The New Orleans Hurricane Protection System: Assessing Pre-Katrina Vulnerability and Improving Mitigation and Preparedness (2009)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

3 Lessons Learned in Hurricane Katrina and Its Aftermath T he tragedy of Hurricane Katrina and its impacts exposed the many weaknesses in the hurricane protection and preparedness systems for the greater New Orleans metropolitan region. The long history of the authorizations and appropriations, construction, and maintenance of HPS protective structures; the numerous organizations and individuals with hurricane preparedness and response duties; the respective roles of structural and nonstructural approaches in preparedness, and; the large geographic region over which the HPS extends, all complicate ex post evaluations of Hurricane Katrina impacts. Careful appraisal of the root causes of those impacts, and the identification of viable actions for improving preparedness, are essential for reducing the prospects of the recurrence of such an event in the future. This chapter offers technical, organizational, and policy recommendations for improving hurricane preparedness for New Orleans and southeastern Louisiana and responds to the portion of this committee’s statement of task to “determine lessons learned from the Katrina experience and identify ways that hurricane protection system performance can be improved in the future at the authorized level of protection.” The chapter is based on this NAE/NRC committee’s views on the primary lessons learned during the Hurricane Katrina experience, as well as advice on how they might be acted upon and responded to. It reflects the committee’s review of the IPET report and the committee’s collective experience in geotechnical engineering, hurricane wave and storm studies and modeling, water resources planning, and natural hazards mitigation and preparedness. Many of the lessons presented below do not represent new findings that were learned for the first time during and after Hurricane Katrina. On the contrary, many have been widely recognized and recommended for years by experts and practitioners in the fields of natural hazards, emergency preparedness, civil defense, and other related fields. Unfortunately, much of this information had not been adequately implemented as part of comprehensive hurricane planning and preparedness for the greater New Orleans metro region. This section is presented in the spirit that in the future, these lessons will be more widely appreciated and understood and that hurricane mitigation and preparedness might be enhanced. 21 

22 The New Orleans Hurricane Protection System THE NEW ORLEANS HURRICANE PROTECTION SYSTEM Hydrologic Realities and the Limits of Protective Structures Despite its strategic and economic importance, the New Orleans region always has been vulnerable to flood and hurricane storm surge hazards. The Mississippi River delta is a low-lying region surrounded by waterbodies— namely, the Mississippi River, Lake Pontchartrain, and Lake Borgne—that rise and can overflow during hurricanes and floods. The proximity of New Orleans and southeastern Louisiana to the large, shallow continental shelf of the northern Gulf of Mexico make the area highly vulnerable to Gulf hurricanes and storm surge. The origins of today’s New Orleans hurricane protection system date back to U.S. Army Corps of Engineers’ planning studies in the mid-1950s and issuance of a 1962 interim survey report for the Lake Pontchartrain and Vicinity Hurricane Protection Project (LP&VHPP; Woolley and Shabman, 2007). The major principle guiding the system’s construction and maintenance, as well as post-Katrina repairs and strengthening, has been to “make the city safe.” In this large region of varying topography and elevation, and as demonstrated by Hurricane Katrina and past storms in New Orleans and elsewhere, this guiding principle—although noble—is flawed. Modern protective structures and diligent maintenance and repair efforts can help reduce the risks of hurricanes and storm surge. In fact, the ability of these structures to help protect against storm surge was demonstrated in New Orleans during Hurricane Gustav in early September 2008. The drama surrounding the storm surge of Hurricane Gustav, which nearly (but did not) overtopped a protective (T-wall) structure along New Orleans’s Inner Harbor Navigation Canal was broadcast to a national viewing audience. In that instance, that protective structure clearly resulted in a reduction in flood damages in the low lying areas behind that structure. Protective structures, however, do not provide certain protection against all storm surges. They can be overtopped in large storms and there always is the risk of future—even with well-constructed and maintained structures. Thus, even in areas behind well-built structures, some risk—referred to as “residual risk”—will exist to inhabitants and structures. Structures can reduce some hydrologic risks but all flood and hurricane storm surge risks in this region never can be fully eliminated. It therefore is critical to consider a guiding principle for these protective structures as one that seeks to reduce risks from hurricanes and storm surge—but recognizes that such risks cannot be fully eliminated and, as such, augments flood and hurricane protection by protective structures with complementary measures such as floodproofing of buildings, evacuation plans, and comprehensive land use planning. In fact, the IPET recognizes and supports 

