is intended to minimize the potential for disrupting lives and property a second time as efforts to protect and restore Louisiana unfold in coming years.
Finally, the LCA Study calls for a long-term study of the possibility of establishing a new lobe of active delta development through a diversion near Donaldsonville, Louisiana. Termed the Third Delta, this proposed restoration feature was among a group of possible features2 that was shown to yield limited benefits at a substantially higher cost than the projects identified for funding in the LCA Study. An alternative scenario for retention of sand and silt now lost beyond the shelf break would involve diverting the main flow of the Mississippi River toward the west of
its present main channel somewhere between New Orleans and Head of Passes. An intermediate- and long-term consequence of this action would be the abandonment of the active Birdsfoot Delta by the Mississippi River. A clear benefit would be the nourishment of eroding coastal reaches to the west. Although this alternative has been widely acknowledged as possible, its feasibility, for various reasons, has not been considered seriously by USACE. Therefore, it is not yet possible to assess the potential advantages and disadvantages of Birdsfoot Delta abandonment at this time. Obviously, implementation of such a strategy would have to be accompanied by the creation of a deep navigation access channel somewhere downstream of New Orleans but upstream of Head of Passes. Though the size of the area it would impact would still make it controversial, some consideration should be given to an alternative or companion to the planned Third Delta, such as a larger-scale diversion closer to the Gulf of Mexico, that would capture and deliver greater quantities of coarse and fine sediments for wetland and barrier island development and maintenance.
Q: What major questions need to be answered to support implementation of the LCA Study? Are the proposed science and technology, demonstration project, and adaptive management programs appropriately structured to fill these information gaps?
A number of technical challenges were identified in the LCA Study that should be adequately addressed through the proposed Science and Technology (S&T) and demonstration project programs (with some modification as discussed below). However, major questions regarding the future magnitude of forces driving land loss and the acceptance by stakeholders of various large-scale projects appear unaddressed by the S&T and demonstration project programs. Both of these questions will be best answered by proceeding with the LCA Study, anticipating to the degree possible, and responding to information as it becomes available. While the knowledge gap associated with the localized role individual processes may play does not preclude successful restoration, it does emphasize the need for a robust adaptive management effort. Thus, the adaptive management program will play a major role in collecting and synthesizing data and charting new directions as appropriate. The S&T Program requires a more explicit statement of program responsibilities and means for setting priorities; it must be integrated more effectively into the central management structure through the adaptive management process and include better representation of social sciences and ecological processes. Additional key questions relate to the causes of land loss, recognizing that the relative role of various processes is location dependent. The future rates of loss are uncertain, and some evidence suggests that the
average rate of land loss across coastal Louisiana may be decreasing. Documented rates of worldwide sea level rise and regional subsidence clearly indicate that in the absence of adequate action, land loss in coastal Louisiana will continue. If, however, the rate of land loss is indeed declining, the potential to more fully offset land loss may be greater as the rate of land building, through various proposed and future efforts, begins to approach the rate at which land is lost through erosion and subsidence.
The S&T Program envisioned in the LCA Study is an innovative and essential element that provides a mechanism for planning and assimilating monitoring results and developing adaptive management strategies. Furthermore, the S&T Program is responsible for model development and maintenance. The proposed S&T Program represents a very positive step in building needed capacity for understanding how coastal Louisiana may respond to various restoration efforts or may evolve in the absence of some of those efforts. However, it is unreasonable to expect any region to have all the necessary experience and human resources to address most effectively the problems at hand. Just as the funding of the LCA Study and its extensions includes a combination of state and federal resources, the scientific and other elements of the LCA Study should draw on the best state, national, and international talents available. Therefore, the LCA Study should direct efforts toward capacity building that enables the program to address its stated objectives by drawing on the widest possible pool of national and international technical expertise. Such capabilities will be especially important as strategies for restoring and protecting Louisiana, in the aftermath of Katrina and Rita, are developed and implemented.
Q: In light of the substantial financial resources that would be required to implement the LCA Study, what are the potential benefits of Louisiana’s coastal restoration to the national economy and the nation’s interests? How best can these potential benefits be more fully evaluated?
