Flood risk

Lead Local Flood Authority

West Sussex County Council (WSCC), as the Lead Local Flood Authorities (LLFA), is responsible for developing, maintaining and applying a strategy for local flood risk management and for maintaining a register of flood risk assets. They also have lead responsibility for managing the risk of flooding from surface water, groundwater and ordinary watercourses. Details of how WSCC work with the district council and other partners to manage flood risk can be viewed on their website.

Arun District Council Responsibility

The district council is a key partner in planning local flood risk management and can carry out flood risk management works on minor watercourses, working with the LLFA and others, including through taking decisions on development in the area which ensure that risks are effectively managed. Arun District Council also act as the coastal erosion risk management authority.

The council is also responsible for the preparation of Strategic Flood Risk Assessments (SFRA) to inform land-use planning and development decisions. Flood risk is a combination of the probability and the potential consequences of flooding. Areas at risk of flooding are those at risk of flooding from any source, now or in the future. External specialist consultants prepare the SFRA in close consultation with the Environment Agency and the LLFA.

Strategic Flood Risk Assessment SFRA 2026

The SFRA 2026 Level 1 Assessment (which supersedes the 2016 version) provides a comprehensive and robust evidence base on flood risk for all areas of the district (excluding the South Downs National Park). The report uses the best available information, including input from key stakeholders, and applies the latest national planning policy and guidance.
Arun District Council Level 1 SFRA Final Report - March 2026 [pdf] 6MB

Appendix A - Data Sources [pdf] 159KB

Appendix B - Sequential Test Guide [pdf] 467KB

Appendix C - Flood Risk Summary [pdf] 4MB

Appendix D - Cumulative Impact Assessment [pdf] 1MB

Note on flood risk mapping

The SFRA 2026 Level 1 Report refers to Flood Risk Mapping as being hosted on Arun District Council's website; however, this is no longer the case. The mapping data is instead available via the Defra Data Services Platform, which is updated by the Environment Agency.

The relevant flood risk mapping can be viewed online:

Update note on Long Term Risk of Flooding - April 2026

Since the SFRA 2026 Level 1 Report was undertaken, there have been further updates to the 'Long Term Risk of Flooding' dataset as it now includes the 'Climate Change 2070 to 2125' data (which shows a much larger area at risk of climate change compared to the climate change layer that has been used in the ADC SFRA 2026 Level 1 Report). As such, the latest dataset (including the 'Climate change 2070 to 2125') data is now shown on the Gov.uk website at the following link:

https://flood-map-for-planning.service.gov.uk/ 

Please note: the latest data should always be considered for any planning decisions/application of the Sequential/Exception Test.

Surface water flood risk

Surface water flooding affects a large proportion of the district. In recognition of this, various county and local standards have been adopted: Supplementary Requirements for Surface Water.

Villages within the catchments of the Aldingbourne and Lidsey rifes are known to have long standing drainage and surface water issues.  In response, a Strategic Surface Water Management Study has been prepared: Arun SSWMS Final Report [pdf] 34MB