Dublin taking water from the Shannon ?

chillin117

If the proposed system was up and running 100%, Would it have any impact on the current flooding down Shannon way ?

farawaygrass

chillin117 wrote: »

If the proposed system was up and running 100%, Would it have any impact on the current flooding down Shannon way ?

I'm sure dublin have enough water themselves at the moment and only need the water from the Shannon in dryer times of the year. People In the Shannon area are mostly against it so that's says it all I think. They say it would have a bad effect on fishing, tourism etc

Neworder79

chillin117 wrote: »

If the proposed system was up and running 100%, Would it have any impact on the current flooding down Shannon way ?

No. The ESB expert interviewed on Newstalk this week said the proposed water intake for the Dublin was about 1/100 th the current flow and would make no difference.

The current proposal is just a pipe without a storage resivor.

pedigree 6

chillin117 wrote: »

If the proposed system was up and running 100%, Would it have any impact on the current flooding down Shannon way ?

I think the population of china taking the water for drinking wouldn't have an impact on the current flooding.

M.T. Cranium

Too late now obviously, but in these situations I wonder if there's any economic basis for a storage reservoir for overflow, it would probably need to be adjacent to Lough Derg and would be a fairly massive engineering project, but suppose you had an extension of Lough Derg behind controlled barriers and then could distribute water from that second lake during dry weather. I suppose nobody would want to see a higher level for Lough Derg which is the easier way of doing the same thing. What I don't have an easy picture for is this -- any land adjacent to Lough Derg that could be transformed into said reservoir without harming either economic or cultural resources? Or even higher up the river (at some point you go too high up and lose the full flood control potential of such a scheme).

As these events seem to be about six years apart, maybe something to think about between now and 2020-21? Smaller versions might involve large outlet channels to more distant reservoirs in more expendable areas. Or you could just have outlet channels into pipes that took some route to the sea (either through controlled pumping or underground gravity-based flow) and dumped the excess water into the Atlantic if this is a recurring problem.

I assume Lough Derg is a natural feature with some control of water levels now. What about a second lake upstream somewhere between Athlone and Portumna (sure somebody will point out there now is one)? Any territory in there that seems expendable to the greater good? Has this been discussed already?

M.T. Cranium

So I took a quick look at the terrain around Lough Derg, noting there is a feature on the northwest shore that appears to be a peat bog or dried up version of same, with a slight embankment keeping Lough Derg from spilling into it (also it has a slightly higher elevation). So if it's about 1% the size of the lake but was dredged to a depth of 50 metres which is twice the average depth of the lake, it would represent a 2% extension of the lake. Water could be allowed into that as needed to maintain the outflow at the south end. Just one no doubt impractical idea among many I could offer.

I also noticed that while the land is fairly flat all the way west to Galway from the river, it generally rises 40-50 metres before falling back to sea level going west, so any plan to ship water west would require either tunnels or locks. Maybe a larger pleasure boating canal might help in both tourism and water management. A storage lake could be included in that concept somewhere close to the outflow from the Shannon (before the land starts to rise very much).

Dazzo

One of the big problems with the lower shannon is that it is tidal all the way to limerick city. High tide in limerick city would be an important factor in the e.s.b determining how much water to let through both the original shannon route and the headrace to ardnacrusha hydro. Both controlled at the same weir. Flooding up-wier or flooding down-weir? fecked if they do and fecked if they don't..

Dazzo

its also worth noting that the shannoon falls something like 100ft from killoloe to limerick city. (open to correction) A distance of maybe 13/15 miles. Before the building of Ardnacrusha power ststion by siemens there was a renowned local beauty spot in Doonas, a townland of Clonlara in Co. Clare where the shannon dropped 40ft in a series of rapids. What would the shannon have done with similar rainfall pre-ardnacrusha?

Chavways

What I can't understand is the ESB not releasing water from the head race in Ardnacrusha and also down the old River Shannon 3 or 4 weeks ago.

