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Shannon level reduction

Posted by Tillerman53 
Shannon level reduction
25 November, 2017 18:32
RTE reporting on 6 pm news that weirs on Shannon to be removed, resulting in a 30cm drop in levels below Athlone. Anyone heard about this??

Tm53
Re: Shannon level reduction
25 November, 2017 21:17
I too heard/saw that info on this evenings News. It would seem, judging by the way the film footage showed the weir at Meelick, that the Powers Dat Be have plans to do some remedial work to the weir. WI have already removed trees and widened the waterways in the area upriver from Meelick during the past few weeks. In doing so, on the cut that flows to the left of the main navigation near Lusmagh, they have left an unmarked hazard (ie a very shallow strip that the digger could'nt reach from the land) and unsuspecting boaters could easily run aground.
Re: Shannon level reduction
25 November, 2017 21:43
Just wondering how a 30cm plus drop in the level might affect navigation, and is this to be a permanent or long-term change.
I assume this is a result of the recent flood study involving all stakeholders including WI and IWAI, so how come no word from them??

Tm53
Re: Shannon level reduction
26 November, 2017 10:15
Think the official announcement stated 30-45cm drop in levels......
Definite effect on navigation unless serious deepening work being done also

Rgds
Richard
Re: Shannon level reduction
28 November, 2017 20:00
Kevin Boxer Moran has announced he has a 5 year Plan. He said "he is Trilled to announce a €6 million fund to to remove Meelick Weir and 18 pinch points along the shannon, he stated this will reduce the Shannon level below Athlone by 18 Inches" .. (did you ever hear of such Nonsense)
Look at this You Tube video from a recent Flooding Conference held in Athlone, this statement is at about 10.40 minutes into video [youtu.be]
He also goes on to claim OPW and Waterways Ireland are in agreement with this !!!!!!
Remove the weir, do they Know if you remove the Weir then they will creat a whole set of Problems else where, Firstly the shannon bed will have to be deepened for man many Miles
Re: Shannon level reduction
28 November, 2017 20:01
Kevin Boxer Moran has announced he has a 5 year Plan. He said "he is Trilled to announce a €6 million fund to to remove Meelick Weir and 18 pinch points along the Shannon, he stated this will reduce the Shannon level below Athlone by 18 Inches" .. (did you ever hear of such Nonsense)
Look at this You Tube video from a recent Flooding Conference held in Athlone, this statement is at about 10.40 minutes into video [youtu.be]
He also goes on to claim OPW and Waterways Ireland are in agreement with this !!!!!!
Remove the weir, do they Know if you remove the Weir then they will creat a whole set of Problems else where, Firstly the Shannon bed will have to be deepened for man many Miles
Re: Shannon level reduction
28 November, 2017 20:17
Hi,

I called WI regarding this yesterday and was assured that the navigation would not be affected and would most certainly be maintained. It is hoped to both deepen and widen the navigation channel to compensate for any lowering of the water level. It is still in the early stages of planning and WI are well aware of their responsibilities to maintain the navigation.

Regards,
Natalie,
Hon. Secretary,
Lough Derg Branch.
Re: Shannon level reduction
28 November, 2017 20:28
Good to hear, but it will still put limits on where boats can go around the lake.

Tm53
Re: Shannon level reduction
28 November, 2017 21:43
I found this Link also and seems to contradict the weird idea to remove the Weir dated 1st June 2017
[galwaybayfm.ie]
Re: Shannon level reduction
29 November, 2017 09:42
Greetings,

My contacts in WI say that they and OPW have agreed to examine the possibility of lowering the level all year round by 18 inches which is the height of the weir boards. (Basically they would leave the weir boards off all year round). They say they have identified 16 pinch point that will require excavation to maintain navigation.

This agreement to examine the possibility of lowering the level has been made in the context of the Shannon State Agencies Group. Work is only beginning on this.

They say that when some progress has been made on the investigations, they would like to consult with their stakeholders including the IWAI, HBA etc.

Personally I would be concerned that even if they succeed in lowering the levels to permit adequate draught, they wouldn't significantly increase the flow rates at any of the choke points such as Shannon Grove, Birds/Grants Islands/Shannonbridge etc. Flow rates in those areas are already a bit too high for my liking.

My thought process is that if they lower the level then in order for the same volume of water to go downstream, you have to increase the velocity because the channel cross section area is reduced. That will cause problems for slower vessels and also increase scouring in the channel. Presumably their study will take all these things into account.

Colin
GMY Chang Sha (4.5kts on a good day!)



Edited 1 time(s). Last edit at 29/11/2017 09:43 by Colin Becker.
Re: Shannon level reduction
30 November, 2017 17:37
Does this mean that the Dubs can't pinch any water? Or will they lower the level even further!!!!!!!
Irish management of the fluid world is about on par with Maggie May's gang doing the "Brexit Waltze"!!!

Mac Brandrick
'Marion of Wimborne' (aground off Parker Point!)
Re: Shannon level reduction
30 November, 2017 19:42
Hi Colin
Many thanks for the clarity on this.
Can I ask what you mean when you say "reduce by 18 inches which is the height of the weir boards", what are the weir boards.
Robbie
Re: Shannon level reduction
01 December, 2017 10:33
Hi Robbie,

The main arc of the weir at Meelick has a system where they can raise the level of the crest of the weir by 18" by inserting wooden planks into slots on stanchions along the crest. If you look closely you can see them under the walkway. The idea is that at summer levels when there is very little flow, it raises the water level a bit for safe navigation. When there's lot's of water in the winter they take them off to clear the water away.

Don't have the full story but it seems that when the lock was built, either someone got their levels a bit wrong or more likely, they encountered some hard material in the level upstream that they couldn't shift and so came up with this system to allow summer navigation. At the time there were some very large steamers using that section like the Lady Lansdowne which more or less filled the whole lock so they would have been unhappy if there wasn't enough water.

Colin
Re: Shannon level reduction
01 December, 2017 12:21
Hi Colin
Many thanks you are mind of valuable information, thanks for clarifying this for me.
Regards Robbie
Re: Shannon level reduction
02 December, 2017 15:28
Greetings,

This appeared in yesterday's Offaly Independent.

Seems to somewhat contradict what WI said but maybe it's just a question of emphasis.

Thanks to JD for the clipping.

Colin
GMY Chang Sha

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