On 05/08/2019 12:54, NY wrote:
"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 ;-)

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?