Flood risk and new developments

Flood risks for planners

Flood risk management interacts with spatial planning by:

• using the planning process to avoid locating unnecessary new development in areas of high flood risk
• addressing flood risk to new developments whilst not increasing flood risk off-site
• managing surface water run-off of new development appropriately in consultation with the Lead Local Flood Authorities

Information relating to flood and water management in West Northamptonshire is set out in our Local Flood Risk Management Strategy.

Planning policy context

The National Planning Policy Framework (NPPF), explains how local plans should take account of flood risk. A local plan should set out the strategic priorities and policies for an area, including those to deliver the infrastructure for flood risk.

Local planning authorities can develop policies which contribute to the active management of flood risk and can include:

• allocating new development outside areas of high flood risk or securing of flood protection measures
• protecting watercourse corridors and green networks
• avoiding new culverting of watercourses
• actively encouraging the de-culverting of watercourses
• requiring sustainable drainage systems (SuDS) in new developments
• using Section 106 agreements from the Town and Country Planning Act or community infrastructure levy (CIL) to secure suitable surface water drainage arrangements 
• encouraging the use of in-built property level resistance and resilience measures 

The current Joint Core Strategy Local Plan for West Northamptonshire include policies on flood risk (Policy BN7 Flood Risk). The Local Plan is currently being reviewed with an expected adoption in 2026.

Strategic Flood Risk Assessments

The NPPF and its supporting Technical Guidance, state that Strategic Policies should be supported by Strategic Flood Risk Assessments (SFRAs).  

SFRAs are evidence base documents which assess the risk of flooding from all sources, taking into account climate change and are normally prepared in consultation with the Environment Agency, relevant Water and Sewerage Companies (WASCs) and other relevant flood risk management bodies including emergency planning and drainage teams. 

Read SFRAs within West Northamptonshire.

Sequential and exception tests

For some planning applications these tests will be needed. The Government has produced guidance of how to carry out these tests.

Water Cycle Studies

We are updating the Water Cycle Study for West Northamptonshire which will form part of the evidence base for the Local Plan.

Water Cycle Studies and Strategies (WCS) identify any tensions between new development proposals and infrastructure and environmental requirements in relation to water supply and drainage and identify appropriate solutions.

They are used to inform:

• housing allocations and numbers
• phasing of development
• where developer inputs may be required for new infrastructure

Surface Water Management Plans

Surface Water Management Plans (SWMPs) set out how local floods can be managed. Their purpose is to take into account the risks of all types of surface water flooding and ways to mitigate it. They provide information on local flood risk.

Development management/control

West Northamptonshire Council Local Planning Authority will consider flood risk from all sources when determining planning applications.

We have local guidance and standards to support the Local Planning Authority in considering surface water drainage proposals in West Northamptonshire, and to assist developers in the design of all surface water drainage systems.

The guide sets out the standards that we apply in assessing all drainage proposals, as well as the information we require to be submitted as part of the planning application.  

For a planning consultation, we will:

• encourage pre-application advise
• screen all planning applications at the validation stage for flood risk from all sources – river, groundwater, and surface water flood risk
• ensure that all relevant information sources have been utilised by the applicants – has the Lead Local Flood Authority, the Environment Agency, Internal Drainage Boards, and all relevant Water and Sewerage Companies been contacted for site specific information?
• ensure that the sequential and exception tests have been applied correctly
• ensure that an appropriate Flood Risk Assessment has been submitted, which demonstrates that the development will be safe for the lifetime of the development, has safe access and egress in times of flood, and will not increase flood risk elsewhere
• ensure that sustainable drainage has been incorporated where appropriate

Neighbourhood plans

Communities can also ensure that new development adequately plans for flood risk. Neighbourhood planning provides a powerful set of tools for local people to ensure that they get the right types of development for their community. 

Last updated 08 March 2024