please empty your brain below
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The area around Parliament used to be an island, as the name of the local conservation group, the Thorney Island Society, implies.
David | 26.09.19 - 7:41 a.m. | #
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If I'm correct in believing that Ordnance Survey spot heights are based on the *mean* sea level at Newlyn in Cornwall, then at high tide in London, Westminster would already be under several metres of water if it weren't for the existing flood defences.
Close to where I live in Rotherhithe there are stretches of the river with no defenses whatsoever (for example, Durand's Wharf) so in the event of a failure of the Thames barrier, most of the Rotherhithe peninsular and adjacent Bermondsey could be inundated.
Richard | 26.09.19 - 7:51 a.m. | #
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Richard is correct - and they are based on an historic mean sea level too.
Not sure what the tidal range in the Thames is, but it would seem likely that several of these places are below sea level at a normal high tide - so thanks to the defences
Ian | 26.09.19 - 7:56 a.m. | #
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large areas of east london underwater, i dont see the problem with that
todd | 26.09.19 - 7:57 a.m. | #
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So more problems for Crossrail.
Still Anon | 26.09.19 - 8:42 a.m. | #
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Tidal range in central London varies, but is usually about 4½-6½m.
Tides are measured from a local 'Chart datum', which at Westminster Bridge is 2.9m below 'Ordnance datum' (mean sea level) at Newlyn.
Every day high tide on the Thames is at least 2½m above 'mean sea level', and sometimes 4½m. Our river defences serve us well.
diamond geezer | Homepage | 26.09.19 - 8:43 a.m. | #
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Fulham has always been at flood risk, the Parsons Green Club records the major flood of 1928
Environment Agency flood risk maps are quite sobering; Luckily we live on the "high ground" on this map.
But as it's only a few inches higher I'm not really expecting to be safe
Peter in W14 | 26.09.19 - 9:32 a.m. | #
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Wasn't there a film a few years back called Flood or something similar - based on what would happen if London ever flooded?
I don't think I've seen it. Now I'm not sure I want to!
Cornish Cockney | 26.09.19 - 9:49 a.m. | #
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Before the Thames Barrier arrived there was a scary poster / map on the platform at Wandsworth Town station the other side of the river from Fulham showing the local area likely to be flooded in any tidal surge.
Air raid sirens would be used to warn people of the need to head for higher ground.
Of course since the poster came down hundreds more homes have been built in what will soon once again be a flood danger zone. Luxury pad alongside the Thames anyone?
ap | 26.09.19 - 10:12 a.m. | #
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at what point are the various tube lines and other underground excavations in danger of being inundated
Caz | 26.09.19 - 10:44 a.m. | #
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Yes, there was a film about London flooding a few years ago. I recall a rather impressive CGI sequence of a floodtide racing up the Thames and inundating the city, and David Suchet playing the Prime Minister.
Adrian | 26.09.19 - 11:17 a.m. | #
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@Adrian. Yes, I remember that film. It was called Flood. Some of the special effects were, as you say, impressive, but overall the film was pretty weak. There were moments of high drama that made me laugh.
Great Aunt Annie | 26.09.19 - 11:41 a.m. | #
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The sea rise map you've linked to at the start of the article shows Downing St dry at 13m (by which point huge swathes of London are shown underwater). I can't understand how this links to the entry about Westminster being 2m above sea level. The map seems to shows areas like Southwark and Fulham being at much greater risk.
Am I misunderstanding something?
Eric | 26.09.19 - 11:47 a.m. | #
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...or the Ordnance Survey map is wrong.
...or they're measuring something different.
diamond geezer | Homepage | 26.09.19 - 11:53 a.m. | #
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More scaremongering, which if taken to its logical conclusion, predicts humanity is doomed. something will eventually wipe-us-out. be it our own doing or some extinction-level-event beyond our control.
