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|A Few thoughts on the Severn Barrage
If you ever wondered what the severn barrage might consist of then this is a very good read
THE SEVERN BARRAGE DEFINITION STUDY
It was obviously a very costly and recent report, so you can bet your life it would carry a bit of weight in any proposed development.
Reading this and its decription of how the sluices would operate I've tried to sort out what the potential tidal levels would be.
Potential Ranges/ Curves.
PDF page 21 of this report as online - cites potential generating flow patterns with regard to existing HW and LW tidal flows.
This appears to show a LW level held at approx half spring HW - about 6.5m
They also claim the max HW levels would be slightly less than at present - both above and below the barrage, with a few exceptions. HW level would obviously still fluctuate between the neap and spring heights - but the curve between the 'pegged' LW height and HW would be drastically altered.
From their scenario -
0hrs through to +3hrs HW - a HW stand, constant height.
+3hrs through to -4½HW - gradual, constant fall to pegged upstream LW level ( about 6.5m)
-4½hrs through to -3hrs - LW stand - constant height ( at pegged level)
-3hrs through to 0hrs - 'Normal rise' from 'half tide' ( pegged LW ) to HW for the day.
What this is doing essentially - is holding the HW level for three hours - then slowly releasing it at a constant rate right through the LW downstream of the barrage, up to about -4½HW - when generating stops and the LW level is pegged, at about 6.5m, for about 1½hrs - the seaward side 'catching up' on the level about -3hrs HW. Then a normal rise to the HW for the day.
I also read of, ominously, - 'and its eight man made islands and four marinas' - we all know who will be in on the act for the marinas, Mr Crest N!- and wouldn't he like to get his hands on Avonmouth and Portbury site for development !
THE most important issue here would be free, 24hr access - as is the case with Cardiff. Even that has its drawbacks - ie, WHY can vessels not anchor in the enclosed Cardiff Bay ? - We all know why - in deference to the profits of the Marina and Quayside charges.
As soon as you have an 'enclosed area' - little people with pens to push love to start writing 'rules'.
This somehow is the most worrying thing of the whole potential venture - not the wildife, not the generating or the road links - the fact that you are "selling the Estuary" - to private capital, somehow. I don't see it anyones to sell - if anyone owns it, I do, - part share, as a taxpayer.
However, I fear that any private money in this is going to be rubbing its hands with glee that they have every leisure craft north of the barrage over a barrel for access.
The environmental issues, of course, are going to be a major one - but I really doubt it will deter the developers one iota. As with all these things - the government will say ok if they feel there are any political 'brownie points' to make - then will happily pass it off to private development, so it costs them nothing, and whose only concern is profit
Actually - once constructed - I don't think it would particularly put off the wildfowl - after all, some of them are flying half way around the world to come here - I'm pretty sure they can cope with a few altered mudflats and a new concrete cliff to play on !
If this ever goes ahead - it will be nothing short of a dramatic change to this area. It would certainly lose some of its 'unique' quality to the local sailor. Its common to go out all day. even on a holiday and hardly see another boat. The prospect of little tide, hence easier sea conditions, less range, longer HW stand will be either a blessing or a curse.
Should we lose an empty, wild open estuary - and if not, who are we saving it for ?
It would destroy the 'sailing solitude' of the area - a potential max 'artificial' tidal stream of about 1 kt, plus less influence from down channel sea conditions - would tame the waters.
So will it all happen ? - not quite yet, but I reckon its a cert at some point. So best I get all the sailing in I can around here - so I look back on it someday.
Just don't try charging me if I want to sail to Watchet !