12.16 As described above, climate change is likely to mean wetter winters and more extreme weather events in South Somerset and therefore potentially more frequent flooding. National planning policy[1] states that a sequential, risk-based approach should be applied to avoid development in areas of flood risk, taking account of the impacts of climate change.

12.17 South Somerset's Strategic Flood Risk Assessment (SFRA) highlights areas at risk of flooding from rivers (see relevant Proposals Map Inset maps), and identifies flooding incidents that have occurred in the past from rivers, surface water, sewer flooding, and groundwater. Some areas in and around Yeovil are within Flood Zone 3 (high flood risk), as are parts of many of the Market Towns and Rural Centres. Langport/Huish Episcopi and Ilchester are settlements where flood risk is a particular issue.

12.18 The aim of the Sequential Test set out in the NPPF[2] is to steer new development to areas at the lowest probability of flooding i.e. Flood Zone 1. Proposals in Flood Zones 2 or 3 will need to consider alternative sites that have a lower risk of flooding. In the first instance the area to which the 'search' for reasonably available alternative sites will apply will be District-wide, but there will be cases where this area of search will be smaller. Some examples of justifying a reduced 'area of search' include it potentially being impractical to suggest that extensions of existing business premises, such as farm holdings, could be developed elsewhere in the District; and where there is a need for new development that has a defined catchment area such as a school, hospital, or doctor's surgery.

12.19 Surface water flooding is also an issue at many of the main settlements in the District, particularly Yeovil. Sustainable Drainage Systems (SuDS) are encouraged as they mimic natural drainage by reducing the amount and rate of water flow following rainfall, therefore reducing the risk of surface water flooding. SuDS have several other benefits such as removing pollutants from urban run-off at source, ensuring that new developments do not increase flood risk downstream, and combining water management with green space which can increase amenity, recreation and biodiversity value (known as green infrastructure – see Policy EQ5). The SFRA states that there is a relatively high potential for SuDS in South Somerset due to the permeable underlying geology.

12.20 The Environment Agency produce Catchment Flood Management Plans (CFMPs) to identify strategic flood risk management policies in river catchments over the long term (50-100 years). The River Parrett CFMP covers most of South Somerset, and states that in the future the main problems in Yeovil may be related to higher intensity summer storms that overwhelm the local sewers and smaller streams.