How can the UK prepare for the floods to come?

http://www.theguardian.com/environment/2015/dec/29/how-can-the-uk-prepare-for-the-floods-to-come

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The government formally identified flooding as the greatest climate change related threat to the UK in 2012, a warning amply illustrated by the current floods devastating the north of England.

The 2012 report said up to 3.6 million people could be at risk from flooding by the middle of the century. So what can be done about it? Every time a community is flooded the understandable response from local people tends to be the same: more should have been done. Higher barriers, bigger walls.

There are, however, a number of possible ways to combat flood risks, ranging from multi-million pound infrastructure projects to DIY-scale domestic jobs. Beyond that lie the more politically unpalatable considerations of whether some areas are so flood-prone they are no longer viable.

Finally, the experts warn that the rules themselves have changed. In the past, flood experts based defences on historical records; on how to withstand once-a-century deluges. But such events are now not just more common, they are occasionally more fearsome than expected.

Physical barriers

These remain on the front line of flood defence, mainly for larger communities where the major construction costs are justified by sufficiently large populations.

Sarah Whatmore, professor of environment and public policy at Oxford university, who has led studies on flood defences, said some of these – even major ones such as the barriers on the Thames in London and in York – might need to be re-thought in the era of climate change.

“We probably need to rebuild or re-scale those interventions, at very large expense,” she said. “The likelihood is that there is now this additional intensity or frequency.”

This leads to the issue of cost, not least what the climate change committee, which advises the government, warned in 2014 was a big gap in public spending.

The government is aiming to raise £600m in “partnership funding”, including from the private sector, where developers building in flood-prone areas contribute to the cost of defences.

Earlier this month, the government said it had so far raised £250m. However, just £61m came via the private sector, meaning £189m came from local councils – possibly not a viable future source of flood protection money given the spending cuts.

Related: PM defends government spending as cost of floods set to top £5bn

Natural defences

These sorts of schemes, often intended to slow the water run-off from hills and so stop flood defences being overcome, runs counter to old ideas of dredging and channels to direct the water towards the sea as fast as possible.It appears to often be effective, as well as being cheap enough to make them cost-effective in lower population areas such as Cumbria and Somerset.

Whatmore led a project in flood-prone Pickering, north Yorkshire, which saw local people plan new defences with flood modellers. While the original plan involved an expensive flood wall in the town, the collaborative effort came up with two other sorts of barriers. The first was permeable wood debris dams on the uplands around the town, mainly cleared for sheep grazing, to hold up water flow. Lower down were earth “bunds”; smaller, part-concrete structures designed to divert some flow away from the town.

Severe winter rain in 2014, when only the wood dams were finished, saw no flooding, according to Whatmore. “In a very awkward way, for these things to be actually tested requires a major weather event, which none of us wants,” she said. But they really do bring benefits. Cheap does not equal ineffective.”

Related: North-south divide cited as factor in Yorkshire flooding devastation

The home front

Such natural defences can be more small scale still. The Environment Agency has worked with the Royal Horticultural Society on the Greening Grey Britain campaign, intended to persuade people against concreting or paving over grass or earth, thus slowing water run-off and relieving pressure on drains.

Another approach is to accept that some flooding might take place, but to make homes better protected and easier to repair. Preparations can include a “toilet bung” to stop floodwaters washing sewage into a home, grass roofs to limit water run-off, and air bricks that seal when floods reach them.

On Monday, the deputy head of the Environment Agency, David Rooke, spoke of the need for such measures. “We will need to have that complete rethink, and we’ll need to move from not just providing better defences but looking at increasing resilience so that when properties do flood they’ve got solid floors, waterproof plaster, and electrics have been moved,” he said. “Then people can get back into their homes and businesses very quickly.”

The ‘managed retreat’

In some coastal areas, this is already the orthodoxy. An unpublished Environment Agency analysis last year predicted that over the next century almost 7,000 homes and buildings will be sacrificed to rising seas and erosion around England and Wales, with the cost of protecting them more than the £1bn value written off.

In 2013, a tidal surge along the east coast of England saw numerous properties lost to the waters. Whatmore warns that such an attitude might be necessary for some inland areas prone to flooding where new properties are still being built.

“There are some areas if people persist with building in known flood-prone areas, we simply won’t be able to protect them. It’s simply not a sensible place to be putting this kind of activity,” she said.