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THE THAMES BARRIER

Photo by Claude Schneider -

The Thames Estuary
The Thames Estuary, Claude Schneider

The construction of the Thames Barrier was an eventual result of the 1953 floods. It took 29 years from the initial alarm to the final working barrier. The history can be found in 'The Thames Barrier' by Stuart Gilbert and Ray Horner.
Various solutions and sites were examined during this time. The designs included -
1960s proposal for a Thames Barrier

Thames Barrier 1960s design
Proposal for Thames Barrier, 1960s

A Lift Barrier

Thames Lift Barrier design
Thames Lift Barrier design

A Swing Barrier

Thames Swing Barrier design
Thames Swing Barrier design

A Retractable Barrier

Thames Retractable Barrier design
Thames Retractable Barrier design

The design chosen in the end was the revolving rising sector gate. A scale model was built to show the principal -

Thames Barrier Model
A model showing a cross section through a gate, showing how the gate is revolved.
You can get an idea of the scale by looking at the scale figure in a white coat in the left hand service tunnel

The revolving rising sector gate in its four possible operating positions -

Thames Barrier Positions
The revolving rising sector gate's four positions.

Note the top right closed position with the flood levels marked. The point has been made that if (when?) a surge overtops the closed barrier this will not necessarily be a disaster for London upstream of the barrier. There is so much room in the river above the barrier that if it has closed substantially before high tide the barrier could be overtopped by 0.8m and the level at London Bridge only rise by 0.3m. However the defences downstream would have been overtopped by 0.6m and this might well have caused unacceptable flooding. It would however clearly count as 'writing on the wall'! If this began to happen on a regular basis it would obviously mark a new urgency in finding a replacement strategy.

Reinforced concrete piers, founded on the solid chalk 16 metres (52.8 feet) below the water line, support steel gates, which can be lowered, to allow shipping to pass, or raised to block surge tides and prevent flooding in central London.
Coffer dams (watertight boxes of interlocking steel plates) were first sunk into the bed of the river. The water was pumped out and the piers constructed.
A main working area was set up on the south bank to receive and distribute the vast amount of materials required.
On the north, a huge dry dock was built in which the concrete sills were cast. After manufacture, the dock was flooded and tugs towed the sills into position between the piers. They were then flooded and sunk to the level of the river bed, 16 metres (52.8 feet) below. The largest of these units measured 60 metres (194.7 feet) by 27 metres (89.1 feet) by 8.5 metres (28 feet) and weighed 10,000 tonnes. They had to be manoeuvred into a confined space, against a fast flowing current and placed within a maximum permitted tolerance of 10 mm (under 1/2 inch).
The piers and the sills form the supports and seating for the gates, and platform bases for the operating machinery, so they had to be accurately built.
Reversible hydraulic rams - one pulling and one pushing - are used to move rocker beams connected to discs at each end, and these rotate the gates into any of the four required positions.
Floating cranes were again used to accurately position this machinery.

 

Thames Barrier Construction
one of the large sills being towed from the flooded dock out to the piers.
Others under construction beyond.

 

The Thames Barrier - A Systems Study, Chris Wallace -

This land-mark civil engineering project is one of the success stories of British civil engineering ...
 
Other difficulties encountered and countered were problems with the river-bed geology affecting the bed/pier interface; collision of a ship with a coffer dam and of course, bad weather.
 
One unanticipated problem arose in the sheeting of the roofs to the piers. The doubly curved roof had to be laid in narrow strips which were joined by turning the edge of one sheet up and folding the edge of the next sheet over it, in a direction to make the joint water proof. On one side a right handed plumber could do the job normally, but the other side could only be done by a left-handed plumber, or a right-handed plumber working upside down. Fortunately it appears that enough left-handed plumbers were recruited.
[ or right handed plumbers willing to be hung upside down! ]

 

1984: Queen Elizabeth II opened the Thames Barrier -

Barrier Opening Letter Cover, 1984
Thames Barrier Opening Letter Cover, 1984

 

Thames Barrier, Myers 2005
Thames Barrier, Doug Myers 2005

 


Thames Barrier, seen from below

Unplanned Barrier closures - the figures are complex. Ignoring the test exercises and closures initiated for other than tide/surge and river flow causes gives this graph which uses the figures from (numbers from Environment Agency, Hansard):

Thames Barrier Closures by year
Barrier Closures against tidal surges and river flows.

