"Roland Perry" wrote in message
...
"Within the last few years new valves have been placed in the dam to
expedite rapid drawdown in emergencies: presumably, this is happening
now."

Although the question being asked in this thread is "if that's the case,
why also use lots of pumps".

Precisely.

If the pumps are draining into the same waterways that the normal exit
valves (which now permit rapid drawdown) flow into, then there is no
advantage - unless the rate-limiting step is the rate at which water can
flow out of the drawdown valves, rather than the rate at which water can
flow away from the area.

If the pumps are draining into other waterways (eg rivers rather than the
canal system) then there *is* an advantage in using pumps because it avoids
overloading the canal - but the photos this morning
https://www.bbc.co.uk/news/uk-englan...shire-49247226 show the pumps
discharging onto the emergency spillway half way down on the opposite side
to the collapse, so into the same place that the spillways and the normal
drawdown valves go, which is presumably the canal.