In message , at
11:31:36 on Tue, 6 Aug 2019, Robin remarked:
On 06/08/2019 11:09, NY wrote:
"charles" wrote in message
...
I don't see how you can possibly infer that. It's *possible* but given
the speed with which fast moving water can erode riverbanks etc, it
seems
equally likely that this was an "acute. event.

If the water had been going over the slipway, then I'd agree with your
suggestion.* But it wasn't.
I thought on the day that the news first broke about Whaley Bridge
there was a video which showed a lot of water cascading over the full
width of the spillway. I got the impression that this was a recent
video dating from a day or so earlier, with the implication that it
was after this that they slabs were found to be cracking.
Interesting that
https://www.bbc.co.uk/news/uk-englan...shire-49247226 shows them
taking the outlet of the pumps over the lower part of the spillway on
the opposite side to the collapse. I'd have thought they'd want to
avoid any more water flowing over the spillway in case of undermining
of the earth fill beneath the concrete.

Indeed. The spillway was being asked to do its job. But ISTM as yet
unclear if the problem was lack of maintenance, poor design, or more
water than it was designed to handle.

Some rather more than averagely informed comments are at
https://www.sciencemediacentre.org/e...s-that-the-wha
ley-bridge-dam-has-been-damaged/

"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".
--
Roland Perry