Southsea Coastal Schemea

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£949.7m worth of assets including 8,077 homes and 704 commercial properties in Southsea are at risk from flooding from the sea over the next 100 years. Modelling has shown that a major flood event would result in 4,114 properties inundated with water with a further 3,963 properties indirectly affected by the flooding through loss of access. 

In the worst affected areas water would be fast flowing with depths over 4 meters deep posing a considerable danger to public safety (See picture below). Five scheduled ancient monuments, multiple nationally and locally listed structures, three conservation areas, one registered park and key infrastructure also lie within the area at risk. 

Flood extent showing depth of water (Present day 1 in 200 year event)

The Southsea Scheme will replace 2.8 miles (4.5km) of ageing coastal defences from the Garrison Church to the Royal Marines Museum.

With current defences reaching the end of their existing life (some dating as far back as World War II), it is important that we adapt our coastline to reduce flood risk moving into the future. An overview of the historical development of Southsea can be seen here.

If improvements are not undertaken the current defences will continue to deteriorate with an increasing risk to property and live. Sea level rise and increased storminess predicted over the next 100 years will continue to put Southsea’s coastal defences under increasing pressure.

Southsea Seawall Failures 2016/2017

The project aims to mitigate increasing risks of flooding from the sea, and high tides & winter storms.

The coastline has been divided into seven sections to allow future construction to be phased, to minimise disruption during the works. The work is likely to take up to six years to complete once construction gets underway. Click here for our background document on the Southsea Coastal Defence Scheme.

Who is developing this scheme?

The Eastern Solent Coastal Partnership on behalf of Portsmouth City Council are leading this project to develop options to reduce flood risk into the future.

The Southsea Coastal Flood Defence scheme is one of the largest coastal defence schemes in the UK. The new defences will stretch 4.5km along Southsea’s frontage from Long Curtain Moat to Eastney Barracks and will reduce the risk of significant flooding for over 100 years.

Southsea Design Concept.  

The development of the scheme is guided by the North Solent Shoreline Management Plan, a high level policy document setting out a framework for future management of the coastline. For more information on this and its relation to the Portsea Island Coastal Strategy, click here.

The scheme is being delivered by an Integrated Delivery Team (IDT) incorporating Portsmouth City Council, Eastern Solent Coastal Partnership, Balfour Beatty and the lead Design Consultant to be appointed shortly. 

Public events

A big thank you to all who attended our exhibition events back in November 2014. The events were very successful, with several hundred people attending and providing feedback on the plans. To view this exhibition report, please click here.

A presentation and briefing note was also provided for elected members in late July. You can view the presentation here and the briefing note here.

Coastal defence options

The preferred option for the scheme is a sloped revetment with a setback wall. This was selected from a long list of hard and soft engineering options after assessment against Social, Environmental, Technical and Economic factors. The total cost of delivering the scheme based on the concept design is £89.2 million.

Map showing the 7 sub-frontages of the Southsea scheme

Detailed documents on the defence options are available below:

Coastal Defence Material Types

Coastal Access

If you wish to find out more please contact us by emailing

This project has the opportunity to:

  • Reduce coastal flood and erosion risk to people and property
  • Improve and enhance the coastal environment
  • Enable regeneration of the Southsea frontage
  • Promote high quality urban design
  • Improve access to and the enjoyment of the coast

How is the project funded?

Portsmouth City Council have been allocated £5.9m of grant funding from central government to progress the design phase of the project. This comes following approval of the schemes Outline Business Case by the Environment Agency, Defra and HM Treasury.

On completion of the initial design phase in late 2018 the Council will present a Full Business Case to government to apply for the funding for the construction works.