Barrage move could stave off Ennis flooding disaster

GRIM predictions of rising sea levels has prompted a renewed call for the relocation of the Clarecastle tidal barrage downstream to safeguard Ennis from “rapid flooding on an unprecedented scale”.

Chartered building surveyor Fergus Merriman is concerned about scientific reports predicting sea level changes upwards of 600 mm in just five years and what that will mean for Ennis and other vulnerable Clare areas.

Other forecasts indicate the glacier in the in Antarctica is rapidly breaking apart and could raise sea levels by over two or possibly three feet.

Even if the lowest predictions of sea level change come to fruition and national and local governments don’t act soon then Ennis would be in trouble, said Mr Merriman.

He warned this can’t be addressed by continuing to raise earth dams, which are at risk of “rotational shear” when the weight of water on one side topples the weight of the earth on the other – an issue that led to massive flooding in Holland in the past.

“This is a real risk to large parts of Ennis that think they are safe behind an earthen wall not designed for sea level surcharge,” said Mr Merriman.

“Leadership is needed to fast-track the proposals for relocating a fit-for-purpose barrage to the obvious location downstream of Clarecastle where it could safeguard the entire Ennis basin at a stroke and cope with sudden sea level change.

“We could see the sudden and permanent inundation of Ennis, the central commercial area permanently flooded and thousands of houses destroyed with perhaps loss of life too if earth embankments suddenly failed at night as has occurred elsewhere due to storm surge only.”

While the barrage slows the tide coming into Ennis, Mr Merriman pointed out it doesn’t stop it fully and isn’t working properly.

In an interview with the Clare Champion, he said the structure of the barrage needs to be thoroughly examined.

New turbines could be installed for the relocated barrage to generate 300 kilowatts of power, which could be reversed into pumps to pump out water in times of high tide and flooding.

If the new barrage was constructed in a dry dock in Limerick before it was floated in sections into place in a cost effective manner, he estimated that it could be put in place for about €20m.

One of the advantages of his plan is huge tracts of land to the East of Ennis that are currently regularly flooded during periods of high rainfall in the winter could now be developed for commercial and residential purposes.

“You could use the River Fergus for leisure purposes with the provision of a lock, which you can’t do at the moment. Pleasure boats for tourists and visitors could go up and down the river. We see examples of this plan working around the world with lots of benefits. At the moment we are spending huge sums of money building higher and higher walls.”

“I remember when I was younger bringing my daughter to feed the ducks along the quays in Ennis, which we can’t do anymore.”

A new barrage situated between existing natural higher ground on each side of the river would protect the greater Ennis basin from tidal influence, generate energy, allow shipping to pass and actively control river levels to prevent flooding.

During storm flood or tidal surge events the barrage closes and the newly formed basin acts to attenuate the river flow while tide rises beyond a set point.

If the attenuation pond peaks, the turbines are energised to pump out excess water to sea to actively prevent surcharge beyond pre determined levels.

Mr Merriman believes this project can host a wide variety of value centres to create a vibrant locality attracting high net worth individuals from local, national and international customers year round including a 400 berth marina, water sports facilities, sailing training centre, sail boarding and rowing centre, boatyard and marine engine workshop.