Drawn up by Mayor Boris Johnson, Thames Water, the Environment Agency and London Councils, the proposals include a number of initiatives aimed at ensuring rain back is diverted from sewers into the soil.
The partners say decades of building over gardens and other open spaces has effectively ‘waterproofed’ the city and is driving greater amounts of water into its ageing server system.
Unless action is taken to reverse this trend the group warns London could be at risk of a major flood by 2050 when the sewer network is expected to be at full capacity.
Proposals to tackle the threat include building rain gardens and green roofs to increase the amount of permeable surface for water to soak into.
Such measures would sit alongside the Thames Tideway Tunnel project which will increase the capacity of London’s sewers and protect the River Thames from sewerage overflows.
Matthew Pencharz, the mayor’s lead advisor on environmental issues, said: “We need new sewers like the Thames Tideway Tunnel but cannot keep building them endlessly, which is why sustainable drainage is necessary.
“Today’s action plan is just part of a wider initiative by the Mayor of London to encourage sustainable development, which is vital to support our city’s population as it continues to grow.”
London Assembly members have previously warned of the harm caused by paving over garden areas and today one AM called on the Mayor to ensure anti-flood measures are included in all new developments.
Green party’s Darren Johnson commented: “Surface water represents the greatest flood risk to London.
“The Mayor’s plans must ensure that all new housing developments design in urban drainage that prevents run off during heavy rainfall and the risk of flooding to adjoining areas and properties.”
Mr Johnson says the mayor should “call for further tightening of permitted development rights to tip it in favour of gardens dominated by rain gardens, open deep flower beds, lawns and green open spaces with paving and other covered surfaces kept to a bare minimum”