The LCA Study states that “execution of the LCA [Study] would make significant progress towards achieving and sustaining a coastal ecosystem that can support and protect the environment, economy, and culture of southern Louisiana and thus contribute to the economy and well-being of the nation.” The economic analysis provided within the LCA Study and its supporting documents, however, includes only cost-benefit analyses of alternative approaches to meet ecosystem restoration objectives, as is consistent with USACE policy for evaluating projects proposed as National Environmental Restoration efforts. Evaluating the benefits of restoring coastal Louisiana in terms of national economic interests, as implied by the statement of task, would have required USACE planners to carry out analyses more consistent with proposing the effort as a National
Economic Development project. USACE officials appeared to view the efforts described within the LCA Study as falling under National Environmental Restoration as opposed to National Economic Development and, thus, did not attempt to identify and meaningfully quantify the contribution to the economy of the nation. Since the information necessary to evaluate proposed coastal Louisiana efforts in terms of the national economy is not provided in the LCA Study, there is insufficient information available for the committee to comment credibly. Carrying out such an analysis would require significant effort and resources beyond those available to the committee in the 10 months following the release of the LCA Study in November 2004. This said, some components of such an analysis can be articulated.
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 demonstrate that substantial economic interests are at stake in coastal Louisiana and that these interests have national significance. The immediate impacts of Katrina underscore the importance of New Orleans, and adjacent areas of the Gulf Coast, to the national economy. Establishing the true, national economic significance of efforts to restore coastal wetlands in Louisiana as proposed in the LCA Study, however, must go beyond simply identifying and characterizing these components and should include an analysis of how specific restoration efforts will preserve or enhance the value of these components (i.e., some restoration efforts may have little influence on the vulnerabilities of specific components of the natural and built environment in coastal Louisiana) and should determine how the national economy would respond to the loss or degradation of components (e.g., what is the capacity for similar components in other regions to compensate for the loss and on what time scales?). If, as implied by the statement of task, greater emphasis is to be placed on the national economic benefits of restoring and protecting coastal Louisiana, future planning efforts should incorporate meaningful measures of the economic significance of these projects to the nation consistent with procedures normally employed to determine the value of a project or a suite of projects for National Economic Development. As a greater understanding of the short- and long-term economic impacts of Katrina and Rita becomes available, a more meaningful effort to evaluate the national economic significance of protecting the natural and built environment in coastal Louisiana will be possible. Such information would provide an important context for decision making; however, it will still be important to understand the role wetlands play in protecting specific components of the overall system and to determine
how specific restoration efforts can enhance that protection. While wetlands and adjacent barrier islands and levees are known to reduce impacts from waves, their more complex role in reducing storm surge is less well known. Surges contain multiple components, including barometric tide effects, wind stress-induced setup, wave-induced setup, and Coriolis forces. As was pointed out repeatedly in the public media during Katrina and Rita, in the northern hemisphere the eastern side of a hurricane tends to drive water northward in a counterclockwise manner. If a storm stalls off a coast for a significant period of time, it will continue to drive water onshore for a prolonged period, regardless of the nature of any intervening wetland or barrier island. Thus, the potential for reducing risk due to storm surge from a particular storm is more difficult to predict.
Conversely, the significance of the coastal Louisiana wetlands to the nation in terms of both their inherent uniqueness and the ecosystem services they provide is more thoroughly documented in the LCA Study, its predecessor reports, and the scientific literature. Although efforts to restore and protect Louisiana’s wetlands will likely provide some unknown but potentially significant protection against coastal storms and hurricanes, those efforts should not be evaluated primarily on their significance for National Economic Development.
Q: Does the phased approach outlined in the LCA Study provide an adequate basis to start developing a comprehensive coastal restoration plan to achieve the broad goals articulated by Coast 2050?
