Flooding – dam incompetence

Impetus

I was in Cork city this morning around noon. The tide was out, and there was about 1m of unused capacity in the river system – to dump additional flood waters in anticipation of next week’s rain, without a risk of flooding. In times of heavy rainfall, reservoir water should be dumped at maximum safe flow levels (ie to prevent future flooding), making use of all exit points to the sea, to provide buffer space to hold future rainfall during high tides. The powers that be have not learned a lesson from November 2009.

http://www.boards.ie/vbulletin/showthread.php?t=2055751080

I attempted to check river levels at https://waterlevel.ie and found that the nearest river level gauge on the River Lee was in Ballymakera, some 55 km upstream of Cork city. Ballymakera has a few hundred people at most. The greater Cork area has over 300’000. And no real-time river level reporting on the internet in Cork city.

It is a simple matter to put real-time water level gauges at high risk points in low lying areas, available on the internet, whose readings can be used to guide the amount of water released from upstream hydro power stations. The issue of maximising power generation should be thrown out the window in the circumstances. One wind turbine would produce more power than the River Lee could.

The incompetence of the people responsible is alarming.

Carawaystick

How do you know the esb don't have a river level measure on the Lee? I'd imagine there would have been a measure at the power station on the right bank near the Marina.

Impetus

Carawaystick wrote: »

How do you know the esb don't have a river level measure on the Lee? I'd imagine there would have been a measure at the power station on the right bank near the Marina.

The Marina is not the weakest point in the system. The weakest points in the system are along the river near the bridges in the city centre. www.waterlevel.ie have no gauges on the River Lee anywhere in Cork city. I was in town again today, and the tide was low, and the river had again about a meter to spare below bridge critical level.

If these data on levels were collected and fed back to the sluice gate control room at Inniscarra (or more likely Ardnacrusha from where the Iniscarra dams are remotely controlled), the water could be dumped at maximum safe velocity to take advantage of low tide periods, and empty the reservoirs, in anticipation of further rainfall. Incompetence is causing all this flooding and flood risk. Not mother nature!

Markcheese

I passed the upper lee by the gearagh about 3 weeks ago.. and was surprised at how low the water was ... i've no idea if the esb watching long range forecasts though...i'm assuming the esb know exactly how long water released from inniscarra takes to clear the city ... but wether they can increase flow to coincide with low tide ...
I'm pretty sure the lee has been bank full... from lee fields back to inniscarra for the last couple of weeks though ..

Impetus

Markcheese wrote: »

I passed the upper lee by the gearagh about 3 weeks ago.. and was surprised at how low the water was ... i've no idea if the esb watching long range forecasts though...i'm assuming the esb know exactly how long water released from inniscarra takes to clear the city ... but wether they can increase flow to coincide with low tide ...
I'm pretty sure the lee has been bank full... from lee fields back to inniscarra for the last couple of weeks though ..

I have no doubt that the release of water is controllable (electro-mechanically) and remotely. In the 2009 flooding, media reports said it was done remotely from Ardnacrusha. It seems to me that there is a culture/instruction within ESB to maximise the use of the water for generation purposes. Instead of proactively dumping water during periods of risk, making maximum use of low tides. To do so you need to be able to monitor the river height in the city centre at the most critical flood risk points, and slowly increase the sluice gate opening, until you are getting close to safe high water mark at these critical points. If this happens you reduce the flow slightly so it continues to maximise the discharge rate, while at the same time not flooding the place.

The entire process should be automatically monitored in real time. However there is nothing to stop one from doing the job manually - even if it means putting observers watching the river in the city at critical times, who can call the control centre on a mobile phone and give the person in the control room feedback.

I am sure ESB is paying met.ie for accurate rainfall forecasts. They are also available here:

http://www.wunderground.com/cgi-bin/findweather/getForecast?query=Cork%2C+Ireland

You click on customise and check the precipitation accum. total, and hourly liquid precipitation boxes and it shows up as green on the chart on an hour by hour basis.

