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Reflections on the Thames Barrier: A Conundrum

The Thames Barrier at Woolwich was completed in 1983, 30 years after the Great Flood of 1953 caused the loss of 300 lives, the displacement of 100,000 residents from 24,000 inundated houses and flats, and immense agricultural damage on the East Coast and in the Thames Estuary. Some 200 miles of railway, 12 gasworks and two large power-stations were put out of action.

Central London had escaped by a whisker with only minor flooding and water levels in the River just inches below the parapet walls on either bank. Calculations of the scale of damage if the flood level had been only a foot or two higher concluded that over one million residents would have been flooded out with disastrous consequences for the stability of buildings, extensive damage to the underground railway system, disruption of the capital’s roads and surface transport network and a heavily reduced supply of electricity, fresh water and gas. The excellent Victorian sewage system would have been overwhelmed with back-flooding of effluent into many houses and a huge noxious spillage into the tideway. There would also have been major damage to London’s river-based manufacturing industry and port facilities, only just beginning to recover from the heavy bombing by the Luftwaffe in World War Two. As most of the emergency generators and essential communications equipment were located below ground in the new high-rise developments and most older buildings in the Westminster area, the Government itself would have lacked the ability to coordinate an adequate response to such a disaster when many of its own departments and buildings were flooded and out of action.

Tackling a Heightened Risk

A general consensus quickly emerged that protection of the capital was an urgent priority, but there was deep disagreement on how that protection could be provided.

The Dutch, who for centuries had led the world in the science of building dams, dredging and river management, pointed to their successes in recovering large estuary areas for agriculture, new industry and residential development by the construction of huge sea-defences, some more than 20 miles long. The technical solution they advocated was a permanent barrier or barrage with shipping locks and dredged access to be located in the vicinity of Southend on the north side of the Thames Estuary and Sheerness on the south side. Alternatively, a similar barrier might be constructed where the River was much narrower close to Tilbury on the North Bank and Gravesend on the south side, but the problem here was the narrowness of the shipping channel and the curvature of the River which affected the siting of the new locks.

An accident at the Barrier in October 1997 when the Sand-Kite, an aggregate dredger, misjudged its approach and became firmly jammed in one of the gates.