Grumpy Anon | 26.09.19 - 12:09 p.m. | #
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Some areas, quite possibly including Drowning Street, will not flood until sea levels rise considerably more than their own height. That is why there are spot heights with negative values on Ordnance Survey maps.
The Mediterranean would have to rise 60 metres before it would overtop the pass separating it from the Jordan Valley and the Dead Sea
timbo | 26.09.19 - 2:57 p.m. | #
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London Transport used to display flood precaution posters on Underground station platforms. A similar one issued under the British Rail and London Transport branding was posted widely around the rail network.
If you heard the siren, you had 4 hours to travel across / out of the risk area, during the latter two of which, affected services would be run down to close.
I remember the sirens being tested one day when at school - probably in the late 70's. There was ample warning that it was a test drill, but it was still eerie. Given the cold war context, we wondered what one would do if they sounded for other reasons.
Good news for the group who want to bring the Rivers Tyburn and Effra back to the surface.
NickW | Homepage | 26.09.19 - 3:22 p.m. | #
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There are still floodgates in place at some (Thameside) locations on the Tube, but I do not think they are operative. Yet there must *be* a plan.
David | 26.09.19 - 3:28 p.m. | #
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Interesting to see that the prediction on the map you show would give the house I grew up in, in Dartford, a nice (?) view of the lapping flood waters. Just the right side of the railway fortunately.
Christine | 26.09.19 - 3:42 p.m. | #
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My recollection is that at the western end of the Jubilee Line station at Canary Wharf there are very wide escape staircases comimg up from both the concourse and platform levels. The thresholds of the exit doors are about 2m above the normal water level in the wet dock, some 10m away.
There are also large air input and extract shafts (leading down to the trunking over each track) in the same location.
I believe that the tunnels at Canary Wharf are connected to all the other deep tube tunnels.
strawbrick | 26.09.19 - 7:13 p.m. | #
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'London Calling' by the Clash sounds strangely prophetic. As does the 'English Civil War'. I think it was 'White Man in Hammersmith Palais' that had the lyrics 'if Adolf Hitler flew in today, they'd send a limousine anyway' - 40 years too early.
Paul Adderley | 26.09.19 - 11:42 p.m. | #
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An interesting source of local flood risk information is in the:
Strategic Flood Risk Assesment (SFRA)
and Surface Water Management Plan (SWMP)
that all councils had to prepare and make available. Many are online and downloadable.
The level of detail may vary. Additional information or large scale maps may be available as separate appendices. Some councils have joined forces with one combined SWMP or SFRA.
For example, Croydon:
[SWMP] [SFRA] [flood management plan]
The plans often contain a wealth of information of the area that local history buffs may find interesting.
Rogmi | 27.09.19 - 12:57 p.m. | #
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To get a rough idea of how the height in an area varies, look at the elevation in Google Earth as you scroll around (shown as elev on the bottom right hand row of text). I don't know precisely what this is based on, but the Thames at Westminster is 0m, the junction of Downing St/ Horseguards Rd is 5m and the main gate at Buckingham Palace is 6m. The figures may not be that accurate.
The elevation figure in GE is useful to get a rough idea of the layout of an area with regards to potential water courses (natural or man made) and scrolling around will show where the peaks and troughs of the land are likely to be.
Rogmi | 27.09.19 - 1:08 p.m. | #
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There's only one widely-used source of open source global elevation data, which is what the flood map website is probably using. It was generated by bouncing light off the Earth during one of the last Space Shuttle missions.
The problem is in built-up or forested areas it usually shows the heights of the tops of the buildings/trees rather than the ground, which might explain some of the discrepancies with Ordnance Survey.
Graham | 29.09.19 - 8:41 p.m. | #
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The Environment Agency have a LiDAR dataset that is collected for flood mapping, but that is widely used for other purposes.
The data can be downloaded, or more simply viewed here. The "DSM" includes buildings, vegetation etc but the "DTM" is processed to remove those and so is similar to the ground surface.
Geo_rich | 30.09.19 - 10:12 a.m. | #
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