Southampton has approximately 35km of coastline including Redbridge, the Docks, Northam, St Denys, Woodmill, Bitterne Manor, Woolston and Weston. Tidal flooding is the greatest flood risk facing the city with approximately 10% of the city being identified as at risk. Areas of the west bank of the Itchen Estuary are particularly vulnerable to flooding due to lower land levels.
There are currently no formal raised flood defence structures in the city, however the council is developing a new flood defence scheme to reduce flood risk to large areas of Northam, St Marys and Chapel and also working directly with smaller communities at risk of tidal flooding.
Surface water flooding
Due to the urban nature of the city, Southampton is particularly vulnerable to surface water flooding. This type of flooding is often very difficult to manage as it can happen anywhere following heavy rainfall. The city has an extensive drainage network to manage surface water, however when rainfall is particularly intense or prolonged, it is possible for the drainage network to be overwhelmed, leading to localised surface water flooding.
To work towards the reduction of surface water flooding, the council will be requesting the implementation of Sustainable Urban Drainage Systems (SuDS) in new developments. We are also working closely with our highways partner and Southern Water to help improve the drainage networks across the city and to identify areas that may benefit from smaller surface water management schemes.
Southampton has a number of classified Main Rivers which are the responsibility of the Environment Agency, including the River Test, River Itchen, Tanners Brook, Holly Brook, Rolles Brook, Monks Brook and Blighmont Crescent Stream, as well as a number of smaller streams and watercourses which the council is responsible managing.
Any person who is proposing to carry out works to a river or ordinary watercourse should first check whether they require an Environmental Permit from the Environment Agency or from the council.
Our current understanding of groundwater flood risk is limited due to the complexities of representing the flow and where groundwater is likely to emerge. There are believed to be a number of perched water tables within the city which increases susceptibility to potential groundwater flooding, with issues becoming known after periods of persistent rainfall. We are aiming to increase our knowledge of groundwater flooding through use of data collection and analysis.
Flood Risk to your property
You can find out specific information on the flood risk to your property by visiting the Environment Agency Website and searching your postcode. If you have experienced flooding, you can report it to the council, as this information helps us improve our knowledge of flooding and can help when developing future flood risk schemes.