DSM’s Roel Marissen is one of the founding fathers of this invention. Under normal circumstances the floater and sail/membrane are wrapped up under ground. When a tsunami hits the beach, the floater rises and the sail expands. The sail and floater are firmly anchored with cables and therefore a wall is created that stops the water.
The cables and the membrane (which is only 1 centimeter thick) that catch the enormous force of the tsunami are made of Dyneema®, a fabric that is fifteen times stronger than steel.
The construction is tested at Deltares in Delft, the Netherlands, where the most extreme circumstances were simulated. The membrane passed the tests easily. Even with simulated waves higher than 20 meters, when some water surpasses the sail, the flood barrier was not subverted and stopped the rest of the water.
For a clear explanantion of how this construction works, see the movie below.
Sources: www.dyneema.com & www.limburger.nl