Changes to the London Plan and How it Will Affect Flood Risk in the Capital

Flood Risk and Development in London

Development in London is subject to National Policy, adherence to the National Planning Policy Framework (NPPF). Therefore, all development located in Flood Zone 2 or 3 is required to be supported by a Flood Risk Assessment, FRA.

Additionally, given that London is heavily urbanised, there is an increased risk of flooding from Surface Water. Large areas of Central London consequently at risk of flooding from surface water. Those areas greatly affected have been defined as critical drainage areas by each respective London Borough / Local Planning Authority (LPA) across Greater London.

Development in Flood Zone 2 and 3 or a Critical Drainage Area is required to have a Flood Risk Assessment to validate the planning application and in compliance with the NPPF.


What is the London Plan?

In addition to adherence to the NPPF. London operates a separate planning policy document – The London Plan. As of December 2019, the latest London Plan was published.

The London Plan is an important planning document that sets out how the City will be designed, functions, its contents influence most if not all decisions made with a focus on Planning – Transport, Environment, Economic Development, Housing, Culture and Health and Health Inequalities.

The London Plan is legally part of each of London’s Local Planning Authorities’ Development Plan and must be taken into account when planning decisions are taken in any part of Greater London. The latest plan runs from 2019 to 2041. However, some of the more detailed elements of the Plan, such as the annual housing targets, are set for only the first ten years of the Plan.

Why is the London Plan needed?

The population of London is projected to grow by 70,000 every year reaching 10.8million in 2041. This means that just to meet demand there is a need to support the construction of new residential dwellings / residential units. Dealing with such demand requires policies to promote Good Growth.

How does the London Plan impact Flood Risk and Development?

Of particular focus and interest-specific to flood risk and water management are policies SL12 and SL13 of Chapter 9 – Sustainable Infrastructure. These policies are evolutions of previous London Plan Policies 5.12 – Flood Risk Management and 5.13 – Sustainable Drainage.

Of the new policies of SL 12 and SL 13. SL 12 has evolved significantly since being recognised as 5.12. The new policy SL 12 – Flood Risk Management, places greater emphasis on London Boroughs and their respective Lead Local Flood Authority’s, to work collaboratively with the EA, developers and infrastructure providers. The new policy focuses much more on the Management of Flood risk across the capital.

So how does Policy SL 12 – Flood Risk Management, impact new development in Flood Zones?

Paragraph C of Policy SL 12 focuses specifically on new development.

C. Development proposals should ensure that flood risk is minimised and mitigated and that residual risk is addressed. This should include, where possible, making space for water and aiming for development to be set back from the banks of watercourses.


What is the residual risk and what is its importance?

For large areas of London, it is protected by the Thames Barrier which provides a standard of protection for up to 1,000 years. Central London also benefits from the presence of linear defences. In combination, these defences provide resilience to the City being subjected to flooding. Without the presence of these defences, London would experience flooding regularly. The Residual Risk is that What If these defences were to fail. The failure of these defences is also known as Breach. Our team have access to the EA models to allow us to understand whether your site is located in an area that could be affected by a residual risk. To find out more, please click the following

Additional changes to the emphasis of the developer, include Paragraph F of SL 12.

F. Development proposals adjacent to flood defences will be required to protect the integrity of flood defences and allow access for future maintenance and upgrading. Unless exceptional circumstances are demonstrated for not doing so, development proposals should be set back from flood defences to allow for any foreseeable future maintenance and upgrades in a sustainable and cost-effective way.

The EA would traditionally be responsible for the upgrading and maintenance of defences that they own. There are occasions where if the asset/ defence is not of their ownership the maintenance would be the responsibility of the landowner – riparian owner. Paragraph F now emphasizes that the developer works with the EA and Local Authority, collaboratively to improving and maintaining the flood resilience to the City.

The Environment Agency operates a system nationally known as Flood Risk Activity Permits, although not explicitly detailed in Paragraph F of Sl 12, the principles of setting development back from flood defences is encouraged to allow for future maintenance and upgrades. Should you want to discover more about Flood Risk Activity Permits.

For Major Developments in London, there is now a greater focus for Developers, to support Development plan development proposals that contribute toward the delivery of measures set out in the Thames 2100 Estuary Plan (Paragraph D). There is a promotion to introduction Natural Flood Management Methods into development proposals due to their multiple benefits including increased flood storage and creating recreational areas and habitats. It is considered that major applications are more agile to promote such methods (Paragraph G).

How can we help you?

Our team at VATN have supported hundreds of developments across London and as such have a diverse knowledge base that can support you and your development.

The team can draw reference to previous projects whilst also advising on specific London Borough policies in combination with the London Plan and NPPF of what is to be accepted and permitted by an Authority and their respective Lead Local Flood Authority. We welcome the opportunity to work with you. Should you have a project in London and you are unsure if a Flood Risk Assessment is required, contact of one our team and we will be happy to talk through whether an assessment is required.

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Aegaea work alongside home owners, private developers, planning consultants, architects, local authorities, international development agencies and contractors. Aegaea know exactly how to help you.

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