"Gareth's was W7 now W10 Downstairs Computer" wrote
in message news:qi9466
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*.

Figure usually given as 100,000 gallons per lockful

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 ;-)