Kathriona Devereux: Should Cork take the plunge... and construct a tidal barrier?

How will we make changes to cope with the more regular occurrence of extreme weather events? asks Kathriona Devereux in her weekly column
Kathriona Devereux: Should Cork take the plunge... and construct a tidal barrier?

ONGOING PROBLEM: Flooding on Fr Mathew Quay in Cork city last November. Picture: Eddie O’Hare

IT wasn’t your imagination — February was very wet. Parts of Ireland received three times the amount of rain than an average February.

Watching the Shannon flood victims grapple with the devastation of flooding a mere four years since their last major flood event is heart-breaking. The stress and distress of having your home or business flooded is hard to imagine.

Many Corkonians don’t have to imagine and can fully empathise, because Cork residents and business owners have endured serious flood events in the past. And, without intervention, will endure them again.

As we continue to burn fossil fuels, warm the planet and change the climate, we have to take two courses of action. Firstly, mitigation, reduce and stop our use of fossil fuels to slow (and eventually stop) global warming.

Even if the whole world gave up fossil fuels tomorrow, we are locked into changes that have started already and we are looking at an increased global temperatures of approximately 1.5 to 2 degrees by 2050. This will bring about a sea level rise of half a metre in the next 30 years.

If we don’t change our ways, we are looking at greater temperature increases and higher sea level rises. And more flooding.

Which leads to adaptation. How will we make changes to cope with the more regular occurrence of extreme weather events?

Flood defence for Cork is a hot topic that has got bogged down in disagreement.

The Office of Public Works’ (OPW) Lower Lee Flood Relief Scheme plans to build and raise quay walls and pumping stations around the city. Opponents to the scheme want the ESB dams to protect Cork city from river flooding and want a tidal barrier constructed to protect the city from tidal surges.

Tidal barriers are nothing new — the Thames Barrier has been in place since 1983, protecting £200billion worth of property and 1.3 million people who live on the city’s flood plains.

London has plans to extend its defences and is actively planning how it manages flood risk up to the year 2100.

The Thames Estuary 2100 Plan (TE2100) will protect Londoners from the predicted rise in sea levels of 90cm by 2100, but is adaptable up to a worst case scenario of a 2.7 metre sea level rise by 2100.

It’s projected that the first 25 years of TE2100 will cost an estimated €1.5billion.

In Ireland, where we’ve lost all sense of meaning when it comes to the placement of zeros and decimal points, €1.5billion doesn’t seem outlandish if you add up all the human heartache and potential insurance claims of the future.

In The Netherlands, where half of the country is prone to flooding and a quarter of the country is below sea level, flood defences are part of life.

At the port of Rotterdam, a colossal tidal barrier called the Maeslantkering — the size of two Eiffel towers toppled over — is designed to protect the port city during a tidal storm surge from the North Sea. It cost €450 million and took six years to build.

It’s a tremendous feat of engineering, but in The Netherlands, after decades of hard engineering solutions, they are also embracing the idea of ‘room for the river’.

With rising sea levels and increased extreme rainfall events, the Dutch are accepting that flood events are going to happen and are re-designing urban landscapes to allow for it.

This push back against hard engineering solutions is one of the arguments against the OPW’s €140million Lower Lee Flood Relief Scheme.

Opponents of the scheme say relying on demountable defences and pumping stations leaves the city exposed if technology fails or someone makes a mistake.

Last August, the residents of Coonagh, Co. Limerick, were badly flooded after the highest recorded tidal surge of the year, combined with double the average rainfall, a sluice gate at a flood defence was left open and people’s homes were destroyed. The Office of Public Works apologised for its role in the flood.

Elsewhere, Clonmel in Co. Tipperary has a successful demountable flood defence system installed, while Galway is protected by an inflatable Aquadam — an effective, but temporary and unsightly, solution to the Atlantic ocean pouring over the quay walls at the Spanish Arch.

The OPW say that the Lower Lee Flood Relief scheme will protect 900 homes and 1,200 businesses but it will not protect the areas east of the city centre containing the Docklands and Tivoli Docks which are earmarked for development and major regeneration.

In the Italian city of Venice, the €6billion Mose floodgate project has been bogged down in controversy. Plans for it started in the 1980s and the project is still not operational.

The devastating flood that hit Venice last year caused authorities to declare a state of emergency, and demonstrates how delayed defences cause destruction.

In Ireland, we have a poor track record of completing major infrastructural projects on time and on budget. The OPW question if a tidal barrier can be built in Cork for €140million.

Supporters of the tidal barrier solution say it will be easier, cheaper and less disruptive to deliver and will offer better protection because when Cork city floods, everyone knows flood water comes up sinks and toilets and not just over quay walls.

Great cities around the world have tidal barriers — London, Rotterdam, St Petersburg.

Should Cork be ambitious and join that list, and become an example for future tidal barriers that may be needed in Limerick or Dublin by 2050?

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