England's Death Valley

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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

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: England's Death Valley
snipped-for-privacy@electrooptical.net says...
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We've been doing hydraulic engineering for hundreds of years. I think we  
have imported expertise from The Netherlands, where they depend heavily  
on it...

Mike.

Re: England's Death Valley
On 2020-03-29 15:20, Phil Hobbs wrote:
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It was drained using steam-driven pumps in 1851.

Jeroen Belleman

Re: England's Death Valley

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  Then they filled it back with an even worse, more sinister fluid...
humans.

Re: England's Death Valley
On 2020-03-29 09:57, Jeroen Belleman wrote:
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Yeah, but why does it stay dry?  Have they kept pumping for 170 years?  
My back garden is a former pond bottom, so I think about such things.  
(I have a deeply committed relationship with my storm drain--it's 12  
inch ID, and runs across the lot, under the street, and about 300 feet  
down the street before it reaches the level of the municipal drain.)

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: England's Death Valley
On Sunday, March 29, 2020 at 3:15:31 PM UTC-4, Phil Hobbs wrote:
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Maybe they built clay walls around it to keep the water out.  
The opposite of a pond?  
It also depends on where the water table is.  (ground water level.)

I need to do some 'hydraulic engineering' on my gravel driveway.  
The 'upstream' trench needs to be dug out.  
I've got an old tired backhoe and as long as I take it easy
it should be a fun job.  

Does your storm drain clog?  12" ID sounds big!  
I've got a number of ~4" drain pipes under my drive way.  
And this ~2" diameter thick walled plastic tube.  
That a jam into the exit and entrance holes if/ when  
a pipe clogs.  

They also make these cool water powered (from a garden hose)
balloon expanding things that you can send down smaller pipes  
and blow 'em out with water. The end of the hose is a nozzle and  
then the expanding part, at full water pressure the balloon expands  
and wedges into the walls of the pipe.  As the nozzle is spraying  
water into the obstruction.    

George H.  
  
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Re: England's Death Valley
On Sunday, March 29, 2020 at 4:37:25 PM UTC-4, George Herold wrote:
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ace
  
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Huh?  What???  Is there no rain in Great Britain?  

I had that conversation with someone in a newsgroup once.  Seems in Netherl
ands they have a great deal of land reclaimed from the sea.  Yes, they have
 to have dikes to keep out the sea, but they also have large ponds to catch
 the rain water and pumps to pump it into canals leading to the sea.  

If Holme Fen is not near the sea I suppose they can pump the water into a r
iver.  

--  

  Rick C.

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Re: England's Death Valley
On 2020-03-29 16:37, George Herold wrote:
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England is a famously rainy place that gets little sun.  I'd expect it  
to fill up with fresh water pretty fast.

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It needs to be big.  In Hurricane Floyd we had eight feet of water  
sitting over the drain.

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We've had the roto rooter guy check it out a couple of times, but it's  
been fine for 60 years so far.

Cheers

Phil Hobbs
(second-longest tenure on his block--30 years this coming December)


--  
Dr Philip C D Hobbs
Principal Consultant
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Re: England's Death Valley
snipped-for-privacy@electrooptical.net says...
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Yes, the many people who got flooded out in central parts of England  
this autumn and winter are not thanking the Covid-19 lockdown for  
interfering with their recovery...

Mike.

Re: England's Death Valley
On Sunday, March 29, 2020 at 5:41:37 PM UTC-4, Phil Hobbs wrote:
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Fair enough.  I live down hill from ~100 acres of farm land.  
I mostly think about diverting the run-off to keep some part 'dry'.
But it doesn't really do that much... the soil is mostly clays,  
and if you dig a hole anywhere*.. it fills up with water in no  
time.

George H.  
*well except for a couple of 'sand hills' that I think are left over from  
the last glacier.  
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Re: England's Death Valley
On 2020-03-29 21:15, Phil Hobbs wrote:
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Well, yes, I suppose so. That's the way it's done in the
Netherlands. It doesn't take all that much. A few hundred
kilowatts can keep a huge area dry.

Jeroen Belleman


Re: England's Death Valley
On 30/3/20 7:40 am, Jeroen Belleman wrote:
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I visited one of the old windmills, and calculated its power output at  
somewhere around 20kW. Quite a big structure, but probably not very  
efficient. Its job was to lift water less than 10m into a drainage canal.

Re: England's Death Valley

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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.


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~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
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Re: England's Death Valley
On 2020-03-29 17:30, Adrian Tuddenham wrote:
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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.

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: England's Death Valley
On 29/03/20 22:55, Phil Hobbs wrote:
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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.

Re: England's Death Valley
On 2020-03-29 19:36, Tom Gardner wrote:
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The Severn has a tidal resonance like Fundy, doesn't it?

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: England's Death Valley
On 30/3/20 11:36 am, Phil Hobbs wrote:
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The ocean doesn't need to be resonant. Super high tides occur at the  
"corners" of any ocean - like slop in the corner of a square bucket or  
pool. The Severn feeds that tidal slop into a shock-line that sharpens  
the pulse until it breaks - as happens in a few dozen places elsewhere  
in the world.

Tides in the Buccaneer Archipelego (north-western Australia, opposite  
Indonesia) regularly exceed 10m - slosh from the Indian ocean. There's  
no funnel leading to a tidal bore there AFAIK. The biggest one is in China.

If it wasn't for these effects, tides would be exactly equal around the  
world; about 1m following the moon adding to 0.5m following the sun.

CH

Re: England's Death Valley
On 30/03/20 01:36, Phil Hobbs wrote:
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It has a tidal bore like Fundy; Fundy is the only higher
one I believe.

I'm not aware of any resonance effects. The bore is created
by the overall funnel shape. It is noticeably higher with
westerly winds an low pressure.

Re: England's Death Valley
On 30/03/20 01:36, Phil Hobbs wrote:
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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.


Re: England's Death Valley
On 2020-03-30 04:25, Tom Gardner wrote:
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Was Chebyshev from Southampton? ;)

Cheers

Phil Hobbs

(Opportunities to make numerical analysis jokes don't come round that  
often.)

--  
Dr Philip C D Hobbs
Principal Consultant
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