Flood Risk Assessment
ESP prepares detailed flood risk assessments that identify flood hazards and support sustainable planning and development proposals
A flood risk assessment is critical for planning permission applications, as it assesses the risk and impact of flooding on a development site.
When considering whether a new development should proceed, a flood risk assessment can provide evidence that the site will remain safe from flooding in the future. This assessment also considers any impact from climate change or other changing environmental factors. When risks are identified on the development site the flood report also offers potential solutions to the risk of flooding, assisting the developers, architects and surveyors to safely mitigate these risks.
A flood risk assessment comprehensively evaluates a development proposal to assess its potential flood risk from:
- River sources (fluvial)
- Sewer sources
- Estuary / coastal sources (tidal)
- Surface water (pluvial)
A flood risk assesment ensures appropriate measures are identified to mitigate any potential hazards. Flood Risk Assessments are often a requirement of planning applications, especially if the development site is in a Flood Zone.
Often causing significant damage and in some cases loss of life, it is imperative that pragmatic and safe solutions be provided to match existing developments and patterns. Flood risks present significant constraints on existing and new developments. In extreme cases, planning blight can prevent much needed improvements to facilities in existing settlements leading to urban decay. The consequences of flooding can be severe and present significant risks to people and property.
In recent years, despite advance warning, large flood events have occurred with increased severity and significantly increases in financial loss.
What Is a Flood Risk Assessment (FRA)?
Recent Flood Risk Assessment Projects
Case Study 1: Caerphilly Flood Consequence Assessment
We have been involved in the FCA through two phases of development, and have undertaken iterative assessment to address the flood risk posed to the development.
We were instructed to commence an assessment of the general site about the likely impact of flooding from the Rhymney River which is present to the south.
Once it was understood what ground levels could be utilised to reduce the risk posed by flooding, the development was then progressed in two phases, with each phased assessment being undertaken to determine satisfaction of all local and national guidance, e.g. Technical advice note (TAN) 15: development and flood risk.
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Why Do You Need a Flood Risk Assessment?
The objective of an FRA, Flood Risk Assessment (England) or FCA, Flood Consequence Assessment (Wales) is a formal report that accompanies a planning application for development. It is used to develop a full appreciation of the risks and consequences of flooding and demonstrate the development can be implemented with minimal risk to life and property, without increasing flood risk elsewhere.
Once a Flood Consequence Assessment has been undertaken, it can be used as part of a suitable planning application (if a favourable outcome is achieved) or can be used to target further specialised assessment, such as flood modeling, development iteration and discussions with stakeholders and regulators.
When Is a Flood Risk Assessment Needed?
Flood Risk Assessments will vary based on the topography and of the site along with the flood zone the site is situated in. The site is defined as greater or less than 1 hectare while Flood zones are classified as one of the following zones:
- Flood Zone 1 – 1 in 1000 or 0.1% or less annual probability of flooding
- Flood Zone 2 – 1 in 1000 or 0.1% to 1 in 100 (1%) annual probability of flooding
- Flood Zone 3 – More than a 1 in 100 (1%) annual probability of flooding
The Environment Agency and Local Authority Strategic Flood Risk Assessment provide information about the flood zone classification for a site. An FRA will also be need if the development site is 20 metres or less from an Environment Agency main river.
A flood risk assessment is need in the following circumstances:
- For sites in flood zone 2 or 3 including minor development change of use.
- If the site is situated in a flood zone 1 and larger than 1 hectare (ha).
- Less than 1 ha and in flood zone 1 including change of use.
- Flood zone 1 areas with critical drainage issues as detailed by the Environment Agency.
For all sites (discounting highly vulnerable development in Zone 3) there needs to be a justification test, which includes:
- An assessment of the development, its impact, the potential consequences of flooding
- Mitigating/supporting measures such as flood resilient design (see adjacent Insert courtesy of DEFRA)
- Flood management plans
- Evacuation plans
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Why Choose ESP As Your Flood Risk Consultants
We are experienced in providing such solutions and have influenced the application of Government policy through input to appeals and public inquiry. Our projects have addressed flooding risks from rivers, culverts, and the sea, ranging in scope from protecting individual houses to facilitating regional development schemes. We have been producing Flood Consequences Assessments in Wales for over 15 years (see our Caerphilly Case Study) and have witnessed the evolution of the information and considerations required for these assessments.
