Dublin’s flood defenses are protection against rising sea levels

Dublin’s flood defenses are designed to protect the capital against sea level rises “to the end of the century” according to Dublin City Council’s most senior flooding expert.

A study by scientists at Maynooth University, published in academic journal Ocean Science in recent days, confirmed the sea in Dublin Bay is rising at approximately double the rate of global sea levels.

The research project, led by the Hamilton Institute and ICARUS Climate Research Centre, found sea levels in the bay are rising faster than climate change models had predicted.

Gerry O’Connell of the council’s flood projects and flood warning division, said the division had supplied data to the project and had been aware of the higher rates of sea-level rise in the bay for many years.

“We have recorded about 130ml in Dublin Bay in the last, more or less, 20 years so that’s about twice the global average, but we have incorporated that into our flood designs and our flood responses.”

About 20,000 properties are at significant flood risk in the city, but most are already protected by flood defences. For areas where new defenses are planned, interim measures have been put in place to protect against flooding Mr O’Connell said.

“All the flood defenses have taken estimated sea level rise up to the end of the century,” Mr O’Connell said, incorporating the analysis of the trends seen over the last 20 years.

“In places we have new flood defenses planned, like in Sandymount and Clontarf they will incorporate that too, but currently we have temporary measures which take care of the current sea level risk,” he said.

“We also have flood warning systems and we can put temporary measures and sandbags in place depending on what level of sea and wave action we are anticipating.”

The council hopes to start work on the Sandymount promenade flood defenses later this year or early next year and is at the design stage for the flood scheme in Clontarf and north of the promenade in Sandymount.

The council in 2008 secured permission from An Bord Pleanála for flood defenses in Clontarf, one of the main victims of extreme tidal flooding in 2002. However, they were rejected by locals largely on the grounds they would spoil the view of the bay.

The council offered to reduce the height of the protective embankment, but this also met resistance. Eighteen months ago it came forward with a new scheme, which it hopes to submit to An Bord Pleanála in 2023 following more public consultation. In the meantime, large yellow sandbags remain stationed along the coast.

Separately protections have been implemented and are continuing on Dublin’s three main rivers – the Liffey, the Tolka and the Dodder.

While cities by their nature have higher flood risks due to lower levels of vegetation and the extent of hard surfaces, Dublin has inherent disadvantages due to its extensive coastline and reclaimed lands.

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