134. The 695th Lord Mayor's Lectures: The Thames Barrier – Immediate Future or Long Past? 7 March 2024
This was a super presentation by the Water Conservators' Thames Warden, Professor Carolyn Roberts. She pointed out that many people in London are living in a floodplain and flooding is a matter of probability: it does and will happen.
Issues include the length of warning
time, and time of day for evacuation.
Much depends on the type of event - snowmelt and heavy rain and high
tide (1928), tidal surge (1953) - and everybody’s level of preparedness. There are major challenges - persuading
politicians and the public that this is an issue, against a backdrop of not
trusting experts and general disbelief that it will happen. What is urgently needed is a prioritisation
of the risks and challenges, of what can be saved or protected. There is an urgent need for better cooperation
amongst organisations, and an understanding of the indirect implications of
emergency planning decisions (such as those which emerged during the flooding
in Gloucestershire in 2007).
Carolyn pointed out that the Thames Barrier
is part of a greater provision against flooding of the Thames: there are eight
other barriers on tributaries, 200 miles of walls and embankments, many in
private ownership (of which 2.5% were below par in 2021), and 400 other
structures such as floodgates, outfalls and pumps. There are also some ‘buffer’ areas of
important ecological interest such as saltmarsh, generally not considered in
1970s but which have increased a little in area.
·
1.4mm/yr rise 1911-2018
·
3.6mm/yr1990-2018
·
EA predict cumulative rise 2000 to 2125 1.6m (without ice sheet
collapse)
Thames Estuary 2100 Plan and Ten-Year Review:
The original Plan was intended to raise defences downstream
in 2040, upstream in 2065 and replace the Barrier by 2070. Now the prediction
is for 2050 for upstream defences, no change downstream. The proposal is to reassess options by 2030,
and decide on a replacement strategy for the Barrier by 2040, rather than 2050.
Provided it is not too late!
This lecture is well worth watching again!
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