However the following Hansard (Parliamentary reporting) question and answer reveals a rather more complex situation - (quoted from Hansard June 2005)

Norman Baker: To ask the Secretary of State for Environment, Food and Rural Affairs if she will list the occasions on which the Thames Barrier has been closed in each year since its inception; and what estimate she has made of the number of occasions when it will be closed in (a) 2010, (b) 2020, (c) 2050 and (d) 2100.
 
Mr. Morley: The Thames Barrier is closed to protect London from high water levels in the River Thames. These high water levels result from tidal surge conditions in combination with high freshwater flows following rainfall over the Thames catchment.
The Barrier closures may be characterised as predominantly tidal-influenced (T)
or predominantly rainfall/fluvial-influenced (F).
Since inception, the Thames Barrier has been closed to prevent flooding during the winter flood season (generally October to April) on 92 occasions as follows:
 

Tidal Fluvial Total
198283 1 0 1
198384000
198485 000
198586011
198687101
198788000
198889101
198990134
199091101
199192101
199293404
199394347
199995224
199596404
199697101
199798101
199899202
199900336
20000116824
200102314
20020381220
200304101
200405303
 
Forecasting the frequency of future closures of the Thames Barrier depends on two principal factors:
(a) The impacts of climate change on sea and river levels based on the climate change scenarios currently available; and
(b) The extent to which these levels may be reduced by other flood risk management measures used within the Thames Estuary in conjunction with operation of the Thames Barrier.
Depending on the balance of factors described above, The Environment Agency's early studies indicate that the estimated frequency of closures will be as follows.
 
2010: 1020 closures per year
2020: 2035 closures per year
2050: 6*75 closures per year
2100: 30*325 closures per year
 
The lower figure for each year indicates the best predicted outcome based on lowest climate change scenario impacts and maximum use of flood management mitigation measures implemented from 2030 (shown by *).
The higher figure for each year indicates the worst potential outcome based on maximum climate change predicted impacts with no additional flood management mitigation measures implemented from 2030.
 
The Environment Agency is currently planning for the future of flood risk management within the Thames Estuary. For this purpose, it has established a project called Thames Estuary 2100 based at the Thames Barrier. The purpose of the project is to produce a flood risk management plan for the tidal part of the Thames Estuary covering the next 100 years.

Since the above figures were given:
2005-6 total 3?

18-JAN-07 2030-0300 [high river flow, storms]
21-JAN-07 1100 [high river flow, storms]
22-JAN-07 1200-1730 [high river flow, storms]
18-MAR-07 0930-1530 [Surge 0.8m, 6.55m at Sheerness]
08-NOV-07 [surge]
09-NOV-07 [surge]
25-NOV-07 [surge]
24-JAN-08 1400-1500 [high river flow, Spring tide]

2007: total 7
 
The Thames Barrier and the future risks of flood
 
 
Met Office Climate change and the Thames Estuary, September 2008

BBC BARRIER NEWS

 
 
