Shannon Floods 2009

This page originally provided links to other pages about individual waterways areas affected by the floods of November 2009. I have now (February 2011) removed most of those pages and included some of the highlights here.

The floods allowed us to see what the water levels might have been like before Ardnacrusha was built, when all the waters of the Shannon went down through O’Briensbridge, with a canal from Errina to Plassey. The effects on the old Limerick–Killaloe Navigation are covered here.

Lough Derg

Dromineer

Here are some photos of the water level in the public harbour and in the Shannon Sailing marina in Dromineer on 21 November 2009.

And on 25 November, when the water was so high that it was not possible to get to Shannon Sailing without chest-high waders:

Garrykennedy

25 November 2009:

Killaloe-Ballina

22 November 2009:

The Coastguard rescued boats from the wall and from the marina opposite: it was feared that, if swept down on to the bridge, they would block its arches and increase the pressure on the structure.

25 November 2009:

Derg Marina, Ballina, suffered damage from the floods:

Off the navigation: Castleconnell

26 November 2009:

27 November 2009:

28 November 2009:

The floods

I started photographing the high water levels on the Shannon and the old Limerick Navigation below Killaloe because I wanted to know what they would have looked like before Ardnacrusha was built, when the whole flow of the Shannon went down the river. Since Ardnacrusha was built, the ESB has used Parteen Villa Weir to send 10 tons (cubic metres) of water per second down the old course of the river and up to 400 tons through the power station. If there is anything left over after that, the excess is sent down the old course.

Most of the time, the water level on the old course has been much lower than it was before Ardnacrusha (although the minimum levels continued to be set by the regulating weirs at Corbally and World’s End, Castleconnell), and the current has been slower. The ESB has on occasion sent extra water down to create more excitement for kayakers travelling over the Falls of Doonass from Castleconnell downstream. The water levels in the canal sections of the old navigation (Killaloe, Plassey–Errina and Park Canal) also seemed to be rather low.

The floods of November 2009 required the ESB to send large amounts of water down the old route, and it was nice to see the river and the canal full. However, the water continued to rise to such an extent that the river overflowed and flooded its banks. That was not so nice.

It seems to me that many people wanted accurate information about the floods; they wanted predictions of what would happen; they also wanted to understand how the system works and what was going on. Although this site got hundreds of visitors every day, I don’t think that this, or any other, site, or indeed any other source of information, that met people’s needs, and in some cases the information provided was inaccurate or misleading.

For example, we had this nonsensical statement: “Earlier, the ESB released 10% more water than usual to alleviate pressure at Ardnacrusha.” I took that version from the IOL website but the same information was carried on RTE radio. Now, the usual discharge from Parteen Villa Weir down the old course of the river is 10 tons/cubic metres per second. So was IOL telling us that ESB was now sending down 11 tons per second? A 1-ton increase would not have led to anything like the floods we experienced. So whatever the increase was 10% of, it wasn’t the usual discharge down the river. I don’t know what the ESB originally said to the Gentlemen and Ladies of the Press but, whatever it was, the said L & G didn’t know enough either to interpret it properly or to ask the requisite follow-up questions. That sort of thing doesn’t help public understanding — but nor does the shortage of public descriptions of how Shannon levels are actually managed.

There were also problems at a somewhat lower level. For instance, both the AA and RTE reported, over several days, that the only route open to Castleconnell was via Daly’s Cross. But if you wanted to go to Stradbally North, Castleconnell, eg to the Castle Oaks House Hotel, you couldn’t have got there via Daly’s Cross. The “back road” from the new roundabouts near Finnegans pub was open to Stradbally, the Castle Oaks and Chapel Hill; the floods caused a blockage at the Ferry, at the bottom of Chapel Hill. So you couldn’t get from the Castle Oaks to the centre of the village, or vice versa, without going back to the N7, but you could reach the Castle Oaks without going to Daly’s Cross. I don’t know how common such errors were, but reports about where I live were 100% wrong.

The ESB press statements

From 23 November 2009 onwards, the ESB issued a series of press releases about the Shannon floods. It might be useful to review what they said.

Monday 23 November 2009: ESB said that the flooding along the Shannon was the highest on record. It had been discharging more water down the old course of the river for some days, but …

… the release of higher volumes of water downstream will become unavoidable later today. […] Localised downstream areas can expect higher flood levels as a result.

Tuesday 24 November 2009: ESB issued three statements. The first said that:

ESB personnel have been meeting since early this morning to assess the flood situation on the Shannon. This involves a review of water levels downstream from Parteen Weir to assess the impact of the additional discharge. Flow measurements are also taken upstream from the weir, at Lough Derg and are also taken to indicate the scale of water volume still coming into the lake. An assessment of the water levels must be considered with the Local Authorities and Emergency Services who are co-ordinating the response to the unprecedented rainfall levels. An update will be issued mid-morning.

