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Water levels

Posted by Tony Baker 
Water levels
05 November, 2017 19:14
Does anyone know how much more ESB is going to lower the water level in Lough Derg, it's already way down!
Re: Water levels
05 November, 2017 21:17
Still relatively high up here at Leitrim/Carrick, so likely they'll keep dropping for a while.

Tm53
Re: Water levels
05 November, 2017 22:11
I wonder if they are still maintaining the required minimum of 8'6" above the sill at killaloe lock?
Re: Water levels
06 November, 2017 09:45
A week ago in Mountshannon, the level was higher than it has been for quite a while.

Dermot,
"Cheetah" 304.
Re: Water levels
06 November, 2017 11:07
Quote:
Tony Baker
Does anyone know how much more ESB is going to lower the water level in Lough Derg, it's already way down!

Hi Tony. Due to Ardnacrusha which requires maintaining the safety of the dykes in Parteen lake and the head race canal, ESB are forced to maintain water levels on Lough Derg between a fairly narrow band of minimum and maximum safe levels (i.e. to avoid undermining the dam, dykes and banks). This is unlike Lough Ree where water levels can vary dramatically. Even during the exceptional flooding of 2009 and 2010 Lough Derg did not attain the sort of levels on other parts of the Shannon. Likewise in periods of low rain fall the levels on Derg will never be allowed to drop as low as on other parts of the Shannon navigation. At the moment the water levels between Athlone weir and Victoria lock appear to be very high. A few weeks ago Athlone weir was almost flat. Noel
Re: Water levels
06 November, 2017 11:29
Quote:
Dermot Mangan
A week ago in Mountshannon, the level was higher than it has been for quite a while.

The level was noticeably low in Dromineer yesterday (Sunday) - based on just looking at position of my boat vis a vis the finger which is hinged at the inner end but free to drop or rise at outer.

I wasn't sailing my boat so didn't check depth sounder.
Re: Water levels
06 November, 2017 11:57
The level has been up and down like a yo yo for the last 2 weeks. But only through a range of less than a foot.
It has been changing overnight.

Les 41M
Re: Water levels
06 November, 2017 12:37
The level in Killaloe can change by over a foot in only 12 hours depending on the operation of the hydro plant. It drops noticeably if four turbines are rapidly brought online, and rises correspondingly after four turbines have been phased offline creating a micro surge. Another interesting one is Lough Derg's famous tidal surge that can be caused by a prolonged period of very strong southerly winds which can drive the water level in the northern end of the Lough up to 18 inches higher than the southern end. It can be particularly pronounced and visible at Portumna as the downstream river current meets the north flowing surge caused by the prolonged southerlies causing the level to rise.
Re: Water levels
06 November, 2017 14:41
Hi Noel, that 18 inch drop surprised us in the CSIG as well. The flow can extend down from Portumna quite a bit. I was out a few says ago, and although it was calm I was only making 3 knots out of Gortmore going north. It was only when returning I noticed I was doing 7 knots that it struck home how far that flow reaches and how strong it can be.

Les
Re: Water levels
06 November, 2017 14:55
Are you sure you unplugged your shore power lead Les?
Re: Water levels
06 November, 2017 16:01
Quote:
Tony Baker
Does anyone know how much more ESB is going to lower the water level in Lough Derg, it's already way down!

Hi Tony
Lucky Lough Dergers as you guys seem to enjoy a relatively constant level, well most of the time.
Our level on Lough Ree and above is very high for the time of year, the level now is nearly 3 feet higher than it was this time last year.
Our winter level was great all last winter, and most people assumed that the level was being maintained at that, due to recent very bad Flooding Xmass 2015
So it is very hard to understand using that logic why the level is so high at the present.
If we were to get a lot of rain anytime soon, there will be flooding again " I mean there will be Blood "
Re: Water levels
06 November, 2017 18:48
From sourced in kayaking circles, they are doing maintenance on two of the turbines in the dam, weather it is as a result or coincidence, the release through Parteen on the river has been larger than normal for the amount of rain that has fallen recently) and not or a regular schedule.



Edited 1 time(s). Last edit at 06/11/2017 18:50 by Andy4B.
Re: Water levels
24 November, 2017 16:52
Before this downpour, (4 Nov 2017) the water level at Portumna Bridge was 33.40m above Poolbeg level.
On 21 Nov it was 33.46.
This morning at 9am it was 33.69. - That up 23cm in 2 days.

So glad it was down.

It means it has the capacity to absorb all that water thats now coming down the Shannon Basin, hopefully without repeating the disastrous damage caused by flooding in 2009/10 and 2014/15.



Edited 1 time(s). Last edit at 24/11/2017 16:53 by Brendan Hayes.
Re: Water levels
24 November, 2017 17:00
Gas that you mentioned that Noel. I measured the water level before and immediately after Hurricane Ophelia - difference in water level was 22cm.

I wouldn't have believed it was possible for the wind to physically blow that amount of water from bottom to top of Lough Derg.

I suppose its the closest we'll ever see to a level change approximating a tide in the inland waterways!
Re: Water levels
26 November, 2017 14:07
The water levels are recorded at regular intervals and are available online. Here is the link for the guage in Carrick-on-Shannon [waterlevel.ie]
Re: Water levels
26 November, 2017 22:25
Water level this afternoon at Kilgarvan was 9'9" above Killaloe lock sill.
Re: Water levels
03 December, 2017 22:36
Interesting to read of a measured water level difference on Derg caused by the wind.

Not that it is at all relevant to Irish inland waterways, but a few times I have sailed on the Baltic which is tideless and remarked at the sea defenses put in place along the German Baltic coast. It was explained to me that due to wind changes throughout the year they have to reckon with water level changes of up to four feet or so, nothing to do with the tide.

At Heiligenhafen following a westerly September gale our water level had dropped almost three feet, remaining down for a couple of days. Presumably all that water had been blown over to the East side.

Tom K.
Re: Water levels
03 December, 2017 22:59
Interesting to read of a measurable water level difference on Derg caused by the strong winds.

Not that it is relevant to Irish inland waterways, but I have sailed on the Baltic, which is tideless several times. At places along the German coast I remarked at the size & strength of their coastal defenses and it was explained to me that throughout the year persistent winds tend to push vast volumes of water about, resulting in level differences of up to four feet or so.

In Heiligenhafen, near Fehmarn following a September westerly gale our harbour wall level had dropped nearly three feet and remained low for a couple of days. Presumably all that water had been blown East.

Tom K.
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