Local planning authorities: strategic flood risk assessment
Find out how local planning authorities can complete a strategic flood risk assessment.
As a local planning authority, you need to carry out a strategic flood risk assessment to assess the risk to your area from flooding.
If you’re a local planning authority and you need to review a planning applicant’s flood risk assessment, read the guide on reviewing flood risk assessments.
You’ll use the strategic flood risk assessment to support your local plan and to help make planning decisions. Planning applicants will refer to your strategic flood risk assessment when carrying out their flood risk assessment.
Find out which level of assessment to complete
There are 2 levels of strategic flood risk assessment. All local planning authorities must do the level 1 assessment.
You must also do a level 2 assessment if you need to develop inside flood zone 2 or 3.
Contact the Environment Agency or your lead local flood authority if you’re not sure if you need to do the level 1 or the level 2 assessment.
Level 1 strategic flood risk assessment
The level 1 assessment needs to have enough detail for the sequential test to be applied.
You need to produce a report or commission a flood consultancy firm to produce a report that will make up your strategic flood risk assessment. The report needs to have maps that show the entire area that your local planning authority covers.
These maps need to show:
main rivers - use the Environment Agency’s flood map to check where these are
any other rivers and streams
development sites that have been allocated in the local plan as well as sites under consideration for future allocation in the local plan
flood zones including the functional floodplain (land where water has to flow or be stored in times of flooding) if there is one
Your report also needs to have an assessment of the risk of flooding in your area. Consider in this assessment flooding from all sources (eg surface water drains) not just the rivers and sea, and include an allowance for climate change.
This assessment needs to list:
areas at risk from other sources of flooding
existing measures in use in your area to manage flood risk (eg flood gates) - state where they are and how effective they are
areas that are covered by flood warnings
an area with critical drainage problems as notified by the Environment Agency
areas that may need surface water management plans
locations that may have an increased flood risk if there’s additional development
Your report also needs to contain advice for applicants carrying out site-specific flood risk assessments and to tell them If there’s anything specific they need to do to manage flood risk. For example, you need to tell applicants which sustainable drainage techniques are suitable for major and other developments. An example of a major development is one carried out on a site of more than 1 hectare.
You can contact the following organisations for help with compiling your strategic flood risk assessment:
- Environment Agency
- your lead local flood authority - contact your local council to find out who this is
Level 2 strategic flood risk assessment
The level 2 assessment needs to have enough detail for the exception test to be applied.
Your level 2 assessment needs to assess existing flood defence infrastructure (eg flood barriers). Your assessment should state where the infrastructure is and what condition it’s in - ask the people who operate and maintain it (eg your local authority or Internal Drainage Board).
You also need to assess the risk of flood defence infrastructure failing during the lifetime of the development. Include in your assessment an allowance for climate change as well as wave height and direction for assessments in coastal areas. Consider what the consequences of failed flood defences would be for the area.
If there’s anything specific planning applicants need to do to meet the requirements of the exception test, you also need to state this.