You can even get detailed forecasts further upstream in the Lee - eg
http://www.wunderground.com/q/locid:EIXX3370;loctype:1

sheesh

I wonder if a level measure is required. as it is tidal surely it is predictable also the 1 meter of capacity you say was there the level at the time would be set by the sea level.
so they could have been draining the reservoir and it would have been the same level as the level of the water would have been set by the level of the sea.

mickdw

Impetus wrote: »

I have no doubt that the release of water is controllable (electro-mechanically) and remotely. In the 2009 flooding, media reports said it was done remotely from Ardnacrusha. It seems to me that there is a culture/instruction within ESB to maximise the use of the water for generation purposes. Instead of proactively dumping water during periods of risk, making maximum use of low tides. To do so you need to be able to monitor the river height in the city centre at the most critical flood risk points, and slowly increase the sluice gate opening, until you are getting close to safe high water mark at these critical points. If this happens you reduce the flow slightly so it continues to maximise the discharge rate, while at the same time not flooding the place.

The entire process should be automatically monitored in real time. However there is nothing to stop one from doing the job manually - even if it means putting observers watching the river in the city at critical times, who can call the control centre on a mobile phone and give the person in the control room feedback.

I am sure ESB is paying met.ie for accurate rainfall forecasts. They are also available here:

http://www.wunderground.com/cgi-bin/findweather/getForecast?query=Cork%2C+Ireland

You click on customise and check the precipitation accum. total, and hourly liquid precipitation boxes and it shows up as green on the chart on an hour by hour basis.

You can even get detailed forecasts further upstream in the Lee - eg
http://www.wunderground.com/q/locid:EIXX3370;loctype:1

I like the thread title!
Are you seriously saying that the esb actually retain full reservoirs even when unprecedented rainfall is expected and they don't take the opportunity to let water off when the rivers are low.
If that is the case, it's shocking and they should be held liable if clear opportunity existed to release water.

TheChizler

sheesh wrote: »

I wonder if a level measure is required. as it is tidal surely it is predictable also the 1 meter of capacity you say was there the level at the time would be set by the sea level.
so they could have been draining the reservoir and it would have been the same level as the level of the water would have been set by the level of the sea.

Good point, the height of the river is mainly a function of the riverbed level, the tide, and what's let through Inniscarra, I doubt the handful of tributaries between the dam and the city make much of a difference.

Also the ESB more than likely have their own private level measures which aren't on that website.

Edit: I stand corrected, tributaries make up 30% of the catchment area downstream.

http://www.lee.cfram.com/reservoirs.html

Impetus

sheesh wrote: »

I wonder if a level measure is required. as it is tidal surely it is predictable also the 1 meter of capacity you say was there the level at the time would be set by the sea level.
so they could have been draining the reservoir and it would have been the same level as the level of the water would have been set by the level of the sea.

It is not just the river Lee flow rate variables. You also have the River Bride, which is draining a different catchment area. Fine the river level as far as tidality is measurable based on tide tables. But it seems to me that there is no excuse for not having accurate real-time gauges at low city centre points to monitor the overall real river height. The River Bride is not restrained by the dams.

Impetus

TheChizler wrote: »

Good point, the height of the river is mainly a function of the riverbed level, the tide, and what's let through Inniscarra, I doubt the handful of tributaries between the dam and the city make much of a difference.

Also the ESB more than likely have their own private level measures which aren't on that website.

Why do we have an expensive open, state paid for https://waterlevel.ie website? Which completely ignores river levels in the second city? Surely incompetent. The ESB may have their own facilities - but this smells like Oirish wasteful duplication

Impetus

mickdw wrote: »

I like the thread title!
Are you seriously saying that the esb actually retain full reservoirs even when unprecedented rainfall is expected and they don't take the opportunity to let water off when the rivers are low.
If that is the case, it's shocking and they should be held liable if clear opportunity existed to release water.

I am saying that the ESB should go overboard to empty the reservoir as fast as possible during high flood risk times such as we have at the moment, making maximum use of low tides. You can't predict future random rainfall precisely (which patch of ground the water will fall on and into which river that might flow). You just have to leave "the bath as empty as possible" so it can retain unexpected and expected precipitation.

TheChizler

Impetus wrote: »

Why do we have an expensive open, state paid for https://waterlevel.ie website? Which completely ignores river levels in the second city? Surely incompetent. The ESB may have their own facilities - but this smells like Oirish wasteful duplication

Who's incompetent in this scenario? Just because levels for the Lee aren't reported on that site doesn't mean the ESB aren't fully informed.

