Local effects of climate change: protecting Dublin from flood risks

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Ireland has experienced devastating floods in recent years which has affected thousands of people and caused millions of Euros worth of damage. Nowhere in Ireland has remained untouched by the deluges now part of our annual weather pattern. I met with Ray McGrath from the National Weather Centre to find out how Ireland is being affected. Ray have we seen changes in our weather patterns in recent years? Well in the case of rainfall it looks like there has been an increase in the amount of rainfall that is falling over Ireland. And is it more deluges of rain or what’s the pattern? The heavier rainfall events have increased in frequency. Are we seeing changes in our oceans also? Yes. The most obvious change is that the temperatures in the oceans are increasing and this is leading to more moisture being pushed into the atmosphere. That of course means that there is a greater potential for more extreme weather.

Of course this is more likely to lead to flooding events. The east coast is now susceptible to surge events bringing higher than usual tides which combine into perfect storm scenarios such as what happened in 2002. The way it works is the surge actually sucks up the ocean surface and this in combination with a wind which may be pumping, pushing the water towards the coastline this is what effectively creates the surge conditions. If this happens to coincide with a high tide, it obviously worsens it so you can get a much greater surge effect affecting the coastline and the research we have done in Met Éireann it does indeed suggest that in the future climate change will bring more intense surge events to these coastlines. Being on the frontline is something Dubliners have known about for a long time. 200 years ago Dublin was a sea port on a wide estuary surrounded by marshland. We’ve a long history of reclaiming land that was liable for flooding but back then the big storm was looked on as a rare event.

Not anymore. The residents of Dublin’s East Wall were badly hit in 2002 and have been living in fear of another storm ever since. Most of it came from the sea originally to that point but it was a mixture of canal and sea water because it came up the Liffey, up the canal and of course once the canal level went too high it overflowed. It was terrifying for me walking around in it I have to admit but in saying that, the elderly people and to look at their faces, and to look at their homes devastated with the dirt five foot up the walls; it was absolutely horrendous. We were out of the house for 7 months. Had to get the builders in: floors, walls, furniture everything thrown out, rip it all up. It wasn’t just a matter of drying out stuff, this stuff was destroyed. Over €6 million has been spent in the risk area on defences and early warning systems have been put in place to give the residents the highest levels of alert.

There is a number of defences put out there. There’s a monitor out at the Kish which’ll give us advanced warning of the sea and there’s depth warnings in both of the rivers in the Tolka and in the Liffey which at least is a help. At least we will know in advance if something is going to happen. Dublin City Council has an emergency plan coming into force soon. We have a lot of volunteers in the area, at the moment we have the church set up in case of an emergency that we can bring people, particularly the elderly. It’s the elderly and the infirm we need to get out of the area quickly if we did have another flood. The changes coming mean rethinking our strategies for everything: from river and sea defences, to where we build and live in the future.

Mark Adamson from the OPW showed me the first line of flood defences for Ringsend being built on the Dodder by Dublin City Council. These are flood protection works that we are currently building to protect against tidal flooding, such as the very severe event that happened in February 2002 here in Ringsend. What happened? Well the sea level came up the river and spilled over the banks flooding some areas to a depth of maybe 3 metres so the wall we are currently leaning on here is to protect against exactly that kind of flooding. So all of these houses here were flooded in 2002? That’s right yes. So what are they actually doing? Well over here they’re currently putting in piles and they’ll be building a defence wall to protect against the high sea levels. So what sort of work have we got to do in the future to protect us against what’s coming with flooding? Well we’ll obviously keep building flood protection schemes such as these for areas of significant existing risk. We’re also producing flood maps to identify other areas that are at risk or that could be at risk if people were to build in them.

The massive development that has changed the face of our cities over the last 10 years hides what’s happening beneath our feet. Under the millions of tonnes of concrete, are water courses now cut off and rivers and streams we’ve diverted. Tom Leahy told me about the Dublin City Council strategies to future-proof the city. we’ve seen some big floods in recent years are we going to see more floods in Dublin? Well Duncan, Dublin is located in the floodplain of 3 major rivers. 200 years ago the land we’re standing on was once under the sea. That’s just one of the challenges we face. Over the years Dublin has grown. It’s been intensively developed, houses wherever you see and we’ve changed water courses as well. So each of those poses its own challenge and hazard which we have to deal with. So how are you going to deal with these sorts of challenges? Well we have noticed that the weather patterns have changed quite significantly. We’ve also noticed the phenomenon called pluvial flooding, now that’s a very technical term, the Dutch have a much better name they call it “monster rain”.

What it means is very heavy monsoon-like rainfall that falls over a short period of time will overwhelm any drainage system. So that’s a challenge, one of the challenges we’re going to have to deal with. Is this the sort of flooding we’ve seen in the last couple of years? Yes, particularly last August and September that’s exactly what happened to Dublin. We had 3 floods in 2 months and the intensities were the sort of recurrence period that would be one in 150 years. Dublin City Council’s new strategy is being created and funded in tandem with European partners who face the same problems we do. The Flood Resilient Cities Programme follows on from the Safer Programme and looks to deal with the effects of “monster rain”. Well the sort of things that we can do, we can look at ways to control water flow at source, we’ve also identified the areas that might be at risk and logically they’re close to the coast and then if we know there is a high risk at a particular time we can mobilise all the resources of the State, fire brigade, emergency services, our own City Council personnel.

We can also link in with householders because everybody has a part to play in making their own property that little bit more flood resilient. When the next flood comes another team ready are Commandant John Moriarty’s Civil Defence volunteers. They’ll be on the front line to back up the fire brigade and I joined them on one of their drills. We learned a lot from the floods back in 2002 where we didn’t have the equipment; people were going into flooded areas and contaminated water in fire gear whereas now we have dry suits to protect them and so on. They’ve been trained by Dublin Fire Brigade in water awareness; our boat people obviously are trained in relation to water and so on. So there’s been a lot of training has been going on over the past number of years and we’ve also a lot of vehicles, a lot of four wheel drive vehicles which are very suitable for the flooding scenarios. Right guys how’s it going there? There is a way of laying these is there? There is a way of laying them yeah. You bring them close to each other first is it? Yes.

It’s the first line across and the next ones go in between and you can see where they cause the seal here. And that’ll totally seal water? That’ll totally seal and have a look at the door we went in with a line then right across the front of the lower part of the lower sandbag as well when we were finished building up. The fear at the back of my mind is that we get the combination of torrential rain with a very high tide and onshore winds and we get a combination of coastal flooding and torrential rain and rivers overflowing. That’s kind of a nightmare scenario. Flooding is a problem we all share throughout Ireland. As an act of nature it can’t be totally avoided, but we can lessen its worst effects. As we look for the solutions for the future we should focus on the underlying causes of climate change that we are currently failing to address..

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