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The factor of safety (FS) of levees and floodwalls with relief wells to underseepage is predicated on the blanket thickness and relief well performance. In urban environments with limited right of way, relief wells are an option for addressing underseepage and sand boil development. Instead of adding more wells if problems persist, this study investigates the potential of active pumping at relief wells as an alternative to increase levee and floodwall factor of safety against underseepage. Optimization of relief well operations is achieved by a multiobjective mixed-integer nonlinear programming (MOMINLP) approach. The relief well operations optimization is demonstrated at the Inner Harbor Navigation Canal (IHNC), New Orleans, Louisiana, near the Seabrook Bridge at Lake Pontchartrain. Relief well evaluation at the water level corresponding to the 500-year return storm shows high total head at most IHNC West relief well sites. Relief well operations optimization provides decision makers useful tradeoffs between averaged FS deficit, total pumping rate, and the number of pumping wells for making pumping decisions. This study found that the Pareto-optimal solutions provide reasonable pumping rates, where all of the midway between relief wells in the IHNC West may meet the requirement FS>1.5. The study also found that minimizing the number of pumping wells and minimizing the total pumping rate are influential objectives for deriving efficient pumping strategies. Sensitivity analysis on IHNC water stage found that FS improvement becomes marginal after total pumping rate reaches a threshold, especially at low IHNC water stages. [ABSTRACT FROM AUTHOR]

Hurricane Katrina created a catastrophe in the City of New Orleans when the storm surge caused the levee system to fail on August 29, 2005. The destruction of housing displaced hundreds of thousands of residents for varying lengths of time, often permanently. It also revealed gaps in our knowledge of how population is recovered after a disaster causes widespread destruction of urban infrastructure and housing. In this article, I identify social, spatial, and temporal explanatory frameworks for housing and population recovery and use them to review research findings on mobility—both evacuation and migration—after Hurricane Katrina. The review reveals a need for a comprehensive social, spatial, and temporal framework for explaining inequality in population displacement and recovery. [ABSTRACT FROM AUTHOR]

The article discusses the residents living near the U.S. Mississippi River's relationship with the river, heavily referencing anecdotes from the author's experience of growing up on the mouth of the river in New Orleans, Louisiana. An overview of the impact of the Mississippi River on Plaquemines Parish, Louisiana, including in regard to the 1927 Great Mississippi River Flood and the 2012 Hurricane Isaac damage to the parish when the Mississippi River water went over the levee, is provided. INSET: 59.

An essay is presented on the misconceptions and myths surrounding the hurricane Katrina that struck in New Orleans, Louisiana on August 29, 2005. These myths include the breach of levees the day after the hurricane, the failure of the levees on the Mississippi River, and the intensity of the storm that it overwhelmed the city that resulted in massive flooding.

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The article focuses on the use centrifuge for scale modelling of levee-sections on the 17th Street, Orleans and London Avenue Canals as part of the Interagency Performance Evaluation Task Force (IPET) investigation into levee breaches after Hurricane Katrina in New Orleans, Louisiana. It observes mechanism which lead to breaching of the levee in the models which stemmed from a water-filled crack forming in the front of the flood wall. The crack leads to rotation of flood wall land wards.

Erosion was one of the major causes for the failure of New Orleans levee system during Hurricane Katrina. Protection of flood walls from erosion failure can be achieved in many different ways. This study consisted of experimental research to develop engineered flood wall surfaces that can reduce the erosion energy of the plunging water before the water hits the levee surface, so that the flood protection system becomes more resilient. Test results were compared to hydrodynamics simulation results by using FLOW3D. The results revealed that the erosion resistance of levees can be substantially reduced by providing protective structures at the surface of the flood walls. An effectively designed protective structure could reduce the erosion depth as much as 40% and extend the erosion time as much as 400%. [ABSTRACT FROM AUTHOR]