Lessons Learned in Hurricane Katrina and Its Aftermath 23 this principle in its report. Again, from the IPET report: “…No matter how well designed an HPS may be, some level of residual risk always remains: risk is never reduced to zero. Therefore, even with the construction and strengthening of the New Orleans HPS, some residual risk will always remain (IPET, 2008, VIII-12). Similarly, in a 2006 report from the Interagency Levee Policy Review Committee, that group noted that, “Levees only reduce the risk to individuals and structures behind them; they do not eliminate the risk. In fact, in many cases, they can create significant and potentially catastrophic residual risk that may increase if conditions in the region change, if levees are affected by natural events, or if the levees are not properly maintained” (Interagency Levee Policy Review Committee, 2006; italics in original). In 2007, the Association of State Floodplain Managers issued a position paper entitled “Levees: The Double-edged Sword” (ASFPM, 2007). This paper discusses many of the pros and cons of relying too heavily upon levees for flood protection. Several conclusions and recommendations from the ASFPM are relevant to hurricane protection in New Orleans and are consistent with this NAE/NRC committee’s views on lessons learned in the Hurricane Katrina experience. Key points from the ASFPM report thus are presented in Box 3-1. BOX 3-1 Views from the Association of State Floodplain Managers on Flood Protection Provided by Levees The Association of State Floodplain Managers (ASFPM) 2007 report, “Le- vees: The Double-edged Sword” is a thoughtful and succinct exposition of the pros and cons of relying on levees to provide flood protection. Many of the report’s rec- ommendations overlap and are consistent with the lessons learned section in this NAE/NRC committee report. This box does not list all of the ASFMP report find- ings and recommendations; rather it presents those that are most relevant to this committee’s report. Elected officials, business owners, and citizens in the New Orleans region interested in another perspective on some of the limitations of relying too heavily upon levee systems will find the ASFPM document of interest. Several key points from the ASFPM paper—and that are especially rel- evant to this committee’s report—are contained in a paragraph in the paper’s Introduction: Because of the nature of levee failure flooding, the ASFPM believes that levees are not a wise community choice and should never be used to protect undeveloped land so development can oc- cur in the flood risk area behind the levee. However, many levees already exist in the nation, especially in communities that were built right on the river or coast, usually at a time when the nation was convinced it could engineer its way out of flooding. Where levees already exist, or where a levee appears to be the best option after careful analysis of all alternatives to mitigate the incidence of flood- ing to existing development, the ASFPM advocates that levees (1) continued 

24 The New Orleans Hurricane Protection System BOX 3-1 Continued must be designed to a high flood protection standard; (2) must be frequently and adequately inspected, with all needed maintenance continufunded and performed (if this does not occur, the levee must be treated as nonexistent); (3) should be used only as a method of last resort for providing a LIMITED means of flood risk reduction for existing development; and (4) are inappropriate as a means of protecting undeveloped land for proposed development (ASFPM, 2007, all caps in original). Other relevant quotes from the ASFPM paper for this committee’s report and hurricane and storm surge protection in New Orleans are: In those cases in which a levee is found to be an appropriate mea- sure to protect urban areas or to be credited for protection, the levee should be constructed to a high level of protection. As described in various reports, the level of the 500-year flood, plus freeboard, is considered an appropriate minimum protection standard with urban areas. . . The 500-year standard for levee design is just as arbitrary as the 100-year standard so the question becomes, “what level of risk to public safety can we accept?” When one compares the potential for fire damage to an individual home, case history would indicate that a 100-year standard falls far short of the level of protection afforded by modern fire systems . . . today’s fire systems tend to significantly limit the degree to which an entire community can be affected by fire, yet we continue to use a much lower threshold in levee design that most certainly will result in community-wide inundation. An added element of risk in current design practices is the lack of designing “planned failure” into levees. When levees fail, either by structural failure or overtopping by flood waters that exceed the de- sign event, the results are often catastrophic . . . In many instances it is useful to design levees to withstand overtopping, or to control the overtopping to a limited number of spillways designed into the system. The aim is to prevent the loss of the levee, by allowing it to be overtopped and slowly flood the area in planned locations rather than randomly, so that damage is reduced and the community can recover more quickly. There is now widespread misunderstanding of the true risks associ- ated with levees. This in turn has helped lead to the current over-re- liance on structural solutions to reduce the impact of flooding, and to the creation of a false sense of security among those living, working, or seeking to build in areas behind levees. Communication with citizens and stakeholder groups is rarely an explicit consideration when levees are permitted or built, or in the development of policy for levee design, insurance, or regulation. . . Communication of the residual risk associated with any levee is key to public understand- ing and acceptance of appropriate public safety and flood risk reduc- tion policies in the nation. 

