When the Thames Barrier was built in the 1980s as a sleek stainless steel-capped bulwark to protect Londoners from flooding, it was designed with extra capacity in case melting glaciers caused sea levels to rise.
“Climate change wasn’t even in the dictionary,” said Andy Batchelor, 63, the operations manager who began work on the barrier the day it was opened by Queen Elizabeth II on May 8, 1984.
Although the barrier was built to last 50 years – until 2030 – the Environment Agency, the public body that operates and maintains it, has since said the infrastructure will protect London until 2070.
Now, as it marks its 40th anniversary, there are questions about the strategy as scientists warn the capital is at risk of being inundated by rising sea levels, intensifying storms and more flooding.
“It’s a nice, big, sexy barrier,” said Hannah Cloke, professor of hydrology at the University of Reading, saying the infrastructure is currently doing a good job of protecting Londoners.
But she added: “We are going into a future where we know the climate is changing and we know there will be even more rain.” . It definitely doesn’t look the same as it did when the Thames Barrier was designed and built.”
The barrier was intended to protect Londoners from rising sea levels and the north-south tilt that is causing the south-east of the country to gradually sink.
According to the EA, it protects the Houses of Parliament, the O2 Arena and Tower Bridge from tidal waves, and also protects 116 rail and tube stations, 300km of main roads and homes worth £321bn.
Built on a floodplain, London has always been vulnerable to river flooding. The diarist Samuel Pepys recorded that his house was “miserably flooded” in 1663. But it was a tidal wave that killed 300 people in 1953 that triggered the construction of the barrier.
Since construction, the gates have been raised more than 221 times, including 50 times in the 2013/14 season – the busiest season ever. Although the weather is closely monitored, the decision to close the gates – “in anger,” as Batchelor puts it in a military phrase – is usually made about 12 hours in advance.
Meanwhile, the number of gate closures is increasing, with the annual total expected to increase 30-fold by 2030. The repeated closures cause more wear and tear on the barrier and prevent maintenance work from being carried out.
“If we have to close the Thames Barrier more than we thought, it will have a shorter lifespan [of the existing barrier]Cloke said.
The EA plans to make a decision on how to strengthen the barrier by 2040. Options include increasing their height; Construction of a new barrier with sluices on the existing site to improve resilience; or an entirely new structure downstream. Another plan is to create “flood reservoirs,” reservoirs where excess water can be diverted.
Meanwhile, the EA is developing a 15-year program to raise the flood walls that line both sides of the Thames east of the barrier through Kent and Essex by a further half a meter by 2040. That in central London will increase by half a meter by 2050.
Batchelor insisted the barrier, which is manned 24 hours a day, would continue to protect Londoners. “It is a sleeping giant that springs into action when it is needed,” he said.
He is proud of the carefully designed backup systems, such as power on both sides of the river, and predictive maintenance that prevents disruptions before they occur. The stainless steel caps never needed to be cleaned, he adds.
The gates were designed by engineer Charles Draper, who was inspired by his gas stove taps. They usually lie flat on the bottom of the Thames, but can be turned up to block the river’s flow. It takes up to 90 minutes to fully close, starting with the outer gates, creating a steel wall that prevents water from flowing upstream.
Experts say the barrier has been so successful that people have forgotten the extent of the city’s vulnerability to flooding. In the 1970s and 1980s, a shrill siren warned Londoners when they were in danger, while posters and television adverts gave instructions on what to do if the water rose.
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But experts say the alarm bells are ringing again. The climate resilience review in London, commissioned by London Mayor Sadiq Khan, found that only 9km of the 126km of flood defenses west of the Thames Barrier were “high enough to survive beyond 2050”.
Emma Howard Boyd, former EA chair who oversees the London report, said: “We need to continue to focus strongly on the major infrastructure that needs to be built to continue to keep London safe.”
The barrier took decades to plan and eight years to build. In 1982 it cost around £535 million, which is equivalent to around £2.6 billion today.
Shortly after taking office in 2010, the government cut the budget for flood defense in England and Wales. A decade later, it announced £5.2 billion in spending on flood defenses, double the 2015-21 figure, albeit after previous spending cuts. At the time, the government said it would protect 336,000 properties by 2027.
Since then, the number of properties expected to be protected has been reduced by 40 percent to 200,000 due to cost increases, the National Audit Office said. Each new barrier is expected to cost billions.
“We should celebrate this barrier,” Cloke said. “It has done an excellent job protecting Londoners from flooding. But we have to focus on the future. We need that [new] Barrier. We need to resolve the issue soon.”