Changes To The London Plan And How It Will Affect Flood Risk In The Capital

Development in London is subject to National Policy and adherence to the National Planning Policy Framework (NPPF).

Therefore, all development located in Flood Zone 2 or 3 must 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 are 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 Zones 2 and 3 or a Critical Drainage Area requires a Flood Risk Assessment to validate the planning application and comply with the NPPF.

What Is The London Plan?

In addition to adhering to the NPPF, London operates a separate planning policy document—the London Plan.

The London Plan is an important planning document that sets out how the City will be designed and function.

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 Plans and must be considered 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, support the construction of new residential dwellings/units is needed.

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, specifically regarding 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, emphasises London Boroughs and their respective Lead Local Flood Authority 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 what would happen if these defences were to fail.

The failure of these defences is also known as Breach.

Our team has access to the EA models, which help us determine whether your site is located in an area that could be affected by residual risk.

Additional changes to the developer’s emphasis 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 is traditionally responsible for upgrading and maintaining the defences that they own.

However, there are occasions when an asset/ defence is not under their ownership, and maintenance is the responsibility of the landowner—the riparian owner.

Paragraph F now emphasizes that the developer collaborates with the EA and Local Authority to improve and maintain the city’s flood resilience.

The Environment Agency operates a system nationally known as Flood Risk Activity Permits.

Although not explicitly detailed in Paragraph F of Sl 12, the principle of setting development back from flood defences is encouraged to allow for future maintenance and upgrades.

For Major Developments in London, there is now a greater focus on 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 of introducing Natural Flood Management Methods into development proposals due to their multiple benefits, including increased flood storage and the creation of recreational areas and habitats.

Major applications are considered more agile to promote such methods (Paragraph G).

How can we help you?

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

The team can reference 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.

If you have a project in London and you are unsure if a Flood Risk Assessment is required, contact one of our team members, and we will be happy to discuss whether an assessment is required.