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21 February 2024

Britain cautioned over 'water invasion'

The futuristic design sketches of the city of Portsmouth, which is one of the UK's highest floods-risk areas. (SUPPLIED)

By Staff Writer

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, in a futuristic project report released recently by the Royal Institute of British Architects' (Riba) think tank Building Futures and the Institution of Civil Engineers (ICE).

The think-piece Facing up to Rising Sea Levels: Retreat, Defend, Attack warns that the future of coastal cities is in jeopardy due to rising sea levels, sinking landmasses and an increase in storm frequency.

With more than 12,000km of coastline, radical thinking is urgently needed to protect the UK's at-risk communities from extreme flooding, it warned. Six futuristic scenarios were master-minded by a group of top architects, civil engineers, city designers, planners, developers, policy-makers, ecologists and futurologists.

Riba President Ruth Reed said: "The scenarios we have created are extreme, but it is an extreme threat we are facing. Approximately 10 million people live in flood risk areas in England and Wales, with 2.6m properties directly at risk of flooding from rivers or the sea. However, if we act now, we can adapt in such a way that will prevent mass disruption and allow coastal communities to continue to prosper. But the key word is 'now'."

The report urges UK Government, built environment professionals, planning authorities and the public to focus on tackling the man-made obstacles that currently prevent such solutions being made a reality.

Chair of the ICE steering group Ben Hamer added: "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.

"This requires a strategic vision at local and national level, more co-ordination and improved communication between stakeholders, and some very creative thinking about how solutions can be developed to be financially sustainable."

Focusing on Kingston upon Hull and Portsmouth, two of the UK's highest flood risk areas, the research 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.



Hull sits 40km from the North Sea on the north bank of the tidal Humber Estuary. It is bisected by the River Hull, which is liable to flooding. To make matters worse, the city is very flat and low-lying and consequently has to be constantly drained by pumps. The port is of national strategic importance.

Hull retreats

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

Hull defends

With 90 per cent 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 are designed to allow for development on top of the walls, which also help offset the cost of the construction of the new defences.

Hull attacks

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


The city of Portsmouth is located on Portsea Island on the south coast of England. It is densely populated and surrounded by water on all sides, leaving it extremely vulnerable to tidal flooding.

Portsmouth retreats

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

Portsmouth defends

The total line of defence is reduced by building new tide gates to the harbour, which can be closed when a tidal surge is predicated. Marine traffic is 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' is built for the outer coastline, with the potential for commercial, residential and recreational development. Developers pitched for segments to develop, but also maintain.

Portsmouth attacks

In 2010, a scheme is 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 are 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 includes stilted and floating communities.

The report also said: "In the UK, we are failing to move beyond the status quo and traditional and lowest common denominator solutions – the line of least resistance – demonstrating a lack of inspiration, ambition and long-term sustainability. If all the stakeholders have clear responsibilities and lines of communication then some of the progressive scenarios outlined in this document could begin to emerge. The public also needs to be better equipped to choose and engage with the futures they want for their communities. Our system of planning and decision-making is epitomised by a disjointed series of cycles and timelines that restrict our ability to plan in the long term; the four-yearly electoral cycles, the 10-15 year local spatial planning framework, the 10-20 year infrastructure development timeline. This is out of sync with the long-term horizon for climate change; changes to our coastline that will present themselves in 50, 75 and 100 years time, the rapid changes expected to our climate and environment and the slow rate of urban replacement. We must develop mechanisms that can integrate and we need to look beyond the short-term cycles of political decision making and plan making."

Additionally, it said: "The finite resources the UK has for flood defences mean, we cannot defend everywhere and must accept change in some guise. It will take good design strategies and creative financial solutions to solve the problem. Partnerships with the private sector will be crucial, and this will entail ensuring that the development opportunities are created which provide every prospect of generating a commercial return for investors."

The full project, including sketches and details of the proposed 'new cities', will be exhibited at the Building Centre in London until January 29, before travelling to Portsmouth between January 15 and 27.

Building Futures is the Riba's think tank on issues affecting the future of the built environment. It was established to create space for discussion about the needs of society from the built environment and, consequently, the built environment professions in 20 years and beyond. The group aims to highlight and promote those working with new technologies and developing new ideas, which will contribute to the future of towns and cities.

The Institution of Civil Engineers was founded in 1818 to ensure professionalism in civil engineering. It represents 80,000 qualified and student civil engineers in the UK and across the globe.

10m people live in flood risk areas

The length of the UK coastline is about 12,429km compared to the coastline of Italy (7,600 km), Spain (4,964 km), France (3,427 km) and The Netherlands (451km).

Home insurance firms are set to lose £4 billion (Dh24bn) a year by 2035 on repairing flood water damage.

Annual flood defence spending must be increased to a minimum of £750m (currently £500m) just to maintain design-specification levels of protection.

About 10 million people, in 5.5 million properties, live in flood risk areas in England and Wales, with 2.6m of those properties at direct risk of flooding from rivers or the sea.

In England the cost of claims from flooding in June and July 2007 exceeded £3.5bn.

In January 1953, more than 300 people died and 24,000 homes were flooded on the east coast of England after flood defences were breached.

In Hull, after 100mm of rain fell in 24 hours in the Summer of 2007, 600 streets, 9,000 homes and 91 of the city's 99 schools were flooded.


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