THE GOVERNMENT'S latest strategy for flood risk management includes putting in measures to make existing homes built on flood plains more flood resilient.
One practical solution put forward by civil engineer John Forrest is Tilt-Dam - a permanent demountable flood defence system.
The system was developed with help from the ICE's research and development enabling fund and underwent a peer review last year before being launched at Great George Street last month.
Tilt-Dam was conceived in 2003 when Forrest learned about magician Paul Daniels' unhappy experience of living next to a flood-prone stretch of the Thames.
'I thought there had to be a way of permanently protecting properties from flooding, ' recalls Forrest.
orrest is a structural engineer and admits that until he started thinking about TiltDam he had had no experience of designing flood defence structures. 'But I thought I'd try some original thinking'.
Forrest's main design principle was to create a structure which could hold water back during fl oods, but was virtually invisible when not in use. He also wanted the device to be permanently available, reliable, require no power and be quick and simple to operate by just two adults.
But to make the concept a reality required building and testing a prototype. Enter the ICE's research and development enabling fund in July 2004, with cash and the right people to carry out a peer review of the design.
Tilt-Dam is a 3m long 1.5m wide steel and concrete structure built over a pit and able to pivot about a point. In the upright position, the structure separates the wet and the dry sides with a watertight seal at the bottom. In the horizontal position the structure is flush with the ground and can support nominal traffic loads.
'In the back of my mind, I had the idea of a simple lock gate - most of them leak, but they still work. For my design to work, it had to be able to deal with water, ' says Forrest.
He considered that water would inevitably fi d its way through the seal, so a drainage duct and pump had to be located on the dry side.
Maximising natural forces was also an important design principle and the 'gate' is counterbalanced to help it swing into the upright position. When multiple Tilt-Dams are erected next to each other, watertight seals are also designed to be maintained using pressure from flood water.
A prototype was built in the car park of building research body BRE in December last year and testing revealed that it took only three minutes to erect each unit.
But the real test will be to use it in the fi eld. Forrest is looking for funding to erect 9m of TiltDam to prove it works under flood conditions.
He believes that Tilt-Dam will cost between £1,000 and £1,500 a metre run. Interest in the device already ranges from providing fl od protection to wealthy home owners, to being used on seaside promenades.
For more information visit www. tiltdam. co. uk