Flood Risk Assessments: A Practical Guide for Planning and Development
- May 14
- 3 min read
Flood Risk Assessments (FRAs) play a central role in the planning and development process, particularly as climate change, policy expectations, and data availability continue to evolve. From small residential schemes to major infrastructure projects, FRAs help decision‑makers understand whether development can be delivered safely and sustainably in relation to flood risk.
What Is a Flood Risk Assessment?
A Flood Risk Assessment (FRA) is a formal planning document that evaluates the risk of flooding to a site, both now and in the future. It demonstrates to local planning authorities and statutory consultees that a proposed development will be safe for its intended use and will not increase flood risk elsewhere.
In England, FRAs are informed by national planning policy and technical guidance published by the Environment Agency and central government. Official guidance sets out when an FRA is required and what it should include.
FRAs sit within the wider policy framework of the National Planning Policy Framework (NPPF), which requires flood risk to be considered early in the planning process and managed through the application of the Sequential and Exception Tests.
An FRA considers multiple sources of flooding, including river, surface water, tidal, groundwater, and interacting drainage systems. It also identifies whether organisations such as the Environment Agency, Lead Local Flood Authorities (LLFAs), Internal Drainage Boards, or water companies are expected to be consulted during planning.
When Are Flood Risk Assessments Required?
Flood Risk Assessments are required for many different project types, not just large developments. They are often needed where a site lies within Flood Zone 2 or 3, where development exceeds set size thresholds, or where localised surface water flood risk is present.
National flood mapping published by the Environment Agency plays an important role in screening sites for flood risk during the early stages of site selection.
Local authorities may also reference Strategic Flood Risk Assessments (SFRAs) to guide planning decisions and identify locally significant sources of risk:
What Does a Flood Risk Assessment Aim to Achieve?
A Flood Risk Assessment typically aims to:
Establish the level and sources of flood risk
Assess proposals against national and local planning policy
Review whether layout and design are acceptable
Identify impacts on flood risk both on and off site
Recommend appropriate mitigation measures
Mitigation measures often align closely with surface water management and Sustainable Drainage Systems (SuDS), with best‑practice guidance published by CIRIA in the SuDS Manual.
Even where mitigation is feasible, some developments may still be considered inappropriate in higher‑risk locations, particularly for more vulnerable land uses.
How Flood Modelling Is Transforming FRAs
Advances in flood modelling technology are enabling more confident and consistent Flood Risk Assessments. Rather than relying solely on static datasets, modern approaches allow practitioners to better understand flood behaviour across a site and test design and mitigation options more effectively.
Flood Modeller supports this shift by combining high‑quality data, scalable modelling, and outputs tailored to planning decisions.
This enhanced approach helps reduce uncertainty and supports clearer engagement with regulators and planning authorities.
Learn More
To support professionals through each stage of the Flood Risk Assessment process, Flood Modeller has launched a brand new webinar series focused on practical guidance, modelling workflows, and planning‑ready outputs.
Register for our upcoming webinar series and get ready to explore the Flood Risk Assessment process from start to finish. Can't attend live? No problem! You can still register to gain access to the recording, presentation slides, and handouts.
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