Climate Change in the 1840s

The following is an extract from a book called "The Industrial Resources of Ireland" written in the 19th century. It describes flooding that took place in Lough Derg over a few weeks in the winter of 1840:

The water levels of Lough Derg effectively increased by about 25% or a quarter over a month. The current rate of water level changes there are only about 2-3% :

http://www.esbhydro.ie/Shannon/06-Pier-Head-Killaloe.pdf

Also, interesting to note that by the 1840s, the cycle of winter flooding followed by droughts in summer was a well recognised problem in Ireland.

River Shannon Floods 1920 to 1950 - A Timeline

When more than 100 homes flooded in Athlone in 2009, homeowners were told that it was a once-in-100-years event. Six years later a similar event has unfolded - Irish Times, 12th December, 2015.

1930 Newspaper Headline (Irish Times)

I have researched newspaper archives and other reliable archive sources to verify the accuracy of the above quote. Are storms and floods like we are getting now "one-in-a-hundred-events"?. From the research I have done, I think that most Irish people who lived through the 1920s, 30s and 40s would balk at such a suggestion, especially those who lived around the Shannon Basin. Between 1920 and 1930, there were five exceptionally wet years - a-five-in-an-eleven-year-event - almost a one-in-two-year-event. Rain - Rain -  and more Rain was the constant weather pattern for this period, putting serious pressure on food and heat sources and putting the country on the brink of famine on a number of occasions for the first time since the 1840s.

By all accounts, we have been very lucky in the 21st Century. 

1923 - Heavy rains in October left thousands of acres of farmland around the basin of the Shannon waterlogged. Many crops were destroyed or unable to be harvested. Bogs were inaccessible meaning that turf could not be drawn away.

1924 - One of the worst flooding events in the Shannon region occurred in August after it rained continuously for 4 days.  It was reported that it was the worst flood in the Shannon region for forty years. The river burst its banks for many miles and large quantities of hay floated away. Potatoes turned black, corn was destroyed and turf unattainable. In the worst areas, there was talk of famine. The heavy rains affected other areas of the country aswell from Donegal to Dublin, completely destroying any hopes for a good harvest season in most places around the country.

By November of the same year, farmers threatened the Government with a "No Rent Campaign" if they did not maintain the Shannon at a "proper level". At the same time, it was agreed by all that it was an abnormally wet year.

1925 - Building of Ardnacrusha Hydro Dam begins. Locals at Lough Derg form a committee to oversea it's effect on river levels during and after construction.

1926 - In February, after four days of rain, the Shannon begins to flood again leaving "a great number of farm hands idle".

1927 - In July and August, some parts of Leitrim suffered severe flooding destroying three bridges and damaging many more. On the evening of October 28th, a major storm off the West coast of Ireland claimed the lives of 45 fishermen at sea.

1928 - In March, heavy flooding was reported around the Pullagh area with the local priest travelling one and half mile to church by boat.

However, things got much worse in November with the Shannon region suffering its worst floods since 1924. An experienced boatman drowns in the floods while rowing a boat from Shannonbridge to his home in Clonfert. People had to temporarily move out of their homes in Banagher. Railways, roads and large areas of crops were submerged.

The ESB dam at Parteen flooded and the water level at Killaloe was 10 feet higher than anytime in the previous 10 years. All low lying areas between Clonlara and Mountshannon were completely flooded leaving potatoes crops and hay destroyed.

Heavy rain and snow swept the country once again after Christmas bringing more floods and people had to move out once again.

There were also reports of dykes bursting in Belgium and Holland and the army being called in to assist with flood damage.

1929 - This year began with a drought after the much heavier than normal rains of the previous year. In April, it was reported that salmon were scarce and that fishing was at a "standstill". However, by September, the Shannon rose six feet over it's summer level. At Tarmonbarry, the country is described as like an "island sea". Athlone's athletic grounds are under three feet of water and Shannonbridge's famous potato crop is destroyed. Farmers around Carrick on Shannon and Roscommon area are the worst affected, with rainfall so heavy that many farmers find themselves in a serious situation.

1930 - After 1930, the idea of an "abnormally wet year" becomes a thing of the past as periods of very heavy rainstorms becomes the climate norm around the Shannon and elsewhere. There is no talk of "climate change". In January, people are once again leaving their homes around the Shannon. In Cork, the River Feale suffers it's worst flooding for 50 years due to a mixture of melting snow and heavy rainstorms, causing considerable destruction to property. The flooding gets so bad that the river changes course at one point, leaving an island two acres in extent, and destroying one of the best salmon pools. An electric pole only just erected some 15 feet from the bank was dislodged by the floods as it ate it's way under it.

The flooding eventually gets so bad around the Rivers Suck and Shannon that houses not flooded since 1924 are inundated with flood water of depths of up to twelve inches high. It is reported that houses "miles away" from the river Shannon are flooded and "rendered uninhabitable". The floods remain at an abnormal level for at least two months. The water rose so fast over a period of two days in January, that families who had moved back in to their homes had to move out once again after these two days. In Killaloe, water reaches the bedside of a sick man who had to be evacuated to safety.

Elsewhere, large areas of land in Offaly become so saturated that no winter ploughing can be done and there is much crop devastation around the River Barrow where it rises three feet above normal levels. Much of the sugar beat crop is lost around Leighlin Bridge and Borris, where weather is described as the "worst for many years". Wide areas are also flooded in North Galway.


After this 1932 had some flooding in areas while 1934 had very low levels of rainfall, the lowest since 1887.  Winter 1936 sees the return of widespread flooding around the Shannon Region while the floods during the winter of 1938 are regarded as the worst since 1924 with floods lasting for over 2 months.

