Cork county was under an orange weather warning on the day that a one-in-227-year flooding event hit the town of Midleton, which submerged the bottom floors of 682 properties in dark, sludgy water.
Storm Babet dumped a month’s worth of rain on Midleton and its surrounds over 36 hours on October 17th and 18th, 2023. The Owenacurra and Dungourney rivers burst their banks and rain overwhelmed the drains.
Like most people, Midleton resident Caroline Leahy didn’t think much of the orange warning. Her husband was at home and went out to get a coffee when he realised something was wrong.
Their house flooded quickly. “Within 10 minutes, water was coming in the front and back doors. It reached 3ft inside, so it was kitchen countertop height. The whole downstairs was a right-off. There was a car floating down the street at the back of the house,” said Leahy.
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The problem with these county-wide warnings issued by Met Éireann, said Indiana Olbert, lecturer in engineering at the University of Galway, is that they lack “granularity” and don’t account for the complex forces that make specific places more at risk.
She used the devastating floods in Cork city in 2009 as an example: “We call it compound [flooding], which means there are a number of drivers that did the flooding. And the main one is the river.” Heavy rain fell in the mountains in the north and drained into two reservoirs making it “difficult to manage”, explained Olbert.
“But the second big driver is seawater levels that propagate from far off from Atlantic oceans thousands kilometres away ... [The storm] surge moves into the harbour, in this case Cork harbour, and travels up the way north to an estuary of the river Lee. And where the two waves meet, the river and a seawater level, it’s actually Cork city.”
Six months after the flood in Midleton, researchers from the World Weather Attribution group at Imperial College London said the town had “dodged a bullet” due to the low spring tide that allowed the river water to flow into the sea. Although the river water level was 2.5m higher than normal, the sea was just 78cm above normal, meaning properties closest to the sea were the least affected.
Galway city similarly got “lucky” during Storm Éowyn in January of this year, said Olbert, because the storm surge gathering in the Atlantic hit the coast at a relatively low tide.
As the climate warms, however, researchers predict that these intense rainfall events will happen much more frequently and will affect places that were not previously vulnerable to flooding.
To understand the future climate in Ireland and prepare better for the risks, Met Éireann announced it would award a total of €2.8 million in funding to six research teams across University College Cork, the University of Galway and Maynooth University last month. They are tasked with devising short- and long-term predictions about the changing climate and strategies to adapt our infrastructure to those scenarios.
As one of the recipients of the funding, Olbert and her colleagues will develop a “sophisticated” flood forecast using artificial intelligence and pilot it in Cork, Limerick and Galway. This would give local authorities, residents and businesses information so detailed that each street can get a sense of how likely it is that they will be under water.
“It’s a very short-term forecast, a three-day forecast, to predict if the flood might occur and, if so, where specifically so all the resources, people, sandbags and barriers can be placed in the right place and at the right time”, said Olbert.
The five other research teams will largely continue their work on the TRANSLATE project, which has produced a standard national climate and weather prediction model – a bible if you will – with which Government departments, local authorities, businesses and homeowners can plan for the future.
The team managed by Enda O’Brien, computational scientist at the Irish Centre for High-End Computing, will produce maps that offer insights into how the climate of each 2km² on the island is likely to change under various emissions pathways. They will also be making an “experimental” climate forecast for the next 10 years.
O’Brien hypothesises that if global temperatures increase between 2 degrees and 3 degrees by 2100 compared with pre-industrial times, the frequency of events where more than 12.5mm of rain falls within three hours will double or triple all over the country. This change will be “quite dramatic”, said O’Brien “where they were relatively scarce historically”, such as in the midlands and in Ulster.
O’Brien’s calculations produce “return periods” for extreme rainfall events – the length of time in which an equivalent storm can be expected to occur in that place again. Planners and engineers use these return periods to design roads, drains and other infrastructure to endure and manage flooding.
“There is a real-world impact of these numbers”, explained O’Brien.
The real-world impact is the expertise of the flood risk management and climate adaptation division of the Office of Public Works (OPW).
Mark Adamson, who heads up the division, acknowledged the additional risks posed by climate change. In Limerick, he says, a “100-year flood today would cause about €90 million of damage”. Whereas if that were to occur “once we’ve already had a metre of sea level rise, then the damage goes up to over a billion [euro]”.
He said “[W]e are progressing the current flood relief programme as fast as we can and we are doing that with an eye towards the future in terms of climate change. We’re not just building for now and hoping for the best. We are looking forwards.”
However, progress is slow. Galway City Council announced in June that work on the “Coirib go Cósta” flood relief scheme will not begin until 2030. It will be designed to protect the city’s inhabitants against one-in-200-year coastal flooding events and one-in-100-year river flooding events.
According to Olbert, the current problem with flooding in urban areas traces back to the decision in the Middle Ages to build towns on bog land near coasts and rivers. Cork city was “a site where people should never have moved in. We just started to build on it, and built the centre of the city around it.
“But the thing is that we still tend to build in places without looking at the current situation and what’s coming in the very near future ... I don’t think we’re very good at incorporating future risks,” said Olbert.
Adamson’s reasoning was that “If we banned all development and redevelopment in flood zones, all of our urban centres would simply decay over time.”
Under pressure from local authorities and residents of flood-prone areas, Minister of State Kevin “Boxer” Moran announced last month that the OPW would make additional funding available to local authorities for small-scale flood relief and coastal erosion protection works.
Construction of the Midleton permanent flood relief scheme is due to begin in 2027. In the meantime, the town’s residents face the prospect of more floods without insurance, an early warning system and adequate defences.
“So many people are really scared in the winter and the rain. People won’t even stay away one night from their home at all, even in the summer,” said Leahy.
“It’s a very hard thing to be scared in your own home.”