Lessons Learned in Hurricane Katrina and Its Aftermath 25 A related lesson from the history and construction of the Lake Pontchartrain and Vicinity Hurricane Protection Project regards the construction of protective structures in low-lying areas, with subsequent settlement in those areas. With the construction of levees and other protective structures, settlement and development took place in the areas behind those structures, and the population of the city grew. As with many structures built to protect against riverine or coastal flooding, the Lake Pontchartrain and Vicinity Hurricane Protection Project promoted a false sense of security that areas behind the structures were absolutely safe for habitation and development. Unfortunately, there were substantial “residual” risks in these areas behind the protective structures that never were adequately communicated to the public and that were not adequately considered in the settlement of many of these areas. LESSON: There are many inherent hydrologic vulnerabilities of living in the greater New Orleans metropolitan region, especially in areas below sea level. Post-Katrina repairs and strengthening have reduced some of these vulnerabilities. Nevertheless, because of the possibility of levee/ floodwall overtopping—or more importantly, levee/floodwall failure—the risks of inundation and flooding never can be fully eliminated by protective structures no matter how large or sturdy those structures may be. Future Footprint of the Hurricane Protection System Given the specific areas of overtopping and the substantial damage to the pre-Katina HPS, some rethinking about the extent and configuration of the HPS structures—or its ‘footprint’—would seem to be a pressing priority. The pre- Katrina HPS footprint clearly had many flaws and vulnerabilities: The system did not perform as a system. In some areas it was not completed, and in others, datum misinterpretation and subsidence reduced its intended protective elevation. The capacity for protection varied because of some structures that provided no reliable protection above their design elevations and others that had inadequate designs leaving them vulnerable at water levels significantly below the design intent. The designs of the levee-floodwall structures along the outfall canals were particularly inadequate (IPET, 2008, p. I-2). It is entirely appropriate therefore that discussions of the future HPS plans would focus on how a new—and different—system footprint would be designed and implemented. For example, the creation of a smaller footprint might offer advantages in terms of cost, inspection and maintenance requirements, and the 

26 The New Orleans Hurricane Protection System prospect to create a more manageable system of protective structures. At the very least, pros and cons of a smaller footprint should be a topic for discussion and debate. Nevertheless, it appears that post-Katrina rebuilding activities are taking place largely according to the pre-Katrina HPS design without discussions of how a safer and more reliable design might be configured. The additional investments necessary to rebuild and strengthen the HPS according to the pre-Katrina footprint, which included roughly 350 miles of levees, are substantial. The required investments will be far greater if these structures are to be made higher or sturdier. They also would be greater if the levees are to receive more frequent and thorough inspection and maintenance. Furthermore, regardless of the level of investments, the residual risks of hurricane storm surge always will be significant for some areas behind these protective structures. LESSON: The pre-Katrina footprint of the New Orleans HPS consisted of roughly 350 miles of protective structures including levees, I-walls, and T-walls. There was undue optimism about the ability of this extensive network of protective structures to provide reliable flood protection. Future construction of protective structures for the region should proceed with these lessons firmly in mind and in the context of a more comprehensive and resilient hurricane protection plan. NONSTRUCTURAL ASPECTS AND OPTIONS Relocation People will continue to live in this region, but flood protection and preparedness plans should be implemented with some criteria for priority areas for protection. That is, even if vast amounts of resources were available, it likely would not be possible to provide equal degrees of storm surge protection to all areas of the greater New Orleans region. For instance, higher-elevation parts of the region—such as areas on the natural Mississippi River levees—inherently are safer than lower-lying areas—such as extensive areas below sea level in St. Bernard’s, Orleans, and New Orleans East parishes. Areas at or below sea level are especially dangerous, and protective structures never can provide certain protection against hurricane storm surge and flooding. Reconstructing all pre-Katrina protective structures, and creating settlement patterns just as they existed before Katrina, simply would position the city and its inhabitants for additional, Katrina-like disasters in future big storms. Although it can be a politically charged topic, the option of voluntarily relocating some structures and residents is one means to help improve safety and reduce flood damages. The Corps has recognized the value of voluntary buyouts and relocations in another study it is conducting in southern Louisiana. 

