Flood Risk

Southampton is a low-lying coastal city and is therefore susceptible to flood risk from tidal inundation, surface water, rising groundwater levels and possible wastewater infrastructure overflow during extreme weather events.  In addition, there is a risk of fluvial flooding from the rivers Test, Itchen and a range of smaller brooks and watercourses, including culverted watercourses. 

Several areas of the city are already at higher risk from tidal flooding, with areas adjacent to the coastline falling into flood zones 2 or 3, most notably along the western banks of the River Itchen (the Itchen Riverside Quarter), where the Council and Environment Agency are working in partnership to prepare the River Itchen Flood Alleviation scheme.  Elsewhere tidal risk is currently generally low.  However, as a result of climate change, flood risks will increase.  Rising sea levels over the next 50 to 100 years will increase the areas affected by tidal flood risk, and the depths of flooding in areas already affected.  Significant parts of the central areas and the city centre will be at increased risk if no action is taken.  Wetter winters and generally drier summers (with intense incidents of rainfall) will increase the risk of surface water flooding as water is unable to soak into dry ground or the capacity of watercourses or sewers is exceeded.  However, the Council has a statutory Local Flood Risk Management Strategy which provides a strategic and integrated approach to managing all sources of flooding.  The Council is the lead local flood authority for the area and will ensure that all new development manages flood risk appropriately.