T
Tom Gardner
Guest
On 31/03/20 02:00, Phil Hobbs wrote:
It /does/ look like that, doesn't it - or at least
a really badly terminated transmission line
https://flood-warning-information.service.gov.uk/station/1034
https://flood-warning-information.service.gov.uk/station/9264
OTOH on the Severn at Portbury Docks there is a
nice sinewave.
https://flood-warning-information.service.gov.uk/station/3014
A bit further upstream at Sharpness Docks it looks
more like a half-wave rectified signal (the docks/canal
are behind lock gates)
https://flood-warning-information.service.gov.uk/station/2071
Further upstream at Minsterworth, where the bore
is at its highest, it looks like an RC response
to an impulse.
https://flood-warning-information.service.gov.uk/station/2051
On 2020-03-30 04:25, Tom Gardner wrote:
On 30/03/20 01:36, Phil Hobbs wrote:
On 2020-03-29 19:36, Tom Gardner wrote:
On 29/03/20 22:55, Phil Hobbs wrote:
On 2020-03-29 17:30, Adrian Tuddenham wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2020-03-29 09:57, Jeroen Belleman wrote:
On 2020-03-29 15:20, Phil Hobbs wrote:
Looking up the length of Great Britain, I discover that there's a place
in Cambridgeshire called Holme Fen that is ten feet below sea level.
I get how that could happen in the desert, but in England???
Cheers
Phil Hobbs
It was drained using steam-driven pumps in 1851.
Jeroen Belleman
Yeah, but why does it stay dry? Have they kept pumping for 170 years?
That is just a fleeting moment in England's long history.
In Somerset there are areas of land at, or just below, *average* sea
level. The water is pumped into rhines (canals) slightly above the land
level and large lock gates are opened to empty it at low tide. Then the
gates are closed to prevent the high tide flooding back.
It's just like deriving a negative supply from a sinewave centred on, or
just above, zero.
Ten feet is a long way for a tidal system. BC and Nova Scotia get tides
like that, but most places don't. Plus it depends on the phase of the moon.
I see a 3.4m tidal range every day - or at least I
did before last week. Storm surges can add another
metre so that it flows over the top of lock gates
in the city center.
I also see the river suddenly get up to 2m deeper
(with surfers travelling upstream) and start
flowing backwards.
But that is on the other side of the country,
the River Severn.
The Severn has a tidal resonance like Fundy, doesn't it?
The other local phenomenon is that Southampton gets
4 high/low tides a day, as the water goes up the
English Channel and around both sides of the Isle
of Wight.
Was Chebyshev from Southampton?
(Opportunities to make numerical analysis jokes don't come round that often.)
It /does/ look like that, doesn't it - or at least
a really badly terminated transmission line
https://flood-warning-information.service.gov.uk/station/1034
https://flood-warning-information.service.gov.uk/station/9264
OTOH on the Severn at Portbury Docks there is a
nice sinewave.
https://flood-warning-information.service.gov.uk/station/3014
A bit further upstream at Sharpness Docks it looks
more like a half-wave rectified signal (the docks/canal
are behind lock gates)
https://flood-warning-information.service.gov.uk/station/2071
Further upstream at Minsterworth, where the bore
is at its highest, it looks like an RC response
to an impulse.
https://flood-warning-information.service.gov.uk/station/2051