Tag Archives: drainage

Quadrupling Kerry’s canals

I thought there was only one canal in Co Kerry, but there were three more at Lixnaw. They’re still to be seen and they have interesting associations.

Thanks to Ewan Duffy of Industrial Heritage Ireland for the tip-off.

Athlone 1889

To the Editor of the Athlone Times 24/8/1889

Dear Sir

I understand that the Athlone Board of Guardians passed a resolution at a recent meeting in favour of the drainage of the Shannon. May I ask, is it the object of these enlightened gentlemen to destroy the navigation of 240 miles passing through our country, which no law can ever restore; or can it be possible they so far despair of the future traffic of the country under the management of their Parliament, in College Green, as to feel warranted in doing away with such a natural and beautiful highway for trade.

I happen, myself, to be in a position to judge the agricultural part of the question, and after the experience of 25 years of the lands which are subject to the Shannon flooding, I have no hesitation in saying that the meadows are greatly improved, and I may mention that in no way could these lands be more profitably farmed than by meadowing.

To the Athlone people, it seems to me a matter of the greatest importance, or do they realise that their beautiful river is about to be turned into a mere cesspool, their traffic to be left at the mercy of the railway companies, and their boating excursions on their fine lake to be made almost impossible, as this drainage will create such a current at the opening of the lake that it will require their strongest efforts to force a boat against it, and even after overcoming this difficulty, they would have little to look at but white shores and barren rocks.

I remain, Mr Editor, Faithfully yours… R D Levinge, Carnagh

Thanks to Vincent P Delany for this.

Managing the Shannon

Sometimes you have to wonder about politicians and their grasp of reality. Take, for instance, young Mr Adams, Sinn Féin TD for Louth. There he was in the Dáil the other day, talking about flooding on the Shannon, and saying (amongst other things):

No single agency is responsible for the management of the River Shannon. Will the Taoiseach give full responsibility to the OPW for management of the Shannon?

Can Mr Adams have forgotten that, under the Good Friday Agreement, a cross-border implementation body called Waterways Ireland, reporting jointly to the Minister for Fairytales in the republic and the Minister for Marching Bands [a Sinn Féin MLA] in Northern Ireland, is responsible for navigation on certain named waterways including the Shannon?

Giving the Office of Public Works full responsibility for the management of the Shannon would require renegotiation of the Good Friday Agreement [and perhaps some later agreements]. I gather that the members of HM Devolved Administration in Northern Ireland delight in doing that sort of thing, but reducing the powers of the largest of the cross-border implementation bodies might not be wise.

 

 

Why the Shannon floods

From the search terms used, it seems that many people are visiting this site with questions about Parteen Villa Weir, water levels, Shannon floods and so on. They are not this site’s primary focus, but some non-technical information might be of interest.

The best place to start is with a map of the Shannon International River Basin District. As the Shannon RBD site says,

The Shannon International River Basin District is the largest in Ireland at more than 18,000 km2 in area. It covers the natural drainage basin of the Shannon river itself, stretching from the source of the River Shannon in the Cuilcagh mountains in Counties Cavan and Fermanagh to the tip of the Dingle peninsula in north Kerry. It also includes coastal parts of Kerry and Clare which drain to the sea. It flows through 18 local authority areas and is also an international RBD as a small portion of County Fermanagh in Northern Ireland drains underground to the Shannon Pot.

The district is about one fifth of the area of the island, one quarter the area of the state. Rain that falls on that area of land ends up in the Shannon (or in a few small rivers in Clare and Kerry that flow to the sea). Some goes to the Shannon estuary or its tributaries; most flows into the non-tidal Shannon, which means the river upstream of Limerick.

The nature of the Shannon

Ireland has been described as saucer-like, with a high rim and a low flat centre. It’s not entirely true, but there certainly is a very large central plain, and the Shannon flows down through the middle of that. And, because the land it flows through is flat, the river falls very little.

In 113 miles from Leitrim to Killaloe, the Shannon falls just over 30 feet; the navigation channel needs only five locks. [By way of contrast, the Thames has 45 locks over 135 miles; the Trent has 12 locks over 42 miles.] So extra rainwater allows the Shannon to spread out, covering a much wider area, and it takes time for that water to drain away downstream. But many of the rivers that flow into the Shannon have been subjected to drainage schemes, so they can get rid of their flood waters quickly … into the Shannon.

Why don’t they open [or close] the weirs?

There are some weirs on the Shannon, designed to keep a minimum depth in the river for navigation; there are also some natural obstacles that hold water back. But once the level has risen high enough, water simply flows over the top of the weir, and there is nothing useful anybody can do — apart, of course, from farmers’ representatives and politicians, who can always make use of a photo opportunity.

