Feb. 2, 1998 BLACKSBURG, Jan. 31, 1997 -- The numbers are reaching astronomical proportions -- two billion dollars in damages in the West during this past winter and 36 deaths. One year earlier, the Pacific Northwest suffered from nine deaths and $1 billion in destruction. In early 1995 more than $3 billion in damages and 27 deaths were recorded.
All of these figures relate to just one form of natural disaster -- flooding. As weather patterns have taken on some rather bizarre twists in recent years, the price tags on life and property have been enormous.
Although there is no one sure fix to the problems of flooding, veteran Virginia Tech civil engineer Ray Plaut is a strong advocate of inflatable dams.
"Inflatable dams are long, cylindrical, flexible structures anchored to a concrete base and abutments...they can raise the height of existing dams or spillways, impound water for recreational basins, divert water for irrigation or groundwater recharging, prevent river backflows due to high tides, and control water for hydroelectric production," Plaut explains.
He sees their next use as a means to protect buildings and towns from high flood waters.
Citing the Midwest flood of 1993, Plaut recalls that the citizens of Davenport, Iowa decided against the construction of a levee so that they could continue to enjoy their view of the Mississippi River and have access to the water for recreational purposes. When the river rose eight feet that year, causing millions of dollars in damages and clean-up costs, Plaut says a "possible solution would have been a set of inflatable dams along the riverbank, deflated and lying flat when not needed and then inflated before the flood waters arrived."
This proposal would have allowed the citizens of Davenport to retain their picturesque landscaping, and simultaneously have some measure of flood protection.
Inflatable dams were first used in the 1950s, and Plaut notes considerable improvements have been made since their initial development by N. M. Imbertson of the Los Angeles Department of Water and Power. At that time, they were manufactured with the trade name Fabridams by Firestone Tire and Rubber Co.
Presently, most inflatable dams are manufactured by two Japanese companies, and of the approximately 2,000 inflatable dams currently in operation, most are in Japan. They require little maintenance, do not corrode or require painting, and are durable under extreme temperatures and harsh conditions.
At Virginia Tech, Plaut's interest in inflatable dams started with Earnest Marshall's Master's thesis in 1983, a feasibility study of the use of temporary inflatable structures for flood protection in place of sandbags. Since then, Plaut has continued this research with the support of the National Science Foundation (NSF).
Others from the University who have participated in inflatable dam research are several former Virginia Tech faculty members, Oner Yucel, J. N. Reddy, Dan Walker, and Stergios Liapis, as well as current member, Demetri Telionis, and a number of graduate students.
As a result of their work, they foresee the potential use of anchored and unanchored inflatable structures in a variety of ways to provide flood protection. Plaut says, "Inflatable dams could be constructed along a riverfront in place of levees, to be deflated and out of the way (allowing access and views) except when needed. They could be installed around critical facilities, again only inflated when flooding is imminent. Transportable water-filled or air-filled structures could be used to replace sandbags, requiring less effort and no serious disposal problem afterwards."
Among the current locations using inflatable dams are sites on the Susquehanna River, Pa. and the Los Angeles River, Calif., Weeks Falls, Wash., Broadwater Power, Montana, Detroit Sewage, Mich., and Sand Creek, Kansas.
A key advantage of this type of dam, Plaut says, is that it can be deployed in a short amount of time, while a similar flood protection operation using sand bags would require much longer.
"Inflatable dams and tubes can provide an alternative to levees and sandbags in protecting buildings and towns from flooding," Plaut concludes.
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