How to do a Flood Risk Assessment:


If you are looking to develop a particular property or site within a flood risk area, the National Planning Policy Framework (NPPF) requires that a Flood Risk Assessment (FRA) is conducted.

A Flood Risk Assessment is required when a development is located within Flood Zone 2 or 3, located within a Critical Drainage Area, or is greater or equal to one hectare and located in Flood Zone 1. Generally, the assessment is conducted to ensure that the development is safe and doesn’t exacerbate flood risks for others.

Without a supporting Flood Risk Assessment, the planning application may be denied.

What is a Flood Risk Assessment?

A Flood Risk Assessment is a document that reviews a development in its proposal form to assess the risk of flooding, and type of flooding; groundwater, river (fluvial), surface water (pluvial), estuary/coastal (tidal), or from sewer sources. It should also take into account the surrounding area and whether the development may pose a flood risk to areas nearby.

What does a Flood Risk Assessment Involve?

Each report is unique and tailored to the particular land, property, or development project being assessed. It should consider full details of the location, and surroundings using specific data and software, which can include topographic data, LiDAR data, and hydraulic modelling.

The report should assess the proposed use of the development, the number of people who will be on site or use the development, and how it will impact on flood risk in the local area, along with how the risk can be managed to ensure the development proposed is both safe and suitable over its lifespan. The report must be in line with necessary legislation and the National Planning Policy Framework.

The data is often complex and displays modelled flood extents at a site, showing the proposed developments vulnerability to varying flood risk scenarios and climate change variability allowances.

Can I prepare a Flood Risk Assessment Myself?

In short, yes. There is nothing stopping anyone from conducting their own Flood Risk Assessment for their proposed development, however whilst unqualified personnel can produce their own Flood Risk Assessments, FPS Environmental would not recommend this.

Accurately assessing flood risk can be complicated, especially where specific software is required to handle the raw model data. Alongside this, laypeople are not likely to carry suitable insurance for their assessment, which could pose future issues.

Developing a site is a costly process, and to ensure best practice is followed, early engagement with a Flood Risk Consultant is recommended. This will allow the optimal outcome for the site to be proposed, saving time and money over the development.

Getting a qualified professional to conduct a Flood Risk Assessment is always recommended and highly advised.


Appointing a Professional Flood Risk Consultant

Every property is unique with regards to the construction type, and external factors such as local drainage, geology, infiltration, and topography. Understanding the relationship between these site factors, alongside Flood Risk Model data is highly important. A qualified professional will have a keen eye for detail and understand how these factors all link, as well as their impact on potential flooding.

Flood Risk Assessments should be extremely thorough and detailed. The report must assess all elements of the proposed designs and compare them with varying flood model scenarios. Often these scenarios are assessed over the development’s lifetime, meaning that climate change allowance flood model data is often used to assess the flood depths at a site in the future. This requires a trained professional’s expertise and experience, as proposed plans may need to be altered to compensate for future climate change allowances. This may involve technical discussions with the project Architect.

If a Flood Risk Assessment is not thorough, covering all required aspects, the development will likely be rejected by local planning authorities. These rejections can cause lengthy delays to the planning application and commencement of the development.

Alongside legislative requirements, a detailed Flood Risk Assessment should help reduce and mitigate the flood risk to the property, and ensure the development does not exacerbate the risk for surrounding properties. A Flood Risk Consultant should hold Professional Indemnity Insurance which covers their advice.

How Can We Help?

At FPS Environmental we have considerable experience undertaking Flood Risk Assessments across a diverse range of properties, flood zones, and development proposals.

We use the most up-to-date and high-tech data available, combined with working collaboratively with a range of sectors such as the Environment Agency, Architects, Lead Local Flood Authorities, and with the client. The process ensures all relevant information is analysed during our Flood Risk Assessments, giving our clients reassurance, in depth information and the understanding they need.

If you’re unsure and need advice about a proposed development, contact our team of specialists who can help and advise at or call 020 8050 3194.

More Posts You May Find Interesting