Paving gardens to park big cars exacerbates flash floods

A TREND for big cars has increased the risk of flash floods because households use their front gardens for parking, the UK’s infrastructure tsar has said.

Flash floods hit several parts of the country last week, as heavy rain in the wake of the drought overwhelmed drains and sewers.

Homes, train stations and hospitals were inundated, after warnings from the Met Office that vulnerable homes should evacuate.

Sir John Armitt, chairman of the National Infrastructure Commission, said paving with impermeable concrete was exacerbating the problem.

“It has in part been driven by the increased ownership of big cars,” he said. “The roads get narrower and so cars get dented and scratched. People want to get their cars off the road and pave over their gardens to have somewhere to park.

“It’s staggering when you look at a 1970s and a 2020s car how much bigger they are. We think ‘gosh we used to travel around in those?’ They look minute now.”

A 2015 Royal Horticultural Society report found three times as many front gardens paved over as in 2005, a trend it said was vital to reverse.

Half of all front gardens are paved over in London, which saw some of the worst flash flooding this week.

Sir John added: “If you get the opportunity to rebuild some of your water attenuation systems, you can say, let’s try and not concrete over everything, let’s use more flexible drainage systems, let’s use some natural ways of absorbing water, rather than drains.”

Impermeable driveway surfaces include paving, tarmac and concrete. These materials result in more run-off as they are unable to soak up water.

Permeable driveway surfaces include gravel and brick pavers, which allow water to penetrate and avoid accumulation. Sir John said the preference for parking in front gardens was likely to increase as the popularity of electric cars grows because drivers will want to avoid trailing cables outside their homes.

Planning guidance for London already suggests permission for concrete front gardens and driveways should be denied unless they are “unavoidable”.