We need to prepare for a world of more rain and floods

The recent floods in Midleton have had a shattering impact on the local community and businesses. It’s hard for anyone who hasn’t personally experienced the damage wrought by flood waters to fully comprehend the scale of the disaster for those affected. Because flood waters are contaminated by sewers, the affected buildings have to be completely gutted, and most of the contents thrown out.

While occasional flooding has always been with us, the changing climate is making things much worse. The International Panel on Climate Change has said: “It is very likely that heavy precipitation events will intensify and become more frequent in most regions with additional global warming.”

In early September, a devastating rainstorm in Greece’s Volos region was on a scale never previously recorded – where recorded weather events go back 3,000 years to Homer’s time. This storm destroyed a quarter of Greek agricultural land, drowned up to 100,000 animals and resulted in a number of deaths. It then moved on to Libya, resulting in thousands of deaths. Storm Elias then battered Volos again three weeks later.

The frequency of extreme weather events, and the destruction they cause, has been rising. While not all floods can be prevented, it is essential that Ireland invests in flood defences to deal with future exceptional weather events.

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The National Adaptation Framework, published in 2019, was the first set of consistent Government plans on how best to deal with the consequences of climate change. One of the most detailed sectoral plans was the Office of Public Works (OPW) Flood Risk Management Plan. Using the latest available research, the OPW mapped out the whole country, showing the likelihood of flooding occurring in each location in the coming years.

The plan estimates that 95 per cent of properties at risk within the communities assessed to be liable to flooding can be protected by flood relief schemes

Based on this evidence, a programme of remedial works has been incorporated into the National Development Plan to try to prevent future floods. The works are prioritised based on the probability that a flood will occur in the immediate future and the potential consequences if it does: how many households and businesses will be affected. The plan estimates that 95 per cent of properties at risk within the communities assessed to be liable to flooding can be protected by flood relief schemes.

While these plans recognised that Midleton was at risk, and it was next in the queue for action, that is too late for all concerned. The growing impact of climate change argues for accelerating flood protection work in the National Development Plan.

In line with OPW’s plans, we need to direct additional civil engineering resources towards flood prevention. Of course, with limited resources, this will mean less available for other priorities, but this is one of the costs of climate change.

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The flood maps for Ireland show, unsurprisingly, that Cork city centre is at high risk of flooding – it has been a frequent event in recent decades. However, given its hilly nature, most of the rest of the city is not very vulnerable.

If we are to protect our cities later in this century, planning for such infrastructure should begin today. Better to do it too early rather than, as in the case of Midleton, too late

By contrast, the flood maps show a large portion of Dublin being potentially at risk. Flooding is seen as a possibility covering an area from near Croke Park and southwards to Butt Bridge, TCD, Ringsend, and all of Sandymount. The chances of such a catastrophic flood are currently assessed as a one in 200-year event. However, the OPW study also shows that such an event could become much more likely if sea level rises by half a metre, and a really frequent event if sea level rises by a full metre. Scientists tell us that, as a result of global warming, ice is melting ever faster in Greenland and the Antarctic. Even if the temperature rise were halted today, melting ice will cause the sea level to continue rising for the rest of the century.

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To prevent a possible catastrophic flood of Dublin, Cork or Limerick, could take a huge investment in flood defences. Experience elsewhere in the Netherlands and London shows that such defences take decades to construct. If we are to protect our cities later in this century, planning for such infrastructure should begin today. Better to do it too early rather than, as in the case of Midleton, too late.

We also need to invest in nature-based solutions, such as strategic planting of trees and other vegetation that raise the capacity of soils to absorb water. Fifty years ago we moved into our home, which had a sodden back garden, and planted a silver birch. We have never had a waterlogged garden since, as the tree’s roots have absorbed excess water.