Lessons Learned in Hurricane Katrina and Its Aftermath 27 Entitled “Louisiana Coastal Protection and Restoration” (or LACPR) the Corps is conducting a comprehensive hurricane protection analysis and is considering a broad range of flood control, coastal restoration, and hurricane protection measures (USACE, 2008). A section of its 2008 draft technical report includes discussion of nonstructural measures and alternatives. That section states that: For the purposes of the LACPR plan formulation, buyout/ relocation of structures and elevation of structures are considered to be the most viable nonstructural measures for overall applicability across South Louisiana. . . Nonstructural measures, such as buyouts and relocations, can provide opportunities for alternate uses of the vacated flood plain, such as ecosystem restoration, recreational development, or urban green space (USACE, 2008). A report from a National Research Council committee reviewing the Corps’s LACPR study concurred with these statements from the Corps draft report, concluding that “The relocation option often provides an excellent means for improving safety and reducing potential damages” (NRC, 2008b). LESSON: The planning and design for upgrading the current hurricane protection system should discourage settlement in areas that are most vulnerable to flooding due to hurricane storm surge. The voluntary relocation of people and neighborhoods out of particularly vulnerable areas—with adequate resources designed to improve their safety in less vulnerable areas—should be considered as a viable public policy option. Floodproofing and Strengthening Critical Infrastructure New Orleans presents a special and complex situation with regard to hurricane preparedness and planning. There are large numbers of structures and residents in areas across the city near or below sea level. This situation poses considerable logistical challenges to relocation efforts, and it also prompts tough questions about the future of the city. For those many structures and residents in vulnerable areas that are not amenable to relocations, major floodproofing measures are recommended in order to improve public safety from hurricane storm surge. This committee especially endorses the practice of elevating the first floor of building to at least the 100-year flood level, and preferably to a more conservative elevation. The more conservative elevation reflects a later finding in this report regarding the inadequacy of the 100-year flood level as a flood protection standard for a large urban center such as New Orleans. In addition, attention should be given to strengthening critical 

28 The New Orleans Hurricane Protection System infrastructure, such as electric power transmission and distribution facilities, water supply systems, natural gas, telecommunication networks, and the system of storm water collection and pumping facilities essential for removing flood water from New Orleans. Improvements in building codes and construction practices also are essential to well-designed housing and infrastructure that are able to withstand a major levee breach. Electric power is essential for proper functioning of infrastructure, and is especially important for the operation of flood water pumping facilities. Hurricane Katrina caused unprecedented damage to the electric power system in and surrounding New Orleans through flooding of substations in low-lying areas and wind damage to overhead transmission lines. The electric power system was slow to recover; four weeks after Hurricane Katrina—when nearly 20 percent of regional customers were without power—Hurricane Rita struck an already weakened system, causing further extensive damage. The loss of electric power interrupted the flow of critical oil and refined petroleum products by shutting down pumping stations that were otherwise functional. The restoration of power, so important for emergency response, community safety, and economic recovery, was further delayed by lack of a comprehensive plan by government agencies to integrate emergency operations with the return of electricity. The pumping facilities for flood water are of key importance in New Orleans. The reliability of the pumping system requires an assessment of power availability, plans for restoration of electricity from utilities, and the ability to protect and support pump station operators during an extreme event. The strengthening of critical infrastructure requires careful planning. The loss of population in New Orleans after Hurricane Katrina affects directly the sustainability of critical infrastructure, through loss of revenue from both public and private utility rate payers. The restoration and maintenance of critical infrastructure therefore requires coordination with neighborhood restoration, dealing with the uneven density of the post-Katrina population, and the development of innovative public/private partnerships. LESSON: When voluntary relocations are not viable, floodproofing measures will be an essential complement to protective structures—such as levees and floodwalls—in improving public safety in the New Orleans region from hurricanes and induced storm surge. This committee especially endorses the practice of elevating the first floor of buildings to at least the 100-year flood level, and preferably to a more conservative elevation. The more conservative elevation reflects a subsequent finding in this report regarding the inadequacy of the 100-year flood as a flood protection standard for a large urban center such as New Orleans. Critical public and private infrastructure—electric power, water, gas, telecommunications, and flood water collection and pumping facilities— should be strengthened through reliable construction, ensuring reliable interdependencies among critical infrastructure systems. 