At noon that day, it said that levels on Lough Derg had stabilised overnight but that more rain was forecast and that much water was still entering Lough Derg. ESB had not increased the discharge from Parteen Villa Weir but it would issue another statement later. In that later statement, issued at 4.15pm, it said that it would not increase the rate of discharge from Parteen Villa Weir down the river.

Wednesday 25 November 2009: two statements were issued. In the first, issued at 11.00am, ESB said that water levels in Lough Derg had increased significantly, to record levels. Its statement was not entirely clear:

The discharge of water from Parteen Weir must be increased today. The total rate of water discharge from Parteen Weir is not expected to exceed the rate set on Monday.

If the discharge was to be increased, but was not to exceed the levels on the Monday, when and why was it decreased in between? What does ESB intend to convey by using the two different phrases “the discharge of water” and “the total rate of water discharge”? I think they mean that a high rate was used on Monday, was reduced at some time before Tuesday but was about to be increased again, but I am not sure. Note that ESB did not give any figures for the rate of discharge or the volume of water discharged. ESB did point out that:

… it is expected to cause increased flood levels downstream of Parteen Weir by an estimated three inches as it is discharging into an already flooded area.

In the second statement, at 5.00pm, ESB said that the rate of discharge would not be increased overnight.

Thursday 26 November 2009: at 5.00pm, ESB said that there would be no overnight increase in the rate of discharge.

Friday 27 November 2009: the first of two statements was issued at 9.30am. ESB said that Lough Derg’s water-levels were still rising, but were rising more slowly:

… the rate of increase has fallen with an increase of 1cm recorded over the last 24 hours.

Accordingly, the rate of discharge from Parteen Villa Weir would remain unchanged, and ESB expected the flood levels to stay the same.

At 5.00pm, ESB said that it would maintain the same rate of discharge overnight.

Saturday 28 November 2009: at 9.30am ESB said that Lough Derg’s water level had fallen by 1 centimetre overnight and that the discharge rate from Parteen Villa Weir would remain unchanged; downstream flood levels were expected to remain the same.

Sunday 29 November 2009: at 9.45am, ESB said that Lough Derg’s level had fallen by 3cm and that the rate of discharge from Parteen Villa Weir would remain unchanged. Downstream flood levels too were expected to stay the same.

Monday 30 November 2009: in its first of two statements, at 10.00am, ESB said that Lough Derg had fallen another 6cm in 24 hours. As a result, the rate of discharge from Parteen Villa Weir had been reduced overnight by 7% and there might be further reductions over the following 24 hours. The water level below the weir was expected to go down by 7–8cm during the day. In a second statement, at 5.15pm, ESB said that Lough Derg’s level remained “stable” and that the rate of discharge had not been changed and would not be increased overnight.

Tuesday 1 December 2009: in its first of two statements, at 10.00am, ESB said that Lough Derg had fallen another 7cm in 24 hours. As a result, the rate of discharge from Parteen Villa Weir had been reduced overnight by another 7% and there might be further reductions over the following 24 hours. The water level below the weir was expected to go down by 7–8cm during the day. At 5.15pm, ESB said that the situation was stable and that discharges would be reviewed next day.

Wednesday 2 December 2009: at 9.30am, ESB said that Lough Derg had fallen by another 5cm in 24 hours: Parteen Villa Weir’s rate of discharge had been reduced overnight by another 6% and downstream water levels would probably fall by another 6–7cm during the day. And at 5.30pm it said that

The situation on the River Shannon remains unchanged since this morning and the discharge rates throughout the day were maintained.

Thursday 3 December 2009: at 9.30am, ESB said that Lough Derg had fallen by 6cm in 24 hours and Parteen Villa Weir’s rate of discharge had been reduced by 5%; water levels downstream were expected to fall by 4–5cm. There was no change by 5.00pm.

Friday 4 December 2009: at 10.00am, ESB reported that Lough Derg had fallen by 5% and Parteen Villa Weir’s discharge by 6%; water levels downstream were expected to fall by 4–5cm.

Saturday 5 December 2009: at 10.ooam, ESB said that Lough Derg was down by 5cm and was thus back at its previous record high level, while Parteen Villa Weir’s discharge rate was down 7%. There was no prediction for downstream levels. ESB had reported total falls on Lough Derg of 38cm, so the new record was about 15″ above the old.

Sunday 6 December 2009: at 10.00am, ESB said that Lough Derg was down another 3cm and Parteen Villa Weir’s discharge rate  was down another 7%.

