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The Thames Barrier

What is it?
The Thames Barrier is a flood prevention device that spans the River Thames, which runs through London, England. It is the second biggest movable barrier against floods in the world after the Oosterscheldekering flood barrier in the Netherlands. The Thames barrier was built to protect London from the possibility of floods in high tides and storms. London is a city at risk of flooding, and, as history shows, has suffered from severe flooding in the past. When the Thames flooded in 1928 fourteen people are reported to have died but it was in 1953 that the biggest disaster occurred. The Thames flooded badly, affecting 1100 homes and contributing to the deaths of 300 people. This was due to the fact that the flood was exceptionally large. It affected the North Sea and caused problems in the Netherlands too, where 2000 people tragically lost their lives. Experts suggest that London will be even more at risk of flooding in the future for a variety of reasons which include the rise in high water level and the fact that Britain is moving – the north and west are tilting upwards and the south and east are sinking, albeit slowly.

When was it built?
When it was first suggested that a barrier be built the idea met with resistance because large ships needed to reach London Docks. This problem was solved with the growth of containerization (where goods are shipped in large containers) and the opening of a new port outside London at Tilbury. In 1974 work on the barrier began. Woolwich was chosen as the site for the barrier because the banks of the Thames were straight there, not curved, and because the river bed at that point was strong enough to support the weight of the construction. The barrier is more than 500 metres wide with rotating gates to control the flow of the waters. The four gates in the middle are just over 20 metres high and weigh 3,500 tonnes each, and no less than six of the gates are navigable. The project was so large that it was another ten years before the Queen officially opened it. The cost of the construction, at the time, totalled £534 million.

Does it work?
Apparently so, and more and more frequently. The barrier was raised to stop London flooding a total of four times in the 1980s. In the next decade it was employed 35 times and since 2000 it has been raised 75 times, not including the monthly raising for tests and maintenance work. The Environment Agency, responsible for the barrier, says that the average tides in London have increased by 6.5 mm in recent decades, though they cannot be sure that this is due to climate change.

Using the data available to them at the time of conceiving and constructing the barrier, the scientists and engineers who worked towards its creation could predict that it would keep London safe far into the future. However, the sea level has risen more quickly that could have been predicted 40 years ago. Nowadays estimates forecast that the barrier will be able to prevent London flooding for the next 50 or 60 years. Beyond that the outlook is less assured.

See also: What can be done to prevent flooding...?

Quick Quiz: Read the clues below and write the solutions on a piece of paper. Then take the first letter of each answer and rearrange them to find the hidden word connected with this Talking Point.

1. When the Thames flooded in 1928 fourteen people are reported to have died but it was in 1953 that the biggest disaster __________.

2. Britain is moving – the __________ and west are tilting upwards and the south and east are sinking, albeit slowly.

3. When it was first suggested that a barrier be built the idea __________ with resistance because large ships needed to reach London Docks.

4. Woolwich was chosen as the site for the barrier because the banks of the Thames were __________ there.

5. The four gates in the middle are just over 20 metres high and weigh 3,500 tonnes each, and no less than six of the gates are __________.

6. The project was so large that it was another ten years before the Queen __________ opened it.

7. Nowadays estimates forecast that the barrier will be able to prevent London flooding for the next 50 or 60 years. Beyond that the __________ is less assured.