Which of Ireland’s coastal areas are most at risk from flooding and erosion? Which places are frequently hit by storms and wave over-topping? Which beaches – beloved by generations of Irish families – are in danger of being washed away? Which communities might eventually have to face relocation as their areas become more vulnerable?

Now we have the data to address these questions, thanks to research which revealed the places and communities most likely to be adversely affected by coastal hazards like flooding and erosion. A study by researchers from the EPA-funded DETECT project at University College Cork examined the entire Irish coastline at 250m (820ft) intervals. Each coastal segment was classified from “very low” to “very high exposure”.

The geographical distribution of coastal hazards varies considerably across the country – some coastlines are frequently impacted by storm waves and winds; others are composed of soft, easily erodible material; and some are low-lying and prone to flooding from storm surges.

Areas where these elements combine – Ireland’s very high exposure coastlines – are vulnerable to a perfect storm of climate hazards.

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The coastal communities around Ireland living within these exposure “hotspots” – defined in the study as an area within 500m of a very high exposure coastline – are battling numerous challenges. Hotspots are to be found in every county, and while many are sparsely populated, hotspots in urbanised coasts, like the five in our map, reveal just how many people and homes could be at risk.

In the area surrounding Salthill in Galway city, for example, an estimated 7,500 people live within an exposure hotspot. This area is prone to coastal flooding from wave overtopping and storm surges. These can be particularly destructive when combined with high tides and driving southwesterly winds, as was seen in Galway during Storm Debi in 2023.

In Dublin city, Sandymount and Clontarf were also revealed by our research to be significant coastal exposure hotspots. These hotspots are home to an estimated 6,301 and 4,466 residents respectively.

Coastal flooding has been a long-standing issue for these low-lying suburbs. And while both areas having existing defences in place, they require upgrading due to deterioration and also to account for rising sea levels.

Plans to improve coastal flood barriers for these and many other areas around the country are currently under way. However, contentions over design plans have frequently led to delays in implementation, with local councils often resorting to temporary measures such as sand bags to reduce the impacts of flooding.

Engineered coastal flood defences are typically designed to withstand a one-in-200 year flood event, but growing evidence of storms increasing in frequency and severity means such events may occur much more often than that. Future defences must also account for rising sea levels, with 25cm above present levels planned for Galway city, for example. Projections of global sea levels vary, but they could rise 1.1m above 1900 levels by the year 2100 under high greenhouse gas emissions scenarios. Together, these factors risk shortening the lifespan of coastal defences, locking communities into repeated, costly cycles of upgrading and replacing defence infrastructure.

The primary concern for other parts of the country is erosion. Exposure hotspots encompassing Bettystown and Laytown in Meath, and Rush and Portrane in Dublin are each home to over 4,000 residents – with homes, businesses and infrastructure located just metres from an encroaching shoreline. There has also been a noted depletion of sand from the beaches adjacent the Bettystown and Portrane. In both instances, this sand appears to have been deposited further to the north.

Such movement is part of the natural process of longshore drift. A series of groynes have been used at Pilmore beach near Youghal in Co Cork (another hotspot location with almost 2,000 exposed residents) to limit longshore drift for decades. However, issues of erosion continue to persist.

Previous mitigation strategies in these areas have relied on a “hold the line” approach, which strives to maintain the coastline in a static position, often through use of hard, engineered coastal defences. However, these can cause reflected wave energy to pull sand away from a beach – which not only does harm to the amenity value of the beach, it also starves the local dune vegetation of the sand it needs to develop.

Coastal regions are highly dynamic, interconnected systems. Any intervention needs to be carefully planned and monitored. Working with nature, rather than against it, is often the wisest move.

[ Ireland must prepare ‘evacuation’ plans for coastal areas as climate change intensifies, says expertOpens in new window ]

There are numerous, community-led initiatives to restore coastal habitats along Ireland’s coast – such as those ongoing in the Maharees peninsula in Co Kerry and Seafield in Co Clare. These can serve as case studies for the efficacy of nature-based-solutions for coastal protection.

New housing or infrastructural developments cannot be located in high exposure areas. Governments must invest in initiatives that build local knowledge – ensuring those most vulnerable to these hazards are also the most informed.

Kevin Walsh is a geoscientist and a PhD student in the Geography Department at UCC.

© The Irish Times