The centre of London is at risk from catastrophic flooding that would make Hurricane Sandy's impact on New York pale in comparison, one of the UK's most senior businessmen has warned.

Sir Ian Cheshire, chief executive of multinational DIY company Kingfisher, which owns B&Q, has called for the creation of a national flood plan and said that responsibilities for water management are currently scattered among too many departments at national and local government level.

Cheshire, who led a government taskforce last year on the role of ecosystems, said the UK has to concentrate on adaptation and those still in denial about global warming should wake up and recognise "these events are connected to the fact that climate is fundamentally changing".

After studying the data last year, Cheshire said he was shocked that the risk to London from a storm surge or a breaching of the Thames Barrier was so little recognised and warned there was a threat of "disaster of epic proportions" in the capital. "If the Thames barrier is breached or fails for some reason, then the topography of London creates a massive problem because a lot of it is low-lying in the centre. If you combine that with the opportunity for water to get in the underground, as it did in New York, you've got a huge swath of central London being knocked out."

The worrying fact is the Thames barrier is recording increasingly higher rates of surge and has been closed more frequently, Cheshire added. While he believes it's still a "manageable risk", people need to start thinking about the problem "much more radically".

"This is sort of sci-fi disaster movie territory … It would be foolish to say there's a 50% probability this will happen in the next two years but I think when you start seeing 300-year events coming up more frequently, we start to worry about the level of adaptation that we've already got."

Cheshire believes the UK lacks a systemic understanding of how to prevent and manage flooding and pointed to three areas requiring long-term action. The first is to think about whole water catchment areas instead of worrying about where the water ends up. This involves looking upstream to get to grips with the issues such as adapting farming techniques and other soft flood defences.

This means a whole slew of initiatives "rather than just trying to build a bit of concrete at the end to stop water coming in" Cheshire said. He identified the lack of one body with the remit to tackle such initiatives as a major problem. He identified the lack of one body with the remit to tackle such initiatives as a major problem and asked whether water catchment management authorities can be set up with that explicit responsibility to also bring together all parties.

"You can't just assume this is going to go away. And I think that's the big message as a sort of wake-up call to say, this requires a national level of effort."

In a sideways swipe at the political squabbling that has come in the wake of the floods, Cheshire said the government needed to plan for the long term, rather than flood defences becoming a "political football that can be used around budget time. It needs to have a five- to 10-year view of how to manage the problem as opposed to 'we need to put some concrete in here quickly' or 'dredge this particular river'."

A second major area that needs to be addressed, according to Cheshire, is Britain's cities have become less resilient to flooding as a result of increased building density and the concreting of gardens, which means water is unable to soak away.

The third area of action is for individuals to start protecting their properties more effectively, through simple measures including the building of walls and ditches.

Kingfisher has itself been affected by the recent deluge with its Aberystwyth store put out of action twice by flooding and many more of its stores being affected in Poland. Cheshire called for businesses to wake up and respond, including understanding what their potential exposure is, given that many still don't consider flooding to be a risk. He also said there needed to be a fundamental change in the mindset of companies to recognise how they take our environment for granted.

"Most businesses don't think themselves as having any relationship with the ecosystem, that it's something very abstract, far away," he said. "They believe you get water, air and all these other things for free so it doesn't really matter. So I think making the shift in mindset is important so people understand that they have that dependency and work out where they're dependent. That is a very big awareness raising exercise."

Cheshire called on companies to start speaking to their customers about the issue, because there was a risk that once better weather comes, the issue of flooding will fade from people's minds.

"After these floods, it would be a tragedy if we get into the summer and everyone's forgotten about it, and then we wake up again this time next year and we've done nothing with it," he said.

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