Lessons Learned in Hurricane Katrina and Its Aftermath 29 Evacuation The pre-Katrina warning and evacuation plans and measures for New Orleans and southeastern Louisiana were extensive. There were ongoing media announcements for days before Katrina made landfall, weather forecasters tracked the storm carefully and their forecasts were reasonably accurate, and extensive efforts were made to warn residents of the approaching storm. There were road signs and flyovers that allowed for large volumes of traffic to move in one direction, and a very large percentage of the population was successfully evacuated out of New Orleans and to other communities. Despite the best efforts of city and state officials, police and fire departments and other public safety personnel, and many others, however, the collective plans and efforts were inadequate to safely evacuate all residents, especially the sick, poor, and elderly. Hurricane evacuation poses special planning and decision making challenges for the city of New Orleans and southern Louisiana. On the one hand, evacuations are stressful, inconvenient, expensive, and are especially difficult for ill and elderly residents. The unpredictable nature of hurricanes as they approach land means that there will be evacuations in instances in which a hurricane does not strike a given city or region. An area may have multiple and legitimate evacuations in a single season, and concerns over public safety make evacuations a way of life in coastal areas threatened by hurricanes. At the same time, successive evacuations in which a hurricane does not strike a given city or region will contribute to “evacuation fatigue.” Even though evacuations in which a storm dissipates or veers away from a city are inevitable, evacuation fatigue is a social and a political reality. It affects decision makers and it affects the public, and can encourage a “ride the storm out” mentality, thereby reducing the efficiency of future evacuations. Finding the correct balance between public safety concerns and the issuance of evacuation orders as a storm approaches, while trying to minimize possible evacuation fatigue, is a challenging decision process for elected officials and emergency managers. As no structure can ensure complete protection against all floods and storm surges, an efficient evacuation program will be a part of comprehensive hurricane protection. As is pointed out in its own Lessons Learned section of the Executive Summary in its draft final report, the IPET noted that, “The emergency response preparedness and efficiency of evacuation prior to a storm is a key component to reducing risk to life and human safety” (IPET, 2008, p. I-5). The IPET Volume VII also concluded that “Loss of life and evacuation planning should be an integral part of hurricane protection system planning and design as well as in local planning and operation. Especially vulnerable portions of the population warrant special consideration” (Vol. VII-14). An improved and more efficient evacuation program for New Orleans will be based on further and more systematic studies, plans, and communication. A 

