Landslides of peat soils that occurred on mountain ground in the Glenelly valley last August have been described as a “one in 3,000-year event” by an upland landslide specialist.

Speaking at an event organised by DAERA in Cranagh, Co Tyrone, last week, Dr Alan Dykes from Kingston University London said that landslides occurred in 13 areas within the valley on 22 August 2017, with some of these areas involving several individual landslides.

“There have only been 10 events similar to this in the whole of the British Isles in the last 50 years. It is not something that you are going to expect to see again,” Dykes told farmers.

“Rainfall records show that ground was fairly wet before the storm.

‘‘The nearest weather station shows that at least 50mm of rain then fell within three hours on 22 August. I think the actual rainfall in this local area was considerably higher than that, but we have no records,” he said.

Dykes pointed out that it was not the large volume of rain that caused the landslides, but the short space of time in which the volume of rain fell. He presented rainfall statistics which suggested that 50mm of rainfall within 24 hours in an area is a one in 150-year event, whereas 50mm in three hours is a one in 3,000-year event.

Dykes acknowledged that climate change could mean it’s increasingly likely that high rainfall will cause flooding in a given river every few decades, or even every few years. “By comparison, the probability of multiple landslides at any specific location is vanishingly small,” he said.

Farmers were also told that soils that were not eroded by the landslides last August will require an even higher rate of rainfall to move off in a landslide in the future.

Recovery

Dyke’s advice for the restoration of upland ground affected by landslides was to let it regenerate naturally in a process that could take several years. “If you leave disturbed peat, it tends to recover quicker than if you disturb it further. The peat will dry out, shrink and degrade and then grass will grow on it,” he said.

He also made it clear that there was no benefit in fencing off areas of landslides to prevent sheep from walking or grazing on them.

Flooded land eligible for 2018 BPS

Lowland ground that is still covered in material from last August’s floods, as well as upland ground disturbed by landslides from the same time, can be claimed for area-based payments in 2018.

Aidan McEvoy from DAERA said that farmers in the north west with flood or landslide affected land in 2018 should claim the area in their Single Application Form and submit another force majeure form.

He told farmers at the meeting in Cranagh that claims will be assessed in a case-by-case basis and that evidence of attempts to make land eligible (in lowland areas) should be submitted with forms.

“However, force majeure does not apply in 2018 to land that has been permanently removed from agricultural use. This could be an area that has been washed away by a river moving course or areas that are now bare rock and won’t regenerate,” McEvoy said.

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