We regularly work with stakeholders and regulators to approach developments in a practicable and safe way while maintaining a pragmatic approach for our clients. Some of our previous FCA case studies can be found here.
Our flood risk assessments provide a detailed analysis of multiple sources of flood risk proving specific mitigation strategies that apply to your development.
Within your FCA or FRA you’ll be provided with clear advice that:
- Satisfies local and national planning policies
- Includes a cost-effective plan for the mitigation of flood risk
- Equips you to make educated changes to designs as required
- Mitigates the risk of the development into the future
- Supports any planning permission process undertaken
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Frequently Asked Questions
What Can Cause a Flood Risk?
Many factors can cause flooding and flood risk, these include:
- Local topography
- Surface water run-off
- Rivers and coastal proximity
- How land is used
- Vegetation coverage
- Drainage systems
- Hardstanding
- Groundwater
- Rainfall
- Quarries
- Geology
- Mines
- Proximity to lakes, reservoirs or artificial water bodies
- Existing flood defences
- Climate change
Why is a Flood Risk Assessment Required?
A flood risk assessment can be required for a range of reasons including:
- Validating planning applications
- Satisfying planning conditions
- Facilitating land or property purchases
- Sale or divestment of a site
- Conducting general due diligence
- Complying with requirements of lenders, mortgage, or pension funds
- Business risk assessment
Is My Site in a Flood Zone?
Is the Site in England?
A Flood Zone is defined by the Environment Agency for planning purposes. You can identify the flood zone for your site by entering your postcode into the Environment Agency Flood map tool available here.
Is the Site in Wales?
A Flood Zone is defined by Natural Resources Wales for planning purposes. You can identify the flood zone for your site by entering your postcode into the Development Advice map tool available here.
Is the Site in Scotland?
A Flood Zone is defined by Scottish Environment Protection Agency for planning purposes. You can identify the flood zone for your site by entering your postcode into the Scottish flood hazard and information map tool available here.
Who Uses a Flood Risk Assessment?
- House builders and developers – to assess risks on prospective or current building projects.
- Property professionals – including architects, planning consultants, and land agents who need to understand flood risks when advising clients.
- Legal professionals – for due diligence and when handling property transactions in flood-prone areas.
- Lenders, banks, or mortgage providers – to evaluate risks for properties they finance.
- Businesses – especially those purchasing or leasing properties in areas with potential flood risks.
- Private individuals – when buying property or land that could be at risk.
Can you Complete a Flood Consquence Report For Welsh Sites?
Yes, we can complete a flood consequence report for Welsh sites. An FCA uses the same tiered framework as FRAs for sites in England, and this is something we can help you with, so do get in touch if you need an FCA completed.
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Speak To Our Experts Today
Earth Science Partnership is a leading expert in flood risk assessments across Wales, England, Scotland, Northern Ireland and Ireland. We have decades of combined experience in our team of industry-recognised experts.
Our work, for homeowners, land owners, developers, and investors is completed in compliance with the latest, relevant industry best practices and guidance. We understand that every project is unique, so we deliver our services tailored to your needs.
If you’re looking to complete a flood risk assessment, the ESP team can support you with a straightforward, cost-effective solution for your planning permission application.
Author
I am a UK Registered Ground Engineering Specialist and Chartered Engineering & Environmental Geologist with significant experience in Site Hazard Assessment, Remediation, Design, and Implementation across the Geoenvironmental and Geotechnical sectors in the UK and abroad.
I often work in multi-disciplinary teams advising other engineering and design professionals on the implications of ground hazards.
My work involves undertaking design, planning, management, and reporting of ground investigations. For example investigations for new developments and many bespoke studies including:
- Assessment of hydrogeological settings, materials for earthworks.
- Impact of abandoned mine workings.
- Remediation and stability assessment of soil and rock slopes/landslides, most notably the Pantteg Landslide in the Swansea Valley for which I have guided and presented assessments to Local Authority officers and the general public.