A Flood Risk Assessment, or FRA, is a technical report that reviews the flood risk to a site.

Why is an FRA required?

An FRA is required to demonstrate that:

  1. The flood risk to a proposed development is acceptable, and that development is directed to areas of lower flood risk where possible.
  2. The flood risk to areas outside of a site is not increased as a result of a proposed development; and,
  • Appropriate flood mitigation measures are provided where required.

Assessing flood risk is important as the level of risk could mean that:

  1. Development proposals may need to include flood mitigation or flood resilience measures to minimise the effects and impacts of flooding; or.
  2. Development may not be permitted at all.

When is an FRA required?

An FRA is typically required to be submitted as part of a planning application for:

  • Any site greater than 1 hectare;
  • Any site located in Flood Zones 2 or 3 as identified on the Environment Agency Flood Map for Planning;
  • Any site which could be affected by other sources of flooding such as surface water, groundwater, or reservoirs; and/or,
  • Any site located within a Critical Drainage Area.

Further details of the requirements for an FRA can be found on the UK government website:


Flood risk should always be considered at the outset of a project to ensure the proposals account for any flood risk mitigation measures that may be required.

What is included in an FRA?

An FRA should review the flood risk to a site from all sources:

  • Fluvial flooding from rivers and other watercourses.
  • Tidal flooding.
  • Surface water flooding.
  • Groundwater flooding.
  • Sewer flooding.
  • Reservoir flooding.
  • Flooding from artificial sources.

The level of risk is determined from assessing:

  • The frequency of flooding – assessing how often flooding is likely to occur at a site.
  • The effects of flooding – the potential flood extents, flood depths and duration of flooding that could be experienced at a site.
  • The impacts of flooding – assessing who and what may be affected during a flood, and what the potential damage and consequences may be.
  • Site specific conditions – how the geography and characteristics of a site may influence any of the above flooding conditions.
  • Historic flooding records.

What information is required for an FRA?

It is important to collate as much information to assist in assessing the flood risk to a site. Information can be gathered from:

  • Consultation with the Environment Agency (EA), Natural Resources Wales (NRW) or Scottish Environment Protection Agency (SEPA).
  • Consultation with the Lead Local Flood Authority (LLFA).
  • Consultation with any other authority that may be able to provide information relating to a site such as Internal Drainage Boards (IDBs), Local Planning Authorities (LPAs), Highways Authorities, Sewerage Undertakers, and other environmental authorities such as Natural England.
  • Review of flood risk documents such as Preliminary Flood Risk Assessments (PFRA) and Strategic Flood Risk Assessments (SFRA).
  • Review of flood maps.
  • Review of other site information including topography, geology, and environmental designations.

Where the level of flood risk to a site cannot be adequately determined from any of the above sources, it may be necessary to undertake technical assessments as part of the FRA, such as river modelling, to identify the risk.

How can flood risk be managed?

Once the risk is identified it must be considered alongside the proposals for a site. The vulnerability of the proposed development will determine what flood mitigation and flood resilience measures may be required.

If necessary, the FRA should propose flood mitigation measures to ensure the flood risk to a proposed development is minimised, managed or mitigated. A technical assessment of any proposed mitigation measures may be required to ensure they will not exacerbate flood risk elsewhere.

Surface water management measures in the form of Sustainable Drainage Systems (SuDS) are also typically required to ensure any increase in surface water run-off does not impact areas outside of the site.

I am unsure if I require an FRA.

FPS Environmental Ltd can answer any queries you may have relating to Flood Risk Assessments. Please get in touch and we would be happy to help and explain the options available to you.

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