30 The New Orleans Hurricane Protection System more efficient evacuation program and strategy will include not only public announcements and plans for re-routing traffic, but also alternatives that may make evacuations less imposing and burdensome. For example, the construction of additional and better short-term emergency shelters in nearby areas may improve efficiency and compliance with evacuation orders. Longer- term improvements may include the siting of facilities of elderly or chronically ill patients in areas less vulnerable to hurricanes and where evacuations may be less necessary and frequent. The evacuation of a large metropolitan area such as New Orleans presents numerous logistics and related challenges. To ensure public safety, residents must be evacuated well in advance of approaching hurricanes, and considering uncertainties in storm paths, the decision heavily favors issuing an evacuation order “better safe than sorry.” This means that there will be evacuations in areas and cities that ultimately are not affected by a given storm, and a city or region may have multiple, legitimate evacuations in a single season with no actual storm damage. Evacuation fatigue can result from repeated evacuation orders and will affect the decision making of public officials and the effectiveness of future evacuations. It is exceptionally difficult to strike the correct balance between ordering legitimate evacuations to ensure public safety and the reality of evacuation fatigue. LESSON: The disaster response plan for New Orleans, although extensive and instrumental in successfully evacuating a very large portion of the New Orleans metropolitan area population, was inadequate for the Katrina event. Thus, there is a need for more extensive and systematic evacuation studies, plans, and communication of evacuation plans. A comprehensive evacuation program should include not only well designed and tested evacuation plans, protocols, and criteria for evacuation warnings, but also alternatives such as improved local and regional shelters that could make evacuations less imposing. It also should consider longer-term strategies that can enhance the efficiency of evacuations, such as locating facilities for the ill and elderly away from more vulnerable areas that may be subject to frequent evacuations. Risk Communication Clear and effective risk communication is a fundamental component of a reliable hurricane protection and preparedness program. Effective communication of hurricane and storm surge risks represents a substantial challenge for scientists, engineers, and public officials, in that often-sophisticated science and engineering concepts must be summarized and explained in terms that most citizens will be able to grasp. Risk communication has for many years been a field of formal inquiry 

Lessons Learned in Hurricane Katrina and Its Aftermath 31 and research, and a recent volume of collected papers considered many of the broad lessons learned in the field of risk communication as a result of Hurricane Katrina (Daniels et al., 2006). The contributors to this volume wrote on topics ranging from risk and decision analysis, natural disaster insurance, and risk management. According to the editors of this volume: Katrina revealed a large gap between the capacity of our policies and institutions and our needs, as individuals and as a society. We need a fresh understanding of the problems and new and creative solutions to tackle them. That is the most important lesson of Katrina, and if we fail to learn it, Katrina’s legacy will not be “bigger and better.” It will be “bigger and worse.” (Daniels et al., 2006). Unfortunately, in the greater New Orleans metropolitan region, the residual risks associated with living behind levees either were not well understood, or not well communicated, or both. Again, the Interagency Levee Policy Review Committee: “The public at large and public officials generally do not understand the residual risk to those living behind levees” (Interagency Levee Policy Review Committee, 2006). Effective communication of the vulnerabilities of the New Orleans region to hurricanes and storm surge will encompass many of the concepts discussed in this report and evaluated in the IPET report, such as uncertainties of storm surge inundation estimates, changes in vulnerabilities over time, effective evacuation planning, and so on. Increasing public awareness of hurricane and storm surge risks will constitute an ongoing challenge for the Corps of Engineers, the State of Louisiana, parish and city governments, and local and regional media outlets. LESSON: Before Katrina, there was a limited understanding and appreciation of the residual risks of living behind levees. Improvements in future hurricane preparedness and response will depend partly upon improved public understanding of these risks. In order to enhance the communication and appreciation of these risks, it will be important to extend the work of the IPET and to refine, simplify, and communicate consistently the risks of hurricanes and storm surge to the region’s residents, including how those risks vary across the region. Effective communication of the risk- based findings from the entire IPET report will be enhanced by creating a professional summary and compilation of the entire IPET draft report with layman’s terminology (see earlier recommendation in this report). 

32 The New Orleans Hurricane Protection System THE 100-YEAR LEVEL OF FLOOD PROTECTION The concept of level of protection is central to levee design and flood protection. In the United States, the use of structures designed to protect against the 100-year flood has become a standard practice. The history of this 100-year standard derives from both administrative convenience and its importance in determining rates of flood insurance under the federal National Flood Insurance Program (NFIP; see NRC, 2000, for more details on the National Flood Insurance Program, the 100-year flood, and levee certification procedures; also see ASFPM, 2007, for discussion of flood protection and levee standards for urban areas). In repairing and strengthening of the hurricane protection system, significant attention has been given to protection at the 100-year level. IPET has focused part of its analyses on the 100-year level of protection (both Task Force Guardian and the Corps’ Louisiana Coastal Protection and Restoration (LACPR) study also have used this standard in the context of their efforts). Given the inadequate protection afforded by the pre-Katrina hurricane protection system, it is understandable why one would choose to focus first on providing protection from at least a 100-year event. However, for heavily urbanized regions, the 100-year standard level of protection from flooding generally is inadequate. For example, a structure located within a special flood hazard area shown on an NFIP map has a 26 percent chance of suffering flood damage during the term of a 30-year mortgage (http://www.fema.gov/faq/faqDetails.do?action=I nut&faqId=1014). The IPET team also concluded that “The 100-year de facto standard is far too risky for the continued vitality of our economy that is highly dependent on the viability of the public infrastructure and the continuity of the economy.” The 100-year standard has driven levels of protection below economically optimal levels, has encouraged settlement in areas behind levees, and resulted in losses of life and vast federal expenditures following major flood and hurricane disasters. LESSON: The 100-year level of flood protection is a crucial flood insurance standard. It has been applied widely across the nation and it is being used in some circumstances in reconstruction and planning activities in the New Orleans region. For areas in which catastrophic levee failure is not a major public safety concern, and where large floods would not imperil evacuation routes, the 100-year standard may be appropriate. For heavily- populated urban areas, where the failure of protective structures would be catastrophic—such as New Orleans—this standard is inadequate. 