The bottleneck

Almost all the water that enters the non-tidal Shannon will eventually flow through Killaloe, the town at the southern end of Lough Derg [it’s on the west bank, in Co Clare; the east bank is Ballina, in Co Tipperary].

As James Robinson Kilroe wrote in 1907,

[…] we have the formidable barrier at Killaloe, naturally damming up a considerable depth of water in Lough Derg, and the river falling away southward by a series of rapids which correspond with drops in the canal, south of O’Briensbridge […], along an alternative course, possibly one used by a branch of the Shannon.

The diagrams with that article are worth a look.

In the twelve Irish (fifteen statute) miles between Killaloe and the tidewater at Limerick, the river falls about 100 feet: more than three times its fall from Leitrim to Killaloe. In the nineteenth century, the water level at Killaloe used to change by about eleven feet between summer and winter — even without storms.  The old Limerick Navigation, including the canal Kilroe mentioned, could drain only a small amount of water (which could put the navigation out of action); the rest went down the river’s original course through the Falls of Doonass.

The relief channel

Nowadays, the Falls of Doonass are a shadow of their former selves, and the water level through O’Briensbridge, Castleconnell and Plassey is much below its previous levels. I suspect that the older, larger trees along the river show the original level, with the newer, smaller trees having grown since the 1920s.

The cause was the construction of a relief drainage channel in the 1920s. This channel is controlled by a weir at Parteen Villa [not to be confused with Parteen]. Switch between the modern Street Map and the Historic views here to see what has happened.

Actually, of course, it’s not a relief drainage channel. The weir [sometimes referred to as the Hydro Dam] controls the flow of water to the original course of the Shannon [the right-hand or eastern channel, which gets the first 10 cubic metres of water per second] and the headrace for the hydroelectric power station at Ardnacrusha [the left-hand or western channel, which gets the next 400 cubic metres of water per second, 100 for each of its turbines]. The power station was built to use that 100-foot fall of the Shannon, concentrated between Killaloe and Limerick, to generate electricity.

But one effect of the construction of Ardnacrusha was to provide a channel, the power station headrace, capable of taking [at least] 400 cubic metres of water per second away from the original river channel, thus reducing the likelihood of flooding.

Cumec

Water experts talk about cumecs: a cumec is a flow of one cubic metre, or 1000 litres, of water per second. And a cubic metre of water weighs about one [metric] tonne, which is roughly the same as an imperial ton. So one cumec is one ton of water per second, which is a lot.

It was said, on 8 December 2015, that the ESB, using Parteen Villa Weir, had released 315 cumec down the original course of the Shannon on the previous day and had increased that to 375 cumec. If the Ardnacrusha headrace was getting 400 cumec, then the amount of water being discharged from Lough Derg and the upper Shannon had doubled.

Floods

As far as I can see, the Shannon has always flooded. The 2009 floods affected some nineteenth century houses, which I guess would have been flooded even worse before Ardnacrusha was constructed. However, I suspect that more houses have been built on the flood plain since then. But I don’t see that there is any way to prevent Shannon floods.

Envoi

There is a good article in the Irish Times of 9 December 2015; it will no doubt disappear behind a paywall at some stage.

Here is an ESB infographic about the Shannon.

Down to the sea in steps

On 28 January 1907 James Robinson Kilroe [near the bottom of the page] of H M Geological Survey read to the Royal Irish Academy a paper on “The River Shannon: its present course and geological history” [Proceedings of the Royal Irish Academy Vol XXVI Section B No 8 Hodges, Figgis & Co Ltd, Dublin; Williams & Norgate, London 1907]. I thought that Plate V was interesting.

Shannon Derg to sea

Plate V

Kilroe wrote:

It will be perceived that instead of the river being shallow over the unyielding Silurian slate-rock, set almost vertically, and striking across the river-course, it is deeper than over the limestone of Lough Derg, and much deeper than over the comparatively easily eroded Old Red Sandstone at Killaloe. The river-bed actually drops below the datum line above the town, while at the town it is 100 feet above datum.

Old Red Sandstone strata are here to be seen in the river-bank, and Silurian rocks in situ in its bed. A barrier is thus formed, partly of Silurian, and partly of Old Red Sandstone rocks, which without the artificial impounding weir would retain the waters of Lough Derg to a depth of some 104 feet opposite Derrycastle — two miles above Killaloe.

One might have expected to find a fairly level shallow bed from Killaloe northward, a sudden drop from slate-rock to the sandstone floor, and  a pronounced wide, well-formed valley in the limestone district southward to Limerick.

None of these elements exist; instead, we have the formidable barrier at Killaloe, naturally damming up a considerable depth of water in Lough Derg, and the river falling away southward by a series of rapids which correspond with drops in the canal, south of O’Briensbridge […], along an alternative course, possibly one used by a branch of the Shannon.