En s'installant, en 1718, dans la région marécageuse de la vallée inférieure du Mississippi, les colons prirent des risques énormes pour leur santé. Les condi- tions régnant dans les environs de La Nouvelle-Orléans, préjudiciables à la santé humaine, étaient en forte contradiction avec les avantages stratégiques et économiques que la région offrait. Les colons réussirent à s'adapter rapidement à leur nouvel environnement. En plus de s'habituer à la chaleur, à l'humidité, aux marais et aux moustiques, les habitants modifièrent les terres pour qu'elles soient plus adaptées aux besoins des colons et présentent moins de risques sanitaires. Cherchant à se protéger des épidémies et des maladies, les français combinèrent les connaissances des ingénieurs royaux sur place à des méthodes de contrôle des maladies utilisées en Europe. Ayant reçu une formation solide en France, les ingénieurs prenaient en considération les conditions topographiques particulières de la colonie pour créer des méthodes adaptées aux exigences des colons. Les plus importantes de ces mesures furent la construction de levées et le creusement de fossés pour protéger les terres des inondations qui auraient non seulement endommagé les maisons et les récoltes des habitants, mais aussi généré des miasmes. Les fonctionnaires coloniaux tâchaient de prévenir l'apparition des épidémies en promulguant des ordonnances sanitaires très similaires à celles des villes européennes du Moyen Âge et de l'Ancien Régime. En outre, la santé des colons fut améliorée par l'établissement d'hôpitaux très tôt dans le développement de la colonie. Cependant, malgré l'engagement fort des fonctionnaires royaux, toutes ces mesures n'auraient pas pu réussir sans le soutien des colons et leur acceptation des mesures adoptées. [ABSTRACT FROM AUTHOR]

Abstract: Wave and combined wave-and-surge overtopping was significant across a large portion of the hurricane protection system of New Orleans during Hurricane Katrina. In particular, along the east-facing levees of the Mississippi River-Gulf Outlet (MRGO), the overtopping caused numerous levee breaches. This paper will focus on the MRGO levees, and will attempt to recreate the hydrodynamic conditions during Katrina to provide an estimate of the experienced overtopping rates. Due to the irregular beach profiles leading up to the levees and the general hydrodynamic complexity of the overtopping in this area, a Boussinesq wave model is employed. This model is shown to be accurate for the prediction of waves shoaling and breaking over irregular beach profiles, as well as for the overtopping of levees. With surge levels provided by ADCIRC and nearshore wave heights by STWAVE, the Boussinesq model is used to predict conditions at the MRGO levees for 10h near the peak of Katrina. The peak simulated overtopping rates correlate well with expected levee damage thresholds and observations of damage in the levee system. Finally, the predicted overtopping rates are utilized to estimate a volumetric flooding rate as a function of time for the entire 20km stretch of east-facing MRGO levees. [Copyright &y& Elsevier]

Hurricane Katrina and the resulting failure of the levees that surrounded and protected New Orleans generated a significant detained volume of stormwater within the urban area of New Orleans. Between the inundation resulting from levee failure and eventual pumped evacuation of stormwater from the urban area of New Orleans, a large mass of storm-entrained particulate matter (PM) was deposited in the inundated areas. This study examined the granulometry and granulometric distribution of metals for post-Katrina surficial PM deposits recovered from 15 sites (10 inundated and 5 non-inundated) in New Orleans. Results of this examination were compared to pre-Katrina data from New Orleans. While post-Katrina analysis of PM indicates that Pb, Zn, and Cu concentrations for PM are reduced for all sites, inundated sites had higher Cu, Pb, and Zn concentrations for the settleable (∼25-75 μm) and sediment (>75 μm) size fractions. A comparison between total metal concentration and the bioavailable (leachable) fraction for PM reveals that inundated sites had up to 19% higher leachable metal concentration compared to non-inundated sites. The reduction in PM-bound total metal concentrations for recovered PM can be explained through a combination of scouring (and therefore change in granulometry from pre-Katrina) that resulted from transport of suspended PM by storm flows and pumped evacuation; as well as leaching and PM-based redistribution from extended contact with rainfall and during stormwater detention. New Orleans has been exposed to elevated levels of metals through decades of activities that include vehicular transportation, chemical, industrial, and oil production facilities resulting in higher metal concentrations for urban soil-residual complexes. As a result, the influent storm flows associated with Katrina as an episodic event cannot solely explain the distribution and fate of PM-associated metal concentrations. [ABSTRACT FROM AUTHOR]

Levee failures during Hurricane Katrina left 85% of New Orleans flooded, 1,500 dead, and about 400,000 homeless. Three separate investigations into the levee failures have been concluded, yet none of these studies conclusively determined why the St Bernard polder flooded so deeply, despite Team Louisiana’s conclusion regarding early failure of the Mississippi River Gulf Outlet (MRGO) levees. Detailed wave and hydrodynamic modeling reported here reveals the cause of extensive breaching of the MRGO levees and how that created a very efficient conduit of surge water into the heart of the city. [ABSTRACT FROM AUTHOR]

