Strategic Flood Risk Assessment - Christchurch
The National Planning Policy Framework (NPPF) requires all local planning authorities to prepare a Strategic Flood Risk Assessment (SFRA) in consultation with the Environment Agency, to refine information on areas at risk of flooding, taking into account all sources of flooding and the impacts of climate change. The results of the SFRA are used to direct development away from areas at greatest risk of flooding.
The main purpose of the 2019 Christchurch SFRA is to provide a comprehensive and robust flood risk evidence base to support the production of the BCP Local Plan, the selection of site allocations within it, and to guide day to day development management decisions. This is done through the application the 'Sequential Test' and the 'Exception Test'. National planning guidance further advocates a tiered approach to flood risk assessment and identifies two levels of the SFRA:
- Level 1: where flooding is not a major issue and where development pressures are low. The assessment should be sufficiently detailed to allow application of the Sequential Test
- Level 2: where land outside Flood Zones 2 and 3 cannot appropriately accommodate all the necessary development creating the need to apply the NPPF’s Exception Test. In these circumstances the assessment should consider the detailed nature of the flood characteristics within a Flood Zone and assessment of other sources of flooding
Advice for the general public - not for planning purposes
The SFRA is prepared for future planning purposes - if you want to know if your property is at risk of flooding now, to check if you are at risk of flooding, and for advice on what to do if you are, please refer to the Environment Agency Flood Maps
Advice for developers – SFRA for planning purposes
Sequential test for new development
The NPPF was updated and released in 2019 and provides clarity on application of the sequential test for planning purposes. The NPPF confirms that the SFRA should be the starting point for the Sequential Test for permitting development. The sequential test should take into account current and future impacts of climate change as confirmed by NPPF paragraphs 155, 157 and 158.
The first stage in undertaking the Sequential Test is to identify all available sites within the search area which would be suitable for the type of development being considered. When undertaking the Sequential Test in Christchurch, sites from the latest published Christchurch and East Dorset 5 year land supply should be assessed. This will require the assessment of 5 year land supply sites from Christchurch and East Dorset as this is the adopted local plan area.
The 2019 SFRA confirms the climate change scenarios and future flood zones which should be used for the purposes of the Sequential Test. For residential purposes and application of the sequential test present day flood zone 2 and future flood zones 3a and 3b should be applied including a 40% uplift in rainfall to 2133.
For ‘less vulnerable’ uses associated with commercial development, a 30% uplift in rainfall should be applied to 2093. These scenarios also include predicted sea level rises for the 2133 and 2093 time horizons. For commercial purposes and application of the sequential test present day flood zone 2 and future flood zones 3a and 3b should be applied including a 30% uplift in rainfall to 2093.
These scenarios also include predicted sea level rises for the 2093 and 2133 time horizons. The application of these flood risk scenarios for the sequential test is consistent with the NPPF and has been agreed by the Environment Agency.
This flood risk mapping is available via our Interactive map.
Exception Test / Site Specific Flood Risk Assessments:
Further guidance is included within Section 4 of the Christchurch SFRA Level 2 report regarding the climate change allowances which should be applied for the purposes of performing the Exception Test or for a site-specific flood risk assessment. These scenarios are also available through our interactive mapping.
Level 1 Strategic Flood Risk Assessment
The Level 1 SFRA delivers a strategic assessment of risk from all sources of flooding in Christchurch. It also provides an overview of policy and guidance for planners and developers including detailed explanations of the Sequential and Exceptions tests. The following main report and appendices are available:
Level 2 Strategic Flood Risk Assessment
Following the completion of the 2019 Level 1 SFRA for Christchurch, the Level 2 SFRA was prepared to support the Exception Test, and forms part of the detailed evidence base for preparation of the BCP Local Plan to inform site allocation and to determine whether additional strategic mitigation measures will be required to deliver the required development.
It provides the starting point for developers to fully address the relevant climate change forecast flood levels (tidal, fluvial, surface water, sewer) for the 2093 and 2133 timeframes, which represent the predicted lifetime of commercial (60 years) and residential (100 years) development. The following main report is available:
Detailed mapping for both fluvial and tidal flooding is provided including Flood Zones 2, 3a and 3b factoring in climate change predictions. Depending on the proposed development type, it allows the relevant climate change scenario to be selected. Section 4 of the Level 2 report sets out detailed guidance for using the SFRA mapping.
Please contact the planning policy team if there is any uncertainty as to which flood risk mapping should to be referred to for a particular form of development.