Just on your OP; while the tide is out maybe the dam is letting out water at the max it can without causing flooding in communities closer to it, the level up here could be borderline flooding but look fine in the city when the tide is out.

mickdw

Impetus wrote: »

I am saying that the ESB should go overboard to empty the reservoir as fast as possible during high flood risk times such as we have at the moment, making maximum use of low tides. You can't predict future random rainfall precisely (which patch of ground the water will fall on and into which river that might flow). You just have to leave "the bath as empty as possible" so it can retain unexpected and expected precipitation.

Yes I understand you. Do they not do this though. It's downright irresponsible if they don't.

Stinicker

Ardancrusha should be demolished and let the Shannon drain again instead of flooding half the country. The economic benefits or getting rid of Ardnacrusha far outweigh the minuscule amount of Electricity it generates now.

Markcheese

Impetus wrote:

It is not just the river Lee flow rate variables. You also have the River Bride, which is draining a different catchment area. Fine the river level as far as tidality is measurable based on tide tables. But it seems to me that there is no excuse for not having accurate real-time gauges at low city centre points to monitor the overall real river height. The River Bride is not restrained by the dams.

The bride valley is a totally different shape to the lee valley . Its mainly wide and flat (from crookstown to the lee anyway, so its flooding and the effect is very different ...

fits

Stinicker wrote: »

Ardancrusha should be demolished and let the Shannon drain again instead of flooding half the country. The economic benefits or getting rid of Ardnacrusha far outweigh the minuscule amount of Electricity it generates now.

It generates 2% of our total powee requirements. Thats not miniscule at all.

Markcheese

Stinicker wrote:

Ardancrusha should be demolished and let the Shannon drain again instead of flooding half the country. The economic benefits or getting rid of Ardnacrusha far outweigh the minuscule amount of Electricity it generates now.

I cant say that I know much about the shannon system - but wouldnt there be a very high risk of increased flooding below ardnacrusha if you got rid of it .

Capt'n Midnight

Tide predictions for Cork
http://www.ukho.gov.uk/EASYTIDE/EasyTide/ShowPrediction.aspx?PortID=0753&PredictionLength=2

Difference high and low tide is six hours.
There is the slight problem that water takes time to flow down stream.
How fast does the river flow ?
If it was 10Km/hr then releasing water 55Km upstream would mean you'd have to do it at high tide to hope the pulse reached there at low tide. And if the speed changes as it would do if there was more water might change the arrival time.

IIRC on the Shannon it takes days for the water to flow down.

Impetus

UCC has a river water height monitoring station at The Maltings*. This is on the net at:

http://77.74.50.157/cfw/

"It is our ambition to expand the system and implement a relatively dense network of up to 15 monitoring stations in the Lee and sub catchments around Cork. This roll-out of new monitoring stations will rely on sponsorship of new stations. However, with commitments of support from hardware suppliers, and ongoing support from IDS Monitoring and Partners the cost of new stations for this project is significantly reduced. To find out more about sponsorship of a new station or maintaining an existing station please click here. "

"What the numbers mean...

The station at the Lee Maltings is located near the Mercy Hospital. The water level values on this station are based on a local datum. If water Levels at this station exceeds 4.8m it is possible that some locations (e.g Probys Quay) will see start some minor flooding. If the water exceeds 4.9m it is likely that the flood will spread and threaten some buildings. A reading of above 5.0 m at this station is usually associated with more significant flooding at the eastern end of Oliver Plunket Street and may spread to other areas. By way of reference the peak water level associated with major flooding on Feb 4th was 5.285m and on Feb 3rd was 5.237m.

The Station at the Angler's Rest is located downstream of where the river Shournagh joins the Lee. Water Levels here are greatly influenced by discharge rates from Inniscarra Dam. Again, this station uses a local datum. A water level of 2.5m at this station is associated with flows in excess of 150m3/s and normally involves flooding of the Lee fields. High flows at this site influence high water in the downstream tidal zone."

*map: https://www.google.com/maps/@51.8984493,-8.4839934,18z

Impetus

Capt'n Midnight wrote: »

Tide predictions for Cork
http://www.ukho.gov.uk/EASYTIDE/EasyTide/ShowPrediction.aspx?PortID=0753&PredictionLength=2

Difference high and low tide is six hours.
There is the slight problem that water takes time to flow down stream.
How fast does the river flow ?
If it was 10Km/hr then releasing water 55Km upstream would mean you'd have to do it at high tide to hope the pulse reached there at low tide. And if the speed changes as it would do if there was more water might change the arrival time.

