PortCities London

Freak weather and the port

The Thames Barrier
 

A city under threat

Although London had escaped disaster in 1953, the floods had shown just how vulnerable the city could be.

Had the tidal surge reached central London, the outcome could have been horrendous. Over a million people would have been in danger. The likely damage to London's infrastructure - water and sewage systems, and power, gas and phone lines - would have disrupted life in the capital for months and cost a fortune to repair.

A barrier proposed

After the floods, an enquiry was set up to work out ways of protecting London in the future. As the old system of embankments was clearly no longer adequate, the enquiry recommended the construction of a flood barrier across the Thames.

Earlier in the century, proposals for a flood barrier included a dam across the Thames in Gravesend and a dam in Woolwich. This would have carried a road across the river.

An Early Proposal for the Thames Barrier.
View full size imageOne of the many failed proposals for a Thames Barrier. © NMM

However, something more sophisticated was needed. In the 1950s, with the port in its heyday, the river still carried heavy traffic. With ships getting larger, any barrier would have to have wide openings.

Several schemes were proposed, but none was satisfactory and the scheme was abandoned. 

The barrier completed

Opening of the Thames Barrier.
View full size imageThe opening of the Thames Barrier. © NMM

By the 1960s it seemed clear that a barrier with movable gates was the way forward. In 1972, approval was finally given for a barrier at Woolwich.

Work began in 1975, and the project took seven years to complete. The Thames Barrier became operational in October 1982, and was officially opened in May 1984.  

How the Thames Barrier works  

Thames Barrier.
View full size imageThe Thames Barrier. © NMM

The Thames Barrier is a set of 10 separate movable gates positioned end-to-end across the river.

Between the gates are the concrete piers housing the operating machinery. 

  

The Thames Barrier Charlton.
View full size imageThe Thames Barrier. © NMM
In the event of a surge warning, the gates are closed to form a steel wall. This effectively closes off the Upper Thames.

When not in use the main gates lie in special recesses on the riverbed to allow ships to pass through. 

Other defences on the Thames

Thames Flood Barrier
View full size imageThe Thames Barrier. © NMM

The Thames Barrier was not the only defence against flooding built in this period. There are more than 30 other barriers, of which the Barking Barrier is the largest.

There are also more than 150 kilometres (94 miles) of embankments and defensive walls along the Thames.  

The future

The Thames Barrier has not removed the danger to London. The danger is growing every year because of a combination of reasons:

  • global warming - sea levels are rising as the polar ice caps melt
  • geology - southeastern Britain is tilting downwards
  • London rests on a bed of soft clay, and the city is very slowly sinking into it.

Because of these factors, tide levels in the Thames Estuary are rising by an estimated 60cm (2 feet) each century.

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