Does anyone know how deep the river is or where I might find out?
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Does anyone know how deep the river is or where I might find out?
Good Question!Quote:
Originally Posted by petromax
No idea!!!!!
As the river is 'tidal' the depth will vary with high and low tides.
Not very helpfull, is it ?
phredd
Apparently it has a mean depth of 15m.
Not as deep as you think. I asked a friend who sails on it, and he said forty feet, now I don't know if that is the highest tide or ordinary tide :PDT_Aliboronz_24:
I thought it would be about 80foot deep or more??Quote:
Originally Posted by verdi
And has any relics or anything of value ever been discovered in the mersey?
Didn't someone recently 'walk' across the Mersey at low tide and he was a good 6ft?
Walk across the mersey >>>>>> walk this way >>>>
http://news.bbc.co.uk/1/hi/england/m...de/4785427.stm
Twas in August 2006.
Phredd
Quote:
Originally Posted by petromax
Hello petromax
As with any estuary, the depths vary. Part of the river has been dredged in order to allow liners, etc., to approach the landing stage. Because the depth of the river decreases after Rock Ferry on the Wirral (Cheshire) side, it was necessary to establish the Manchester Ship Canal so that larger vessels could sail on to Ellesmere Port and Manchester and unload their goods.
Chris
Quote:
Originally Posted by ChrisGeorge
I imagine the QE2 has more than a 15m draught (?) and she has been at anchor for more than two tides in midstream.
The ships using the canal were obviously nowhere near as big a displacement so the canal and that bit of river needn'y be so deep. I think I read somewhere else here that the river channel changed course onto the Wirral side as the stream 'stuck' to the flow of the canal.
How deep are the tunnels? Maybe that would give some idea
The QEII has a Draught of 9.945 meters
So, if the mean is 15m. What is the maximum? Is there a readily avaiable chart?Quote:
Originally Posted by chrismarsden
A website www.merseybasin.org.uk, has a PDF document on it stating that the river has a depth of up to 30m and a tidal range of 10m
Well done sherlock :)
It seems to me that, with global sea levels set to rise, the threat is not so much the River becoming too shallow but rather sea levels becoming so high that sea walls are overtopped.Quote:
Originally Posted by petromax
The two most scientifically likely figures for sea level rise in the next 50 years are about one metre (if the West Antarctic ice sheet retains structural integrity) or approaching 7 metres if it doesn't!
My guess if that a 7 metre rise in sea level would see Pier Head and the new dockside developments inundated? However, there is possibly some mitigating effect in that if sea level does rise a lot then the tidal range at Liverpool might be somewhat reduced as the geography changes.
A Bootle-aligned Mersey Barrage would seem a possible solution, but it then raises the problem of possible in-flooding via the Harrison Drive and Bidston area. Thus returning Wallasey to it's one-time reputation of being an island.
I must get hold of some good ordnance survey maps with contours to satisfy my curiosity. But given that Princes Dock was operated just a few years ago without impounding water, then the whole area must be pretty low-lying.
Think it can't happen? That's exactly what they thought in New Orleans. And of course, if Liverpool is in trouble then London is in bigger trouble. Maybe we will get to see Parliament moved to Bradford yet :)
I believe Strand Street is about 6.5m AOD (above ordnance datum), so 7m plus the tide....I wonder where that contour would be? Liverpool waterfront -a new Venice and no docks?Quote:
Originally Posted by HollyBlack
Congratulations to ChrisO. Sherlock indeed - I looked at that website which is extensive and couldn't find any mention of river depth!
Looking at Howie's post it seems that 7m would take 1,750 years! (at current rate of 4mm per year)Quote:
Originally Posted by HollyBlack
http://www.pol.ac.uk/ntslf/tides/?port=0234
Anybody intrested in tide predictions this is a good site for them
That merseybasin site has an link on the left for 'information'. Click that and the first document link is called 'River Mersey 6 minute expert' That's the one your looking for
Quote:
Originally Posted by petromax
Thank you, that great information.Quote:
Originally Posted by petromax
AOD is mean sea level at the sea observatory in Cornwall. If we assume mean sea level is the same in Liverpool and subtract half the highest common tidal range (ie 4.5 metre) that means The Strand is frequently only 2m above the water in the River.
All agree that the present rate of sea level increase will itself increase but there is wide disagreement about how much. Only the most optimistic estimates have it rising by 0.5m in the next 100 years.
