UPDATED with new new pictures, taken by Deon. It’s easy to tell which are his. There’s more of his stuff here
Because they only carry out a routine closure of the Thames Barrier six times a year, it is treated, in a small-scale, very English kind of way, as something of an event.
There are already a handful of spectators when we arrive at just after half eight on a Sunday morning – middle-aged couples in the main and some young families, cameras ready.
Environment Agency staff are pitching gazebos under which they will explain their work. For the kids are tiny mini-golf courses, no more than 10ft long. Tarpaulin information banners are cable-tied to railings.
We have half an hour or so before things start moving so get breakfast in the Thames Barrier Information Centre café. I leaf through the visitor’s book while they make our cheese and ham toasties.
One unhappy entry is by someone from the Tea Appreciation Society, who attests to his bona fides by stating he has appeared in the Mail Online. He says that on a previous visit he’d commended the management on its serving tea in pots for two but wondered if pots for one could be introduced.
‘I see instead,’ he writes, ‘you have removed all teapots. This has to be a triumph of convenience over any thought for customer satisfaction.’ He finishes by saying he expects a response on the matter and provides an email address. This is all written in large, block capitals.
Another is about the information centre itself, this one in smaller block capitals.
‘Best synthesiser backed information video relating to a London based movable river defense [sic] system I’ve seen all day! On the downside this pen I just stole from the gift shop to write this is rather poor. C White.’
Toasties done, we go back riverside, coffees in hand and wait for the closing. I’m expecting tonnes of water kicking and swirling to the growl and rattle of mechanical shoulders being pressed to the tide.
It turns out otherwise. A siren sounds briefly and things quietly and slowly move into place. There is no discernible drama beyond the appreciation of engineering genius at work. Within an hour or so, the Thames is at bay.
A man in a fluorescent work coat stands by the tunnel underneath the control tower. He is one of five tidal forecasters who between them provide 24-hour cover 365 days a year and says this is a test-run to ensure things are running smoothly.
Today is especially important because winter is coming, when the barrier may be put to proper use and called upon to defend London from the flood. He’s happy to talk so we pump him for facts.
Those remembered include that the difference in level from one side of the barrier to the other will reach around four metres, that the closest it has come to being breached is two metres and that between low and high tide is around seven metres.
The riverbed is deeper on the south side than the north and in the underspithe barrier comes to within 20cm of the bottom when closed, leaving water to rush through at speeds of 30 knots. From the north bank, we will see a moshpit of gulls going mad on the upstream side, preying on the hapless fish flung to the surface by this underwater torrent.
As we talk a cormorant catches a fish too big for it to swallow.
‘Is there much marine life in the river?’
‘Oh, yeah, it’s quite clean now – porpoise, a whale – of course – and seals.’
‘I don’t know what kind they are. Maybe.’
His job is to decide when the barrier needs closing. Some winters this never happens but in 2012/13/14 it did up to 50 times. He says tidal swell comes down the east coast from Norway and, if it doesn’t get soaked up by East Anglia, squeezes up the Thames.
To judge the extent of this swell, he must study tidal charts and ‘artificial’ adjustments, such as low pressure that may cause sea levels to rise. A computer will give him a reading and he studies the background data to consider whether to act on its assessment.
Asked if he ever over-rules the computer, he says on one shift the prediction was for a spike but because there is no low pressure in Norway or anything similar he ignores it. A colleague who takes over for the next shift sees the same data and closes the barrier. It is with a noticeable sense of satisfaction that he tells us he was right – nothing out the ordinary happens that day.
‘But,’ he adds. ‘You have to be certain if you’re going to over-rule the computer.’
Back home I read on the BBC that in December 2013, the Environment Agency said if sea levels continued to rise and there was no barrier, the Houses of Parliament, the O2, Tower Bridge and areas including Southwark, the Isle of Dogs, Whitechapel and West Ham would flood.
But the barrier is giving us no rush and swirl to stare at just now, so we walk to the Woolwich Foot Tunnel, cross under the river and set our direction west through Silvertown, round the back of the huge Tate & Lyle sugar refinery.
For two to three hours we paddle against the tide of London money flowing downriver, its progress marked by beacon towers, its flotsam and jetsam broken-windowed, brick-built industrial units shotgun barnacled with buddleia and graffiti.
Some of these buildings are wrecks, or close to it. Some house food wholesalers, evangelical churches, panel beaters, aggregate and heavy-duty waste contractors, looted gold, dead men’s bones…
We get as far as West Silvertown station, which looks like a spaceship, and take the DLR upstream into the tide’s indifferent heart of Canary Wharf.
In our wake, the barrier stands closed, facing out the other way, shoulder braced, blind to the tide coming at its back.