IIRC on the Shannon it takes days for the water to flow down.

You are only talking about a short distance between the hydro dams and the city centre here. Under 10km. With a few monitoring stations passing data back in real time to the control system for the sluices, it is similar to the issue of maintaining a dynamic green wave of traffic lights along a boulevard, to keep heavy traffic flowing to maximize the carrying capacity of the urban road system. (Yet another issue beyond the capability of Irish local authorities).

There are two main issues:

1) Dredging and clearing away objects that block the river flow into the sea and
2) Using real-time data on river levels collected at critical points along its path, to control the movement of the sluice gates on the dams.

When I was young, I often saw several dredging boats working along the River Lee to clear the river basin of mud. I have never seen a single dredger of late.

If you missed the radio interview on RTE Drivetime with the lady in Clare who was involved with getting a low loader (truck) to evacuate her mother who was wheelchair bound from a house which was under flood attack, you might want to listen to it. The non-wheelchair bound members of the household used a boat to escape:

http://www.rte.ie/radio1/drivetime/programmes/2015/1214/753512-drivetime-monday-14-december-2015/?clipid=2054873#2054873

Click on the item on Clonlara, CE

Impetus

Markcheese wrote: »

I cant say that I know much about the shannon system - but wouldnt there be a very high risk of increased flooding below ardnacrusha if you got rid of it .

Please listen to the interview at the bottom of http://www.boards.ie/vbulletin/showpost.php?p=98118748&postcount=20 if you haven't already heard it on RTE R1.

Markcheese

Port of cork regularly dredge down river of the bridges ... methil marra remove shopping trolleys ect and other junk from both channels reasonably frequently ... dunno if theres much point in dredging the river in the city itself ...

Impetus

fits wrote: »

It generates 2% of our total powee requirements. Thats not miniscule at all.

It seems to me to generate 27 MW, which is about 0.45% of the total demand - based on 6 GW.

https://www.esb.ie/main/about-esb/power-stations-pdfs/ESB_LEE_HYDRO_STATIONS.pdf?v=20140801

It is a matter of priority - do you want the city to be flooded for your 27 MW (or part thereof - because when it is wet, this baby is running at close to capacity anyway). Fine ESB (by whatever brand name may have some insurance - but electricity consumers have to pay the premium in higher electricity charges).

It is a matter of priority. An issue which appears to beyond the comprehensive of overpaid ESB group idiots. And gov.ie regulators. And the court system of Ireland.

The soaking wet banana republic, run by ejits.

If anything this dam could generate far more electricity, if it was fitted with more in number and more in energy efficient turbo generators. Discharging far more water at the same time (which discharge should be driven/controlled to take maximum advantage of tidal levels).

Impetus

A picture of the River Lee today, taken at 12h35, showing the spare capacity of the river (at a guess close to 80cm with spare for comfort) to carry more water at the time in question. A capacity wasted. Meanwhile above the dam, the water levels are high. The low tide today was at 15h44.* (leaving several hours to dump water, without any risk of flooding).

The dam is the main solution available to store excess short-term rainfall to prevent urban flooding.

This flood prevention resource is being wasted by incompetent people, who operate by remote control from nearly 100km away from the point of reality and they seem to have zero knowledge of the real-time water level, at critical points in the system.

https://s3-eu-west-1.amazonaws.com/riverimage2000/20151217_123558%5B1%5D.jpg

*https://www.sailing.ie/Portals/0/Cobh%2012-2015.pdf?ver=2014-06-13-000000-000

L

Impetus wrote: »

It seems to me to generate 27 MW, which is about 0.45% of the total demand - based on 6 GW.

From memory, Ardnacrusha is about 90MW. It's ~4 of those units.

Impetus

L wrote: »

From memory, Ardnacrusha is about 90MW. It's ~4 of those units.

So? My number referred to Carrigadrohid on the River Lee - please see the ESB info on this site which I attached before adding your gems to this thread :-)

(Carrigadrohid on Lee appears to be remotely controlled (sluice gates etc) by Ardnacrusha on Shannon staff, who appear to be operating in the blind.

Presumably the minuscule amount of power generated by this plant does not warrant the staff cost?