The two major components of the LCA Study, a series of restoration and demonstration projects designed to be implemented over a 10-year time frame and the development of a robust intellectual infrastructure to inform future project design and implementation, are at the heart of the phased approach referred to in the statement of task. This approach has decided advantages and disadvantages. As is clear from the LCA Study, simply keeping pace with land loss in Louisiana will require an ongoing effort. Any substantial gains in the next few decades will require a robust effort, an effort that needs to be well informed by a thorough understanding of both the natural physical and ecological processes involved and the viability of various restoration techniques to address land loss at a massive scale. Establishing methods that allow projects to evolve in the face of increased understanding is prudent. Conversely, limiting project selection to those features where construction can be initiated in 5–10 years presents a significant handicap for laying the groundwork for a comprehensive, multidecadal effort.
For example, the 10-year implementation criterion resulted in the selection of projects that already existed in the USACE and the CWPPRA planning process. This time constraint precluded consideration of projects
with solid potential for long-term benefits that had not yet been fully designed (precluding the initiation of construction in 5–10 years). Similarly, this criterion and the need to demonstrate solid near-term success likely precluded large-scale and innovative projects that (1) affect significant sediment delivery to the system (such as abandonment of the Birdsfoot Delta), (2) maximize synergistic effects for reducing land loss over longer time scales by the selection of strategically located or larger-scale projects, or (3) address some of the difficult issues associated with stakeholder response. While the efforts preceding the LCA Study have achieved a laudable degree of unanimity among stakeholders on the conceptual restoration plan, this unanimity will be tested by the difficult decisions associated with implementation of the larger-scale projects designed to achieve a more effective delivery of sediment, water, and nutrients over a larger area. The project selection procedure requires more explicit accounting of the synergistic effects of various projects and improved transparency of project selection to sustain stakeholder support. Furthermore, beneficial, synergistic interaction among projects cannot be assumed but should be demonstrated through preconstruction analysis.
It is important to note that, by definition, the activities proposed within the LCA Study are intended to lay a foundation for more effective and robust efforts to preserve and protect coastal Louisiana. By its own analysis, the LCA Study points out that constructing the five restoration features it proposes would reduce land loss by about 20 percent (from 26.7 km2 per yr [10.3 mi2 per yr] to 22.3 km2 per yr [8.6 mi2 per yr]) at an estimated total cost of roughly $864 million (or $39,400 per hectare [$15,900 per acre]) over the 50-year life of the projects, not including maintenance and operational costs.
Actual land building will be experienced only in areas adjacent to the implemented projects. The significant investment represented by these projects and the efforts to develop the tools and understanding necessary to support future restoration and protection efforts will yield a substantial return of benefits only if future projects are carried out in a comprehensive manner. The funding required to carry out the activities described in the LCA Study should be recognized as the first of a funding continuum that will be required if substantial progress is to be made. A comprehensive plan to produce a more clearly articulated future distribution of land in coastal Louisiana is needed. Such a plan should identify clearly defined milestones to be achieved through a series of synergistic projects at a variety of scales. (While a comprehensive plan is needed, this does not necessarily imply endorsement of the draft LCA Comprehensive Study, which was not formally released or reviewed as part of this study.) The review detailed in this report found no instance where the proposed activities, if initiated, would preclude development and
implementation of a more comprehensive approach. Conversely, many examples were identified where implementing the proposed activities would support a more comprehensive approach. Thus, the efforts proposed in the LCA Study should be implemented, except where specific recommendations for change have been made in this report and only in conjunction with the development of a comprehensive plan.
As the State of Louisiana and the nation begin to recover from Katrina and Rita, efforts to restore wetlands in Louisiana will likely compete with reconstruction and levee maintenance or enhancement efforts. As this report and numerous other NRC reports have pointed out, efforts to design and implement water resource projects (including environmental restoration and flood control projects) should be carried out within a watershed and coastal system context. Ongoing discussion of long-term response to Katrina and Rita underscores the need to consider restoration and reconstruction as a seamless process that should be informed by a coherent, comprehensive plan that addresses the issues raised in this report. Therefore, efforts to rebuild the Gulf Coast and reduce coastal hazards in the area should be integral components of an effective and comprehensive strategy to restore and protect coastal Louisiana wetlands.