Flood barriers are employed all over the world to prevent a sudden deluge of water from damaging property and potentially taking lives.
A few sandbags lining the floor of a porch will be an effective defence against a small flash flood, but something a little more robust is required to hold back the mighty swell of a river such as London’s Thames.
In 1953, London and the surrounding area was hit by a flood that claimed 307 lives and caused millions of pounds’ worth of damage. It prompted the creation of the Thames Barrier, an impressive feat of engineering that took eight years to build and cost GBP 534 million (USD 839 million) by the time it was completed in 1982. It stretches across 520 metres (1,706 feet) of the Thames near Woolwich and comprises ten separate gates on pivots supported by concrete piers that house the machinery for operation of the gates.
As tends to be the case with all the best engineering designs, the Thames Barrier is based on a very simple concept. Each gate is radial, using hollow cylinders that rotate the barrier through 90 degrees according to whether they’re in open, flood control or maintenance positions. Four central gates over 20 metres (65 feet) high and weighing 3,300 tons each span the middle section of the barrier, with two smaller gates next to them and four non-navigable radial gates that sit above the river during normal flow.
The Thames Barrier place to go
Second Thames flood barrier planned
Thames Barrier – Model shows operation
Stormy waters
The Netherlands – parts of which lie below sea level – was even worse hit: the country’s sea defences buckled under the pressure and killed 1,835 people, 30,000 animals and caused over a billion Dutch guilders (about GBP 360 million/USD 570 million) of damage.