L

Impetus wrote: »

So? My number referred to Carrigadrohid on the River Lee - please see the ESB info on this site which I attached before adding your gems to this thread :-)

You were replying to fits who was talking about Ardnacrusha.

Macha

Impetus wrote: »

So? My number referred to Carrigadrohid on the River Lee - please see the ESB info on this site which I attached before adding your gems to this thread :-)

[mod] *sigh* can't we just all be a little more polite (and a little less passive-aggressive) to each other? Tis the season, etc..[/mod]

TheChizler

Impetus wrote: »

A picture of the River Lee today, taken at 12h35, showing the spare capacity of the river (at a guess close to 80cm with spare for comfort) to carry more water at the time in question. A capacity wasted. Meanwhile above the dam, the water levels are high. The low tide today was at 15h44.* (leaving several hours to dump water, without any risk of flooding).

The dam is the main solution available to store excess short-term rainfall to prevent urban flooding.

This flood prevention resource is being wasted by incompetent people, who operate by remote control from nearly 100km away from the point of reality and they seem to have zero knowledge of the real-time water level, at critical points in the system.

https://s3-eu-west-1.amazonaws.com/riverimage2000/20151217_123558%5B1%5D.jpg

*https://www.sailing.ie/Portals/0/Cobh%2012-2015.pdf?ver=2014-06-13-000000-000

That's not that low, and looks like it's flowing fairly fast. What was the water level like upstream of this in the narrower sections? Water level in the city is largely dictated by the tide, not the discharge from Inniscarra.

Markcheese

I was in the city around 6 last night and the water in the north channel was fairly low - but really flowing fast, if the river in the city had been full to the bridges , ( from released river water ) then up stream would have been badly flooded...

Impetus

TheChizler wrote: »

That's not that low, and looks like it's flowing fairly fast. What was the water level like upstream of this in the narrower sections? Water level in the city is largely dictated by the tide, not the discharge from Inniscarra.

There are two causes of flood risk in Cork. Extremely high tides + wind coming from the wrong direction is one. Another is river/dam mismanagement. In 2009 we had an overflowing reservoir caused by heavy rain, which was forecast about a week in advance, and this was allowed to accumulate in the reservoir with massive consequences for many parts of the city. We are playing with fire by not managing the discharges of this reservoir during periods of prolonged / heavy rainfall. Cork airport weather station reported over 100 mm of rain over the past 7 days to 15.12.2015, in the dozy met.ie site that is a day out of date. Heavy rainfall forecast = keep the reservoir as empty as possible time, and make use of periods when the tide is out to maximise dumping of water - managed up to an engineered water height for the river in the centre of the city.

The entire process (regarding dam management) could be automated, by creating a computer model which takes into account forecast rainfall, water height inside the reservoir, tide table data, and river height at critical city centre locations. The same model could also monitor tidal risks by looking at tide table data and wind speed/direction forecasts.

Impetus

Markcheese wrote: »

I was in the city around 6 last night and the water in the north channel was fairly low - but really flowing fast, if the river in the city had been full to the bridges , ( from released river water ) then up stream would have been badly flooded...

It is a matter of management of the discharge rates based on the parts of the city which are least tolerant to high water. As a secondary precaution, these few points of maximum weakness need some construction work to reduce the risk. This would allow more water to be expelled from the system in periods of heavy rainfall.

Growth in Cork is mainly in the suburbs, and has been. The increases commuting distances and times, and makes the place less easy to provide an excellent frequent public transport system in (ie a daytime/evening maximum wait of 5 to 7 mins for a service - be it bus, tram etc and suburban trains working to a clockface timetable). This requires density to work economically. The metro area stretches from Ballincollig to Midleton - which is about 30km. For a population of about 300'000. This is bad planning. A city should be as close to walkable as possible. The risk of flooding is one issue I would take into consideration when deciding where to put a business premises, or indeed live. The core is the obvious location, if it was sustainably accessible at all times - which is not the case.

The powers that be seem to have learned nothing from 2009, and with the odd exception, this discussion seems to be dominated by people who either have a vested interest in "running the place" or seem to enjoy the odd flood as a bit of random excitement, probably because they live on a hill!

