Environment Agency chief warns about the risk of future catastrophic surface water flooding in the UK
- Published: Friday, 19 October 2018 09:01
In a speech at the recent CIWEM Surface Water Management Conference, Sir James Bevan KCMG, chief executive of the UK Environment Agency warned about the growing risks that the UK faces from catastrophic surface water flooding.
“Surface water flooding is a risk because of its reach,” stated Mr. Bevan. “Of all the flood risks to which our rainy island is subject - from coasts, rivers, groundwater, sewers and surface water – it is surface water flooding which threatens more people and properties than any other form of flood risk. Over 3 million properties in England are at risk of surface water flooding, even more than those at risk from rivers and the sea (2.7 million). Surface water flooding is a risk because of its effect. It hits not just individual homes and businesses, but the whole infrastructure – road, rail, utilities etc – of a town or city, disrupting pretty much all aspects of modern life.
“Surface water flooding is a risk because people don’t know it is a risk,” continued Mr.Bevan. “If you don’t live near a river or the sea, it’s not wholly unreasonable to think that you are not at risk of flooding. But reasonableness isn’t the point. Leon Trotsky once said: ‘you may not be interested in war, but war is interested in you’. Well, you may not be interested in surface water flooding, but it is interested in you. And people who don’t know they are at risk are less well prepared to cope when the risk materialises.”
“Most important of all, surface water flooding is a risk which is growing,” Mr.Bevan warned. “An increasing population means more people are at risk. An increasingly urban population means more people are in cities, where the effects are starker. Development means more concrete, which means fewer places for rainwater to drain safely away. And the more frequent and intense rainfall which climate change is bringing will make flash flooding and overloading of the sewer network more likely and more frequent. That is why the government decided for the first time in 2016 to include surface water flooding on the national risk register.”
Mr. Bevan then set out a possible future scenario:
“Imagine this. It’s another beautiful hot summer day in the South East. Gradually it turns humid, with thunderclouds building up over central London. Then the clouds burst with astonishing intensity. Within minutes water is overwhelming the drainage system. The underpasses start to fill up and the roads become impassable. The Tube stops running as parts of it flood. The city starts to grind to a halt. Then the power goes out. It’s dark, and water starts coming into thousands of homes. It is inches not feet in most places. But in parts of the city it pours into basements, where it’s several feet deep, and people start to drown.
“This nightmare could happen. London is prone to high intensity thunderstorms and has an ageing Victorian sewer system. A smaller version did happen, in Hampstead in 1975 when in a localised thunderstorm it got more than three months of rain in three hours. Four of London’s main-line railway stations were flooded and closed. Much of the Underground was brought to a standstill as tunnels were inundated and the electrics failed. 250 people were made homeless. One day, a much bigger rainfall event than that will happen somewhere in this country. We need to be ready.”