Background: Empirical observations on how businesses respond after a major catastrophe are rare, especially for a catastrophe as great as Hurricane Katrina, which hit New Orleans, Louisiana on August 29, 2005. We analyzed repeated telephone surveys of New Orleans businesses conducted in December 2005, June 2006, and October 2007 to understand factors that influenced decisions to re-open amid post-disaster uncertainty. Methodology/Principal Findings: Businesses in the group of professional, scientific, and technical services reopened the fastest in the near term, but differences in the rate of reopening for businesses stratified by type became indistinguishable in the longer term (around two years later). A reopening rate of 65% was found for all businesses by October 2007. Discriminant analysis showed significant differences in responses reflecting their attitudes about important factors between businesses that reopened and those that did not. Businesses that remained closed at the time of our third survey (two years after Katrina) ranked levee protection as the top concern immediately after Katrina, but damage to their premises and financing became major concerns in subsequent months reflected in the later surveys. For businesses that had opened (at the time of our third survey), infrastructure protection including levee, utility, and communications were the main concerns mentioned in surveys up to the third survey, when the issue of crime became their top concern. Conclusions/Significance: These findings underscore the need to have public policy and emergency plans in place prior to the actual disaster, such as infrastructure protection, so that the policy can be applied in a timely manner before business decisions to return or close are made. Our survey results, which include responses from both open and closed businesses, overcome the ''survivorship bias'' problem and provide empirical observations that should be useful to improve micro-level spatial economic modeling of factors that influence business return decisions. [ABSTRACT FROM AUTHOR]

This article explores the origin and implications of the rumor that government authorities intentionally destroyed the levee fronting New Orleans's lower 9th Ward during Hurricane Katrina. The author argues that these rumors should not be dismissed as fanciful conspiracy theories, but must instead be placed in the context of New Orleans's environmental history. That history includes numerous episodes in which commercial elites colluded with elected officials to place the city's poor and working classes in harm's way during urban disasters. As a result, the levee rumors during Hurricane Katrina may be understood as a form of resistance, a way in which displaced residents of the lower 9th Ward tried to shape the discourse about the causes and consequences of the hurricane, insisting that, rather than being understood as a so-called natural disaster, it must be understood as a human-constructed catastrophe. [ABSTRACT FROM AUTHOR]

The article applies economic analysis informed by the thinking of Austrian School economist Carl Menger to capital invested in New Orleans, Louisiana prior to the devastation wrought by Hurricane Katrina in August, 2005. The authors demonstrate that increasing magnitudes of investment in the city constituted malnvestment, insofar as it all depended upon the integrity of a complex, government-financed system of levees--themselves an example of malinvestment-- that failed to prevent flooding when Katrina struck.

Erodibility of a soil is defined here as the relationship between the erosion rate of a soil dz/dt and the velocity v of the water flowing over it, or the relationship between the erosion rate of a soil dz/dt and the shear stress developed by the water at the water-soil interface. This is called the erosion function. The test used to measure the erosion function of the levee soils is the erosion function apparatus test. The test consists of eroding a soil sample by pushing it out of a thin wall steel tube and recording the erosion rate for a given velocity of the water flowing over it. Several velocities are used and the erosion function is defined. A new erosion category chart is proposed to reduce the erodibility of a soil or rock to a single category number. Twenty three samples were retrieved from 11 locations at the surface of the levees around New Orleans. Thirteen were samples from Shelby tubes while ten were bag samples. The results obtained show a large variation of erosion resistance among the soils tested. Some of the levees associated with the location of the samples resisted the overtopping erosion very well; others eroded completely. On the basis of the erosion test results and of the observed behavior of the levees during the hurricane, a chart is presented which can be used to select soils for overtopping resistance. Numerical simulations were performed using the program CHEN 3D to obtain the distribution of velocity vectors in the overtopping flow and of shear stresses at the interface between the water and the levee surface. The comparison of the numerical simulation results and of the erosion function gives added credibility to the proposed levee overtopping erosion chart. [ABSTRACT FROM AUTHOR]