That was the last statement issued. On 8 December 2009, the Limerick Leader reported that:

The Crisis Management Team, which has been monitoring water levels on the Shannon River, has decided to stand down as fears of flooding recede.

The missing numbers

The second column of this table shows, based on the Office of Public Works Flood Hydrographs to 1 December 2009 (from the OPW website), when the water level peaked on various tributaries of the River Shannon and on the Shannon itself.

The columns to the right of that are based on the ESB press releases quoted above. ESB’s first press release about these floods gave a figure in inches, but after that it went metric.

Note how much information is missing. I don’t know where on Lough Derg and where below Parteen Villa Weir the water levels were measured. And, while ESB has given some figures for changes in water levels, it has not said what the absolute levels were. Nor has it given a figure for the rate of discharge from Parteen Villa Weir to Ardnacrusha and down the old course of the river. If anyone can help to fill the gaps in this table, I would welcome assistance.

Date	Upstream peak water level	Lough Derg (unspecified location)		Parteen Villa Weir discharge to river		Expectations downstream (unspecified location)
		Water level	24hr change	Rate	24hr change	Water level	24hr change
19/11/2009	Gourdeen (Nenagh River, flows into Lough Derg)
20/11/2009	Scariff (Scariff River, flows into Lough Derg)
21/11/2009	Bellagill Bridge (R Suck above Ballinasloe, joins Shannon at Shannonbridge)Ballinalack (River Inny, flows into Lough Ree)Ferbane (River Brosna, flows into Shannon near Shannon Harbour)
22/11/2009
23/11/2009
24/11/2009
25/11/2009	Boyle Abbey Bridge (River Boyle, joins Shannon above Carrick-on-ShannonDrumsna, northern R Shannon				—		+ 3 inches
26/11/2009					—
27/11/2009	Derry Bay, Lough ReeAthlone WeirShannonbridge, Banagher and Meelick Weir (all between Athlone and Portumna)		+ 1 cm		—		0
28/11/2009			– 1 cm		—		0
29/11/2009			– 3 cm		—		0
30/11/2009			– 6 cm		– 7%		– 7–8 cm
01/12/2009			– 7 cm		– 7%		– 7–8 cm
02/12/2009			– 5 cm		– 6%		– 6–7 cm
03/12/2009			– 6 cm		– 5%		– 4–5 cm
04/12/2009			– 5 cm		– 6%		– 4–5 cm
05/12/2009			– 5 cm		– 7%
06/12/2009			– 3 cm		– 7%

---

The floods and some figures

This next table shows the figures from Parteen Villa Weir for each day alongside information drawn from the Limerick Leader flood reports in its online news archive, tidal predictions from Shannon Foynes Port Company and mean daily wind speeds at Shannon Airport from Met Éireann (which does not show wind direction). Some information from Limerick County Council‘s website has been added.

