Doughmore: The Futility of Trying to Fix a Coastline
“The real conflict of the beach is not between sea and shore […] but between Man and Nature. On the beach, Nature has achieved a dynamic equilibrium that is alien to Man and his static sense of equilibrium. Once a line has been established, whether it be a shoreline or a property line, Man unreasonably expects it to stay put”
The quote above, by Gary Soucie from an article in The Smithsonian, is probably more relevant now than in 1973, when it was written.
Soucie uses the term dynamic equilibrium, which means that a system is in a state of constant flux, and is happy to stay that way. A natural coastline is a good example. The coastline is not meant to be fixed in one place; it is supposed to flex and morph according to the sea conditions, to erode during storms and accrete during calm periods.
Evidently, we don’t seem to understand the concept of dynamic equilibrium when it comes to coastlines. We build a human structure on a mobile interface, and then we complain when it moves. Then, instead of putting it somewhere else, we build another structure to try to protect it. We try to “fix” the coastline in one place because we can’t accept that it is supposed to move. We think that a fixed structure designed by humans will work better than a flexible system evolved over millions of years.
The coastal engineering work that is currently being proposed at Doughmore Beach in Western Ireland is a classic case of what Soucie was talking about. A golf course has been built on top of a highly mobile beach-dune system, located at one of the most energetic coastlines in the northern hemisphere. Not surprisingly, the golf course is being threatened by the natural behaviour of the beach-dune system.
So, the owners of the golf course want to put some solid artificial structures there, to “fix” the coastline in place to stop the sea from invading their property. Luckily, the scheme currently being proposed is much smaller and less offensive than the original one, but the intention is still the same: to immobilize a mobile interface, to hold back Nature.
Just so you know: the golf course (and the luxury resort hotel that goes with it) was built in the early 2000s and later purchased by a company owned by Donald Trump. This article is not about Trump or politics. It is about the coastline, Nature and us.
In November 2016, I had an opportunity to travel to Ireland to see what it was all about. The campaign to try to stop the wall, headed by Save the Waves, had just reached 100,000 signatures from around the world, so I thought it was a good time to help. Along with fellow Patagonia ambassador Tom Doidge-Harrison and local legend Pete Conroy, we gave a presentation at Patagonia Dublin, and then traveled across the country to see what was happening at Doughmore Beach.
When I got there I found a pristine natural setting. There was a gently-sloping sandy beach, and at the top of the beach a steeper cobblestone shore called a storm ridge. The whole thing was backed by a system of dunes and a flatter area further inland.
I could immediately visualize how it worked: In largish waves and a high tide the cobblestones would dissipate an enormous amount of energy. If things got stormy, the wave energy might encroach on the dunes and perhaps cause a certain amount of erosion, effectively moving the land-sea interface inland. In really extreme circumstances the water might snake its way through the dunes and temporarily fill up some of the flat area behind, like a flood plain. Then, during the intervening calm periods there would be accretion, with the sediments coming back and effectively moving the land-sea interface seaward again.
I could see that this was a problematical concept for the people who wanted to protect their golf course. You see, the accretionary phase of this natural cycle might take years, or even decades, and people don’t want to wait that long.
In fact, the accretionary phase might take even longer due to things that we ourselves have done. For example, with global warming due to greenhouse gas emissions there will be more big storms like the ones in 2013-2014, during which the erosion phase of the cycle will be intensified. Also, the removal of large amounts of cobblestones to build a road in the 1950s, together with other sand-mining activities, will have made the system more vulnerable to erosion. And with the inevitable sediment deficit to the coast caused by the blocking of rivers by large dams, the accretion phase will be weakened.
The scheme that was originally proposed to protect the golf course would have been a monstrosity. It was a rock-armour toe berm—an artificial structure that looks similar to the existing cobblestone beach, but made of large, immovable rocks fixed at the base of the dune. It would have been 2,500 metres long, up to six metres high and up to 25 metres wide. It would have obliterated the existing cobblestone beach, replacing it with a man-made, fixed imitation.
The original sea wall would have caused a lot of problems. For example:
- Due to the existence of surges called infragravity waves on this type of beach, people walking along the beach during a large swell could have been trapped against the wall.
- The wall would have concentrated a large amount of wave energy in front of the structure, quickly eroding the beach away.
- The surf would have been seriously affected due to backwash.
- The dunes would have been starved of sand.
- Inevitably, the structure would have failed sometime in the future, costing more money in the long run.
Thankfully, the new scheme is not as massive. It would consist of two separate structures at either end of the beach, 650 and 250 metres in length respectively. Instead of a 25-metre wide rock wall, it would consist of metal sheet piles (a metal wall, driven into the ground—see photo below), with rocks placed out to about 10 metres in front of the piles. The whole thing would then be covered over with sand and cobblestones.
As I said, it is much better than what was originally proposed, but it could still lead to a few problems:
- Although the erosion and the base of the structures will probably not be as severe, it could still occur, particularly along the 650-metre stretch.
- The wave energy will be constricted at the ends of the structures, leading to enhanced erosion at those points.
- If the solid structures are covered in movable sediment, this will probably be washed away with the first large swell.
- The construction would still require about 58,000 tonnes of rock, which would mean around 6,000 truck journeys across the fragile dunes.
- Just like the old scheme or, indeed most hard coastal structures, it will eventually fail.
That last point is very important. Trying to hold back the sea with a solid, inflexible structure is like trying to fit a square peg into a round hole. Instead of an integrated system that is happy to flex and morph, there is a solid barrier trying to resist a continuous force. Eventually, the sea will break through and the wall will have to be repaired and reinforced. The initial cost of the structure plus all the rebuilding and reinforcing that would have to be done in the long term, would probably cost a lot more than a more intelligent solution such as moving or adjusting the golf course.
To summarize, the original wall at Doughmore would have been an environmental disaster. Now, thanks to local and international pressure from groups like Save the Waves, a much smaller scheme is being proposed. That’s really great news, and it shows how grassroots environmental campaigning can really make a difference—and it shows that we should never give up.
However, the new scheme is still a fixed structure on a mobile interface, which will eventually fail just like the original one would have done. Save the Waves and the other opposition groups are still concerned that this proposal will establish a precedent and, if approved, will give the golf course justification for further armouring once it fails.
I can’t help thinking that the message isn’t really getting through. Call me a cynic if you like, but it did seem to me like the owners of the golf course decided to reduce the scheme because of all that pressure by environmental groups, not because they suddenly understood why hard structures are not a good idea. For example, their justification for the scheme still shows a lack of understanding of the basic principles:
“The site is open to strong Atlantic breakers which take the fine dune sand into suspension. This dynamic and erosive environment does not allow the sand to return to the beach and rebuild the dunes. Hence the need for immediate protection of certain critical areas.”
In the end, are we going to continue thinking that we can redesign our surroundings better than they evolved naturally, until we turn the entire planet into a grotesque, man-made imitation of Nature itself? Shouldn’t we try a bit harder to adapt our own behaviour to suit to the environment instead of modifying the environment to suit our own behaviour?
For more information, visit Save the Waves.
The Last Beach by Orrin Pilkey and Andrew Cooper: The clearest explanation out there of why hard structures on coastlines are usually bad news.
Coastalcare.org: Also summarizes very well why human interference with the coastline always leads to more problems in the long-term.