Environment: Interview

Fighting floods with water

In a flood situation, how can adding more water help? David Dooleage, inventor of the AquaDam, says fighting floods with water is superior to sandbags.
AquaDams protect a highway from flooding in Manitoba, Canada, in spring 2011./ Credits: AquaDam
Flooding is the most commonly occurring natural catastrophe in the world. In 2010, the international disaster database EM-DAT counted roughly 400 natural catastrophes with at least 100 people affected and of those 182 events - nearly half - were floods. They affected some 179 million people all over the world.

And 2010 wasn’t exceptional. In August 2002, Germany and its eastern neighbour states were hit by a once-in-a-century flood. In 2011, the Midwestern states of the U.S. received rainfall of biblical portions while Australia fought record flooding and a deluge swamped about a third of Bangkok. In July 2012, deadly floods following torrential rains in China left over 300 people dead and caused an estimated 8 billion dollars of damages. Japan also suffered similar rainstorms which killed over 30 people and temporarily displaced a quarter of a million others.

And with global temperatures gradually rising, scientists predict that there are more disasters to come. It’s about time that humans learned the lessons from floods. For example, restoring or maintaining river floodplains (rather than building on them) disperses the power of floods. David Dooleage from Colorado in the U.S. has come up with a novel solution to fend off the floodwaters: the AquaDam.

Allianz Knowledge: What is the AquaDam?
David Dooleage: The AquaDam is a large water-filled tube made of plastic that serves as a flood barrier. The tube can for example encircle and protect a single house or, on a larger scale, a power plant.

The original pattern is simply three tubes, two smaller tubes put inside of a larger tube. The two inside tubes are filled with water and basically balance each other. So the inside tubes are effectively locked in place. They weigh so much that 100 people pushing on a three-foot high and hundred-foot long dam couldn’t push it over. That’s how stable they are.
AquaDams: flood protection A 5 foot (1.5 meter) high AquaDam surrounds and isolates a warehouse from floodwaters. How big is the AquaDam?
We make them up to four meters [13 feet] in height. Normal barriers for homeowners for example are one meter high [about 3 feet]. The longest continuous AquaDam is about 300 meters [1000 feet] long.

Why would you use large AquaDams rather than smaller flood control tools like sandbags?
First of all there is the installation time and effort. The US Army Corps of Engineers performed an installation time study comparing sandbag dams with AquaDams.

A group of trained people could install a 4 x 100 feet sandbag dam in a little over four hours. Two Corps personnel could install a 4 x 100 feet AquaDam in 30 minutes. That’s about three and a half hours difference, a long time when floodwater is filling up your home.

Then there is the cost of disposing of thousands if not millions of sandbags after the flood. AquaDams, however, can easily be removed.

But what about changes in terrain, sandbags can be easily be moulded to the ground?
On uneven ground surfaces AquaDams are flexible too. Actually the tubes fit the ground like a glove. In contrast to sandbags there is absolutely no water leaking through.

What if the water were to crest over the AquaDam?
AquaDams can’t be overtopped. The dam actually grows in height as the floodwater pushes on it. Within the AquaDam there is one tube on the outside next to the floodwater, the other tube next to air on the house side. With increasing pressure from floodwater the outside tube grows in height.
You invented the AquaDam 20 years ago. Why has it taken so long to come to market?
There are several reasons for that. The construction business, for example, doesn’t want something new coming in to replace expensive sheet piling equipment [metal walls or linings used for flood control].

Another thing is the government-backed National Flood Insurance Program. Because of the high destruction potential of recurring floods a lot of insurance companies in the U.S. don’t even provide flood protection. It’s simply too risky. That’s why the government is underwriting and paying for damages with the help of funds collected from homeowner premiums.

So in order to stay capable of acting the government has been more interested in selling flood insurances than concentrating on new flood control solutions.

Has that behaviour changed?
At first it sounded laughable to them to use water to control water. But gradually they have gotten it.

In response to the Fukushima disaster, the U.S. government started considering the possibility of flooding at nuclear plants. They realized that they needed something in place to guard against floods or have some kind of floodwater mitigation plan and the AquaDam fulfils that niche perfectly.

Last year, when we protected a nuclear power plant on the Missouri River from the floods we popped up on the radar. Government officials came to have a look at the AquaDam. The U.S. Army Corps of Engineers have been testing AquaDams for the last couple of years.

How many AquaDams were deployed during the floods in 2011?
The Canadian province of Manitoba bought the most. There about 12 miles of AquaDams were put up.

As a houseowner how much would you typically spend for a three-foot high AquaDam?

Seven thousand dollars. When the flood is over you just deflate it and store it for the next event.

Apart from fighting floods, what else can be done with the AquaDam?
We sell AquaDams for water storage, especially in drought-prone areas. Many customers have bought it for fire protection because their local fire trucks only pack 250 gallons [about 946 liters] of water. We offer a 10,000 gallon unit. AquaDams used for water storage are much cheaper than deploying fire trucks all over the place to defend single buildings.

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