Donald T. Resio, senior technologist in the Coastal and Hydraulics Laboratory at the U.S. Army Corps of Engineers Engineering Research and Development Center in Vicksburg, Miss., had an “ah-ha!” moment when he was trying to figure out how to plug a roaring levee breach: Use a big fabric tube floating in the flood, partially filled with water. Demonstrated at quarter-scale last fall on an 8-ft wide breach in a real levee at an agricultural research station in Stillwater, Okla., the device rolled into place riding the water pouring through the gap. It sealed the hole in 12 seconds flat, to the cheers of a crowd of scientists, levee board officials and engineers.
The principal is as simple as dirt, or simpler, really. A tube of non-stretch fabric, longer than the breach and of a diameter larger than the water depth at the gap, is dropped into the flood and 80% filled with water. Positioned upstream, the current pulls it toward the breach. The bubble of air inside keeps the top above the water as the tube drifts into place, guided by lines from either the levee or an offshore barge. As the tube runs aground near the breach, the roll slows and the tube snuggles into the gap. The current tries to bend it and force it through the hole, but the laws of physics get in the way. The incompressible nature of water and the unyielding fabric of the tube turns it into a rigid plug that conforms to the breach and seals it in a flash.