Centrifuge modeling of the 17th Street Canal and Orleans Canal North levees was performed in this study. During hurricane Katrina the levees on the 17th Street Canal failed, leading to breaches in the outfall canal in the city. Two mechanisms were observed in the centrifuge modeling that could cause a breach. First, a water-filled crack formed in front of the floodwall as the water in the canal rose above the top of the levee. The levees on the 17th Street Canal, which were supported on clay foundations, failed when this cracking led to a translational (sliding) failure in the clay layer commencing at the toe of the floodwall. The levees at Orleans Canal North, where failure did not occur, were also modeled to demonstrate that the model tests could successfully simulate failure and nonfailure conditions. The centrifuge model tests identified the importance of the crack formation in relation to the stability of the floodwall. These tests also confirmed that levee geometry, floodwall depth of penetration, and the underlying soil profile were all critical to the performance of the system under flood loading. [ABSTRACT FROM AUTHOR]

Following Hurricane Katrina an extensive investigation of the performance of floodwalls in the New Orleans area was undertaken by the U. S. Army Corps of Engineers and others. This investigation included detailed study of failures of cantilevered sheet pile “I-walls” during the hurricane. An important lesson from this investigation was that gaps can form on the canal side of I-walls as the water rises in the canal and causes the I-wall to deflect. Once formed, these gaps filled with water, resulting in significantly higher loads on the walls. Gap formation was a key factor in several I-wall failures, and modeling such gaps correctly is clearly an important aspect of analyzing I-wall stability. This paper describes simple procedures for estimating the depths of gaps behind I-walls, for calculating the loads to which they are subjected, and for including them in stability analyses. The effects of gaps on the stability of the 17th Canal and the London Avenue Canal I-walls are discussed. [ABSTRACT FROM AUTHOR]

The failure of the New Orleans regional flood protection systems, and the resultant catastrophic flooding of much of New Orleans during Hurricane Katrina, represents the most costly failure of an engineered system in U.S. history. This paper presents an overview of the principal events that unfolded in the central portion of the New Orleans metropolitan region during this hurricane, and addresses the levee failures and breaches that occurred along the east–west trending section of the shared Gulf Intracoastal Waterway/Mississippi River Gulf Outlet channel, and along the Inner Harbor Navigation Channel, that affected the New Orleans East, the St. Bernard Parish, and the Lower Ninth Ward protected basins. The emphasis in this paper is on geotechnical lessons, and also broader lessons with regard to the design, implementation, operation, and maintenance of major flood protection systems. Significant lessons learned here in the central region include: (1) the need for regional-scale flood protection systems to perform as systems, with the various components meshing well together in a mutually complementary manner; (2) the importance of considering all potential failure modes in the engineering design and evaluation of these complex systems; and (3) the problems inherent in the construction of major regional systems over extended periods of multiple decades. These are important lessons, as they are applicable to other regional flood protection systems in other areas of the United States, and throughout much of the world. [ABSTRACT FROM AUTHOR]

Hurricane Katrina was one of the worst natural disasters in U.S. history. The effects of the hurricane were particularly devastating in the city of New Orleans. Most of the damage was due to the failure of the levee system that surrounds the city to protect it from flooding. This paper presents the results of centrifuge models conducted at Rensselaer Polytechnic Institute and the U.S. Army Corps of Engineers simulating the behavior of the levees at London Avenue North and South that failed during Hurricane Katrina. Those levees failed without being overtopped by the storm surge. Also included are the results of a centrifuge model of one levee section at Orleans Canal South, which did not fail during the hurricane. The key factor of the failure mechanism of the London Avenue levees was the formation of a gap between the flooded side of the levee and the sheetpile. This gap triggered a reduction of the strength at the foundation of the protected side of the levee. The results are fully consistent with field observations. [ABSTRACT FROM AUTHOR]

The geologic history of the New Orleans area significantly influences the engineering properties of the foundation soils beneath the levees. Geologic and engineering data gathered from the levee breaches identify a spatially complex geomorphic landscape, caused by Holocene sea level rise, lateral changes in depositional environments, development of Mississippi River delta lobes, and the distributary channels associated with delta development. Overlying the Pleistocene surface beneath New Orleans are predominantly fine-grained, shallow water sediments associated with bay sound (or estuarine), nearshore-gulf, sandy beach, lacustrine, interdistributary, and paludal (marsh and swamp) environments. These environments define the New Orleans area history during the Holocene and comprise the levee foundation beneath the failure areas. A barrier beach ridge is present in the subsurface along the southern shore of Lake Ponchartrain, which blocked the filling of the lake with fluvial-deltaic sediments. This buried beach impacted the supply and texture of sediment being deposited by advancing distributary channels and influenced the engineering properties of these soils. Marsh and swamp soils beneath the failure area at the 17th Street Canal are much thicker in comparison to those beneath the London Avenue Canal failures because of the influence of the beach complex, and are thickest in the Industrial Canal area. Additionally, human activities in the New Orleans area during historic time contributed to the spatial complexity and affected the engineering properties of the foundation soils. These activities include construction of drainage and navigation canals, groundwater pumping, hydraulic filling of the Lake Ponchartrain lake front, and construction of levees to prevent river flooding. Human activities, combined with the geologic setting and subsidence in this region, are responsible for the unique landscape that was impacted by Hurricane Katrina. [ABSTRACT FROM AUTHOR]