	ESB press statements: 24hr changes			Limerick Leader News archive http://www.limerickleader.ie and Limerick County Council http://www.lcc.ie		Shannon Foynes Port Company Tide Tables 2009		Met Eireann http://www.met.ie
Date	Lough Derg (unspecified location)	Parteen Villa Weir discharge to river	Expected water level downstream (unspecified location)	Areas flooded	Roads closed	High tide: times	High tide: heights (m)	Mean wind speed (knots) at Shannon Airport; gusts if >34 knots
19/11/2009				No reports	No reports	07:5120:24	6.606.30	13.5
20/11/2009				No reports, but floating Christmas tree hits bridge in strong flow on Shannon	No reports	08:2821:03	6.406.10	10.1
21/11/2009				No reports	No reports	09:0721:42	6.305.90	19.8 (gusts to 51)
22/11/2009				Clonlara: two houses evacuated; Army + Killaloe fire service sandbagging 30 others. Levels in Castleconnell and Montpelier “perilously high”	Black Bridge at Plassey (pedestrian( closed); no roads closed in Co Limerick	09:4922:25	6.105.70	23.5 (gusts to 48)
23/11/2009				Shannon BanksFlood warnings issued for O’Briensbridge, Clonlara, Westbury and Shannon Banks	R525 Castleconnell to Montpelier, O’Briensbridge, flooded near railway bridgeMountshannon Road in AnnacottyRoad from Charco’s to Scanlan Park in CastleconnellSpringfield, Clonlara?	10:3423:15	5.905.50	14.1 (gusts to 40)
24/11/2009				Shannon Banks (Hampstead): 22 houses evacuated3 houses evacuated at “Springfield Drive, Castleconnell” (www.lcc.ie). Do they mean Springfield, Clonlara, Co Clare?	“Pedestrian walkways” along canal closed	11:28	5.70	16 (gusts to 37)
25/11/2009		—	+ 3 inches	Brockhaven, MontpelierFishermen’s huts, Plassey	World’s End road, CastleconnellBelmont Road (www.lcc.ie)	00:1312:30	5.405.60	17.5 (gusts to 40)
26/11/2009		—		14 houses evacuated in Montpelier, Annacotty and CastleconnellSandbags issued to residents of Lucas Drive “down river from Shannon Banks”Banks of Groody from Dublin Road to ShannonSt Mary’s Park insulated In total, almost 100 homes evacuated so far in Shannon Banks, Clonlara, Montpelier, O’Briensbridge Water levels 1.3m below 1999 floods on Clancy, O’Callaghan Strands, Harry’s Mall, Mill Road, Lucas Drive, Island Field. Clareville water treatment plant and Bunlicky waste plant operating normally		01:2013:42	5.505.60	12
27/11/2009	+ 1 cm	—	0	City Council to distribute sandbags in Lucas Drive and Corbally (Mill Road beside Shannon, Siul na hAbhann, Meadowbrook)OPW building flood defence from Athlunkard Bridge to Hampstead Park	Castleconnell: Ferry car park to village (www.lcc.ie)	02:2214:43	5.605.60	6.9
28/11/2009	– 1 cm	—	0	No further reports	No further reports	03:1415:35	5.705.80	5.5
29/11/2009	– 3 cm	—	0	No further reports	No further reports	04:0016:21	6.006.00	12.8
30/11/2009	– 6 cm	– 7%	– 7–8 cm	No further reports	Clonlara to Castleconnell pedestrian bridge closed (again)	04:4317:05	6.206.20	6.2
01/12/2009	– 7 cm	– 7%	– 7–8 cm	Flood warning issued in Limerick City in case high tides combine with high discharges and strong windsBoil water notice issued for Montpelier, O’Briensbridge and Bridgetown	No further reports	05:2417:48	6.506.50	14.7 (gusts to 38)
02/12/2009	– 5 cm	– 6%	– 6–7 cm	No further reports	No further reports	06:0618:36	6.606.60	9.3
03/12/2009	– 6 cm	– 5%	– 4–5 cm	No further reports	No further reports	06:5119:25	6.806.70	7.8
04/12/2009	– 5 cm	– 6%	– 4–5 cm	No further reports	No further reports	07:3920:13	6.806.70
05/12/2009	– 5 cm	– 7%	no info			08:2721:05	6.806.60
06/12/2009	– 3 cm	– 7%	no info			09:1621:57	6.706.40
07/12/2009				No further reports		10:0922:54	6.506.20
08/12/2009				No further reports		11:0723:55	6.206.00

The Clare Champion did not seem to have an accessible archive, so the table does not have enough information about the effects of the flood in areas of County Clare (eg Clonlara and O’Briensbridge) outside the suburbs of Limerick.

The missing information

The tables highlight the gaps in the information that was provided, but I don’t even know if I’ve identified the gaps properly. I am assuming that there is, somewhere, some mathematical model of the Shannon below Killaloe, a model that can predict what areas will flood to what extent under what circumstances. And I am assuming that the relevant factors are the rate of discharge down the old course of the river from Parteen Villa Weir, the capacity of the river and, for areas downstream of Athlunkard Bridge, the height of the tide and, for areas even further down, the direction and strength of the wind. But I don’t know if those are the correct factors, never mind what their current values are. I don’t even know the capacity of the old course of the river under (a) ideal and (b) actual conditions, with trees etc blocking it. I don’t know the level of Lough Derg at which the flooded area embankments, Parteen Villa Weir and other infrastructure are threatened: in other words, the level at which Parteen Villa must discharge, no matter what the conditions downstream.

I am not suggesting that I, or any other citizen living below Killaloe, is going to want to run the flooding model on our home computers. But it would help understanding if we knew, in general terms, the factors that govern water levels below Parteen Villa Weir. If nothing else, better understanding might stop citizens calling for a single Shannon authority dedicated to stopping flooding.

A site explaining that would meet one of the needs that I think exists: that for understanding of the system. For the second, accurate  predictions of what will happen, I think that the Powers That Be have done pretty well, but what’s needed is a single site that combines the ESB’s information about discharge levels with the local authorities’ interpretations expressed as identifications of the areas to be hit. There is, it seems, an “inter agency group”; it needs an “inter agency” website and a single team disseminating information.

The third issue is accurate information on current status: areas affected, depth of flooding, roads and paths closed and so on. As many citizens have cameras, some of them built in to mobile phones, a huge amount of accurate, up-to-date information is available. The inter-agency information team should accept such information and integrate it with that from official sources, aerial photos overlaid on maps and so on. It should be possible to have one site where anyone could check the effects of the flood on anything from a housing estate to a small boreen.

Well, that’s what I think.

[lk2atr99]