At present, approximately 13% of Southampton’s land area falls within Flood Zones 2 and 3 (as determined by the Environment Agency’s flood maps); therefore good planning is essential to reduce the impacts of flooding. Any future development within areas where flood risk exists will need to be designed to withstand the possibility of flooding, and be able to manage the effects of flooding to ensure that it is safe over the proposed lifetime of the development. Detailed information of the relevant sources of flood risk facing Southampton both now and in the future, and the requirements that developers must meet are set out in the assessments and guidance documents below.
Partnership for Urban South Hampshire Strategic Flood Risk Assessment (PUSH SFRA)
In 2006, the Partnership for Urban South Hampshire (PUSH) commissioned a joint Strategic Flood Risk Assessment (SFRA) for the sub-region which was prepared in accordance with Planning Policy Statement 25: Development and Flood Risk (PPS25). The SFRA is a critical part of the evidence base for the sub-region and enables the Local Planning Authorities within the PUSH sub-region to make informed decisions on the allocation of land for development in their Local Development Frameworks. The PUSH SFRA was completed in December 2007. The final reports and series of mapped outputs can be accessed via the PUSH SFRA website, using the link below.
Although the data from the PUSH SFRA is still of value, it is important to note that Planning Policy Statement 25 was superseded by the National Planning Policy Framework in March 2012.
Level 2 Strategic Flood Risk Assessment (L2 SFRA)
The Level 2 Strategic Flood Risk Assessment (L2 SFRA) completed in partnership with the Environment Agency in September 2010, progresses and updates the PUSH SFRA. The series of documents produced provide detailed information on the nature of flood risk, both current and future, from all sources across the city, including coastal, fluvial, surface water and groundwater.
The primary objective of the L2 SFRA was to provide Southampton City Council with sufficient information to comprehensively apply the requirements of Planning Policy Statement 25 (PPS25): Development and Flood Risk (superseded by the National Planning Policy Framework in March 2012), and to satisfactorily inform the relevant Local Development Documents of the Local Development Framework. It also identifies a range of potential strategies to manage flood risk and adapt to climate change on major development sites located within flood risk areas.
Click on the links below to view and save a copy of the main Level 2 Strategic Flood Risk Assessment documents:
Level 2 Strategic Flood Risk Assessment Volume 1: Guidance – August 2010
Level 2 Strategic Flood Risk Assessment Volume 2: Technical Appendices – August 2010
Level 2 Strategic Flood Risk Assessment Volume 3: Options and Feasibility – August 2010
For the figures and appendices to the Level 2 Strategic Flood Risk Assessment, please use the following links:
Level 2 Strategic Flood Risk Assessment: (Fig 1.1 – 1.9) Overview
Level 2 Strategic Flood Risk Assessment: (Fig 2.1 – 2.5) Environment Agency Flood Zones
Level 2 Strategic Flood Risk Assessment: (Fig 3.1 – 3.5) Tidal Flood Maps
Level 2 Strategic Flood Risk Assessment: (Fig 3.1.1 – 3.5.1) Duration of Tidal Flooding
Level 2 Strategic Flood Risk Assessment: (Fig 4.1 – 4.5) Tidal Flood Hazard 2010
Level 2 Strategic Flood Risk Assessment: (Fig 5.1 – 5.5) Tidal Flood Hazard 2110
Level 2 Strategic Flood Risk Assessment: (Fig 6.1 – 6.5) Surface Water and Sewer Flooding
Level 2 Strategic Flood Risk Assessment: (Fig 7.1 – 7.2) Groundwater and Geology
Level 2 Strategic Flood Risk Assessment: (Fig 9) – Emergency Planning and Flood Warning
Level 2 Strategic Flood Risk Assessment: (Fig 10.1.1 – 10.1.9) Flood Zones at Key Development Sites
Level 2 Strategic Flood Risk Assessment: (Fig 10.2.1 – 10.2.9) Tidal Flooding at Key Development Sites
Level 2 Strategic Flood Risk Assessment: (Fig 10.3.1 – 10.3.9) Tidal Hazard 2010 at Key Development Sites
Level 2 Strategic Flood Risk Assessment: (Fig 10.4.1 – 10.4.9) Tidal Hazard 2110 at Key Development Sites
Level 2 Strategic Flood Risk Assessment: (Fig 11) – Strategic Flood Risk Management
Flood Risk Assessment Guidance – More Vulnerable Development
The Flood Risk Assessment (FRA) Guidance for more vulnerable development was produced to assist developers and applicants when dealing with the control and mitigation elements of the flood risk management hierarchy in order to manage flood risk and ensure new development is safe.
A copy of the guidance document is available to view and download here:
Flood Risk Assessment Guidance
Site Flood Plan - Guidance and Templates
A site flood plan will be required where it is not feasible to achieve safe access/egress to the development site, and must outline how users of the site can avoid danger from hazards should a flood event occur. The Emergency Planning team have produced the Site Flood Plan overview and template for both developers and owner occupiers, all of which are available below:Site Flood Plan: Overview
Site Flood Plan Template: Developers
Site Flood Plan Template: Owner Occupiers
Sustainable Drainage Systems (SuDS)
In order to manage surface water, developers are encouraged to implement sustainable drainage into new development. The management of surface water should be demonstrated as part of the Site Specific Flood Risk Assessment ensuring the proposed drainage system will reduce flood risk to the site itself and elsewhere, taking climate change into account. Further information on the implementation of SuDS is available from the Susdrain website by following the link at the bottom of this page, and a guide for developers on achieving sustainable drainage is available to download here:
Guide to Sustainable Drainage Systems
Under the Flood and Water Management Act 2010, Southampton City Council will soon become a SuDS Approving Body. This means that once the relevant parts of the Act are commenced, the Council will need to review and approve drainage plans and strategies for development sites before any construction can start on site. This requirement is expected to be introduced in autumn 2014 for new developments, and will be completely separate from the requirement to gain planning permission. The Department for Environment, Food and Rural Affairs (Defra) have consulted on their proposed procedures for SuDS approval. Southampton City Council is now waiting for further announcements from Defra as to the details of implementation.