Mayo's coastline faces largest level of threat from erosion and flooding in the state

Mayo has the longest stretch of "Very High Exposure" coastline in the country, according to the first national map of Ireland's climate hazard risk, published this week by University College Cork.

The Coastal Exposure Index, developed by researchers at UCC's Earth and Ocean Lab, assessed 8,575km of the Irish coastline at 250-metre intervals. Researchers combined 30 years of wind and wave data with information on sea-level rise, storm surges, shoreline type, coastal relief and natural habitats to produce the index.

Mayo recorded 414.5km of coastline classified as "Very High Exposure," the greatest extent of any county in the State.

Communities along Blacksod Bay and Clew Bay were identified as being among the most at risk. Much of the Mullet peninsula falls into the highest risk category, along with areas around Geesala, Doohoma and Ballycroy.

Parts of Achill and the Currane peninsula were also flagged as areas of very high exposure, as was the coastline around Carrowniskey beach near Louisburgh. Sections of Westport and Kilmeena were classed as very high, high and moderate exposure.

The north Mayo coast fared better in the study, with most of that stretch rated low or very low exposure.

Study lead Kevin Walsh, a geoscientist with the DETECT project at UCC, said the research gives, for the first time, a consistent national picture of coastal exposure. "What is particularly clear is that exposure varies considerably from place to place, meaning effective adaptation must take account of local coastal conditions," he said.

Mr Walsh said Ireland's natural coastal habitats are a critical line of defence. "Dunes, saltmarshes, machair and seagrass can help protect our coastline, communities and heritage from growing climate pressures. Protecting and restoring these habitats must be a priority in Ireland's coastal adaptation response," he said.

The study found that natural features such as sand dunes, saltmarsh, machair and seagrass have the potential to reduce exposure along 38 per cent of the Irish coastline by lessening wave impact and stabilising shorelines.

Dr Aaron Lim, Senior Lecturer in Marine Geosciences at UCC and Head of the Earth and Ocean Lab, said the index gives Ireland the chance to plan ahead rather than react after the fact.

"The decisions we make over the coming decade will shape how well our communities, infrastructure, businesses and cultural heritage can adapt to rising seas, coastal flooding and erosion," Dr Lim said.

The study also found that cultural heritage sites along the coast are at risk nationally, with one in five of the 8,871 registered heritage sites within 500 metres of the coast falling inside "Very High Exposure" zones.

Researchers say the index will support government bodies, local authorities and coastal communities in identifying areas that need closer assessment and in prioritising adaptation measures. An interactive online map has also been launched, allowing members of the public to explore exposure levels along their own stretch of coast.