Coastal defence design for Southsea

Metocean and coastal analysis for Portsmouth City Council, supporting the creation of new coastal defences at Southsea

The current defences are coming to the end of their lifespan, which increases the risk of flooding in Southsea. Portsmouth City Council wanted to create defences that would improve the seafront for future generations and stimulate regeneration, whilst protecting the community and preserving the area's unique heritage.

The new Southsea Coastal Defences consist of 4.5km of new sea walls and beaches to protect Portsmouth for the next 100 years.

ABPmer provided all the necessary coastal and marine processes information to support both the design and contractor teams.

To support the principal design of the new structures, we provided a coastal and metocean overview informed by a three-month data collection by our in-house survey team.

As the stability of these defences along key sections of the frontage and their performance in respect to overtopping will be dependent on effective beach management, we also provided beach design parameters to underpin its long-term sustainability.

Other supporting services included: metocean survey; wave and sediment transport modelling; extremes and overtopping analysis; metocean and beach design criteria; weather downtime analysis for construction planning; navigation risk analysis; and dispersion analysis.

In December 2019, the full planning application as well as all listed items and monuments associated with the Southsea Coastal scheme were discussed at planning committee and permission was granted to commence the proposed work.