Harringay, Haringey - So Good they Spelt it Twice!
If it keeps on rainin'...
New River level been looking very high recently - and forecast 30mm rain in one hour tonight...
Tags for Forum Posts: new river, the levee's gonna break
Replies to This Discussion
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Permalink Reply by Karen Alexander on
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The river in Finsbury Park is flooding over the pathway tonight (Endymion Road gate).
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Permalink Reply by Hugh on
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Walking by today, I saw men at work with a digger at the grille towards the Allison-Hewitt end of the river. I asked the digger guy if the blockage at the grille is what had caused the higher levels. He told me it was. A couple of his colleagues were a little further upriver in a boats hacking away at the river bottom weeds. Once cut, they should be caught by the grille and then will be immediately removed by the digger. So immediate danger of flooding over.
I asked why there were two grilles in such close proximity at this point in the river (about 15-20 feet apart). The guy didn't know but he told me that it's the 'only double grille on the entire length of the river'. Any ideas as to why this should be?
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Permalink Reply by JoeW on
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Obviously without filtering, massive amounts of dirty and potentially harmful or poisonous items would flow unimpeded into the Ladder making life a misery for local residents.
I can only guess at why there are two grilles though.
The two grilles are different widths as the river itself narrows before the underground section. Maybe the narrowest grille was built first, but being significantly narrower than the river itself only a few meters upstream, it got clogged up too often? A wider grille was therefore constructed to reduce the frequency of maintenance/unclogging. And they didn't remove the original grille because it still catches some bits of rubbish that the first grille misses, and it's probably a royal pain to clear the underground section if that ever gets blocked.
If there are other sections of the river that get narrow and go underground but only have one grille, then perhaps my theory doesn't hold water.
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Permalink Reply by Sarah on
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Ah, it was looking a bit low on the Seven Sisters Road to Woodberry Wetlands stretch so that's why!
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Permalink Reply by Alyson on
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John Polley of New River Action Group knows a lot about the whole length of New River, and organises walks . . . http://newriver.org.uk/nr/index.php/nrag-history They may be able to shed light on the history of this.
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Permalink Reply by Dick Harris on
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My recollection is that back in the 1980s, before the Wightman to Hamden section of the river was opened to pedestrians, the main grill was located where the footbridge now is. In other words, the gap between the two grills was much great than it is now. All of the work was done by hand by men using long handled forks to drag floating weed up onto the bridge. Clearly, relatively little floating weed reaches the second grill and, when it does, it's much more difficult to handle because it has to be loaded into a wheel barrow before it can be disposed of. It follows that the second grill would not be satisfactory if it was the only one. However, there probably has to be a physical obstacle to prevent any large floating object (a human being for example) that happened to fall into the water between the grills from being swept into the tunnel. Perhaps this is the main reason for the second grill.
I would guess that rainfall has very little direct influence on the level of water in the river. In essence Thames Water has complete control over the rate at which water is diverted from the River Lea into the New River near Hertford. I don't think any land drainage watercourses are routed into the New River anywhere along its length. The problems of flooding probably arise from the kind of practical issues that occur, especially in the summer months, when water weed grows quickly and starts to slow down the flow. If the maintenance regime for clearing the weed cannot keep up, water that has already started its journey down the River may arrive in a section of river faster than it is flowing onwards.
So far this year, flooding in the Wightman-Hamden section seems to have been avoided but the water has been higher than usual and the guys were looking a bit worried last week when their machine threw a track and obliged them to get out the old forks.
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