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Not just a wall: “The flood defences are part of our city, not just infrastructure”
The Southsea coastal defence project is flood protection as destination. Not only does the 4.5km scheme protect Portsmouth from flood damage, it also enhances the city financially, culturally and socially, writes Kimberley France
T he Southsea Coastal Scheme is the UK’s largest local-authority-led sea defence scheme, covering 4.5km around Portsmouth, protecting people and businesses, and delivering new public space. Chris Koster, the scheme’s programme manager, highlights it as “one of the biggest community schemes I’ve ever worked on.”
Construction of the project started in 2020, 10 years after the initial strategy plan was approved with the aim of protecting the city from a potential £1 billion in damage from 4m-high flood depths. With a 1-in-200-year flood standard, the £180 million scheme, set to complete in 2029, aims to save 10,000 properties, 704 commercial properties, three monuments, 74 listed structures and four critical access routes.
“The benefits of the way the project is delivered add up to more than the sum of the project, the outcomes are so much greater,” says Koster. “We’ve curated a delivery model and team to develop a world-class seafront, that has yielded a positive working environment and outcome.”
“Previously the promenade wasn’t a destination,” says Koster. “It had no identity to it, no access or ‘place’ to visit”
The scheme is a collaboration between Portsmouth City Council, Coastal Partners, Historic England, the Environment Agency, LDA Design, maritime contractor VS BW, Wessex Archaeology and others, all working to provide the best solution for each of the challenges faced. “We put everyone together – designers, archaeological, landscape, project managers and more – and then they solved problems together,” Koster says.
Facing community pressure, the project was preceded by one of the widest public consultations ever undertaken by the city. Fears that the project would lead to a big wall blocking the sea led to full transparency in the project’s delivery to create a seafront that is attractive and functional. “Previously the promenade wasn’t a destination,” says Koster. “It had no identity to it, no access or ‘place’ to visit.”
City council leader Steve Pitt adds: “The flood defences, due to our proximity to the sea, are a part of our city, not just a piece of infrastructure. Our residents and businesses benefit from them financially, culturally and socially, as well as interacting with them as part of everyday life in Portsmouth.”
In response to community concerns regarding accessibility and heritage, design consultancy LDA Design was brought in to provide public realm designs better suited to the character of Portsmouth.
“That sense of place can make or break a scheme,” says LDA associate Kirsty Barker. The consultancy has designed visions for six frontages, which seek to celebrate the identity of the area and create a network of spaces that work hard, reducing the divide between the seafront and the greens, ensuring the seafront promotes health and play, and making it active and sociable.
Two of the six frontages are now open – two more will follow soon – and the community is starting to make use of them. There are runners enjoying the cool breeze, children jumping the steps and people relaxing on the benches. There are areas that celebrate history, allow for play, promote the scenery or that provide somewhere to stop and be in the moment.
Consideration of the public has been key to creating a space that works for them – seating added, lighting improved, flooring flattened for accessibility and existing activities enabled. There’s a stripped-back feel to the scheme, as though it’s all about recentring what’s important. It takes the elements key to the seafront – the Victorian lamps, shelters and monuments – and makes spaces around them. People flock to these places along the promenade; a plaza for activities centred on history.
The challenge was how to protect historic structures and the city from climate change while enabling greater access to the seafront
“Seafront communities are quite deprived,” says Barker. “These schemes won’t solve that but we hope they will give them the sense that somebody cares. It’s the starting point of rejuvenation and caring about that history again – activating an area to create change in the long run.”
The defence scheme interferes with 13 listed sites and a scheduled ancient monument, so the challenge was how to protect historic structures and the city from climate change while enabling greater access to the seafront. The design weaves together history and community space.
“It’s about these subtle but powerful interventions,” Koster says, motioning to the new promenade flooring. “We pigmented the concrete to match the mortar in the historical blocks to signify you’re in a historical area.”
The fourth frontage, built around Southsea Castle, creates an “amphitheatre by the sea”. This provides stepped views out over the water and down on the castle, now a museum, which was originally built in the 1500s and is believed to be the first star fort in England. Initial plans to protect the castle involved a 30m single-sheet concrete wall with a thin walkway. But instead, piles were carefully dug around the historic walls where the land is marshy, and the stepped public realm was created – a design change that saved millions of pounds and provided a view of the castle.
The steps also balance out a large pile of rocks to the sea by forming a sloping pathway up to the castle. Cutting through the flowing steps is an archaeological find that had been recorded as lost: the triangular remains of a revetment constructed as part of the castle’s redesign in the late 17th century redesign.
An art installation has been made of the discovery using the archaeologist’s drawings. These have been engraved into metal plates used to protect the discovered walls – a new site for the community to enjoy. A local resident tells me: “We really appreciate the historic atmosphere; that we can walk around the shape of the walls and follow those ancient paths in an accessible way.” The previous path was bumpy and unfriendly to wheelchair users and buggies alike.
There are also more extreme measures used to manage the historic sites. Frontage 1 takes a dramatic twist towards the sea to accommodate 16th-century defence walls and a spur redoubt, with the promenade following the shape of the ruins and submerging them partially for protection.
Not only is there a strong focus on maintaining history but also on managing biodiversity
Despite the shape, the promenade here is still considerate of the context. The designers specified limestone blocks embedded into the concrete wall to match the existing structure and pattern as a reminder of what is buried beneath the users’ feet. The lamps and fencing are colour blocked to blend with the background and create unobstructed views of the area. The attention to detail creates an identity for the promenade that embraces maritime heritage.
Not only is there a strong focus on maintaining history but also on managing biodiversity. Low acidity concrete was used throughout the project to retain water and protect the biosphere. There are also 21 rock pools provided throughout for different seasons of the sea, allowing the biosphere to live as it would in a long-standing environment.
Public art has been incorporated throughout the scheme, with an arts coordinator appointed and a seafront arts plan drawn up. An outdoor art exhibit will activate the frontages that are opening at the end of the year. Hotwalls Studios, which provides affordable workspaces for local artists, will curate a space named the Windbreaker shelter project. Features are set to change three times a year so as to create a destination people will want to return to.
To push public engagement and understanding of the development, a communications team and STEM engagement project provide exhibitions and job opportunities across Southsea. Teaching the residents about the importance of the development has been essential to soothing community concerns. The scheme constructed temporary paths for the public to use to walk around the works, a little interaction that didn’t have to be done but has smoothed the delivery of something new; something extra to make the changes more palatable for everyone.
“We already have an increase in enquiries to host major events on the seafront,” say Pitt. “Tourism and associated industries help provide over 12,000 local jobs in the city, so this is important in that respect,”
Following the success of Blackpool’s seafront rejuvenation, the hope is that Southsea will follow suit, using its sea defence project as a launchpad for regeneration. Citizens are taking notice of the improved area, highlighting its accessibility and ease of use, and are excited that the seaside city is being improved to bring Portsmouth’s slogan “the great waterfront city” to life.
Kimberley France is publishing and events assistant at The Developer, a Part 1 architecture graduate and a freelance artist
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