Portsea Island Flood Defence Scheme
Portsea Island is a small, low-lying island which contains a large proportion of the city of Portsmouth. It is the third largest (by population) of any island in the British Isles after the mainlands of Great Britain and Ireland, and has the highest population density.
The scheme, which will reduce the risk of coastal flooding and erosion to the area over the next 100 years, was commissioned by the Eastern Solent Coastal Partnership and made possible through funding awarded to Portsmouth City Council by the EA.
It involves the construction of 1.4km of coastal defences along the north of Portsea Island between Ports Creek Railway Bridge and Kendall’s Wharf.
1.4km of new embankment has been constructed using 42,000 tonnes of earth – sufficient to fill 8 Olympic size swimming pools. Rocks were then placed over the top of the embankment to protect it from erosion. Imported from Norway, the rock was specially selected due to its strength, weather resistance and durability.
On the eastern side of the site a wall has been created from gabions (stone filled wire baskets) to support the new embankment.
A new flood wall has also been constructed around a bridge to reduce the risk of Eastern Road becoming a flood route. A new foundation has been created for the wall by driving more than 400 steel sheet piles into the ground, and the sheet piles have also been extended up and around the electricity substation in the vicinity.
Construction works began in May 2015 and are now substantially complete.
Anchorage Park is the first stage of a wider scheme which will reduce the risk of flooding and erosion from the sea to 4,200 homes, 500 businesses and critical infrastructure, over the next 100 years.
The design of the defences incorporates ideas from local residents, offered during consultation events.
Once the defences are built, the area will be enhanced through an extensive replanting programme. This will increase the diversity of plants in the area, improving the current ecosystems and habitats for wildlife. Paths along the coast will be improved as part of the scheme.