Does it really matter if Lough Derg drops by a foot or so for a few weeks if it would have saved all of this flooding? I do a lot of kayaking on the lower Shannon and the water level was the same as the Summer flow of 10 cumecs up until around half way through November. It was only when the rain really started to hit did the ESB start releasing huge excesses of water resulting in the situation now where there are 440 cumecs going down the old route(currently flooding a lot of UL, Clonlara and a lot of other places).

They also have the 400 cumecs coming down through Ardnacrusha which coincided with the high tides last night and flooded some suburbs around Limerick City.

I know its impossible to predict the weather in this country but personally I think it's inexcusable that this level of flooding is happening again so soon after the last time and nothing has changed. It would be something if it was all caused naturally and there was nothing that could be done but the ESB have total control over how much water is in the Shannon and I imagine they have more weather forecasting information available to them that anyone else, so why has nothing changed?

I don't understand why it isn't just a case of "Its getting late in October. Ireland is always wet in Winter. Lets steadily drain the lake over the next few weeks because more than likely enough rain is going to arrive in the coming months that will fill it back up again and there will be no flooding as a result." Am I thinking of this too simplistically?

Victor

Dazzo wrote: »

its also worth noting that the shannoon falls something like 100ft from killoloe to limerick city. (open to correction) A distance of maybe 13/15 miles. Before the building of Ardnacrusha power ststion by siemens there was a renowned local beauty spot in Doonas, a townland of Clonlara in Co. Clare where the shannon dropped 40ft in a series of rapids. What would the shannon have done with similar rainfall pre-ardnacrusha?

Flooding used to be worse before the Ardnacrusha project.

Chavways wrote: »

the ESB have total control over how much water is in the Shannon

Only on the outflow, not the inflow nor the speed of getting from the top of the river to the bottom.

I imagine they have more weather forecasting information available to them that anyone else

Are you saying they have a crystal ball that meteorologists don't have?

Chavways

Victor wrote: »

Flooding used to be worse before the Ardnacrusha project.

Only on the outflow, not the inflow nor the speed of getting from the top of the river to the bottom.

Are you saying they have a crystal ball that meteorologists don't have?

Nope but I imagine they have all of the Met Eireann data available to them or are at least are in constant contact with Met Eireann.

I just don't understand the difficulty in regulating the flow during the Winter when the water levels are beginning to increase. I know they try to maximise the water flowing through Ardnacrusha so they minimise the flow going through the old river system to do this but everyone knows Ireland is wet in Winter and the last few years have been very wet. Would it not be a fair idea to increment the release of water through the old Shannon as we transition from Autumn to Winter? Lough Derg and the levels in the water bodies above it may decrease slightly but they will increase again when the inevitable rain comes. But instead of all of the rivers and lake backing up and flooding, volume will have been made in the water ways to at least compensate for some of the rain leading to less flooding.

Victor

Chavways wrote: »

Nope but I imagine they have all of the Met Eireann data available to them or are at least are in constant contact with Met Eireann.

I just don't understand the difficulty in regulating the flow during the Winter when the water levels are beginning to increase. I know they try to maximise the water flowing through Ardnacrusha so they minimise the flow going through the old river system to do this but everyone knows Ireland is wet in Winter and the last few years have been very wet. Would it not be a fair idea to increment the release of water through the old Shannon as we transition from Autumn to Winter? Lough Derg and the levels in the water bodies above it may decrease slightly but they will increase again when the inevitable rain comes. But instead of all of the rivers and lake backing up and flooding, volume will have been made in the water ways to at least compensate for some of the rain leading to less flooding.

How does letting water through Ardnacrusha or Parteen Weir change flooding in Carrick-on-Shannon or Athlone, both of which are up-river?

The problem is the river is essentially flat for 200km and is surrounded by flat land. That gobsh!tes looking for handouts carrying on farming, build their houses and businesses or let people build in the flood plain is not the fault of the ESB. This land floods. It has always flooded. It would be cheaper to buy the land and leave it fallow than to drain it.

