Stakeholders involved in the development of the London Surface Water Strategy have confirmed that it will assess flood risk across the city with a deliberate strategy to traverse borough boundaries.
This is the first time a strategy has taken this more “holistic” approach to assessing the risk, damages and potential interventions for surface water in the capital.
Speaking at London Climate Action Week, strategy stakeholders spoke of the importance of the strategy being released in May.
The impacts of severe weather such as flooding and extreme heat are becoming more frequent, with recent reports, including the London Climate Resilience Review, warning that London is underprepared for the impacts of climate change. Alongside this, the Environment Agency’s latest National Flood Risk Assessment data highlights that almost 320,000 properties in London are at high risk of surface water flooding.
The London Surface Water Strategic Group, now called Flood Ready London, was formed in 2022, following the heavy downpours and significant flooding in London of July 2021, and published its first strategy a couple of months ago.
It provides detailed water and geographical information to help the water industry, developers and planners learn more about London’s flood risk to develop policy and design schemes. The group is further advocating for the strategy to inform local action to help prevent and reduce the risk of surface flooding in the capital.
Discussing the release of the strategy, Homes England assistant director of strategy Elizabeth Rappaport said: “We knew the system we had for managing surface water flooding unfortunately wasn’t going to be good enough and that we needed to work together to improve it.
“There are huge risks of surface water flooding, we know that almost 320,000 properties in London are at high risk of surface water flooding and actually 11 times more properties are in areas of high risk to surface water flooding in London than flooding from rivers in the sea.”
London has a highly urbanised landscape with complicated infrastructure networks and its policy and governance is complex and fragmented, with funding, investment and skills in short supply, according to the strategy.
Rappaport went on to describe other challenges faced in London.
“One of the challenges we have in London is there are a lot of basement properties. We’ve identified at least 56,000 basement properties across London and they are understandably especially vulnerable to flooding and they’re not often designed for people to be able to escape during flooding.”
Lambeth Council deputy leader with responsibility for action on the climate, the ecological emergency and advancing sustainable mobilities Rezina Chowdhury also described challenges faced in his specific borough.
“Due to the urban heat island effect, which we’re very, very familiar with in Lambeth, it’s tough on everyone but it’s especially tough on the most vulnerable in in our communities and who have the least financial resilience and capital,” he said.
In order to combat the threats, Flood Ready London has set up catchment partnerships that work beyond boundary borders.
“We’ve created new surface water catchment partnerships, which is the new way of working and is based on detailed modelling that was done to understand the areas of risk,” Rappaport said.
“Particularly to ensure there’s effective cross-boundary working to address the risk because as we all know, if you are living in one borough and the waterfalls in another borough, that can be a bit challenging for your local authority to address because if the waterfalls in up the road from one borough and then goes down the hill into mine. What are the mechanisms for those two local authority to work collaboratively together?”
Chowdhury noted that the flooding doesn’t occur within borough boundaries and so must be dealt with “regardless of administrative or political boundaries.”
“Surface water when it floods, it doesn’t really respect borough boundaries, so the first partnerships are getting started now in central London and the Lea Valley with more plans soon to cover the whole city over the next two years,” he said.
The measures to be taken by the partnerships to help alleviate surface water flood risk will be based upon a hydrological approach.
“They’re based on a hydrological approach that aligns with the way water moves to manage the risk close to the source,” Chowdhury said.
“This won’t replace any great work that’s already happening, it will just build on it. The goal is to unlock more funding and roll out practical cost effective fixes like sustainable drainage, smart planning for big development and stronger infrastructure.”
In devising its hydrological approach, Greater London Authority climate adaptation manager Daniel Bicknall explained how other European cities comparable with London were studied.
“The group worked closely with other cities in the early days of the strategy,” he said.
“We learned a lot from Amsterdam who it’s fair to say they are a leading a leading city when it comes to all forms of flooding.
“Also Copenhagen were pretty instrumental with their cloudburst plan (the cities strategy for dealing with extreme rainfall events).
“One notable difference is London is about 10 times the size of either of those in terms of the strategy and scales so that that added an additional dimension, not to mention many more sort of layers of authorities and governance which will now look to start forming partnerships between.”
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