FloodsWaterworld: Learning to live with flooding
Flash floods, burst riverbanks, overflowing drains, contaminants leaching into waterways: some of the disruptive, damaging, and hazardous consequences of having too much rain. But can cities be designed and adapted to live more flexibly with water – to treat it as friend rather than foe?
In December 2015, Storm Desmond hit the north of the United Kingdom. In its wake came floods, the misery of muddy, polluted water surging through homes, and the disruption of closed businesses, schools, and roads.
Rapid urban growth and progressively unpredictable weather have focused attention on the resilience of cities worldwide not just to extreme events, but also to heavier-than-normal rainstorms, and raised questions as to how flood risk can be managed.
There is of course no one-size-fits-all strategy. For some areas, defense is a possibility. For others, retreat is the only option. “But for those unable to do either, we need to fundamentally rewrite the rule book on how we perceive water as a hazard to towns and cities,” says Ed Barsley, Ph.D. student working with Dr. Emily So in the Cambridge University Centre for Risk in the Built Environment (CURBE). Barsley believes that adaptation and planning for resilience can provide a unique opportunity for increasing the quality of towns and cities (see panel).
Cambridge U notes that Dr. Dick Fenner from Cambridge’s Department of Engineering agrees that resilience to water should be regarded positively. He is part of the U.K.-wide Blue–Green Cities project, which is developing strategies to manage urban flood risk in ways that also pay dividends in many other areas, through ‘greening’ the city. “We want to turn rainfall into a win-win-win event,” he says.
When it comes to dealing with floods, one of the major difficulties that many cities face is the impermeability of the built environment. In a city that is paved, concreted, and asphalted, surface water cannot soak away quickly and naturally into the earth.
Newcastle city center, for instance, is around 92 percent impermeable, and has suffered major flooding in the past. “The ‘flood footprint’ of the 2012 ‘Toon Monsoon’ caused around £129 million in direct damages and £102 million in indirect damages, rippling to economic sectors far beyond the physical location of the event,” says Fenner.
“Traditionally, cities have been built to capture water run-off in gutters and drains, to be piped away. But where is away? And how big would we have to build these pipes if the city can’t cope now?” he adds. The principal behind a Blue–Green City is to create a more natural water cycle — one in which the city’s water management and its green infrastructure can be brought together.