Location Height (feet) Height (metres) Difference (metres) Distance (metres) Slope (%) Distance for the river to drop 1 metre (metres)
Lough Allen exit 164 50
12 82,000 0.014% 6,899
Lough Ree exit 125 38
5 102,000 0.005% 20,916
Lough Derg exit 109 33
33 20,000 0.166% 602
Limerick 0 0

Chavways

Victor wrote: »

How does letting water through Ardnacrusha or Parteen Weir change flooding in Carrick-on-Shannon or Athlone, both of which are up-river?

The problem is the river is essentially flat for 200km and is surrounded by flat land. That gobsh!tes looking for handouts carrying on farming, build their houses and businesses or let people build in the flood plain is not the fault of the ESB. This land floods. It has always flooded. It would be cheaper to buy the land and leave it fallow than to drain it.

I agree that building on flood plains has definitely made the problem worse. If the river flooded on open fields, there would be little issue. Farmers land and livestock would be affected but the number of homes and businesses affected would fall hugely.

You can't deny that a different plan of action with the release from Parteen Weir through Castleconnell would help the towns and areas downstream and reduce the effect of floods if we get similar rainfall to the last few weeks.

I know the flow rate is very slow above the weir because of the small height difference but any kind of increased release for the weeks before a big rain fall would help when the rain does come and **** starts to hit the fan!

amen

I must be doing something wrong but according to new reports the ESB are releasing water at a rate of 350,000 cumecs.

As there 86,400 seconds in a day that gives a water release of 30,240,000,000 every day.

As Lough Derg has a volume of say 0.9km3 that means the ESB is currently releasing 33 times the volume of Lough Derg every day.

Assuming I didn't make a mistake (think I must have) then emptying Lough Derg during before winter starts would have no impact.

Victor

amen wrote: »

I must be doing something wrong but according to new reports the ESB are releasing water at a rate of 350,000 cumecs.

Source? Might that be litres or per hour or day?

NiallBoo

The scale of all of this means that there is no engineering solution.

the pipe to Dublin will be too small to have a noticeable effect, even at normal flows. The amount that the ESB can alter the flow/discharge early is nothing compared to the flow and any reservoir you could build would fill up so quickly that it would be pointless. Even taken all together all these wouldn't amount to a tin of beans and would be crushing expensive. Dredging will cause increased flow and more extreme flooding downstream.

The flow into lough derg recently has been 600-800 cumecs(cubic metres per second). With that amount of water coming through the river there's simply nothing you can do to stop flooding.

NiallBoo

Victor wrote: »

Source? Might that be litres or per hour or day?

They mean 350 cumecs - but that's going through one channel, there'll be at least as much in the other one.

It also ignores that the ESB aren't able to completely empty lough derg and only have an operating range of something like 40-50 cm in lake height.

Although they messed up they maths, the point they were making is valid.

kevin7

amen wrote: »

I must be doing something wrong but according to new reports the ESB are releasing water at a rate of 350,000 cumecs.

No, your error is the flow rate right now is 1000 times less than what you say.

The rate is about 400 cumecs now for the old river channel. Up from its normal controlled year round rate of 10 cumecs so thats quite a difference.

Just to do the calculations on emptying Lough Derg...just for "fun"...

At a flow of 400 cumecs, in one day thats 34,560,000 cubic metres. If the volume of Lough Derg is 0.9 km3 thats 729,000,000 cubic metres...

So just over 21 days to entirely empty the lake!

amen

kevin7 wrote: »

No, your error is the flow rate right now is 1000 times less than what you say.

Thanks. The numbers didn't really pass a sniff test

NiallBoo

kevin7 wrote: »

At a flow of 400 cumecs, in one day thats 34,560,000 cubic metres. If the volume of Lough Derg is 0.9 km3 thats 729,000,000 cubic metres...

So just over 21 days to entirely empty the lake!

Interesting question, something else factor in would be that in a static lake the flow rate out would constantly diminish.