Failures of I-walls during Hurricane Katrina were responsible for many breaches in the flood protection system in New Orleans. Six breaches were examined in detail by Task Group 7 of the Interagency Performance Evaluation Taskforce. Four of these failures and breaches, which occurred before the water levels reached the top of the wall, were not caused by overtopping erosion. The failure of the I-wall at the 17th Street Canal resulted from shear through the weak foundation clay. The south failure of the London Avenue I-wall was caused by subsurface erosion, which carried massive amounts of sand inland, and removed support for the wall, leading to catastrophic instability. At the north breach on London Avenue, the failure was caused by high pore pressures, combined with a lower friction angle in the loose sand, which resulted in gross instability of the I-wall under the water pressure load from the storm surge. Looking back, with the benefit of 20-20 hindsight, these stability and erosion failures can be explained in terms of modern soil mechanics, exploration techniques, laboratory test procedures, and analysis methods. An important factor in all of the cases investigated was development of a gap behind the wall as the water rose against the wall and caused it to deflect. Formation of the gap increased the load on the wall, because the water pressures in the gap were higher than the earth pressures that had acted on the wall before the gap formed. Where the foundation soil was clay, formation of a gap eliminated the shearing resistance of the soil on the flood side of the wall, because the slip surface stopped at the gap. Where the foundation soil was sand, formation of the gap opened a direct hydraulic connection between the water in the canal and the sand beneath the levee. This hydraulic short circuit made seepage conditions worse, and erosion due to underseepage more likely. It also increased the uplift pressures on the base of the levee and marsh layer landward of the levee, reducing stability. Because gap formation has such important effects on I-wall stability, and because gaps behind I-walls were found in many locations after the storm surge receded, the presence of the gap should always be assumed in I-wall design studies. [ABSTRACT FROM AUTHOR]

A careful program of subsurface sampling and cone penetration test soundings was employed to characterize the geologic conditions beneath the failed portion of the 17th Street Canal levee in New Orleans, where a 150 m long section of the levee and floodwall translated up to ∼16 m when flood waters rose to 1–2 m of the wall’s crest on August 29, 2005, during Hurricane Katrina. The subsurface conditions are characterized by discrete layers of fill placed upon the historic cypress swamp, which is underlain by a deeper, prehistoric cypress swamp. These swamp deposits were consolidated beneath the levee, and in the area of the 2005 failure, the swamp materials infilled a natural depression believed to be an old slough, which dipped below the sheetpile tips for a distance of about 50 m, which corresponds to where the breach appears to have initiated. Detailed examination of the recovered soils suggest that recent hurricanes periodically inundated the swamps with saline and/or brackish water, which cause a mass dieoff of swamp vegetation and flocculation of suspended clays, due to the sudden increase in salinity. These conditions promote deposition of discontinuous clay seams beneath layers of organics, which are then covered by fresh water swamp deposits. This sequence is repeated, like a series of tree rings, throughout the swamp deposits. The cypress swamp deposits lying beneath the levee also exhibit high hydraulic conductivity. These materials contain corky wood, and recovered samples often exhibited densities less than water. Nine of the post-Katrina borings recovered intact samples of a basal rupture surface comprised of organic silty clay exhibited near zero residual shear strength after shearing 80 to 100 mm. [ABSTRACT FROM AUTHOR]

This paper provides an overview of the Southeast Louisiana Flood and Hurricane Protection System that was in place at the time of Hurricane Katrina. Both geography and components of the system are described. A brief description of the development of the storm, the major damage caused, and lessons learned are discussed. [ABSTRACT FROM AUTHOR]

