It can't take the water away fast enough. The rivers below the dam are already near capacity.
By building dams in the feeder steams, the water can be pumped away before it reaches the reservoir.
Marland pretended :
The venturi effect as invented by Dyson.
Presumably canals have to be capable of carrying a flow of water equivalent to each lock being opened every so often to let narrow boats up or down. How big is "a lock's worth", typically, in terms of the amount of water the flows into it when the upper gate is opened and flows out when the lower gate is opened? I imagine it's fairly small compared with the 7000 litres (7 tonnes) of water that were being pumped out every *minute*. Do canals tend to have a maximum boat movements per day limit, not just because of traffic congestion at the locks but because of the flow of water through the canal which could scour its sides?
The reservoir had a spillway to allow for excess water to overflow into (I presume) non-canal waterways. Is there no way to divert water that would normally go into the canal, so it can go into those non-canal waterways instead in an emergency.
Is the problem essentially that the spillway had become damaged? Could the spillway mechanism have safely coped with the excess water if the concrete skin on the spillway hadn't been breached, allowing the earth fill to be scoured away?
The Peak Forest Canal, is indeed downhill all the way to Manchester
With the exception of the LLangollen Canal which is a source of drinking water for Manchester.
Yebbut where to?
Hopefully "lessons will be learned" and dam designs include means of drainage for maintenance or emergency. A bloody big tap at the bottom?
Dyson Hoovers - - - poor suckers for poor suckers?
A Henry at £99 is one third of the price of a dyson
Figure usually given as 100,000 gallons per lockful
How do you remove surplus water from the canal without opening the locks - which are specifically designed to stop that happening. The relevant canal appears to run through Whalley Bridge and is presumably fed by a pipe under gravity.
I suspect the story about blocking the inputs was wrong. The bags of ballast are being used to re-inforce tehdam.
"Gareth's was W7 now W10 Downstairs Computer" snipped-for-privacy@yahoo.com wrote in message news:qi9466
Which is about 450,000 litres. So one lockful would take about 450,000 /
7000 = 640 minutes to empty from the reservoir through the pumps at the rate that was given - one lockful every 10.7 hours.I wonder how often the locks can be emptied without scouring the banks - ie in normal canal usage. I imagine that they are already doing this as often as they can, and the pumping is *in addition* to emptying the reservoir the intended way as often as allowed.
So the rate at which the locks can empty the reservoir is actually a lot greater than the rate at which the pumps are doing it. I'd imagined that it was the opposite way round. Of course there will be water flowing into the canal by surface runoff that hasn't come from the reservoir, and I imagine the normal limit on how frequently the locks can be emptied is based on conditions where the ground isn't already saturated with water.
What is the typical number of lock-emptyings per hour that a canal can handle? I presume there is a peak rate which is a lot higher than the sustained 24-hours-a-day rate ;-)
Draining into a bloody big pipe to the sea or some other "sink" that can accept all the water from the reservoir that needs to be drained.
When boating, you reckon on 1/4 hour per lock (except perhaps on the Tardebigge flight on the Worcs & Brum canal, about 7 minutes, especially if you've got a crew member lock-wheeling at the next lock, making sure it is ready for you to go directly in).
But, if all the locks filled and emptied together, ONLY ONE lockful is discharged at the end of the canal because each lock emptying just makes up the shortfall in the pound up to the next lock.
I suppose that's a bit like the progress of holes in a semiconductor, if you see what I mean?
Nonsense! Have you actually tried it? I?ve syphoned water plenty of times and never had to keep the outlet underwater.
Tim
Well, that doesn't seem very likely to me; I just thought some of the background info - from a reputable source - as to *why* there was (usually) a limit might be interesting. Still, as usual, I am sure you think you know best.
#Paul
Yebbut I doubt that was through a 12" pipe!
Its only basic physics, the sort of thing that you used to learn in primary school before it was all play and no learning.
Are you sure he didn't get the idea from Frank Whittles original jet engine design ?.
My toilet cistern doesn't seem to have this problem
"The Venturi effect is named after Giovanni Battista Venturi (1746?1822), an Italian physicist"
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