45,000 homes and businesses at risk of floods as climate change takes hold
Published 23/11/2015 | 02:30
At least 45,000 homes and businesses are at risk of flooding but more will be threatened as climate change takes hold.
The Office of Public Works (OPW) has warned that global warming will "make flooding worse" in the future, due to more intense rainfall and a rise in sea levels, which will impact on low-lying areas.
Some 300 areas of the country have been identified as being at a high risk of flooding and the OPW has produced detailed maps of some 6,700km of waterway which outline the areas most likely to flood.
Around 90 coastal communities are at risk, while other properties face being inundated as rivers burst their banks following periods of intense rainfall.
A spokesman said that around 25,000 coastal properties were at risk, and another 40,000-45,000 are threatened by fluvial, or river, flooding.
Some properties could be at risk from both.
A document produced as part of a statutory public consultation says that increases in annual rainfall and sea level rises of as much as one metre by the end of the century will heighten the risk in some areas.
"It is expected that the projected changes in our climate will make flooding worse into the future," the OPW said in a consultation document.
"Average sea levels, for example, are known to be rising and this rise is accelerating."
The detail is contained in documents published as part of a public consultation on draft flood maps produced for 300 areas across the country.
It comes after the Irish Independent revealed over the weekend that the country has become warmer and wetter in the last 50 years as climate change takes hold, with most parts of the country experiencing at least an extra seven days of rainfall a year.
The flood maps have been produced as part of the development of a National Flood Relief Plan. This will set out the areas needing investment to reduce risk.
They were produced after 6,700km of watercourses were surveyed and modelled and some 40,000 individual maps are now subject to public consultation.
The manager of the National CFRAM (Catchment Flood Risk Assessment and Management) programme, John Martin, said some properties could be subject to risk from both coastal and fluvial flooding.
He explained: "We have worked on them since 2011, and we went to each of the 300 areas where we showed communities the maps and took comments on board.
"What's important is that this is predictive mapping, trying to understand areas which might be at risk.
"We can now identify what portions of those areas are liable to flooding. We can identify the low or weak points of the river banks where flooding might occur.
"In terms of numbers, we haven't done the intensive analysis on the number of properties (at risk). This analysis allows us to come up with the figures of where the highest levels of risk are."
He said that among the highest areas at risk are Cork, Dublin and Limerick cities, in part because so much of the built-up areas have been developed, meaning that water cannot be absorbed into the ground.
Mr Martin also said that the maps allowed for increased river flows and sea-level rises to be modelled.
"The maps do not incorporate climate change," he added. "That's important because the likelihood of flood risk becoming worse due to climate change is very significant and very real.
"Once we have the current scenario correct, we can introduce additional river flow, or sea level rise, or rainfall run off.
"Getting the baseline data is the most critical bit. Adding climate data is not easy, but you have a baseline, which is reliable."
Cork has the highest number of at-risk areas, at 33, followed by Donegal with 28. In Connacht, Galway has 15 areas under threat, while Dublin has 26.
Once the maps are finalised, areas which would benefit from defences will be identified.
In some places, it may not make economic sense to invest in large-scale projects, but minor works could be undertaken, coupled with measures to protect individual properties.
The Government has previously indicated that as much as €1bn would be required to make these areas safe.
In the capital plan, published in September, some €430m was allocated until 2021 under the flood-protection programme.
The maps can be viewed at www.cfram.ie.