Until recent years it was thought that the West Antarctic ice sheet (WAIS) will stay intact and fail by melting - this would take hundred if not thousands of years because there is so much energy in the latent heat of melting. However, a recent Scientific American article raised the spectre that research suggests it could fail not by melting but by avalanching. Right now the probability looks maybe 50/50 over 50 years. This would move most of the ice off the land so it becomes floating. Indeed there is a positive feedback effect in that a lot of it sits on land today but if sea levels rise it would be floating.
http://www.sciam.com/article.cfm?id=...iet-ice&page=3
If the WAIS does fail (lose structural integrity) then sea levels would rise somewhere between 4.5 and 7 metres causing major worldwide catastrophe since avalanches move with a huge average speed so the sea level rise would occur over a period of just a mere few days. Thankfully, the EAST Antarctic ice sheet is not even slightly threatened - if that went into the sea (won't happen) the effects would be cataclysmic rather than catastrophic (60 metres or so?).
The good news in this is that scientific research will prevent us from being blindsided, we will see this event coming before it happens. Hopefully designers of the new tower blocks being built on the Riverside have learned their lesson from New Orleans and will not be so stupid as to put standby generators with fuel at or below ground level.
OUCH!Quote:
Originally Posted by HollyBlack
It's to be hoped that taller buildings (particularly residential towers) will mean denser cities that will reduce our carbon emissions (by reduced travel to work) and that any new buildings follow a bit of the Sandcastle lead (it's apparently cooled using Mersey water and is an early 'green' building))
There is some interesting information on the Research Centre for Marine Sciences and Climate Change website here.
See also the Proudman Oceanographic Laboratory website here.
Just came across this article - it's worth a read.
Gregory, J (2008) 'Sea Level Rise: What makes prediction so difficult?' NERC - Planet Earth: Spring 2008.
Yep. It varies depending on where in the river. The Sloyne is a natural deep channel at Tranmere, hence the tanker berth - the liners would anchor there. The Sloyne is 60 foot and 90 foot at a high tide (32 foot tides).Quote:
Originally Posted by ChrisO
There is a shoal just off the Pier Head which means liners can't sail at low tide. The depth at the Pier Head is deep enough, about 35 to 40 foot deep at low tide and 30 foot deeper at high. Modern liners have less depth that older ships, They are wider and flat bottomed.
The Crosby Channel has under water training walls that direct current up the channel, which keep it deep and clear. The current goes straight to the Wirral side of the river and down the dredged channel to the Manchester ship canal, keeping this side clear.
When the canal was built there was concern that currents would be affected. They were. The strong current was diverted mainly over to the Wirral side and sanded up the south end docks which required more expensive dredging. Only so much water enters the river on the rising tide and deeper channels will take most of the current (water), as water takes the line of least resistance.
The Garston Chanel is a sort of naturally deeper channel - which requires dredging to be operable by ocean going ships.
The Manchester Ship canal's first design was training walls from Runcorn to the Garston Channel. They thought the city would object. If the city had not objected the Liverpool side of the river would have been deeper with naturally water cut channels.
A barrage from New Brighton to Bootle would make it all academic and all would be deep once dredged inside the barrier, as sand, or little sand, would not be washed into the river by the strong currents.
The same sand is washed in and out from Liverpool Bay. If most of this sand is removed (big task, but not impossible), instead of removing and dumping sand back into the bay, the river would remain very deep.
New York Harbour is only about 15 foot deep on average, with a coiuple of foot tide. Dredged channels were cut for big liners.
Near the ocean the bay's depth was deepened by explosives by the US Army Corps of Engineers to accommodate large container ships. If necessary that could happen at Liverpool.
Liverpool Docks have the advantage of "impounding" - deepening the docks by pumping water from the river at lower high tides. Expensive in fuel to do this. This saved the expense of deepening some docks. Ships would enter the river locks and raised up to the dock's "impounded" depths to accommodate their deep draughts. Fast pumps would fill the locks quickly to get a number of large vessels in on the high tide.
The sea level would have to rise by many, many feet to affect Liverpool. Many feet in sea level rise would be catastrophic world-wide. Liverpool is pretty safe. London would mainly disappear.
Gives depths in metres at the lowest low tide - 1972. It has risen a few inches since.
http://myweb.tiscali.co.uk/watercity/Map-Lpool-1972.jpg
Aha!
Hi,
I don't know about relic's, but the bottom of the river from the Pierhead up to garston will be littered with crockery, glasses, cutlery and many cooking untensils from "The Royal Iris".
In the early seventies I attended a few events on "The Royal Iris" river cruise's and watched their kitchen staff who I guess didn't like washing up so chucked it over the side of the boat.
Makes me think if they did it how many other kitchen staff from other ships and boats had the same idea!
The dredgers end up picking that up.Quote:
Originally Posted by beanie