Magilligan Point shows largest ‘natural’ erosion level over past 193 years

The findings will come as no surprise to north Derry residents who have watched the Point slowly erode over the decades.

By contrast there has been a seaward advance of the coastline at the mouth of the Roe, a section of Benone strand at the Umbra stream, and at Castlerock and Portstewart.

At the mouth of the Bann this is due to jetties trapping sand from both directions, researchers said.

“The largest ‘natural’ shoreline erosion levels were recorded on the western side of Magilligan Point (Co. Londonderry),” Professor Derek Jackson, an expert on coastal processes said.

In a project examining shifting shorelines over the past 193 years researchers used historical maps and aerial photographs to painstakingly examine what changes have taken place from the historical times right up to present day.

The project, funded by the Department of Agriculture, Environment and Rural Affairs, has taken over a year to complete and represents some of the most detailed analysis possible for examining historical changes on coastlines.

Utilising the first (circa 1830) detailed Ordnance Survey maps of the coast and intervening mapping surveys, vertical aerial photographs (from the 1950’s to present day) as well as a recent coastal topographic LiDAR (Light Detection and Ranging) survey undertaken by DAERA, each 25-metre section of coastline was investigated for positional changes.

Open-coast sandy shorelines showed various levels of erosion, apart from build up at the Castlerock-Portstewart Strand complex (due to the extensive jetties at the river Bann entrance which are trapping sand from both directions) and Ballykinler (linked to local geology and inlet exchanges between the inner and outer Dundrum Bay).

Lead researcher on the project, Professor Derek Jackson, an expert on coastal processes, said: “The project was a huge technical task in itself but, in the end, it has produced a fantastic database from which to better understand how the Northern Ireland coastline has changed over historical times.

For the first time, the north has a detailed picture of how dynamic, particularly the sandy stretches, of the coastline are.

This now gives ‘...a much better scientific basis from which to manage these sites in the future,’ he said.

Repairs undertaken after coastal erosion at Lisfannon beach in Donegal to allow parking off road

“Shoreline change data tells us where erosion (or even build-up) of sediments has occurred, and this can help better advise any future planning decisions or other uses of particular stretches of the coast,” Professor Jackson added.

Co-Investigator on the project, Professor Andrew Cooper said: “The largest shoreline advancements recorded in the last two centuries along the Northern Ireland coastline were all induced by human modifications such as extensive land reclamation in sea loughs (mainly during the 19th century), construction or expansions of ports and harbours, power stations, wastewater treatment areas or touristic facilities.

"Rocky coasts, apart from limited rockfalls, were less subject to largescale changes as were shorelines not influenced by human-modified in sea loughs.”

Professor Jackson added: “The project also examined areas where coastal processes are concentrated, inside which sediment is largely contained and moved around.

"A total of seven of these zones, known as ‘Coastal Cells’, were identified, which again helps in future coastal management approaches.”

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