Hurricane Katrina (2005): New Orleans, the Levees and Aftermath

Hurricane Katrina was a powerful Atlantic hurricane that struck the Gulf Coast of the United States in late August 2005, making landfall in south-eastern Louisiana on 29 August. Its storm surge devastated coastal Mississippi and caused the failure of levees and floodwalls that left about 80 percent of New Orleans under water. Between about 1,400 and 1,800 people died, and the slow and confused government response made Katrina a national scandal and a lasting symbol of social inequality and failed disaster planning.

Background: a city below sea level

New Orleans was founded in 1718 on a crescent of higher ground beside the Mississippi River (see founding of New Orleans). As it grew in the 20th century, it expanded into drained swamps between the river and Lake Pontchartrain. Pumping caused the soil to sink, and by 2005 much of the city lay below sea level, in a bowl ringed by levees and floodwalls.

Many of these defences dated from after Hurricane Betsy, which flooded parts of the city, including the Lower Ninth Ward, in 1965. Congress then authorised the US Army Corps of Engineers to build a hurricane protection system, but forty years later it was still incomplete, and parts of it had been built to standards based on outdated assumptions about storms and soils.

The surrounding coastal wetlands, which once absorbed storm surges, had been shrinking for decades because of river engineering, canal dredging and subsidence. Planners had long warned that a major hurricane could flood the city. In 2004 a government exercise called “Hurricane Pam” simulated a catastrophic storm striking New Orleans, but many of its lessons had not been acted on.

Formation and landfall

Katrina formed as a tropical depression over the Bahamas on 23 August 2005 and became a tropical storm the next day. It crossed southern Florida as a Category 1 hurricane on 25 August, killing several people, and then entered the warm waters of the Gulf of Mexico, where it intensified rapidly. On 28 August it became a Category 5 hurricane with peak sustained winds of about 175 mph (280 km/h), one of the strongest ever recorded in the Gulf.

That morning, New Orleans Mayor Ray Nagin ordered the first mandatory evacuation in the city’s history. Most residents left, but an estimated 100,000 or more, many of them poor, elderly, sick or without cars, stayed behind. The Louisiana Superdome was opened as a “shelter of last resort”.

Katrina weakened before landfall but remained very large. It came ashore near Buras, Louisiana, at about 6:10 a.m. local time on 29 August as a Category 3 hurricane, and made a second landfall near the mouth of the Pearl River on the Louisiana-Mississippi border a few hours later.

The flooding of New Orleans

The storm surge pushed water from the Gulf and Lake Borgne into the city’s navigation canals and against its eastern defences. Levees along the Mississippi River Gulf Outlet and the Industrial Canal were overtopped and breached, flooding St. Bernard Parish and the Lower Ninth Ward, where water rose to rooftops within minutes in some places.

Later that morning, concrete floodwalls along the 17th Street Canal and the London Avenue Canal collapsed, even though the water had not risen above their tops. Water poured from Lake Pontchartrain into central and northern New Orleans. By 31 August about 80 percent of the city was flooded, in places to depths of 3 metres (10 feet) or more. Tens of thousands of people were trapped in attics and on roofs, and the floodwater was not fully pumped out until mid-October.

The Mississippi coast

In Mississippi, Katrina’s storm surge was the highest recorded in United States history, reaching about 8.5 metres (28 feet) near Pass Christian. Towns such as Waveland, Bay St. Louis, Gulfport and Biloxi were largely flattened along the shore, and casinos built on barges were thrown inland. Destruction extended into Alabama, where Mobile was flooded.

The damage to the Mississippi coast was overshadowed in national coverage by the drama in New Orleans, but it was among the most complete destruction ever caused by a hurricane in the United States. Whole neighbourhoods were reduced to concrete slabs, bridges carrying US Highway 90 across Bay St. Louis and Biloxi Bay were wrecked, and more than 200 people died in the state. Offshore, Katrina damaged oil platforms and refineries, briefly disrupting fuel supplies and pushing up petrol prices across the country.