Here is an extract from the Plate V map, showing the steps of the (pre-Ardnacrusha) Limerick Navigation between Lough Derg and the sea.

Shannon Killaloe to Limerick

The steps of the canal (click to enlarge)

Upstream

Kilroe wrote of Lough Ree:

The waters of Lough Ree stood some 10 feet higher within recent times than they now do, as proved by evidence of solution, with under-cutting of limestone blocks, to be seen about five miles north-west of Athlone, close to the railway, in the townland of Cornaseer.

Under these conditions the lake must have been, perhaps, twice its width, and for a considerable period. Its ancient surface-level is clearly indicated by the caps of the mushroom-shaped blocks.

And of the Shannon between Lough Ree and Lough Derg:

The extreme flatness of the river between Athlone and Meelick is such that, consequent upon the completion of the Suck Drainage-works in 1892, it was found that the callows along the Shannon above the confluence of the Suck at Shannonbridge were much more liable to sudden and frequent floodings than they previously had been.

The more rapid discharge of the Suck waters into the Shannon, before ordinary extra water had time to pass away, had the effect of modifying the regimen of the main stream to an extent which resulted in an action at law [La Touche -v- The Suck Drainage Board].

I have found only one account of that case, in the Freeman’s Journal of 1 July 1893. The plaintiffs, Messrs Harrison and La Touche, owned land at Cappaleitrim, on the west bank of the Shannon above Shannonbridge. They said that the actions of the Suck Drainage Board had caused their lands to be flooded:

[…] that the defendants brought water from the Suck into the Shannon, containing a drainage of 40 miles, with such velocity and such volume that the Shannon was penned back, and that the back water caused the damage to the lands complained of.

[…] The jury disagreed and were discharged.

I don’t know whether the matter ever again came before a judge.

The Ballycuirke Canal and Lough Corrib

Thanks to Padhraic Conneally, who left a Comment that started the hunt, and to Zara Brady (IWAI Corrib), who visited the site to ask about something else entirely, and finally to Trevor Northage of AnglingCharts.com, who provided the name and other information, we now have two extra Galway waterways to add to the list. They’re both covered, with maps, on this page, although only the larger, the Ballycuirke Canal, gets its name in the heading.

I would welcome more information about both canals. It seems that the Ballycuirke was built for drainage but also used for transport; I would be glad to know more about such transport.

From the Corrib

Padhraic Conneally left a comment on my third page about the Rockville Navigation. He made an interesting suggestion that caused me to look at the OSI maps around the Corrib. It seems that there might be another small navigation to the west of Lough Corrib and, because further information would be welcome, I reproduce Padhraic’s comment and my response here.

There is supposed a similar [ie similar to the Rockville] navigation on the Corrib from the old river to Ross lake via Moycullen lake.

I have been up a channel from the old river in a cruiser almost up to the realigned main road but never further. Fr O’Reilly SJ who was a companion of Maurice Semple author of the series of books on the Corrib was reputed to [have] made the trip in a canoe cutting lots of farmers’ barbed wire on the way!

My response:

Looking at it on the OSI maps, the ~1840 (or thereabouts) Historic 6″ map has a quay at the south end of Ross Lake. From there it seems to be possible to get as far as Lough Down, north of Cloghaun. A lot of the channels are straight, suggesting that they’re artificial.

The later ~1900 Historic 25″ then shows another straight channel from Lough Down, through Cloghaun to Moycullen (Ballycuirke) Lough. From the far side of the lake, an artificial-looking channel curves to the Corrib, joining it at this point. So it might be that the system was developed in the early nineteenth century but linked to the Corrib only in the later part of the century. It might have been constructed for drainage, but that wouldn’t stop it being used for navigation as well.

I hadn’t heard of Fr O’Reilly but I do have two of Maurice Semple’s books. I must have a look in them. If anyone else has information about this, it would be very welcome.

If you know anything about this, please leave a Comment below.

 

 

 

 

The Junction Navigation

Here are some pages about the Junction Navigation in the Ballinamore & Ballyconnell drainage district. It later became known as the Ballinamore & Ballyconnell Canal and later still as the Shannon–Erne Waterway.

The role of the cads and bounders of the Ulster Canal Company in getting a canal built at taxpayers’ expense

The construction of the Junction Navigation at Aghoo (Lock 4)

Lock gear old and new

And here’s a reminder of an old page about the Belturbet-built dredger used in constructing the navigation.

Saving the banks

The banks, the Fergus and the lost island of Islandavanna.

The Erne to Lough Oughter

How they got the dredgers past the distillery in 1857. No pics, alas, but it’s worth using the links to the OSI maps.