Meteorite58

I feel for those whose houses and lands are flooded. But flooding is not going to go to go away so easily. I think a fresh approach is needed to the kinds of houses and farm buildings that are built in these areas prone to flood. The houses need to be built flood proof and fodder needs to be stored high enough off the ground. Expensive probably but what choice is there. I think as farming gets more intensive and the land becomes more drained then the bigger rivers are going to flood more. Any new houses /apartment blocks being built in the future need not flood. May need to demolish some existing houses and raise them up or relocate.

littlema

Meteroite58.......lovely looking houses and a great idea for the young, but what happens when you cannot climb the stairs anymore or you have a wheelchair resident to factor in!! All houses now being built have to have the ability to be converted for someone with a disability to access and avail of all facilities therein.

Schadenfreudia

I guess I wouldn't be the first Dub to note the irony of the whining in some parts of the West about Dublin taking Shannon water even as they are being flooded more year after year? :rolleyes:

Gael23

Why cant the Government stop the ESB from increasing the flow?

testicle

Gael23 wrote: »

Why cant the Government stop the ESB from increasing the flow?

Do you know why the ESB are increasing the flow?

Odelay

ESB have a legal obigation to keep a certain water level on Lough Derg at a certain leval. Also if they reduced the flow it would back up water and increase flodding up river like Athlone. It is a good question you asked but not so simple to answer.

longgonesilver

Schadenfreudia wrote: »

I guess I wouldn't be the first Dub to note the irony of the whining in some parts of the West about Dublin taking Shannon water even as they are being flooded more year after year? :rolleyes:

Gael23 wrote: »

Why cant the Government stop the ESB from increasing the flow?

Victor wrote: »

How does letting water through Ardnacrusha or Parteen Weir change flooding in Carrick-on-Shannon or Athlone, both of which are up-river?

The problem is the river is essentially flat for 200km and is surrounded by flat land. That gobsh!tes looking for handouts carrying on farming, build their houses and businesses or let people build in the flood plain is not the fault of the ESB. This land floods. It has always flooded. It would be cheaper to buy the land and leave it fallow than to drain it.

Location Height (feet) Height (metres) Difference (metres) Distance (metres) Slope (%) Distance for the river to drop 1 metre (metres)
Lough Allen exit 164 50
12 82,000 0.014% 6,899
Lough Ree exit 125 38
5 102,000 0.005% 20,916
Lough Derg exit 109 33
33 20,000 0.166% 602
Limerick 0 0

You are starting to come up with a solution here.;)

Close Parteen weir and let the water build up, in fact build some higher dams and flood the whole area permanently, Shift the gobsh!te farmers and get rid of their co2 belching cattle, and the water will flow all by itself to Dublin, and use the rest to generate more electricity in ArdnaCrusha to reduce carbon emissions.

prunudo

littlema wrote: »

Meteroite58.......lovely looking houses and a great idea for the young, but what happens when you cannot climb the stairs anymore or you have a wheelchair resident to factor in!! All houses now being built have to have the ability to be converted for someone with a disability to access and avail of all facilities therein.

All well and good until you build houses on flood plains and insist on floor level being 150mm above ground level. Ramps can be used to get wheelchairs into higher house. One thing is for sure we can't keep allowing houses to be built and then flooded every 5 years.
There needs to be a total rethink about how planning is approached. Look at the like of the Netherlands where they build below sea level by using good engineering and proper planning.
Sorry for going off topic.

Stealthfins

The only problem with planning and engineering in this country is,you still have the gombeen culture of employing the wrong people,who they like rather than who they need.

Maybe they should employ engineers from Holland who are familiar with waterways.

chillin117

kevin7 wrote: »

No, your error is the flow rate right now is 1000 times less than what you say.

The rate is about 400 cumecs now for the old river channel. Up from its normal controlled year round rate of 10 cumecs so thats quite a difference.

Just to do the calculations on emptying Lough Derg...just for "fun"...

At a flow of 400 cumecs, in one day thats 34,560,000 cubic metres. If the volume of Lough Derg is 0.9 km3 thats 729,000,000 cubic metres...

So just over 21 days to entirely empty the lake!

Good Work ! A working brain is a marvel

Chavways

What about tilting the country so it drains faster?