TheChizler

I don't think there are vested interests here, just skepticism that you can tell the flow rate of the dam from the water level in the city alone.

hytrogen

Impetus wrote: »

I have no doubt that the release of water is controllable (electro-mechanically) and remotely. In the 2009 flooding, media reports said it was done remotely from Ardnacrusha. It seems to me that there is a culture/instruction within ESB to maximise the use of the water for generation purposes. Instead of proactively dumping water during periods of risk, making maximum use of low tides. To do so you need to be able to monitor the river height in the city centre at the most critical flood risk points, and slowly increase the sluice gate opening, until you are getting close to safe high water mark at these critical points. If this happens you reduce the flow slightly so it continues to maximise the discharge rate, while at the same time not flooding the place.

The entire process should be automatically monitored in real time. However there is nothing to stop one from doing the job manually - even if it means putting observers watching the river in the city at critical times, who can call the control centre on a mobile phone and give the person in the control room feedback.

I am sure ESB is paying met.ie for accurate rainfall forecasts. They are also available here:

http://www.wunderground.com/cgi-bin/findweather/getForecast?query=Cork%2C+Ireland

You click on customise and check the precipitation accum. total, and hourly liquid precipitation boxes and it shows up as green on the chart on an hour by hour basis.

You can even get detailed forecasts further upstream in the Lee - eg
http://www.wunderground.com/q/locid:EIXX3370;loctype:1

OP unfortunately you and the media are completely off the mark with what happened in 2009. (Also searching for references to my point seems to be illuded by a media blackout as usual..)
A man was suspected of drowning around the harvest moon back in 2009 in Cork. Both the navy divers, coast guard and fire brigade were searching for the body downstream of Cork city. They had requested to reduce the flow of water out of Inniscarra to assist with the search.
Sadly the ESB were stocking up the reservoir leading up to the incident. Coincidentally we had a monsoon of rain that September and levels at the dam were already at their peak, while there was a stong el Nino reported too, hence the wet September.
At 6pm the dam was brimming and it was approaching the remnant high tide from the harvest moon and as high water hit the management let go all of the water at full rate, submerging cork city and adjacent flood areas.
... there really should have been a movie made about it but I believe rte did make a documentary about it a year later

two wheels good

hytrogen wrote: »

OP unfortunately you and the media are completely off the mark with what happened in 2009. (Also searching for references to my point seems to be illuded by a media blackout as usual..)
A man was suspected of drowning around the harvest moon back in 2009 in Cork. Both the navy divers, coast guard and fire brigade were searching for the body downstream of Cork city. They had requested to reduce the flow of water out of Inniscarra to assist with the search.
.......

I too heard that story. I also heard it was untrue that it affected Iniscarra operations. I don't know which is correct.
It would be interesting to know if it was presented as evidence in the court case taken by UCC against the ESB re 2009 flood damage. The ruling of that court case indicated ESB were negligent.

EDIT: PS Nice pun, OP

TheChizler

two wheels good wrote: »

I too heard that story. I also heard it was untrue that it affected Iniscarra operations. I don't know which is correct.
It would be interesting to know if it was presented as evidence in the court case taken by UCC against the ESB re 2009 flood damage. The ruling of that court case indicated ESB were negligent.

He was a UCC student in my course a few years behind me, I presume the search was mentioned in the court case but not publicised for the sake of family and friends.

hytrogen

two wheels good wrote: »

I too heard that story. I also heard it was untrue that it affected Iniscarra operations. I don't know which is correct.
It would be interesting to know if it was presented as evidence in the court case taken by UCC against the ESB re 2009 flood damage. The ruling of that court case indicated ESB were negligent.

I would expect for liabilities the media probably pulled the story or were told to pull the story as the case proceeded for respect of the bereaved.

It seems like the last few years they started to get the managment correct with little or no major flooding around the main systems and suddenly this year there's complete incompetence running the show now.. typical

Impetus

hytrogen wrote: »

OP unfortunately you and the media are completely off the mark with what happened in 2009. (Also searching for references to my point seems to be illuded by a media blackout as usual..)
A man was suspected of drowning around the harvest moon back in 2009 in Cork. Both the navy divers, coast guard and fire brigade were searching for the body downstream of Cork city. They had requested to reduce the flow of water out of Inniscarra to assist with the search.
Sadly the ESB were stocking up the reservoir leading up to the incident. Coincidentally we had a monsoon of rain that September and levels at the dam were already at their peak, while there was a stong el Nino reported too, hence the wet September.
At 6pm the dam was brimming and it was approaching the remnant high tide from the harvest moon and as high water hit the management let go all of the water at full rate, submerging cork city and adjacent flood areas.
... there really should have been a movie made about it but I believe rte did make a documentary about it a year later

I respect that issue. However it took a whole week from memory of water being held back to find somebody who probably was well downstream by then. One person or a few thousand souls at risk of future death or property wipe-out etc? Priorities please.

