Sea defences designed to protect us from the waves are causing many of our best-loved beaches to erode away, it’s been claimed.
Coastal expert Derek Jackson said we need to make better use of scientific expertise when it comes to managing our coasts.
Prof Jackson says that people build homes in certain places because they admire the view.
But the sea wall they build to protect that home from the storms deflects the waves back and gradually eats away at the beach.
Prof Jackson tackled the issue during his inaugural professorial lecture at the University of Ulster’s Coleraine campus. In it, he outlined how Northern Ireland is now leading the world in coastal research, bringing an improved understanding of the potential danger of coasts across the globe from climate change.
“Modern coastal science has advanced much in recent years due to the advent of state-of-the-art monitoring and computer modelling, revealing a great deal about how coastlines function as a complex environmental system,” he said.
“Management of the beach and dune zone, however, still lacks proper science-led approaches.”
Prof Jackson said most countries are ill prepared for sea level rise. Until now, we have benefited from a geological ‘bounce’ that has seen Northern Ireland rising after its release from a mile-thick icesheet that pressed on it in the last Ice Age. That rise has kept pace with sea level rise, providing us with a level of immunity against the rising waters.
But he warned that reprieve is now disappearing as the geological rebound slows down and within the coming decades, sea level rise is going to start to bite.
And he says our two biggest cities, Belfast and Londonderry, will be particularly vulnerable.
He stated: “Most countries are ill prepared for sea level rise and climate change impacts and Northern Ireland is not exempt.
“The thing is not to over-engineer the coastline. If you pull away and look in detail at the Northern Ireland coastline, a lot of that coastline is human altered with sea defences and rock armour. If you have a defence in place you must continue to keep that defence operational.”
This leads to sea defences gradually destroying beaches.
Prof Jackson said: “If you look at old map evidence, the outer Ards peninsula has undergone a coastal squeeze — the distance between the high water mark and the low water mark has reduced over the last century, primarily because you have nowhere for the coast to flex in and out. The outer Ards area is a hotspot for rock armour and coastal defence, but the width of the coast is much narrower than it was previously.
“The management hasn't caught up with the science yet. There is no joined-up thinking between scientists and the people who manage the coastlines.”
The challenge will be to decide whether to put up more sea defences, to let the sea in or to relocate infrastructure.
Narrowing strands the downside of sea walls
By Linda Stewart
We might think we’re protecting our coasts from the ravages of the sea — yet we’re destroying some of their most unique features.
Professor Derek Jackson said there is evidence that beaches along the outer Ards peninsula are eroding away because of the heavy sea defences designed to protect shore infrastructure.
Old map evidence shows that the coastline of the Ards peninsula — home to scenic beaches such as Ballyholme, Millisle, Donaghadee, Ballyhalbert, Ballywalter and Groomsport — is narrowing, with the distance between the high water and low water marks reducing over the last century.
We’ve already seen a similar pattern in some of Northern Ireland’s most celebrated beaches, as sea walls erected to protect roads, car parks and homes bounce waves back so that they gradually erode the sand away.
Portballintrae Beach and the West Strand in Portrush have narrowed since their sea walls were built in the 1960s and 1980s.
At the time, Professor Andrew Cooper of the University of Ulster warned that it was probably too late for the two beaches which were gradually disappearing as their sand eroded away.
But he predicted that other north coast beaches could vanish if space was not left for the beaches to move back and forth.
Dunes act as buffers against wave energy, temporarily eroding and later building back up.
“When a wall is built behind a beach, it stops the coast eroding and the energy that would have been used bounces off the wall and carries the sand out to sea,” he said. “There is no dune to take the extra sand from and break the energy of the storm.”