Flood wall in the context of "Floodwater"

Flood management or flood control are methods used to reduce or prevent the detrimental effects of flood waters. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and runoff. Flood management methods can be either of the structural type (i.e. flood control) and of the non-structural type. Structural methods hold back floodwaters physically, while non-structural methods do not. Building hard infrastructure to prevent flooding, such as flood walls, is effective at managing flooding. However, it is best practice within landscape engineering to rely more on soft infrastructure and natural systems, such as marshes and flood plains, for handling the increase in water.

Flood management can include flood risk management, which focuses on measures to reduce risk, vulnerability and exposure to flood disasters and providing risk analysis through, for example, flood risk assessment. Flood mitigation is a related but separate concept describing a broader set of strategies taken to reduce flood risk and potential impact while improving resilience against flood events.

As the center of Hurricane Katrina passed southeast of New Orleans on August 29, 2005, winds downtown were in the Category 1 range with frequent intense gusts. The storm surge caused approximately 23 breaches in the drainage canal and navigational canal levees and flood walls. As mandated in the Flood Control Act of 1965, responsibility for the design and construction of the city’s levees belongs to the United States Army Corps of Engineers and responsibility for their maintenance belongs to the Orleans Levee District. The failures of levees and flood walls during Katrina are considered by experts to be the worst engineering disaster in the history of the United States. By August 31, 2005, 80% of New Orleans was flooded, with some parts under 15 feet (4.6 m) of water. The famous French Quarter and Garden District escaped flooding because those areas are above sea level. The major breaches included the 17th Street Canal levee, the Industrial Canal levee, and the London Avenue Canal flood wall. These breaches caused the majority of the flooding, according to a June 2007 report by the American Society of Civil Engineers. The flood disaster halted oil production and refining which increased oil prices worldwide.

Between 80 and 90 percent of the residents of New Orleans were evacuated before the hurricane struck, testifying to some of the success of the evacuation measures. Despite this, not enough attention was paid to those without a car, credit cards, road experience or family living out of town. The Louisiana Superdome was used to house and support some of those who were unable to evacuate. Television shots frequently focused on the Superdome as a symbol of the flooding occurring in New Orleans.

The New Orleans metropolitan area, designated the New Orleans–Metairie metropolitan statistical area by the U.S. Office of Management and Budget, or simply Greater New Orleans, is a metropolitan statistical area designated by the United States Census Bureau encompassing seven Louisiana parishes—the equivalent of counties in other U.S. states—centered on the city of New Orleans. The population of Greater New Orleans was 1,007,275 in 2020. Greater New Orleans is the most populous metropolitan area in Louisiana, and the 45th most populous in the United States. The broader New Orleans–Metairie–Slidell combined statistical area had a population of 1,373,453 in 2020.

The New Orleans metropolitan area was devastated by Hurricane Katrina—once a category 5 hurricane, but a category 3 storm at landfall—on August 29, 2005. Within the city of New Orleans proper, multiple breaches and structural failures occurred in the system of levees and flood walls designed under federal government auspices. The city of New Orleans experienced a steep population decline after the hurricane, though by the 2020 census, it had regained a good portion of that loss.