As detailed in Section 4, a high level screening assessment of currently Allocates Sites within each Borough was undertaken as part of this SFRA. This assessment includes a spatial analysis of the percent of site area within each of the defined Flood Zones, the potential impact of climate change, potential interactions with other sources of flood risk, an initial appraisal on whether the Sequential Test and Exception Test are required and a recommendation on if assessment through a Level 2 SFRA would be appropriate. Allocated Site specific recommendations are included in Appendix A in a spreadsheet format that can be filtered on a borough-by-borough basis and other assessment parameters as required.
The assumptions applied for the assessment are summarised below:
- If proposed use of site is unknown, then vulnerability classification is assumed to be ‘more vulnerable’ (residential)
- Waste management sites with an unspecified use have been given an unknown vulnerability classification as these sites could be either ‘More vulnerable’ or ‘Less Vulnerable’ dependent on the use
- If proposed use is ‘Other’ these have been given an unknown vulnerability classification
- If proposed use is ‘Commercial’ these have been given an unknown vulnerability classification as these sites could be either ‘More vulnerable’ or ‘Less Vulnerable’ dependent on the use
- Gypsy & Traveller sites have been given a ‘Highly Vulnerable’ classification as these sites could be either ‘Highly vulnerable’ or ‘More Vulnerable’ dependent on the property type
- Sites with 0% of areas in Flood Zones 2 and 3a/b do not require the Sequential Test (on the basis that other forms of flood risk are generally manageable on a site by site basis)
- Less vulnerable sites within Flood Zone 2 and 3a/b require the Sequential Test
- More vulnerable sites within Flood Zone 2 and 3a/b require the Sequential Test
- More vulnerable sites in Flood Zone 3a require the Sequential and Exception Tests
- Highly vulnerable sites in Flood Zone 2 require the Sequential and Exception Tests
- Highly vulnerable sites are not suitable in Flood Zones 3a/b
- Water Compatible use in Flood Zones 2 and 3a/b require the Sequential Test
- Level 2 SFRA recommended where Sequential & Exception Tests are needed and Flood Zone 3 extent is greater than 20% of site (and will be a significant constraint on development) or if the site is currently less than 20% in Flood Zone 3, but will be more than 20% under the selected climate change scenario (1 in 100yr event +35%)
- Allocated Sites in Barnet were not supplied with a spatial extent – only centre point coordinates. The development size is assumed to be a 100m diameter circle around the centre point for the purpose of this analysis
- Flood Zone 3a for surface water is defined using the full 1 in 100 extent from the EA Risk of Flooding from Surface Water Map