1938 - The year begins with heavy flooding in February and March but by December 1938, the Shannon is at it's highest level since the ESB hydro generation scheme was built. Postmen deliver letters by boat, schoolchildren also travel by boat, food becomes scarce and cowsheds are raised using peat and plants. Like in 2015, many families are left stranded over Christmas. Many farmers are forced to sell their stock for "want of hay". It was reported that over one day, on the 2nd December between 9am and 1pm, 150 tonnes of water fell per acre- "Not within the memory of any old people was such a deluge experienced".

After this, 1942 and 1944 were reported as above average wet years.

1946 - The worst August weather "for a generation". Heavy rainstorms during August force the Government of the day to issue an appeal in September to save the harvest and there are calls for the army to brought in to help. Many crops, including potatoes, had to be imported from Canada and elsewhere as a result of the flood devastation.

Photo of floods in October two month after the initial storms in August (1946)

Things got so bad that the Bishop of Galway ordered that prayers be said for fine weather at all masses in his dioceses on Sundays. Dublin has its heaviest rainfall since 1932.

1947 - Very heavy snowfalls from late January till mid- March, the most persistent cold spell of the century. Five feet depth of snow in some places in the North. On top of this comes heavy rainstorms. The Shannon floods once again but also the River Erne and River Boyne in Co.Meath.

Flooded lands in Co. Meath where "flood waters stretch as far as the eye can see" (1947)

It's reported that it's "the worst outlook for farmers yet". Tractors are equipped with lights for the first time to allow them to operate during the night to save crops. 

 In April, farmers take the ESB to the High Court accusing them of contributing to the "annual flood damage". I would like to find out more about the results of the case but from what I can make out the case was rejected.

1948 - Widespread flooding during January including Cork, Tipperary, Carlow and Meath. However, this time there was not much damage done to crops. Banagher suffers from flooding later on in December.

1949 - Heavy thunderstorms in August followed a day of "oppressive heat" resulting in flooding of houses up to a depth of three feet. "Violent thunderstorms" hit the country later in October, with Dublin the worst hit. The record breaking rainfall for October in 1949 was broken in 2011 by around 2mm.

1950 - Terrential rain in February causes flooding in the Shannon. Wet weather ruins summer in July and the rain continues for ten weeks well into September. A strong storm in September blows down trees and telephone and ESB poles. A very wet year by any standards.

Shannon Floods - Climate or Contour ?

Guest Post by David Whitehead. BA(Mod. Nat.Sc.)TCD, FIMMM, C.Eng.

"The fact that it has manifested in different locations and it's now moving into the Midlands and it's an evolving situation over a number of days... it may well be associated with climate change - Irish Independent, 9th Dec 15.

Has climate change played a role? Although it can’t be said with certainty that the latest flooding was caused by climate change, scientists have for years been predicting increasingly frequent extreme weather. When more than 100 homes flooded in Athlone in 2009, homeowners were told that it was a once-in-100-years event. Six years later a similar event has unfolded. Locals say that the River Shannon was at a record low for October in Athlone just two months ago - Irish Times, 12th December, 2015.

There are several things that need to be borne in mind when listening to the rhetoric about the causes of Flooding in the Shannon basin- which includes about 20%  of the country.

The first is to remember that much of the Basin lies in the western half of the country which receives a much higher annual rainfall than the east and, not surprisingly, has a higher frequency of high and extreme rainfall events.

The second is to be aware that the altitude  at Lough Allen hydro dam sill is 50m above sea level, where it has been artificially held by the ESB  about 5m higher than its natural outlet  level as a holding pond to control the level at Ardnacrusha Hydro power station. The river falls to 45m above sea level at Leitrim and then only another 12m to Killaloe in Co.Clare. Thus the gradient is 17m in 170 km or 10cm per 1km. This slight gradient has to carry the waters of all the river basin to O’Briensbridge   in Co. Limerick .  Only  five shallow locks are required in all this distance to allow navigation for the full 170 km.

From Castleconnell (in North Limerick) to Limerick the fall is  33 m and it is this fall that provides the head for the Ardnacrusha  hydro scheme. More important is the fact that during the last glacial period the natural course of the Shannon was diverted south eastwards  (by an ice dam ) from its natural course from O’Briensbridge to Parteen (in Co.Clare) – which is more or less followed by the Ardnacrusha head race- to its present course where it cut down through and  crosses a ridge  at Castleconnnell. At this point the river bed is at 25m above sea level while the surrounding land rises to 35 on the east side and 65m on the west side of the present river channel. This constriction as well as those further upstream at Shannonbridge and Clonmacnoise, where esker ridges transect the river's course, together with the low- lying shores of the river and the very slight gradient mean it is not possible for the river to carry away even a normal level of winter rainfall – so it expands onto the surrounding callows which flood most years.

When there has been a prolonged period of rainfall and the major lakes are at their highstand and the callows are flooded and the ground is saturated, a heavy rainfall event will inevitably result in extensive flooding of the river banks.

Add to this the urban riparian developments at e.g. Athlone and the extensive covering of previous drainage catchments with tarmac  by Supermarkets, car parks  industrial estate and and domestic residential estates which carry water very swiftly to the river – much more so than agricultural land does and the scene is set for the sort of thing that happened in recent weeks.

I am sure most Irish readers all learned at primary school that the Shannon basin is  a saucer shaped depression – which is a roughly accurate description  and explains why the old cry of “dredge  the Shannon” is not a workable solution unless the gorge at Castleconnell is blasted out to form a much wider and deeper channel  extending all the way to Parteen – a huge, disuptive and very expensive civil engineering work - it will remain saucer shaped and there will be floods at frequent intervals.

Building windmills to generate electricity and punitively bringing the climate under human control by reducing CO2 emissions  will not change these unpalatable realities!