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Researchers Implement Phased Project To Reduce Levee Failures
November 2007

Earlier this year, the U.S. House of Representatives overwhelmingly approved the Water Resources Development Act of 2007 which authorizes approximately 400 new water resources projects for the U.S. Army Corps of Engineers, including projects for flood control, navigation and environmental restoration. One primary area of concern focuses on the deplorable condition of most levee systems in this country. On the main stem of the Mississippi River alone, there are approximately 1,602 miles of levee in place.

Levees are earthen embankments whose primary purpose is to furnish flood protection from seasonal high water for a few days or weeks a year. Levees are broadly classified as either urban, providing protection from flooding in communities including their industrial, commercial, and residential facilities, or agricultural, providing protection from flooding in lands used for agricultural purposes, because of the different requirements for each. There are five main types of levees:
1. Mainline and Tributary levees which generally parallel the main channel and/or its tributaries;
2. Ring levees which completely encircle or “ring” an area from all directions;
3. Setback levees which generally are built as a backup to an existing levee that has become endangered;
4. Sublevees which are constructed for the purpose of underseepage control; and
5. Spur levees which project from the main levee and provide protection to the main levee by directing erosive river currents riverward.

But when rain, strong currents, and storm surges fall on lands protected by weak levees, the likely result is a major disaster. Hurricanes Katrina and Rita were devastating reminders of this frightening fact. How then can we limit trouble when a levee breaches or, better yet, prevent such a break from ever happening again?

“Any solution will be difficult and challenging,” emphasizes Wil Laska, who manages the Levee Strengthening and Damage Mitigation Project at the Department of Homeland Security’s Science & Technology (S&T) Directorate. “But first, we’ve got to ensure that all the levees in the United States are solid, built correctly and well. We also have to make sure that all repairs are attended to on a rigorously timed basis. No ifs, ands, or buts.”

The levee project is a comprehensive one, spanning four years and operating in three phases. During the first phase, researchers will identify potential technologies and procedures that can rapidly and economically indicate problem locations along a levee, strengthen these existing areas, provide innovative designs for new levees, and repair any breaches. Subsequent phases will test and demonstrate the technologies and procedures. For instance, the U.S. Army Engineer Research and Development Center has developed the Levee Condition Assessment Technology, or LevCAT, which combines geophysical instrumentation with airborne and ground-based research to essentially “see” weak soil under levees.

But when reviewing the overall condition of the country’s levee system, there is another important issue besides horrendous storms which must be taken into consideration – the slow death of our natural buffer zones which protect us from powerful sea surges. River basins, deltas, and savannahs are being congested with soil and debris. Human development and the associated residual waste are causing the surrounding land to sink, and as salt water rushes in, thick expanses of wetland, mangroves, trees and grasses are being poisoned. Without these buffers, storms can push sea surges quite a distance inland. And, as ocean levels rise, as they are doing, low-lying cites will have to protect themselves by using some sort of barriers and pumps to help keep the rising waters out.

Mr. Laska is taking on this problem too. The project also aims to develop approaches and technologies that will duplicate the effect of marshland and reduce the strength of surges. Solutions being considered include: inflatable and drop-in structures that would last just long enough to prevent severe damage; planting fast-growing vegetation to rapidly imitate the effect of marshlands in lowering tides; and ways to reroute flood waters and flood-proof critical infrastructure.

Mr. Laska is part of a small group of experts focused on DHS’s Science & Technology Directorate projects called Homeland Innovative Prototypical Solutions, or HIPS. These projects are designed to deliver prototype-level demonstrations of potential game-changing technologies in two to five years. They come with a moderate-to-high risk of failure, but they can also yield a high payoff if successful.

According to Mr. Laska, “All of these goals are enormously ambitious, but that’s the nature of the work. Right now, the S&T Directorate is looking at just about any decent idea.”

A conceptual video is available from the U.S. Army Engineer Research and Development Center, an S&T Directorate partner. ##

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