The Tsunami Catcher
Tsunami Flood Barrier Concept
10 December 2014 - From 2004’s Indian Ocean tsunami to the 2011 tsunami in Japan, recent years have seen a number of disastrous tsunamis, raising the issue of whether there is anything we can do to protect ourselves better.
The conventional response has always been to build or raise the height dikes and walls. But dikes and walls destroy views and hinder access to the sea. Other ideas, such as installing mobile walls that are hidden until needed also require major investments in digging, installation, and maintenance. Deploying temporary panels requires you to have enough time to install them, and their maximum height is limited because the taller they are the more they bend under the pressure of the water.
A flexible tsunami barrier that floats into place
There may be another way, however. For DSM Dyneema scientist Roelof Marissen, the idea began to take shape when he started noticing above-ground swimming pools made from a thin, membrane-type material. If a fabric could keep water in, it could keep water out, he reasoned. The fabric in question would have to be strong enough to catch a tsunami, and light enough to deploy quickly. Marissen, an expert in Dyneema® UHMwPE fiber, believed he had the material he needed. Dyneema® is both the world’s strongest fiber, considerably stronger than steel, and it floats in water. The idea for creating a new kind of tsunami defense was taking shape.
"Membranes can be rolled, wrapped or folded, and so easily stored." - Roel Marissen
Known officially as the “Tsunami Flood Barrier Concept, made with Dyneema® Membrane" and unofficially as the “Tsunami Catcher,” Marissen’s idea is both simple and realistic: to make a membrane, a flexible barrier, out of Dyneema® fiber. As the video below explains, this would be anchored in a trench just above the sea or ocean floor and held in place with coils of rope, also made with Dyneema®. As a tsunami arrives, the force of the water would lift a float that would make the barrier unfold and rise to the surface to form a wall that would catch and repel it.
“A membrane barrier may provide a good compromise between protection, costs, and effects on local views,” explains Marissen. “Membrane stresses are pure tension while bending moments are absent, making this a mechanically highly efficient construction. The foundations only need to be able to withstand the tension forces which are introduced by the membrane, thus there is no tilting action on the foundation, as would be the case for the foundation of a wall, and membranes can be rolled, wrapped or folded, and so easily collapsed and stored with minimal space requirements. This makes them almost invisible when not needed.”
Strong enough to repel a 20 meter wave
To see if the concept would really work, DSM Dyneema partnered with Delft Technical University to model the new technology, and with the Deltares water knowledge institute to test it. The test involved recreating a scale model of a section of coast. The team then generated a tsunami that involved an initial influx of rapidly flowing water followed by a long period of high water, as it is the long tail that often causes the greatest damage. The barrier deployed and remained upright in all conditions during the test, including when the tsunami exceeded the design height, reaching the equivalent of over 20 meters, when scaled up from the test model. This sent water over the barrier, but didn’t collapse it.
"A one centimeter thick membrane is enough to stop a 20 meter high tsunami." - Roel Marissen
“We now know that a one centimeter thick membrane made of Dyneema® is enough to stop a 20 meter high tsunami,” says Marissen. “This is calculated using a safety margin multiplier of 2.5. Such safety factors are common in technical designs in order to account for unexpected phenomena. This means that, purely theoretically, the membrane would only need to be four millimeters thick to do its job.”
Partners wanted to bring tsunami barrier to market
What next for the Tsunami Catcher? Some aspects require additional research and DSM Dyneema is looking for a partner or government body that wants to get involved. The company would also like to hear from companies that might be interested in making and marketing the tsunami barrier system. If you would like to get involved, contact our science team.
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