As it was on January 24, Storm Éowyn generated the highest coastal surges ever recorded along Ireland’s western seaboard. The Port of Galway recorded a 2.6m storm surge peak - the highest it has ever recorded in modern times, despite the full force of Éowyn hitting when the tide was ebbing. Limerick docks recorded surges of just under 3m - the height of a single story house above mean sea level.
By analysing sea level information from 47 datasets provided by the Irish National Tide Gauge Network and the Office of Public Works, Galway’s School of Engineering has calculated that had the storm arrived a week earlier during the spring tide, the water level would have reached 4.96 metres in Galway city - the height of a double decker bus - inundating Salthill, the city centre, and other low-lying areas.
With Storm Éowyn winds in County Galway recorded as gusting 184 kmph, wind behind a storm surging tide could have been catastrophic, with flooded roads and floating debris massively complicating the City Council's enormous operation to re-open major road routes as soon as Met Éireann's red warning status was lifted. The knock-on consequences for blue light services responding to emergencies, and ESB and telecoms crews attempting to reconnect power and communications in multiple locations may have been severe and prolonged.
In reality, despite Storm Éowyn damaging power infrastructure, and thereby affecting telecoms and water supplies, the timing of the tides during storm's landfall meant Galway's coastal areas experienced very little flooding impact.
“Despite how devastating Storm Éowyn was - oddly - we were incredibly lucky," said Dr Niall Madden, a mathematician and statistician at University of Galway. "The worst of the storm surge coincided with a low and ebbing tide. Had it hit just a few hours earlier, on a full or flooding tide, Galway could have been dealing with a double disaster of record high winds and record high flooding.”
"The data we have recovered from the hours around Storm Éowyn shows just how narrowly tens of thousands of people avoided tidal inundation [with] threats to cities, towns and coastal communities," said Dr Indiana Olbert of the university's College of Science and Engineering. "It is hard to imagine how narrowly we avoided unprecedented storm surge flooding and inundation, in particular in towns and cities.”
Climate change
Olbert warned that her team's analyses can only become more stark as mean sea levels are rising.
“Extensive research suggests that flooding has increased in frequency and severity in recent decades around the world, and this is attributed to climate change. Our analysis of the drivers of flooding in Ireland shows that the anthropogenic climate change – that is the changes related to human activity - will drive more extreme rainfall and generate more intense flooding. Such changes are likely to continue with further warming.
"In future, we will witness more extreme weather events that will result in devastating floods," she said.
In November 2023, Storm Debi made landfall in Galway during a high tide of 4.9m - well below the 6m local range peak - flooding parts of Salthill, Oranmore and the city centre, and causing millions of euro of damage to homes and businesses, with storm surge waves high enough to lift boats out of the Claddagh Basin, and deposit them on quaysides.
