Effects of Hurricane Katrina in New Orleans
The storm surge impacted all 57 miles of St. Tammany Parish's coastline, including Lacombe, Mandeville and Madisonville. The storm surge in the area of the Rigolets Pass is estimated 16 feet, not including wave action, declining to 7 feet at Madisonville. The surge had a second peak in eastern St. Tammany as the westerly winds from the southern eye wall pushed the surge to the east, backing up at the bottleneck of the Rigolets Pass.
In the City of New Orleans, the storm surge caused more than 50 breaches in drainage canal levees and also in navigational canal levees and precipitated 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 (4.5 m) of water. The famous French Quarter dodged the massive flooding experienced in other levee areas.
Most of the city's levees designed and built by the United States Army Corps of Engineers broke somewhere, including the 17th Street Canal levee, the Industrial Canal levee, and the London Avenue Canal floodwall. These breaches were responsible for most of the flooding, according to a June 2007 report by the American Society of Civil Engineers.Oil refining was stopped in the area, increasing oil prices worldwide.
Ninety percent of the residents of southeast Louisiana were evacuated in the most successful evacuation of a major urban area in the nation's history. Despite this, many remained (mainly the elderly and poor). The Louisiana Superdome was used for those who remained in the city. The city flooded due to the failure of the federally built levee system.Many who remained in their homes had to swim for their lives, wade through deep water, or remain trapped in their attics or on their rooftops.
The disaster had major implications for a large segment of the population, economy, and politics of the entire United States. It has prompted a Congressional review of the Corps of Engineers and the failure of portions of the federally built flood protection system which experts agree should have protected the city's inhabitants from Katrina's surge. Katrina has also stimulated significant research in the academic community into urban planning, real estate finance, and economic issues in the wake of a natural disaster
New Orleans was settled on a natural high ground along the Mississippi River. Later developments that eventually extended to nearby Lake Pontchartrain were built on fill to bring them above the average lake level. Navigable commercial waterways extended from the lake into the interior of the city to promote waterborne commerce. After the construction of the Inner Harbor Navigation Canal in 1940, the state closed these waterways causing the town's water table to lower drastically. After 1965, the United States Army Corps of Engineers built a levee system around a much larger geographic footprint that included previous marshland and swamp. These factors created subsidence of up to 8 feet (2.4 m) in some areas due to the consolidation of the underlying organic soils.
A 1999-2001 study using LIDAR technology found that 51% of the terrestrial surface of the contiguous urbanized portions of Orleans, Jefferson, and St. Bernard parishes lie at or above sea level, with the highest neighborhoods at 10-12 ft (3.05-3.66 m) above mean sea level, while 49 percent lies below sea level, in places to equivalent depths.
In 1965, heavy flooding caused by Hurricane Betsy brought concerns regarding flooding from hurricanes to the forefront.
That year Congress passed the Flood Control Act of 1965 which, among other issues, gave authority for design and construction of the flood protection in the New Orleans metropolitan area to the Corps of Engineers subject to cost sharing principles, some of which were waived by later legislation. The local municipalities were charged with maintenance once the projects were completed.
When authorized, flood control design and construction were projected to take 13 years to complete. When Katrina made landfall in 2005, the project was between 60-90% complete with a projected date of completion estimated for 2015, nearly 50 years after it first gained authorization. Moreover, another major hurricane flooding had long been predicted, and while the close call of Hurricane Georges in September 1998 galvanized some squabbling scientists, engineers and politicians into collective planning, as at October 2001, Scientific American declared that "New Orleans is a disaster waiting to happen".
On August 29, 2005, flood walls and levees catastrophically failed throughout the metro area. Many collapsed well below design thresholds (17th Street and London Canals). Others collapsed after a brief period of overtopping (Industrial Canal) caused "scouring" or erosion of the earthen levee walls--an egregious design flaw. The American Society of Civil Engineers refers to the flooding of New Orleans as the worst engineering disaster in US history.
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