How does the Thames barrier protects London from floodings

Originally published on February 18, 2014

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The Thames Barrier was built in 1982 on the Thames on the eastern side of the capital at Woolwich, it was constructed to prevent water flowing upstream towards London during high tides, inundating areas upriver and causing flooding in densely populated areas of the capital.

The barrier, made up of 10 steel gates, has a span of 520 metres across the river. Each gate is 15 metres tall.

In an open position, the gates lie flat allowing the Thames to flow freely and ships to pass through the gates.

When the closed position is activated, it takes up to 75-90 minutes for the gates to rotate upwards and create a steel wall that block the river.

In an underspill position the barrier allows a controlled amount of water to pass under the gate and up the Thames.

The recent flooding and heavy rain in the UK mean that the barrier has been closed 28 times since 6 December, which represents one fifth of all the closures - about 150 - since it was inaugurated, according to one of the barrier's controller, Eamonn Forde, quoted by the BBC.

According to the BBC, the barrier was designed to last up to the year 2030, but recent analyses suggested that even with the predicted sea level rise from climate change, the barrier could still be enough to protect London until 2060-70.

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