Planning and Flood Risk in England: What You Need to Know Before You Build
Flood risk planning is a key part of any development in England because of flood risk from rivers, the sea, surface water and groundwater, among other sources. Flood risk planning in England includes checking the flood zone of your area, performing flood risk assessment and if required, sequential and exceptional tests.
The planning authorities in England mostly reject planning applications in flood zones 2 and 3 or at risk of any flooding without an FRA or with an inadequate FRA. This guide covers the flood risk of England and how to effectively plan for it.
How Flood Risk Affects Planning Decisions In England
England faces flood risk from rivers, the sea, surface water, groundwater and reservoirs. In addition to this growing housing demand, climate change is adding to flood risk. For this reason, the National Planning Policy Framework (NPPF) has set strict planning rules.
The NPPF states that the lowest risk zones should always be prioritised for development, and high risk zones should only be considered in exceptional cases. It has also made it mandatory to perform a flood risk assessment for any development in zones 2 and 3 or affected by any flood risk. NPPF also emphasises the Sequential test and the exception test.
The sequential test is performed to first find a low-risk zone and secondly prove that there is no low-risk zone available. In terms of the exception test, it is performed to prove that the development in a high-risk flood zone will be sustainable and protected for a lifetime.
Lead Local Flood Authority and the Environment Agency utilise flood risk assessment reports for decision-making and application approval. In the case of no flood risk assessment, you may face high chances of planning application rejection in flood zones 2 and 3.
When Is a Flood Risk Assessment (FRA) Required?
A flood risk assessment is a site-specific study carried out by a qualified consultant to assess flood risk and propose measures to mitigate the risk. A flood risk assessment typically includes
- Identifying all flood sources
- Proposing mitigation strategies
- Assess how climate change will affect flood risk over time.
There are multiple triggers for a flood risk assessment, and we will look at them all one by one:
- Flood Zones: Any development in flood zones 2 and 3 needs a flood risk assessment.
- Site Size: if the development site is in flood zone 1, but it is 1 hectare or more, it has to go through a flood risk assessment for planning permission
- Surface water and drainage risk: If a flood map for planning shows flood risk from surface water in zone 1 or locals flag a site for future flood risk due to climate change, a flood risk assessment will be required
- Change of Use: If changing a less vulnerable building, like a parking lot, into a vulnerable development, such as a school or a home, a flood risk assessment will be required.
- Official Map update: If the Environment Agency updates its flood map for planning and a previously risk-free zone is flagged high-risk zone, a flood risk assessment will become mandatory.
These triggers for flood risk assessment are there to ensure flood planning at best. To protect people living in England, build long-lasting properties and also conserve the environment.
Applying the Sequential Test in Flood Risk Planning
In England, the NPPF requires a sequential test as part of flood risk planning. This test is performed to direct development to the lowest-risk zone. All flood sources and climate change are considered, and flood risk zone 1 is always prioritised over Flood risk zone ⅔.
The planning and practice guidance defines the flood zones as:
- Flood zone 1: Lower risk zone, with less than 01.% annual flood chance from rivers and the sea
- Flood Zone 2: Medium risk zone with 0.1-1% annual chance of river flooding and 0.1-0,5% chance of annual chance of sea flooding. It is a light blue area on the Flood map for planning.
- Flood Zone 3: The Highest risk zone, which is divided into two parts. Zone 3a, the dark blue area with a 1% or greater river flooding chance and a 0.5% or greater flood probability from the sea. The Zone 3b is a functional zone, where floodwater must flow or be stored.
The Sequential Test Process
The process of sequential testing is step-based and follows the following order:
- First, check if the sequential text applies to your site. If the site is located in zone ⅔, sequential text will be needed.
- The next step is to look for an alternative low-risk site.
- If the alternative lowest risk site in zone 1 is not available, flood zone 2 sites are considered.
- Only if no site is available either in zone 1 or 2, should zone 3 be considered.
- The entire process is documented and submitted alongside the planning application.
Once a sequential test is performed and no lower risk site exists, the next step is the exception test. Which we will cover in the next segment.
The Exception Test: When Higher-Risk Sites Are Considered
The exception test follows the sequential test. Once the sequential test has been applied and it shows no low-risk site is available, development will still follow in high-risk zone 2 or 3. The exception test has two conditions, which must be fulfilled for planning permission.
- Sustainability Benefits: The proposal must prove that the development carries sustainable benefits that outweigh flood risks. In practice, this means the development should be important and beneficial for the area and the public.
- Flood Safety: The mitigation strategies should protect the development for its lifetime. And the development should not increase the risk of flooding elsewhere.
Both parts are part of an FRA, but part A is often argued through the planning justification, and part B is provided as an evidence report in an FRA.
Frequently Asked Questions
You can find your flood zone by using the Enviroment Agency’s flood map for planning. This flood map divides the area of England into three flood zones based on the risk percentage. Once you add your postcode, you will be able to see which flood zone your property is in.
This depends upon the site complexity, flood risk and your service provider. For instance, we at RIDA Reports provide a policy-compliant and resilient flood risk assessment in 48 hours and also provide nationwide service.
Simple answer, yes! In detail, if your site is in zone one but is 1 hectare or bigger, or if the site is in zone 2 or 3, you will need a flood risk assessment for planning permission.
A flood risk assessment should be prepared by an experienced and expert flood risk assessor. RIDA Reports has 21+ years of experience in UK planning policy, Environment Agency data and flood modelling. We provide a robust flood risk assessment in 48 hours to fast-track your planning application and permission.
What’s Included in a Flood Risk Assessment by RIDA Reports
RIDA Reports perform site-specific comprehensive flood risk assessment, according to official flood policies by NPPF and the guidelines of the Environment Agency. Our flood risk assessment includes:
- Site and Location: We include a map or plan of the site, which shows boundaries, nearby rivers and drains, flood defences and major landmarks. It also includes information about the current site plan and possible layout for the development.
- Ground Levels: We perform a detailed survey to understand the predicted flood levels by EA for a specific site and include our proposed ground and floor levels. Making sure the development floor levels are higher than the predicted length of flood that can reach a site.
- Flood Zone and Sources: Our FRA states the flood zones and clearly tells in which zone the site lies. We also study all possible sources of flooding along with their probability and include them in the site-specific flood risk assessment.
- Climate Change: Our engineers take extra measures to understand future climate change and include this information in the FRA. Our goal is to clearly depict how future climate change will affect the flood risk of the site.
- Flood Mitigation Measures: Our Engineers provided mitigation measures to protect the site from flooding for a lifetime. It may include designing strategies and Sustainable Drainage systems to protect the property and manage flood water.
- Safe Access and Egress: We also include safe site access and egress during a flood. We include emergency plans showing safe evacuation routes to dry land.
In summary, our flood risk assessment is a mix of modelling and planning. It typically follows a checklist in guidance.