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Levee Situation In The US
Flood damages and flood risk are increasing in the U.S.
The flooding problem in the U.S. is getting worse.
Average annual flood losses have increased steadily to nearly $6 billion — and they continue to grow.
Many of the nation's levees are more than 50 years old and are showing their age. While there are newer or reconstructed levees, a large number of levees were built in response to the widespread flooding on the Mississippi River in 1927 and 1937, or in California after catastrophic flooding in 1907 and 1909.
Levees reduce the risk of flooding cities large and small; more than 14 million people live behind levees and at least one-third of communities with a population of 50,000 or higher have some portion of their community protected by levees.
If demographic trends hold, we have every reason to believe that more and more people will be living in flood prone areas and behind levees, increasing the importance of their reliability and level of protection.
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Catastrophic flooding is not an irregular occurrence.
When it comes to natural disasters, our memory is short. Whether out of optimism or ignorance, the idea that "it can't happen here" can be strong. However, large flooding events are not uncommon and often widespread.
In many large floods impacting broad swaths of the country, smaller levees in rural areas failed or breached. Although this resulted in significant flooding in those areas, the levee failure in one area was often credited with saving the levees in more populated regions from overtopping or failing under the pressure of the floodwaters.
- Mississippi River Flooding of 2011 — Widespread flooding affected states from Illinois south through Louisiana. While it will be weeks before floodwaters recede and months before the damages are tallied, early estimates are expected to be more than $5 billion. Between 2.1 million to 2.2 million acres of farmland have so far been affected by the flooding in the delta region, or about 1 percent of all United States cropland, according to estimates from the Army Corps of Engineers. Thousands of people have been displaced. Federal levees of the Mississippi River & Tributaries system have largely performed as expected. There has been extensive overtopping of levees on smaller tributaries and backwaters, flooding agricultural land and properties.
- Midwest Flood of 2008 — affected the states of Indiana, Illinois, Iowa, Michigan, Missouri, Minnesota and Wisconsin including 35,000 people evacuated for weeks at a time. Two dozen people across the region lost their lives during the floods. Iowa's agricultural losses alone are estimated to exceed $2 billion. In Cedar Rapids, flood waters overtopped the city's levees and covered 1,300 city blocks inundating city hall, the county jail, the fire and police departments, the public library and 3,900 homes. In the small town of Oakville, Iowa, every building was damaged by the 6 feet of water that rushed into town when the levee unexpectedly failed. After the floods, two-thirds of its population moved away, leaving just 160 of the 439 residents Oakville had before the flood. The bank closed and never reopened. The town lost two-thirds of its tax base, but those who have stayed have resisted suggestions that the town relocate or not rebuild.
- Hurricanes Katrina and Rita in 2005 — 1,810 people died, a majority of these people were over the age of 60; many of the deaths were attributed to the catastrophic failure of levees and floodwalls in the city. There was over $200 billion in direct economic damages to property and untold damage to the regional economy. More than 1 million people were displaced. USACE is spending $15 billion to upgrade the flood protection system. FEMA invested more than $75 billion in emergency relief alone.
- The Great Flood of 1993 — was widespread along the Mississippi River Basin, covered nine states and 31,000 square miles of inundation. Levees on the Mississippi and its tributaries were overtopped or breached in over 1,000 locations. In some places flooding lasted for more than 200 days. Damage from this record flood stage was massive. More than 200 counties were declared federal disaster areas including the entire state of Iowa. 72,000 homes suffered major damage along with 45,000 commercial structures. 12 airports were closed and more than 1,000 miles of road including major interstates. 40 of the 229 federal levees were overtopped or damaged during the flood event. Estimates of the losses from this flood are $15.6 billion (1994 dollars).
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Katrina: A levee disaster unlike any other.
Hurricane Katrina made landfall as a category 3 storm on August 29, 2005. The storm caused severe destruction along the Gulf coast from central Florida to Texas. The greatest catastrophe, however, was in New Orleans. In the city, levees and floodwalls were overtopped by the storm surge and, in some places, failed unexpectedly. Eventually 80% of the city and large tracts of neighboring parishes became flooded, and the floodwaters lingered for weeks. 1,810 people died. A majority of these people were over the age of 60, and many of the deaths were attributed to the catastrophic failure of levees and floodwalls in the city.
