U.S. to Blow Third Hole in Levee as Floods Worsen

Daily News Article — Posted on May 6, 2011

(by Mary Wisniewski, Reuters.com) – Government engineers [blew] up a third section of a Mississippi River levee on Thursday to manage flooding, as a wall of water roared down the nation’s largest river system, threatening towns and cities all the way to the Gulf of Mexico.

The U.S. Army Corps of Engineers blew up a two-mile section of the Birds Point levee Monday night, inundating about 130,000 acres of Missouri farmland in a desperate attempt to ease flooding in towns in Illinois and Kentucky.

Water levels did recede but a second, smaller section was detonated Tuesday afternoon to allow water back into the river. A third and last blast was scheduled for Wednesday but was delayed until 1 p.m. on Thursday by “logistical difficulties,” the Corps said in a statement on Wednesday night.

The Corps, which is responsible for the system of locks and dams along the Mississippi River, would then turn its attention to the growing threat further south.

“The entire system is experiencing flooding and we will continue our fight downstream,” said Major Gen. Michael J. Walsh, president of the Mississippi River Commission, in a statement.

President Barack Obama on Wednesday declared parts of Kentucky, Mississippi and Tennessee as disaster areas due to flooding, freeing up federal aid to help those affected.

Arkansas closed a 15-mile stretch of westbound lanes of one of the busiest road arteries in the nation, Interstate 40, for the first time ever due to flooding, according to the state’s transportation department. More than 31,000 vehicles travel daily through the section of road closed, and 65 to 70 percent of those are trucks, said Glenn Bolick, Arkansas Transportation Department spokesman.

Highway officials were diverting traffic onto rural roads but even some of these were flooded, they said.

Further downstream in Mississippi, some residents of the historic Civil War town of Vicksburg were moving to higher ground on Wednesday to avoid the rising flood waters.

“We are not going to stay here,” said Vicksburg resident Harold Manner. “The families all around us are taking what they can and moving out of here, at least for now.”

The levee system in Mississippi is holding for now but it has never been tested like this before, officials said.

“Compared to the Great Mississippi Flood of 1927 this flood is going to be a lot nastier,” said Marty Pope, senior hydrologist for the National Weather Service in Jackson.

Mississippi Governor Haley Barbour has had sandbags delivered to his Yazoo City home to prevent it from flooding.

Large amounts of rain and melt from the winter snow has caused a chain reaction of flooding from Canada and the Dakotas through Illinois, Indiana, Missouri, Kentucky, Arkansas and Tennessee. It is expected to soon hit Mississippi and Louisiana at the mouth of the Mississippi River.

(Additional reporting by Tim Ghianni in Nashville, Miriam Moynihan in St. Louis; Leigh Coleman in Biloxi, Mississippi and Suzi Parker in Little Rock; Writing by Mary Wisniewski; Editing by Greg McCune and Peter Bohan)

Reprinted here for educational purposes only. May not be reproduced on other websites without permission from Thomson Reuters. Visit the website at Reuters.com.

Background

LEVEES:

A levee, or embankment, is a natural or artificial slope or wall to regulate water levels.
It is usually earthen and often parallel to the course of a river or the coast.
The main purpose of an artificial levee is to prevent flooding of the adjoining countryside; however, they also confine the flow of the river, resulting in higher and faster water flow.
Levees can be permanent earthworks or emergency constructions (often of sandbags) built hastily in a flood emergency.
Levees are usually built by piling earth on a cleared, level surface.
Broad at the base, they taper to a level top, where temporary embankments or sandbags can be placed.
Because flood discharge intensity increases in levees on both river banks, and because silt deposits raise the level of riverbeds, planning and auxiliary measures are vital.
Sections are often set back from the river to form a wider channel, and flood valley basins are divided by multiple levees to prevent a single breach from flooding a large area.
Artificial levees require substantial engineering.
Their surface must be protected from erosion, so they are planted with vegetation such as Bermuda grass in order to bind the earth together.
On the land side of high levees, a low terrace of earth known as a banquette is usually added as another anti-erosion measure.
On the river side, erosion from strong waves or currents presents an even greater threat to the integrity of the levee.
The effects of erosion are countered by planting with willows, weighted matting or concrete revetments. Separate ditches or drainage tiles are constructed to ensure that the foundation does not become waterlogged.
Prominent levee systems exist along the Mississippi River and Sacramento River in the United States. (from wikipedia)

THE MISSISSIPPI RIVER LEVEE SYSTEM:

The Mississippi levee system represents one of the largest such systems found anywhere in the world.
It comprises over 3,500 miles of levees extending some 620 miles along the Mississippi River, stretching from Cape Girardeau, Missouri to the Mississippi Delta.
These levees were begun by French settlers in Louisiana in the 18th century to protect the city of New Orleans.
The first Louisianan levees were about 3 feet high and covered a distance of about 50 miles along the riverside.
By the mid-1980s, the levees had reached their present extent and averaged 24 feet in height; some Mississippi levees are as much as 50 feet high.
The Mississippi levees also include some of the longest continuous individual levees in the world.
One such levee extends southwards from Pine Bluff, Arkansas for a distance of some 380 miles. (from wikipedia)

THE UNITED STATES ARMY CORPS OF ENGINEERS:

The United States Army Corps of Engineers (USACE) is a federal agency and a major Army command made up of some 36,000 civilian and military personnel, making it the world's largest public engineering, design and construction management agency.

Although generally associated with dams, canals and flood protection in the United States, USACE is involved in a wide range of public works support to the nation and the Department of Defense throughout the world.

The Corps of Engineers provides outdoor recreation opportunities to the public, and provides 24% of U.S. hydropower capacity.

The Corps' mission is to provide vital public engineering services in peace and war to strengthen the nation's security, energize the economy, and reduce risks from disasters.

Their most visible missions include:

Planning, designing, building, and operating locks and dams. Other civil engineering projects include flood control, beach nourishment, and dredging for waterway navigation.
Design and construction of flood protection systems through various federal mandates.
Design and construction management of military facilities for the Army and Air Force and other Defense and Federal agencies.
Environmental regulation and ecosystem restoration.

The Corps' vision is having a great engineering force of highly disciplined people working with partners through disciplined thought and action to deliver innovative and sustainable solutions to the nation's engineering challenges. (from wikipedia)