The response

For days, the response to the flooding of New Orleans was slow and confused. Tens of thousands of people sheltering in the Superdome, and thousands more who gathered at the Ernest N. Morial Convention Center, waited in heat and squalor with inadequate food, water, sanitation and medical care. Television images of desperate residents, many of them Black and poor, shocked the nation and the world.

Communications had collapsed, and local, state and federal authorities blamed one another for the delays. The Federal Emergency Management Agency (FEMA), led by Michael D. Brown, was widely criticised as unprepared. On 2 September President George W. Bush praised Brown with the words “Brownie, you’re doing a heck of a job”, a remark that became notorious; Brown was removed from the relief effort a week later and resigned on 12 September. Relations between the White House and Louisiana Governor Kathleen Blanco were strained over control of the National Guard.

Order and supplies improved after Lieutenant General Russel L. Honoré took command of military relief operations, and the Superdome and Convention Center were evacuated by 3-4 September. The US Coast Guard, praised as one of the most effective agencies, rescued or evacuated more than 33,000 people. Reports of widespread violence and looting circulated in the media, but many of the most sensational stories, such as mass killings inside the Superdome, later proved to be false or exaggerated.

The human cost

Estimates of Katrina’s death toll vary from about 1,400 to more than 1,800, depending on how direct and indirect deaths are counted; the National Hurricane Center’s updated figure is 1,392. Most deaths occurred in Louisiana, and a large share of the victims in New Orleans were elderly people who drowned in their homes or died in hospitals and nursing homes cut off by the flood.

More than a million people across the Gulf Coast were displaced, the largest displacement in the United States since the Dust Bowl of the 1930s. Many evacuees from New Orleans were taken to Houston, where tens of thousands sheltered in the Astrodome and other centres, and to cities across the country. Many never returned.

By the numbers

Consequences and legacy

Investigations by the US Army Corps of Engineers and independent engineering teams concluded that the New Orleans flood defences had failed largely because of flawed design and construction, including floodwalls driven into weak soils that were not deep enough. The Corps accepted responsibility in 2006. Between 2006 and the late 2010s it built a new 14.5-billion-dollar system of higher levees, floodwalls, gates and pumping stations, including the Lake Borgne Surge Barrier, one of the largest in the world.

The response led to the Post-Katrina Emergency Management Reform Act of 2006, which reorganised FEMA within the Department of Homeland Security. A congressional report published in February 2006 described “a failure of initiative” at every level of government.

Recovery in New Orleans was long and uneven. Tourist districts such as the French Quarter, on higher ground, reopened within months, while low-lying, largely Black neighbourhoods such as the Lower Ninth Ward recovered slowly. The city’s population fell by about 29 percent between 2000 and 2010. The public school system was largely replaced by charter schools, and many public housing complexes were demolished, changes that remain controversial.

Katrina joined a long list of deadly American hurricanes, from the Galveston hurricane of 1900 to Hurricane Andrew in 1992, and its name was retired from use for Atlantic storms.

Timeline

• 2005, 23 August: A tropical depression forms over the south-eastern Bahamas.
• 2005, 25 August: Katrina makes landfall in southern Florida as a Category 1 hurricane.
• 2005, 28 August: Katrina reaches Category 5 in the Gulf; Mayor Nagin orders a mandatory evacuation of New Orleans.
• 2005, 29 August: Katrina makes landfall near Buras, Louisiana, and again near the Louisiana-Mississippi border; levees and floodwalls fail in New Orleans.
• 2005, 31 August: About 80 percent of New Orleans is under water.
• 2005, 3-4 September: The last evacuees leave the Superdome and the Convention Center.
• 2005, 12 September: FEMA director Michael Brown resigns.
• 2005, 11 October: The Army Corps of Engineers completes pumping floodwater out of the city.
• 2006, 15 February: A House committee publishes its report, A Failure of Initiative.

Why it matters

Hurricane Katrina showed how a natural hazard becomes a catastrophe through human decisions: in land use, engineering, emergency planning and the neglect of vulnerable communities. It remains one of the deadliest and costliest disasters in US history, and it changed how Americans think about flood defences, government responsibility and inequality in times of crisis.