Impetus

High tide was 3.7m at 11h17 this morning. I was walking along the North Mall at the time, and the river height was about at it's maximum safe height.

The river height maxed out at 4.39m at the Maltings around the same time (http://77.74.50.157/cfw/).

This makes me think that the note on this page that suggested that a reading of 5m or above was a problem level, overstates the safe, day to day maximum level for sluice gate manipulation. 4.5m would be more like a maximum safe level. And of course this visual assessment only applies to the North Mall segment of the river bank.

Impetus

Markcheese wrote: »

The bride valley is a totally different shape to the lee valley . Its mainly wide and flat (from crookstown to the lee anyway, so its flooding and the effect is very different ...

Precisely. Which is why we need river level gauges for various points in the city centre, (basic use for internet of things etc) to manage the River Lee flow in relation to rainfall, all over the region. The current number of monitoring points is appallingly inadequate, and badly positioned in relation to the value at risk (including human life). These data should be available in real time to everybody.

Markcheese

The heavy rain of 2009 may have been forecast in advance - the cloud burst in the caha mountains wasnt anticipated by esb... there were cockups in relation to esb and weather forecasts- esb used to calculate the speed of fill of the lee reservoirs based on rainfall levels at inniscarra... unfortunatly the rainfall levels in the upper levels of the lee catchments were substantially higher....

two wheels good

hytrogen wrote: »

I would expect for liabilities the media probably pulled the story or were told to pull the story as the case proceeded for respect of the bereaved.

It seems like the last few years they started to get the managment correct with little or no major flooding around the main systems and suddenly this year there's complete incompetence running the show now.. typical

Sorry, but this is bizarre. A newspaper can report the facts of a story or any statements made an organisation e.g.the ESB, or the evidence presented in a public court case without concerns about liabilities.

A ~€100m court case is unlikely to skirt the tragedy of a family bereavement simply for "respect for the bereaved". The details can still be handles with sensitivity.
If this story was a factor in the management of water levels I would expect the ESB legal team to have included it in the case content. Whether it would have reduced their liablility is another question.

Impetus

two wheels good wrote: »

Sorry, but this is bizarre. A newspaper can report the facts of a story or any statements made an organisation e.g.the ESB, or the evidence presented in a public court case without concerns about liabilities.

A ~€100m court case is unlikely to skirt the tragedy of a family bereavement simply for "respect for the bereaved". The details can still be handles with sensitivity.
If this story was a factor in the management of water levels I would expect the ESB legal team to have included it in the case content. Whether it would have reduced their liablility is another question.

Yes. And perhaps "out of respect for the family" etc..... the people who live in low lying areas of the city, and their rights not to have their premises flooded, to walk the streets freely, etc were ignored?

Impetus

http://77.74.50.157/cfw/


The river height chart linked to above, shows the water level falling every day to 2.6 m or so.

In times of high rainfall, and/or high forecast rainfall, the opening of Iniscarra Sluice gates should cause this chart to be almost a straight line between 4 and 4.4 m. This chart, and ideally others at various critical points, should be the drivers for sluice gate management. Letting it go down to 2.6 and thereabouts is a waste of water drainage opportunity.

When the weather is wet, there is no shortage of water to keep the turbines running. There is therefore no point in collecting large amounts of water in the reservoir, which is putting the city centre at risk.

Markcheese

Great info ... but if the lee is at flood level from the lee fields to inniscarra ( and it is) releasing extra water to coincide with low tide WILL mean flooding (just not in the city) ,regardless of what a water level meter at the lee maltings(tidal area) says ...

