Homeowners should be called on rip-out urban paved front gardens to cut the risk of flooding, according to new research.

In future, the run-off in London could be equivalent to 100 Olympic swimming pools, overwhelming the drainage system.

Dr David Kelly, of Heriot-Watt University, Edinburgh, examined the potential impact that paved gardens could have on urban flooding in Edinburgh, Manchester, London and Exeter.

He applied projected rainfall intensities for each city to simulated paved front gardens.

“Domestic front gardens cover almost 30 per cent of our urban space and play a vital role in managing surface water run-off,” he said.

“Existing urban drainage systems will be inadequate to cope with the level of increased run-off from paved gardens.”

With run-off from impermeable surfaces likely to increase in future, the risk of flooding will rise unless attitudes change.

“Homeowners and policymakers need to focus on de-paving gardens across the UK,” Dr Kelly said. His work predicted that run-off from paved gardens will increase considerably by the 2080s due to extreme storms that will result from climate change.

“In London the run-off could increase by as much as 278,000m3” said Dr Kelly, who added that if gardens were de-paved, run-off could almost be eliminated, if removal of paving was combined with planting.