Secure Planning Approval with Expert Flood Risk Assessments
Planning applications on sites within or near flood zones face significant scrutiny from the Environment Agency and Local Planning Authorities. A professional Flood Risk Assessment (FRA) is essential to demonstrate your development is safe from flooding and won’t increase risk elsewhere.
If you need a flood risk assessment for planning, choose Lucion. Our team of expert flood risk assessment consultants can provide expert insights into whether your development is safe from the risk of flooding, helping you secure the relevant planning permission you need to take your project further.
As part of our flood risk and drainage services, we provide flood risk assessments planning support for developments across a range of sites and locations.
What is a flood risk assessment for planning?
A flood risk assessment (FRA) for planning is a technical report that is submitted alongside a planning application to prove that a proposed development will be safe from flooding and will not increase flood risk elsewhere. It is a material planning consideration used by the Environment Agency and Local Planning Authority to determine the application.
The report considers sources of flooding including rivers, coastal, surface water, groundwater and sewers, and identifies appropriate measures to reduce or manage the risk. It is used to establish layout adjustments, floor levels, mitigation measures and ensure NPPF compliance.
Do you need a flood risk assessment for your planning application?
Typically, you will be required to provide a flood risk assessment for planning application for developments in the UK if your site is greater than 1 hectare, located in Flood Zones 2 or 3, areas with critical drainage problems or places identified by the local council or Environment Agency as having a future risk of surface water flooding issues.
Ultimately, you need a flood risk assessment if your site is in a medium or high-risk fluvial flood zone, or if located in area at risk from other sources of flooding.
Flood Zone 1
Flood Zone 1 is considered low probability, with less than a 0.1% annual probability of river or sea flooding.
A flood risk assessment may still be required In Flood Zone 1 for developments of one hectare or more, sites affected by surface water or future flood risk, and certain other circumstances. It is used to identify all relevant sources of flooding and demonstrate that the development will be safe without increasing flood risk elsewhere.
Flood Zone 2
Flood zone 2 has a medium probability of flooding, so a specialist flood risk assessment is generally required for any developments within this zone.
Flood risk assessment consultants will conduct an assessment that considers the site’s potential exposure to flooding, including future risk from climate change, and identifies measures needed to make the development safe. It can also demonstrate how the proposal meets planning requirements, including the sequential approach where applicable.
Flood Zone 3
Flood zone 3 has a high probability of flooding, meaning a detailed flood risk assessment is necessary for developments within this zone.
It should assess all relevant sources of flooding, consider the development’s vulnerability and demonstrate that it can remain safe throughout its lifetime without increasing flood risk elsewhere. Depending on your site’s characteristics and proposed development, detailed hydraulic modelling and mitigation measures may also be necessary.
It is important to note that flood zone 3 is split into flood zone 3a (high probability) and flood zone 3b (functional floodplain), meaning the planning implications differ between them.
Depending on what the assessment of your development uncovers, our flood risk assessment consultants at Lucion can provide a comprehensive flood response plan or mitigation strategy. This plan includes mitigation measures, drainage strategies, emergency procedures and planning compliance.
Use the Environment Agency’s Flood Map for Planning to see if your development requires a flood risk assessment, then contact us to discuss your requirements.
What our flood risk assessments cover
A flood risk assessment for planning should cover all potential sources of flooding, future climate change impacts and mitigation plans to ensure a development is safe over its lifetime, without increasing flood risk elsewhere.
At Lucion, our flood risk assessment consultants work as part of our wider team of flood risk and drainage services consultants, and identify site-specific flood risks from all sources, including:
- Tidal Flooding: this occurs when seawater or tidal waters inundate normally dry land, often due to high tides, storm surges or coastal events. An assessment informs measures such as finished floor levels, flood-resistant and resilient construction and appropriate site design to reduce exposure to tidal flooding.
- Fluvial Flooding: this occurs from rivers and other watercourses when water levels rise and exceed the capacity of the channel or surrounding defences. It informs development layout and finished floor levels by considering the site’s proximity to watercourses, flood mapping, historic information and hydraulic modelling.
- Surface Water Flooding: this occurs when rainfall overwhelms drainage systems or cannot soak into the ground, causing water to flow or collect across the surface. An assessment can inform sustainable drainage systems (SuDS), site layout, finished floor levels and measures to safely manage water away from buildings.
- Groundwater Risk: this occurs when the water table rises and groundwater emerges at or near the ground surface, potentially affecting buildings, infrastructure and drainage. The FRA considers available groundwater information, local geological conditions, historic flooding and information to identify potential risks.
Additionally, we recommend practical mitigation measures as part of a flood response plan that satisfy statutory requirements whilst maintaining development viability.
Climate change allowances
Climate change allowances are predictions of anticipated change for peak river flow, peak rainfall intensity, sea level rise and offshore wind speed and extreme wave height. Flood risk assessments should consider how climate change could affect future flood risk.
To increase resilience to flooding and coastal change, allowances for climate change should be made in your flood risk assessment based on the Environment Agency’s allowances and other guidance. For tidal sites, sea level rise allowances are specific to the relevant river basin district. England is divided into 10 main river basin districts.
Mitigation measures
A flood risk assessment for planning identifies practical measures to reduce the impact of flooding on a proposed development and help ensure it does not increase flood risk elsewhere.
Measures include setting appropriate finished floor levels, incorporating flood-resistant and resilient materials, providing safe access and escape routes, and ensuring adequate compensatory floodplain storage where required. Flood risk assessment consultants will always select measures that reflect the site’s flood mechanisms, development vulnerability and predicted future flood levels while also considering the clients operational requirements.
Drainage and surface water management
Flood risk assessments consider how rainfall and surface water could affect the development, including existing flow routes, drainage capacity and the potential to increase runoff.
Where required, this can inform the use of sustainable drainage systems (SuDS) and other measures to control runoff, provide attenuation and reduce surface water flood risk.
At Lucion, we also offer both Outline and Detailed Drainage Strategies for Planning Applications, which covers surface and foul water drainage design and SuDS. We can also deliver the required supporting investigations, like soakaway testing.
Early engagement with our flood risk assessment consultants prevents costly delays, planning objections, and design rework that can impact your project timeline and budget.
Choose Lucion to support your flood risk assessments planning needs.
Our flood risk assessment process
A flood risk assessment must be conducted by specialists to ensure data is collected, analysed and reported on properly to ensure your development receives planning permission.
Our flood risk assessment process includes:
- Initial screening: we review the site’s location, proposed development and available flood zone information to establish whether a flood risk assessment is required, before identifying the key sources of flood risk.
- Data/desk study: we gather and review relevant information, including Environment Agency flood maps, historical flood records, topography, watercourses, drainage and climate change allowances, to build a picture of your site’s existing flood risk.
- Assessment (and modelling where needed): we assess how identified flood risks could affect the proposed development, using hydraulic or other modelling where the site’s characteristics, scale or flood risk require more detailed analysis.
- Mitigation and design: we identify appropriate measures to manage flood risk, which may include finished floor levels, flood-resilient materials, safe access and escape routes and sustainable drainage systems (SuDS).
- Report and sign off: we align the findings, modelling, mitigation measures and recommendations together in a clear flood risk assessment for submission with the planning application.
How long does a flood risk assessment take?
The exact timescale for a flood risk assessment depends on the complexity of your site and whether hydraulic modelling is required.
A straightforward flood risk assessment typically takes two to three weeks, whilst sites that require Environment Agency data requests take four to five weeks.
Early engagement helps to manage your timescales effectively. Contact us with your deadline to hand so we can align our flood risk and drainage services with your requirements.