Lessons Learned in Hurricane Katrina and Its Aftermath 33 INDEPENDENT REVIEW FOR ENGINEERING AND DESIGN Selection and support for external review is important to promote fresh thinking as part of large, complex, and interdisciplinary ventures such as hurricane protection system maintenance and operations, and hurricane preparedness planning. Independent review also allows an opportunity for the input of external, expert opinion on issues that may be politically sensitive and that local staff members may be reluctant to raise. This point is especially relevant with regard to the New Orleans hurricane protection system, as there was no organizational process that required continual assessments of project performance capabilities: The absence of a standing, agency-wide process for continuing assessment and reporting of project performance capability left the District to make its own determination as to whether the analytical foundation was adequate for requesting changes to project designs, and for satisfying higher federal authorities and local sponsors that additional project funding was warranted (Woolley and Shabman, 2007, p. ES-17). Additional advice on structuring a peer review process within the Corps of Engineers is in NRC, 2002, which reports specifically on this topic. Relevant findings and recommendations from that NRC report (NRC, 2002) include: • Τhe Corps should institute external review for studies that are expensive, that are highly controversial, that will affect a large area, or that involve high levels of risk; • A review panel should be given the freedom to comment on those topics that it deems relevant to decision makers; and • Review panels should not be tasked to provide a final, “thumbs up/thumbs down” judgment on whether a particular alternative from a planning study should be implemented, as the Corps of Engineers is ultimately responsible for this final decision. LESSON: It is important to enlist periodic external review in the design, construction and maintenance of large, complex civil engineering projects such as the New Orleans hurricane protection system. A “second opinion” allows an opportunity to ensure that calculations are reliable, methods employed are credible and appropriate, designs are adequate and safe, potential blind spots are minimized, and so on. An outside external review group also may be able to state politically sensitive findings or facts 

34 The New Orleans Hurricane Protection System that a government agency may be reluctant to. Such a review team should be adequately independent of the authority that identified it (for further discussion, see NRC, 2002). Periodic Assessments and Updates of Concepts, Methods, and Data A topic related to independent review is a need to ensure that hurricane protection system maintenance, inspection, and upgrades are being carried out consistent with current information of scientific and engineering concepts, methods, and data. As environmental conditions change, data sets are updated, models are improved, and new concepts are implemented, it is important to have a process that integrates this new information into decision making and ensures that the hurricane protection system continues to meet its performance objectives. An example from the New Orleans hurricane protection system of problems that can ensue if this is not done is that of the Standard Project Hurricane, or SPH. The Lake Pontchartrain and Vicinity Hurricane Protection Project used the SPH as its performance standard (Woolley and Shabman, 2007). The original estimate of the level of protection for the Lake Pontchartrain and Vicinity Hurricane Protection Project was in excess of 200 years. This level of protection was derived from the standard project hurricane stillwater design storm surge used in 1962 (Ibid.). By the early 1970s, and with the addition of hurricanes like Betsy and Camille to the windspeed and central pressure databases, recalculation of the level of protection or return interval of the 1962 SPH design surge would have resulted in estimates that were significantly less than 200 years. This is but one example of how changes in environmental conditions, data sets, or models and methods can impinge upon hurricane system performance. A routine process of periodic review of scientific data and concepts could help identify these types of changes, and offer recommendations for related system performance upgrades. There are other examples of why changes in environmental conditions, and updates and improvements in scientific and engineering methods, necessitate reviews and updates. For example, subsidence affects levee elevations and levels of performance of the HPS: levee heights ideally would be surveyed periodically to determine changes in system reliability. Engineering advances in technical methods in the design of I-walls and other protective structures, or updates and changes in materials used in protective structures, ideally would be periodically infused into maintenance and improvements of the HPS. The processes and requirements of congressional authorizations can complicate the incorporation of new scientific information. New scientific information on factors such as changing environmental conditions or design 