Bugsby's Reach: Barrier to Dome




Introduction
Estuary
PLA
QEII Br
Barrier
Tower Br
Custom Ho
London Br
; Frost Fairs
Cannon St Rb
The Great Stink
Southwark Br
Millenium Br
Blackfriars Rb
Blackfriars Br
Waterloo Br
Charing Cross Rb
Westminster Br
Lambeth Br
Vauxhall Br
Victoria Rb
Chelsea Br
Albert Br
Battersea Br
Battersea Rb
Wandsworth Br
Fulham Rb
Putney Br
Hammersmith Br
Barnes Rb
Chiswick Br
Kew Rb
Kew Br
RICHMOND
Twickenham Br
Richmond Rb
Richmond Br
TEDDINGTON
Kingston Rb
Kingston Br
Ditton Slip
Hampton Br
MOLESEY
SUNBURY
Walton Br
Desborough Cut
SHEPPERTON
Chertsey Br
CHERTSEY
M3 Br
Laleham Slip
PENTON HOOK
Staines Rb
Staines Br
Runnymede Br
BELL WEIR
Magna Carta Is
OLD WINDSOR
Albert Br
Datchet
Victoria Br
Black Potts Rb
ROMNEY
Eton
Windsor Br
Windsor Rb
Windsor Slip
Elizabeth Br
BOVENEY
Dorney Lake
York Cut
Summerleaze Fb
MonkeyIsland
New Thames Br
BRAY
Bray Slip
Maidenhead Rb
Maidenhead Br
Below Boulters
BOULTERS
Cliveden
Hedsor
COOKHAM
Cookham Slip
Cookham Br
BourneEnd RFb
Quarry Woods
A404 Br
MARLOW
Marlow Br
Bisham
TEMPLE
HURLEY
Medmenham
Culham Ct
Aston Slip
HAMBLEDEN
Temple Is
Fawley Ct
Remenham
Regatta
Phyllis Ct
Henley Slip
Leander
Red Lion
Henley Br
Angel on Br
Landing
Hobbs Boatyard
Hobbs Slipway
MARSH
Hennerton
Bolney
Wargrave
Shiplake Rb
R.Loddon
SHIPLAKE
Sonning Br
SONNING
Dreadnought
K&A Canal
CAVERSHAM
Reading Br
Caversham Br
Reading Slip
Purley
MAPLEDURHAM
Hardwick Ho
Whitchurch Br
WHITCHURCH
Hartswood Reach
Gatehampton Rb
Goring Gap
Goring Br
GORING
Swan
CLEEVE
Moulsford
Moulsford Rb
Papist Way Slip
Winterbrook Br
Wallingford Br
BENSON
Shillingford Br
R.Thame
DAYS
Burcot
Clifton Hampden
Clifton Church
Clifton H Br
Barley Mow
Long Wittenham
CLIFTON
Appleford Rb
Sutton Courtenay
Sutton Br
CULHAM
Culham Cut Fb
Abingdon Slip
Abingdon
Abingdon Br
ABINGDON
Nuneham Rb
Nuneham
Nuneham Park
Radley Boats
SANDFORD
Rose Island
Kennington Rb
Isis Br
Iffley Mill
IFFLEY
Oxford Rowing
Isis
Donnington Br
Riverside Slip
Boathouses
Punting
Lower Cherwell
Upper Cherwell
Islip
Head of River
Salters Steamers
Folly Br
Bacons Folly
Oxford Fb
Osney Fb
Weir stream
Osney Rb
Bullstake Stream
Osney Marina
OSNEY
Osney Br
Four Rivers
OLD RIVER
CANAL
Medley Weir Site
Medley Fb
Bossoms
Perch
Trout
GODSTOW
Godstow Nunnery
Godstow Br
Thames Br
KINGS
River Evenlode
EYNSHAM
Swinford Br
Oxford Cruisers
PINKHILL
Farmoor
Stanton Harcourt
Bablock Slip
Arks Weir Site
NORTHMOOR
Harts Fb
//Rose Revived
Newbridge
//Maybush
River Windrush
below Shifford
SHIFFORD
Shifford Fb
Tenfoot Fb
Trout Inn
Tadpole Br
RUSHEY
Old Mans Fb
RADCOT
Radcot Cradle Fb
Swan Inn
Radcot New Br
Radcot Old Br
GRAFTON
Eaton Hastings
Kelmscott
Eaton Fb
BUSCOT
Bloomers Hole Fb
Trout Inn
St Johns Br
ST JOHNS
Halfpenny Br
Marina Slip
LIMIT
Inglesham
Hannington Br
Kempsford
Castle Eaton Br
Marston Meysey
A419 Br
Cricklade
SOURCE?
THAMES HEAD
SEVEN SPRINGS