I'm looking at water levels in the harbour at the moment - they could go a lot higher - of course for them to be high (at low tide) from river water you'd have to blow the dam -wiping out ballincolig and the city passage west ect ect in the process.....

hytrogen

So as of yesterday the Straight road is closed from B'collig east roundabout all the way to town, Anglers rest and Iniscarra bridge by the Gun powder mills are flooded, and my sources near the dam say that levels reached as high as they were in 2009 last night due to the sheer amount of rainfall on Tueaday dispite them releasing more than 250MT/s all day yesterday so we could be in for another one perhaps..

Impetus

hytrogen wrote: »

So as of yesterday the Straight road is closed from B'collig east roundabout all the way to town, Anglers rest and Iniscarra bridge by the Gun powder mills are flooded, and my sources near the dam say that levels reached as high as they were in 2009 last night due to the sheer amount of rainfall on Tueaday dispite them releasing more than 250MT/s all day yesterday so we could be in for another one perhaps..

This volume of water should be stored upstream - not causing the N22 to be closed, or worse still flooding the city centre. It would be far cheaper for 'the river management agency' to pay a fee to landowners who have land surrounding Inniscarra and other reservoirs, for temporary right to flood part of their land.

This combined with a series of 'gates' (ie sluice gates, flood gates, call it what you like) could be used to keep overflowing waters where they will cause minimal damage. The land-owner could continue to use the land when there is no 'super-flooding'.

This measure could be supplemented by a system of flood gates at the point where the Lee splits into two channels - allowing the flow rate into each channel to be separately managed. The south channel is much smaller than the north channel - around UCC one could jump across the south channel - an impossible feat over the north channel. This would allow a greatly increased rate of water dumping to take place when large rainfall is forecast while the tide is out - making maximum use of the carrying capacity of the north channel. During periods of heavy tide, the river could effectively be almost totally shut off during the hour or so of peak tide. This would allow the sea water to flow far more inland than if it has a strong river pushing in the opposite direction.

I was just reading this website on cutter suction dredging - published by the company that did the Palm Islands in Dubai. http://www.vanoord.com/activities/cutter-suction-dredger The Rivers Lee and Shannon could benefit from this dredging technique to make the river banks deeper so that they can carry more water and keep the tide at a lower level.

I remember some decades ago when Dutch dredgers reclaimed land around the Tivoli docks in Cork. They used the dredged up silt and sand to create the new land, which is used today for warehouses and factories.

Markcheese

Thats canalisation - aint cheap - and the exact opposite of letting the river food at certain points-
And apart from the balls up by the esb in 09 is it really worth doing ....

hytrogen

What they should really be considering for the Lee is fixing the wier at the gun powder mills, reinstating the canals around that parkland, building dykes (or incentivising the home owners on the banks and flood plains to invest in dyke construction) and dredging the middle course stream areas, possibly to a safe navigable depth for leisure craft or small commercial craft while adhering to the bathing water quality management legislation. That goes for the Shannon too, it's navigable but I wouldn't go swimming there any more

Markcheese

What would reinstating the weir and fixing up the canals do ?? ( I thought the weir was still there ?? )

Impetus

Markcheese wrote: »

Thats canalisation - aint cheap - and the exact opposite of letting the river food at certain points-
And apart from the balls up by the esb in 09 is it really worth doing ....

I have subsequently looked at detailed satellite imagery of the series of reservoirs and dams already in place on the Lee. It seems to me that most of the hardware is already in place. The upstream dams already exist to hold water back, at points where it will do the least damage. Let fields flood around the reservoir, and pay farmers for the use of their probably already soggy field in the middle of winter. I spoke to a farmer (who is not located near this river system) and his view as a farmer was that they would welcome the income opportunity, which would come at little cost to them.

All you need to add is:

1) detailed feedback from river height gauges along both channels of the river, and the reservoirs themselves.

2) A legal and financial provision to engage with farmers and provide for the controlled field flooding.

3) Pro-active reduction in river levels using 10 day rainfall forecasts to maximise reservoir space to store the new rainfall. The limiting factor here is a weir which causes an imbalance of water to gravitate towards the skinny South channel rather than the higher capacity North channel. During the hour or so of high tide during heavy rainfall, simply shut off the river flow from entering the city.

Flooding by the river Lee is caused by river management incompetence, which goes up the line to political incompetence. If this was the Netherlands, there would be no flooding in this area, because the Dutch take the issue far more seriously.

If new hardware is required, it will probably be a form of floodgate for the North and South channels located just West of Wellington Bridge (R846).