This manuscript examines a unique management issue that confronted staff from three separate healthcare providers in the aftermath of Hurricane Katrina. The deaths that occurred in the New Orleans area at St. Rita Nursing Home, Lafon Nursing Home, and Memorial Medical Center were followed by criminal investigations. For caregivers at two of the facilities, criminal indictments were issued. In the U.S., civil litigation in nearly all business arenas is commonplace, especially when there is the possibility that there has been negligence, or that a person has suffered injury or wrongful death. There was after Hurricane Katrina, however, the use of criminal prosecutorial action by the Louisiana Attorney General, which sought to criminalize the actions of healthcare givers who lost patients while facing the challenges of heretofore unheard of failure of levees and the catastrophic flooding that came as the result of those failures. The tragedies at each of the aforementioned healthcare facilities were examined, with attention given to reconstruction of the management decisions at each. The specter of criminal indictment and charges to managers and caregivers for each of the three healthcare facilities, is discussed. Healthcare management implications for the future now must include not only civil liability concerns but also the possibility of criminal prosecution. [ABSTRACT FROM AUTHOR]

The article discusses environmental aspects of New Orleans, Louisiana. New Orleans was constructed on the levees of the Mississippi River to take advantage of the river's transportation potential. The city's location prevents drainage and resulted in high incidence of disease due to nearby swamps. Artificial levees were added to prevent damage due to flooding of the river. A flood in the nineteenth century occurred when a levee broke, leading to public works to heighten the levees and improve the drainage system with canals and pumping stations. The elimination of wetlands reduced the absorption of rainwater.

The article presents author's comments on the Hurricane Katrina and compares the levees that crumbled in New Orleans, Louisiana with such structures built in the 17th century in France. During the reign of Louis XIV, good governance was equated with effective land management. The French looked after these structures which protected their countryside. However the levees in New Orleans broke even before the floods reached the heights and raised questions of moral responsibility in government.

This Article highlights the hazards of hindsight analysis of the causes of catastrophic events, focusing on theories of why the New Orleans levees failed during Hurricane Katrina in 2005 and particularly on the theory that the levee failures were "caused" by a 1977 National Environmental Policy Act (NEPA) lawsuit that resulted in a temporary injunction against the Army Corps of Engineers' hurricane protection project for New Orleans. The Article provides a detailed historical reconstruction of the decision process that eventuated in the New Orleans storm surge protection system, focusing both on the political and legal factors involved and on the "standard project hurricane" risk assessment model that lay at the heart of the Army Corps of Engineers' decisionmaking process. The Article then offers a detailed analysis of how and why Hurricane Katrina overcame the New Orleans levee system. As this analysis demonstrates, the argument that the NEPA lawsuit played a meaningful causal role in the Katrina disaster is not persuasive. Parallel lessons are then drawn for forward-looking disaster policy. The same problems of uncertainty and complexity that confound the attempt through hindsight to attribute causal responsibility for a disaster also confound the attempt to predict using foresight the variety of outcomes, including potentially disastrous ones, that may flow from policy choices. Focusing narrowly on any single parameter of complex natural and human systems is likely to dramatically distort environmental, health, and safety decisionmaking, whether the parameter is a "standard project hurricane" when planning a hurricane protection plan, or the equally mythical "lawsuit that sunk New Orleans" when attempting to allocate responsibility for the plan's failure some forty years later. [ABSTRACT FROM AUTHOR]

Provides information on the Hurricane Katrina collection of the Smithsonian Institution in New Orleans, Louisiana. Observations on levees in New Orleans after the hurricane; Presence of multicolored watermarks on buildings in New Orleans; Collection of materials used by the U.S. Coast Guard during the Katrina helicopter rescue operations.

Climate change forcings are having significant impacts in coastal Louisiana today and increasingly affect the future of New Orleans, a deltaic city mostly below sea level, which depends on levee and pumps to protect from a host of water-related threats. Precipitation has increased in the Mississippi River basin generally, increasing runoff, so that in recent years the Mississippi River has been above flood stage for longer periods of time both earlier and later in the year, increasing the likelihood that hurricane surge, traditionally confined to summer and fall, may compound effects of prolonged high water on river levees. The Bonnet Carré Spillway, just upstream of New Orleans has been operated more often and for longer periods of time in recent years than ever before in its nearly 100-year history. Because all rain that falls within the city must be pumped out, residents have been exposed to interior flooding more frequently as high-intensity precipitation events can occur in any season. A sustainable path for New Orleans should involve elevating people and sensitive infrastructure above flood levels, raising some land levels, and creating water storage areas within the city. Management of the lower Mississippi River in the future must include consideration that the river will exceed its design capacity on a regular basis. The river must also be used to restore coastal wetlands through the use of diversions, which will also relieve pressure on levees. [ABSTRACT FROM AUTHOR]