London
The Next Sponge City?

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In this hot, dry weather, it can be easy to forget the July floods of 2021. London experienced two flash floods in as many weeks and on each occasion, twice the average monthly rain fell in just two-hours, costing councils hundreds of thousands of pounds. And let’s not forget the unprecedented rainfall of August 2022, or the fact that between October 2023 to March 2024 the Met Office announced that the UK had suffered the wettest half-year on record. One thing feels certain; London is under prepared for the impacts of climate change.

Schedule 3 of the Water Management Act 2010 (which was born in response to the 2007 floods) may not be any closer to being enforced but in recent months there have been some reassuring ripples of change happening. TheGLA Infrastructure team launched a ‘Reimaging Rainwater in Highways’guidance document, DEFRA published National Standards for Sustainable Drainage Systems (SuDS) but perhaps most encouraging has been a new London Surface Water Strategy which looks to address the risk of surface water flooding in our city. Could London be the next Sponge City?

The number one purpose of London Surface Water Strategy is to ‘increase resilience to surface water flooding through collective action that benefits people, places and the environment.’  The development and delivery of the strategy is led by the Flood Ready London partnershipmade up of the Environment Agency, London Councils, London Fire Brigade, Mayor of London, Thames Water and Transport for London, supported by Thames Regional Flood and Coastal Committee. This partnership proposes a new fund that will be ring-fenced for strategic SuDS and blue-green infrastructure projects developed through the catchment partnerships with initial contributions from the Mayor of London, Transport for London and Thames Water. 

It is as though Flood Ready London have taken Schedule 3 into their own hands. After vulnerable people, the strategy prioritisesnature-based SuDSand it stipulates that a flexible mixed approach should be used that follows a hierarchy of capture, control and then finallyadapt and respond. There are 10 defined Surface Water Catchment Partnerships that work across administrative boundaries. Flood Ready London will act as a coordinating body to guide partners and maintain progress from now until 2030 by which point the idea is that the strategy will be supported by a dedicated Surface Water Infrastructure Investment Plan.   

The strategy sheds light on some eye-opening statistics: 
• 320,000 properties in London are at high risk of surface water flooding 
• 40% of commercial properties (around 120,000) are estimated to be at risk of surface water flooding 
• To reduce flood risk across the whole of London an investment of £1.8 billion is needed over the next 50 years – or an additional £36 million annually.