Lessons Learned in Hurricane Katrina and Its Aftermath 35 methods can affect original authorizations and may require reauthorizations. In New Orleans, the Corps of Engineers and its project cost-sharing partners were reluctant to incorporate 1979 Weather Bureau revisions to the standard project hurricane concept in 1984 when the project was reevaluated. A significant argument for not incorporating the new information was a fear that the project might have to be reauthorized. At the time, Congress had not authorized any projects since 1974 because of a prolonged debate over new cost-sharing rules that might have affected this project had it been reauthorized (Woolley and Shabman, 2007). Reauthorization would have taken several years at best, the outcome of those discussions would have been uncertain, and there could have been substantial financial implications because of significantly revised cost- sharing formula. LESSON: Changing environmental conditions can affect the performance and operation of large hurricane and flood protection projects. Advances in scientific and engineering theories and methods may render previous assumptions on which these projects were based partly or fully obsolete. Because of these changes and the important implications they may have for expected performance of protective structures, a process should be implemented to ensure periodic review of underlying environmental, scientific, and engineering factors that affect New Orleans hurricane protection system performance. The process for incorporating new scientific information into large flood protection projects, like the New Orleans hurricane protection system, can be affected by congressional reauthorization requirements. Changes or clarifications to congressional policies and reauthorizations as they relate to large construction projects may be necessary to effectively implement findings of periodic scientific reviews. THE FUTURE OF HURRICANE RISK ANALYSIS FOR NEW ORLEANS AND THE GULF COAST REGION The analyses performed by the IPET were extensive and involved the investigation of many factors crucial to effective hurricane planning and preparedness. The IPET studies were not conducted as a standard part of the work program of the Corps New Orleans District office; rather, they represented a specially commissioned set of investigations with a specially appointed team of engineers and scientists. Many of these experts were Corps of Engineers staff from outside the New Orleans District, while some were recruited from academia and the private sector. Some Corps of Engineers staff involved in the study were nearing the end of their careers, and there were some retirements during the 3+-year IPET study effort. As the IPET investigations come to an end, many of the external experts 

36 The New Orleans Hurricane Protection System that participated in the studies will return to their respective careers outside the Corps of Engineers. Much of the IPET “institutional memory” therefore may not be infused sufficiently into Corps of Engineers New Orleans District office, the State of Louisiana, or the City of New Orleans. There thus is the potential for much of the IPET effort to not be adequately implemented into future HPS system improvements and in hurricane planning and preparedness in south Louisiana. The majority of the responsibilities for extending and building upon the IPET studies will fall to the Corps of Engineers New Orleans District office. It will be important that the analyses and findings from the IPET be incorporated into future activities and plans of the New Orleans District, and also the State of Louisiana, the City of New Orleans, and local parishes. LESSON: The IPET has conducted a landmark assessment of the New Orleans HPS that could serve as a platform for future and ongoing assessments of vulnerability, levels of protection, subsidence rates, geological studies, risk assessments, and so on. As the IPET investigations come to an end, many of the external experts that participated in the studies will return to their respective careers outside the Corps of Engineers. Much of the IPET “institutional memory” therefore may not be infused into Corps of Engineers New Orleans District office, the State of Louisiana, or the City of New Orleans. It is essential that these analyses be extended and subsequently built upon by the Corps of Engineers and others, including the FEMA, NOAA, the State of Louisiana, New Orleans regional municipalities, and the region’s universities, engineers, and scientists. To facilitate future work that builds on the IPET studies, a publicly accessible archive of all data, models, model results, and model products from the IPET project should be created.