On 05/08/2019 10:18, NY wrote:
"nightjar" wrote in message
...
On 04/08/2019 21:13, Brian Gaff wrote:
Yes but its really low pressure and if you want to move a lot at a time
there is no benefit to using a siphon. Incidentally, where ARE they
putting
all that water?
Â* Brian


You can see some of the outlet pipes emptying onto the concrete
spillway, on the opposite side from the failure. Other pictures seem
to show more outlets running straight into a waterway.

I may have missed something in the earlier new reports, but why are they
having to *pump* water out of the reservoir? Is there a problem with
taking water out in the normal way? I think it's a canal feeder
reservoir. Can the canals not cope with a greater flow of water into
them than was originally intended?

Canals are designed to lose as little water as possible with each lock
movement so they cannot be used to dump water into without seriously
damaging the mechanisms. There is usually a small bypass for any excess.

Are the water courses that the pumps
drain into separate from the canal network - is the canal not also fed
from them and the spillway?

The natural rivers that drain that area. Snag is you can't dump too much
into them quickly either without consequential flood damage downstream.
They have to balance competing risks.

I don't understand about blocking the streams that feed into the
reservoir? Won't water just build up behind the temporary "dams" that
the Chinooks are making, causing them to burst catastrophically at some
stage in the future?

It buys a bit of time and the trapped water may well soak away more
slowly rather than overtopping the barriers. One trick they have been
using for a while it to put multiple small barriers into high moor becks
to slow the rate it runs off the top in a massive deluge. Mainly to slow
erosion but also to alleviate flooding in some places.

--
Regards,
Martin Brown