From IAN FALLON
In reply to Richard Duvaille’s queries regarding the Thames Barrier,
the chance of overtopping the barrier should the sea level rise by 30 centimetres
is ‘1 in 1000’ (Letters, 16 June).
However, by operating the barrier gates so that the reservoir upstream
of the barrier (formed by closing the barrier at low tide) is partially
filled just before the peak of the tide, this ‘1 in 1000’ chance can be
maintained for an even greater rise in sea level without any flooding occurring.
With regard to Duvaille’s comment about taking the greenhouse effect
into consideration, the barrier was partially constructed before this phenomenon
was considered a problem. The designers were not clairvoyant.
So far, sea levels have not risen at the rate originally allowed for,
never mind any increase caused by the greenhouse effect.
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Ian Fallon Thames Barrier National Rivers Authority London
