What is a Strategic Flood Risk Assessment?

A Strategic Flood Risk Assessment (SFRA) looks at flood risk at a strategic level on a local planning authority scale. The National Planning Policy Framework (NPPF) requires local planning authorities to appraise the risk of flooding in their areas by undertaking an SFRA.

An SFRA takes into account the impacts of climate change and assesses the impact that land use changes and development in the area will have on flood risk. Ultimately, an SFRA functions to demonstrate that the flood risk to and from development will be acceptably safe throughout the lifetime of the proposed development.

SFRA Levels 1 and 2

The different levels of SFRAs reflect the likely risk of flooding from all sources and development pressures.

SFRA – Level 1

A Level 1 SFRA is prepared for areas where flood risk does not pose a significant hazard and where development pressures are low.

SFRA – Level 2

A Level 2 SFRA is prepared when land outside flood risk areas can’t appropriately accommodate all the necessary development and the NPPF’s Exception Test needs to be applied.

Level 1 SFRA Outline

Level 1 comprises of a desk based study, collating and reviewing existing flooding information held by the Environment Agency, Water Companies, the District and County Council and other agencies.

A Level 1 SFRA should include the following:

• Maps showing the local planning authority area, main rivers, ordinary watercourses and flood zones, including the functional floodplain if appropriate, as well as all previously allocated development sites (or sites to be considered in the future).
• An assessment of the implications of climate change for flood risk at allocated development sites over an appropriate time period.
• Areas at risk from other sources of flooding, such as surface water or reservoirs.
• Flood risk management measures, including location and standard of infrastructure and the coverage of flood warning systems.
• Locations where additional development may significantly increase flood risk elsewhere through the impact on existing sources of flooding, or by the generation of increased surface water run-off.
• Recommendations about the identification of critical drainage areas and the potential need for surface water management plans.
• Advice on the preparation of flood risk assessments for allocated and other development sites.
• Advice on the likely applicability of sustainable drainage systems techniques for managing surface water run-off at key development sites.

Level 2 SFRA Outline

A Level 2 SFRA is undertaken where the Local Authority identifies areas of new development in locations at risk of flooding.

A Level 2 SFRA should consider the following in addition to Level 1:

• An appraisal of the current condition of flood defence infrastructure and of likely future flood management policy with regard to its maintenance and upgrade.
• An appraisal of the probability and consequences of overtopping or failure of flood risk management infrastructure, including an appropriate allowance for climate change.
• Definition and mapping of the functional floodplain in locations where this is required.
• Maps showing the distribution of flood risk across all flood zones from all sources of flooding taking climate change into account.
• Advice on appropriate policies for sites which could satisfy the first part of the Exception Test (sustainability benefits to the community that outweigh flood risk), and on the requirements that would be necessary for a site-specific flood risk assessment supporting a planning application for a particular application to pass the second part of the Exception Test.
• Advice on the preparation of site-specific flood risk assessments for sites of varying risk across the flood zones, including information about the use of sustainable drainage techniques.
• Meaningful recommendations to inform policy, development control and technical issues.

Source: Environment Agency Guidance

Strategic Flood Risk Assessment services

Ambiental is a leading flood risk assessment and flood modelling consultancy, offering a range of advanced solutions for central and local government organisations. Our flood data and consultancy services can help local planning authorities to improve their Strategic Flood Risk Assessments through:

• Access to the very latest building level flood data
• An improved understanding of the risk posed by surface water flooding
• Provision of highly precise, and scientifically validated, fluvial, pluvial and tidal flood maps
• Advice and consultancy for improving Level 1 and 2 risk mitigation strategies

For further information, please get in touch with one of our flood risk consultants or call our head office.