London’s flood defence may need replacing far sooner than expected due to extreme weather
Thames Barrier upgrade could cost at least £20bn, senior government officials warn
The Thames Barrier that protects Londoners from flooding may need to be replaced up to two decades earlier than anticipated and could cost at least £20bn, according to senior government officials who warn that an increase in extreme weather has put the vital defence system under strain.
Its 10 steel-capped gates that can restrict the flow of water were erected in the 1980s and built to last until 2030, but the public body that runs and maintains the system has since said the infrastructure can operate until 2070.
It provides crucial protection for the Houses of Parliament, the O2 Arena and Tower Bridge, as well as 116 railway and Tube stations, 300km of major roads and £321bn worth of residential homes.
The Environment Agency (EA) had been planning to make a decision by 2040 on how to bolster the barrier, which spans the River Thames at Woolwich Reach in east London.
But senior government officials at the agency told the FT they believe the barrier might need to be replaced between 2050 and 2060, given its gates have been used more than anticipated owing to an increase in extreme weather caused by climate change. This has led to a degradation of the infrastructure, but also prevented maintenance from being carried out.
Existing climate projections indicate a new barrier will be needed from 2070.
The officials said a decision will probably need to be made imminently about how the barrier should be upgraded as it could take up to 30 years to erect a replacement. They estimate the cost of the works will be close to £20bn, more than double previous estimates of between £6bn and £9bn.
“£6bn is the figure announced publicly for a new Thames Barrier, which is ridiculously low,” one government figure said.
“Whenever you’re working in a live waterway, especially an estuary like the Thames which has huge fluctuations each day, it’s just mega-expensive work,” they added, noting that even £20bn was a conservative estimate.
The current barrier was decades in the planning and took eight years to build at a cost of roughly £535mn in 1982, the equivalent of about £2.6bn today.
“We totally forget how important the Thames Barrier is. We would be two metres underwater in Westminster if it wasn’t there,” said one senior government official. “Climate change hasn’t even really started yet. What it will mean in the UK is cold, wet winters and very intense summer rainfall.”
Options for a replacement include building a new barrier with locks on the existing site to improve resilience or creating a structure further downstream. Another possibility is installing “flood storage areas” — reservoirs and marshlands — to which surplus water can be diverted.
The EA has announced plans to fortify defences upstream, between Charlton in south-east London and Teddington in the city’s south-west, by 2050 to reduce reliance on the barrier itself.
However, officials say there is scepticism within the department about the feasibility of some of these plans, given they would involve engaging with thousands of different landowners, most of whom could be asked to front the costs themselves.
The barrier was also designed to defend against the UK’s north-south tilt, a geographical process by which the south-east of England is gradually sinking.
Since it was built, the barrier’s gates have been raised more than 221 times, including 50 times in 2013-14 — the busiest ever year owing to storm surges that pushed up the tides.
The number of gate closures is increasing, with the annual total expected to reach 50 a year by 2035.
Experts say the barrier has been so successful that Londoners have largely forgotten how vulnerable the city once was to flooding. In the 1970s and 1980s, sirens warned residents when floodwaters were rising, while posters and television adverts offered instructions on what to do.
Caroline Douglass, executive director for flood and coastal risk management at the EA, said: “Flooding has a devastating impact on communities and will only worsen as our climate changes.
“We are actively assessing options for managing tidal flood risk, including consideration of options for upgrading or replacing the Thames Barrier and other associated barriers.”
She added that the EA is “exploring options for funding the essential infrastructure upgrades”.