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Deluges and devastation

On the Edge


On The Edge
Áine Ryan

AN expert report into the devastating Dooncarton landslide in Erris on September 19, 2003 concluded that ‘the expected frequency of such an event is once in 100 years’.
Tell that to Donegal woman Bernie Kearney who was sitting in her bungalow in Urris, Donegal, eating her dinner shortly after 8.30pm on Tuesday, August 22, when she heard a loud bang and then witnessed her entire kitchen flung across the room while her car was pushed through the side of her house. Unable to escape through her front door she managed to jump out a window onto her front lawn and is since living with family members.
I bet such scientific projections are little comfort to this victim of a landslide up the coast.
The executive summary of the Tobin Report, commissioned by Mayo County Council, states that on the dramatic night in Dooncarton, almost 14 years ago, an ‘intense localised rainfall caused multiple landslides on the slopes of Dooncarton and Barnachuille mountains’.
“The primary cause of the more than 40 separate landslides in the Pollathomas area was exceptional rainfall, of such intensity as to overwhelm natural drainage systems in the peat and weathered rock, thereby mobilising sections of overburden through buoyancy and gravitational forces.”
Rainfall analysis revealed that 80 millimetres of water fell on the slopes of these mountains in less than two hours.  
“The expected frequency of such an event is once in 100 years. The localised nature of the event is underlined by the wide variation in the response of rivers in the area, with peak flood records being broken on the Bellanaboy catchment, even as the adjacent Glenamoy catchment, less than six miles away, recorded no impact whatever from the event,” it concluded.
On the night of the Dooncarton landslide 200,000 cubic metres of debris swept down the mountain, leaving 42 families homeless or forced to vacate their homes for varying lengths of time, killing hundreds of livestock, destroying the local graveyard and sweeping interred remains out to sea. It was a miracle that nobody was killed during this catastrophic three-hour deluge of precipitation. The infrastructure of this remote area was destroyed with 20 bridges having to be repaired or replaced in the aftermath.
The Geological Survey of Ireland concluded that while historic rock-formation faults existed in the area, the impact of the exceptional amount of rainfall, which caused the peat bog to slide, was exacerbated by the shrinking and shriveling of roots after a long dry summer.
I live under a hill and don’t want to even imagine how terrifying it would be to be the victim of a landslide. On way too many nights this summer we have all awoken to the pitter-patter of rainfall; except it isn’t pitter-pattering, it is thumping and thundering down on our roofs like Phil Collins or the late Buddy Rich playing their last ever drum solo on their farewell tours.

Donegal deluge   
The recent cataclysm –  when the heavens decided to open over the Inishowen Peninsula –  left 47 families displaced and over 300 roadways damaged. The estimated cost of the destruction to date is exceeding €400 million. While the fallout from Storm Gert has left rural communities on our little island reeling and traumatised, at least there were no lives lost, unlike the human cost exacted by Harvey in Texas, with reports of up to 50 casualties.   
Can you imagine how the citizens of southern Texas were feeling as the impact of record-shattering tropical Storm Harvey took its toll last week? Its devastation has led to curfews and paralysed the big oil metropolis of Houston, with repair and reconstruction estimates at $50 to $75 billion and rising. The Houston metropolitan area felt the brunt of the heaviest rainfall with nearly three feet of rain measured between Friday, 25 and Wednesday morning, August 30. That is circa three-quarters of its annual rainfall in five days.  

Louisiana landfall
Several days later Harvey was making its second landfall as it moved east into south-west Louisiana.
Meanwhile, the sun was shining back here in County Mayo with the smell of autumn slipping in over the horizon. Whether the dark months of winter bring destructive tropical storms with names like Irma, Jose, Katia, Lee, Maria, Nate, Ophelia, Philippe, Rina, Seán, Tammy, Vince and Whitney, is beyond the predictive powers of Met Éireann. Well, we don’t need to be experts to know that the whims of the weather can still confound the accuracy of science and the real fallout from global warming?
Oops! And I almost forgot, that exposer of fake news himself, President Donald Trump, has warned us all that global warming was a concept developed by the Chinese to make US manufacturing non-competitive.
Jesus wept!

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