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Coastal communities need urgent action

15/1/2010

Floating communities are among ideas in future-gazing report.

Retreating inland, creating habitable defence structures and building out into the sea are three options proposed to cope with the extremities of rising sea levels. The options are debated in the research report, Facing up to Rising sea levels: retreat, defend, attack? published today by the Royal Institute of British Architects (RIBA) think tank Building Futures and the Institution of Civil Engineers (ICE).

The report considers Kingston upon Hull and Portsmouth, two of the UK's highest flood risk areas, presents six scenarios set up to 90 years in the future, proposing different solutions based around three realistic briefings:

• Retreat (or managed realignment) - rising sea levels have reduced landmass. Hard engineering defences are no longer sustainable or affordable. Moving the line of defence inland, allowing flood water to occupy previously protected city areas is the only option.
• Defend - there is a growing deficit on flood defences which public funding is not covering, but the benefits of preventing water entering the existing cities still outweigh the costs. Flood defence systems must be made commercially viable to attract private investment.    
• Attack - the population of the UK has increased significantly, meaning building out into the water, via stilted and floating structures, is an attractive option to alleviate pressure inland. This has been proven successful overseas and due to high demand for space the public and private sector are both willing to invest in expanding seaward. 

RIBA President Ruth Reed said: "The scenarios we have created are extreme, but it is an extreme threat we are facing."

Chair of the ICE steering group Ben Hamer said: "A proactive and united, almost war-like approach is needed if we are to win the battle against what is set to be our biggest challenge in the next century, the ‘water invasion'.

"Some very difficult decisions need to be made in the near future, and to do this we need integrated thinking. The UK must urgently change the way it plans, builds and designs at-risk communities."

The scenarios were master-minded by a group of top architects, civil engineers, city designers, planners, developers, policy-makers, ecologists and futurologists, and are summarised as follows:

Kingston-Upon-Hull

Retreat: In 2010 a radical planning policy was adopted, and the majority of the city of Hull retreated East and West, out of harm's way. The old city, now an island, was defended as it was deemd to have significant assets and is now linked to the retreated community by several bridges. Compensation packages for the relocated community were part-funded by savings made by not building and maintaining new flood defences. In 2080 the new settling was branded New Hull, promoting tourism and investment.

Defence: With 90 percent  of the city at risk of flooding, defending from sea-level rise as well as the threat from the River Hull requires extensive investment. The defence  strategy is incorporated into a commercial development, with a series of reservoirs built behind a new outer wall. The reservoirs were designed to allow for development on top of the walls, which also helped offset the cost of the construction of the new defence s. 

Attack: Disused marine infrastructure was recycled and used to create a water community around the port. A decommissioned North Sea oil rig was used as the re-commissioning platform for other rigs. The network of static platforms and floating structures was developed into a mix of residential, recreational and commercial 'land'. The functional floodplain to the north-east was inhabited by floating communities of houseboats. The remaining city was gradually adapted to cope with increased flooding.

Portsmouth

Retreat: In 2010 the fringes of the east of the island were planned for salt marsh restoration, and this was fully formed in 20 years, providing a recreational area boasting diverse wildlife. New hillside terrace developments were built further into the centre of the island, and buildings remaining on the edges found new uses more appropriate to flood risk. Residential houses were adapted, with dwelling moved to top floors and access routes repositioned above ground level. 

Defence: The total line of defence  was reduced by building new tide gates to the harbour, which can be closed when a tidal surge is predicated. Marine traffic was reduced by relocating regular routes. This means there is no need to defend the inner harbour, representing a massive saving in defence infrastructure investment. A new 'living wall' was built for the outer coastline, with the potential for commercial, residential and recreational development. Developers pitched for segments to develop, but also maintain. 

Attack: In 2010 a scheme was drawn up for two-tiered large piers to emerge from the city, linking into existing infrastructure and proving residential, commercial and recreational spaces. The lower tiers were used for traffic. Existing buildings on the island were retro-fitted to adapt to the flood risk, and new developments were built with regular high levels of water in mind. This included stilted and floating communties.  

The project, including sketches and details of the proposed new cities is on view at the Building Centre, London 6–29 January 2010; in Portsmouth 15–27 February and Kingston upon Hull 15–28 April.

For more information, go to www.ice.org.uk.