Thames Barrier

The history of the Thames Barrier

Recorded history of the River Thames flooding goes back a long way.

In 1663 diarist Samuel Pepys wrote of "the greatest tide that was ever remembered in England… all White Hall having been drowned, of which there was great discourse".

In January 1928 flooding hit Victoria and Chelsea in central London – 14 people drowned and thousands had to leave their homes.

A huge tide surge in 1953 killed 307 people in eastern England and sent high waters up the Thames to spill into the streets of London's East End and thousands had to flee.

Until the early 1970s the main flood defence for the capital meant building higher and stronger river walls and embankments.

Although walls are permanent and easy to maintain, making them higher and higher would eventually block out the Thames from view.

Research led the government to decide that the best long-term solution would be a flood barrier with moveable gates built across the Thames.

The former Greater London Council coordinated the barrier project with different contractors building the gates, shore machinery and upstream bank raising works.

Construction began in 1974. The barrier was finished by 1982 and first used in 1983. It was officially opened by the Queen in 1984.

In 2024, it celebrated its 40th anniversary.

Difference the barrier has made

The Thames Barrier is part of a system of flood defences in London.

Without the barrier, frequent tidal flooding of the Thames would submerge buildings along the river as well as the underground.

The winter of 2013-2014 was the Thames Barrier’s busiest time ever.

During this period, the Thames experienced its highest tide since the barrier's construction. It had to close 50 times over 13 weeks.

As a result of the barrier's effective operation, no properties in London were flooded. And with great care, the barrier still remains strong.

The barrier is credited with having helped London grow into a global capital – transforming the lives of millions of people who have worked, lived in or visited London since it opened.

How the barrier was installed

The barrier was built over a 520m wide stretch of the Thames near Woolwich in south London. It divides the river into 4 spans - each span is 61m across.

Engineers chose the location as the banks were relatively straight at this point and the chalk river bed was strong enough to support the barrier.

Charles Draper came up with the concept for the barrier's flood gates, basing their design on the taps on his gas cooker.

The flood gates are circular segments and move into the raised position by rotating. The gates are hollow – they fill with water as they sink and empty as they emerge from the river.

At 20.1m high and each weighing 3,700 tonnes, they were made by Cleveland Bridge UK on the River Tees.

The future of the Thames Barrier

As sea levels rise, the barrier will need to close more often to protect against storm surges.

By 2050, raising the defences west of the barrier will help reduce these closures and extend the barrier's lifespan.

Another half-meter increase will be needed in the latter half of the century.

The barrier will continue to operate effectively until 2070, which is when, based on current sea level rise projections, the current barrier could be overtopped.

There will need to be a replacement option ready to go from then.