On the heels of this disaster, Hurricane Rita made landfall on September 24, further exhausting a region in turmoil. New Orleans was ordered to be re-evacuated on September 21 as the storm was initially forecast to make landfall close to the city. Although Rita remained well to the south and west of New Orleans, a pre-landfall storm surge breached some of the levees and floodwalls that were compromised by Hurricane Katrina, causing major reflooding in New Orleans.
The statistics are staggering:
- The total damages from Hurricanes Katrina and Rita were a staggering $150 billion — $135 billion from Katrina and $15 billion from Rita. This is more than twice the damages from Hurricane Andrew, 9/11, and the Northridge Earthquake combined.
- More than 1 million residential structures were damaged.
- More than 1 million people were displaced; 600,000 were still displaced one month later.
- The U.S. Army Corps of Engineers is spending $15 billion to upgrade the hurricane and storm damage risk reduction system, including the levees, floodwalls, and surge barriers that surround New Orleans.
- FEMA invested more than $75 billion in emergency relief alone.
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Levees and unexpected flooding.
Levees, when performing as intended, reduce the risk of flooding for communities. However, an unexpected levee breach or failure can be catastrophic, with the resultant flooding causing loss of life, emergency evacuations, and insufficient time to reduce damages to property.
The tragedy of Hurricane Katrina in New Orleans has been seared in our collective consciousness, but it is not the only example of levee failures in the United States.
- June 2011 — Under 24 hour surveillance by the local levee district, a levee about five miles south of Hamburg, Iowa, breached in 3 locations over several days as high flood levels on the Missouri River continued to move downstream. After three partial breaches — the levee wall gave way and collapsed upon itself — construction of a secondary levee between the levee and Hamburg was begun. A few days later, the levee failed, with a 300' section of the earthen levee collapsing. The location and timing of the breaches resulted in no fatalities, although significant damages are expected.
- April 2011 — A levee on the Black River southeast of Poplar Bluff, Missouri breached in four locations, sending water rushing into rural Butler County, Missouri. The breaches in the levee south of town relieved pressure on the town of Poplar Bluff and its levees. About 1,000 of the town's 17,000 residents had already evacuated; the extreme rainfall had caused the Black River to overtop the levee in 30 places before the breach. In 2008, flooding damaged or destroyed hundreds of homes in Poplar Bluff, raising doubts about whether the levee was capable of protecting the town during heavy rain. A federal inspection by the U.S. Army Corps of Engineers gave the levee an "unacceptable" rating in 2008, but the private levee district that maintains the levee had been unable to make repairs before the unprecedented rainfall that preceded the 2011 flood.
- September 14, 2008 — After several days of heavy rainfall, a levee on the Little Calumet River breached, resulting in flooding in most of Munster and neighboring Hammond, Indiana, and a presidential disaster declaration.
- January 5, 2008 — A 30-foot section of the earthen walls of an irrigation canal in Fernley, Nevada failed at 4 AM, flooding a square mile of Fernley. At least 18 of the town's 15,000 residents had to be evacuated by boats or helicopters. 1,500 residents were displaced by the flood, with water levels reaching up to 8' in some houses.
- June 3, 2004 - Jones Tract is an inland island that is protected by a series of levees located in the Sacramento-San Joaquin Delta. Â An unexpected breach in the levee allowed water from the Middle River to flood the island, inundating the entire island with more than 150,000 acre-feet of water. The island, which lies 3 meters below sea level, required three weeks to repair the breach, and an additional five months for de-watering after the pumps were shut down.
- January 2, 1997 - A levee on the west bank of the Feather River collapsed at the northern Sacramento Valley community of Arboga, California in Yuba County. More than 100,000 people in Yuba and Sutter counties were evacuated as the towns of Olivehurst, Arboga, Wilton, Manteca, and Modesto were flooded. In total, 290 square miles were flooded, with estimated damages over $1.6 billion. Three deaths are attributed to the flooding.
- Feb 20, 1986 — A day after a large flood had crested a levee on the south bank of the Yuba River collapsed, inundating 36 square miles, flooding 4,000 homes, and forcing as many as 26,000 residents to evacuate the Sacramento Valley towns of Linda, Olivehurst and Arboga.
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