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How Levee Failures Made Hurricane Katrina a Bigger Disaster

August 27, 2020 in History

By Sarah Pruitt

Breaches in the system of levees and floodwalls left 80 percent of the city underwater.

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The ‘Bowl Effect’

Fears about flooding go all the way back to the founding of New Orleans on land in 1717, by the French-Canadian explorer Jean-Baptiste Le Moyne, Sieur de Bienville. Human intervention—including expansion onto drained swamplands surrounding the original city—and the erosion of coastal wetlands only made things worse over the centuries. By the time Katrina arrived, New Orleans lay at an average of six feet below sea level, with some neighborhoods even lower than that.

Surrounded by water—Lake Pontchartrain to the north, and the Mississippi River to the south—and bordered by swampland on two sides, New Orleans has long relied on a system of levees to protect it from flooding. But the city’s low elevation, and its position within the different levee systems, creates a so-called “bowl effect,” meaning that when water gets into the city, it is very difficult to get it out. During Katrina, with many pump stations damaged by the storm, the water stayed in the bowl.

Failures of Engineering

A helicopter drops sand bags to plug a levee break on the east side of the London Avenue Canal in the Gentilly neighborhood of New Orleans, Louisiana. Photographed on September 11, 2005, three weeks after the storm hit.

Before Hurricane Katrina, New Orleans hadn’t experienced a major hurricane for 40 years. After Hurricane Betsy flooded the city in 1965, killing several dozen people and causing more than $1 billion in damage, Congress authorized the U.S. Army Corps of Engineers to begin a major overhaul of the region’s hurricane protection system. Yet due to budget cuts and various delays, the project was only 60-90 percent complete by the time Katrina hit, according to a report by the United States Government Accountability Office.

In the immediate aftermath of Hurricane Katrina, the U.S. Army Corps of Engineers claimed the massive storm had overwhelmed the levee system, which had been designed to protect the region from a Category 3 storm or below. Yet later investigations revealed that some of the city’s levees failed even at water levels far below what they had been built to withstand.

In June 2006, the Army Corps issued a report of more than 6,000 pages, in which it took at least some responsibility for the flooding that occurred during Katrina, admitting …read more

Source: HISTORY

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