Coastal Territorialism

First published in The Surfers Path

© Tony Butt 2009 - Please be decent enough to contact me before plagiarizing my stuff

On most coastlines of the world, there is at least one ‘extreme’ event every winter.  But the last couple of winters here in the North Atlantic, things have been more extreme than extreme. On the night of 10-11th March 2008, the biggest waves ever recorded in the Bay of Biscay caused havoc along the north coast of Spain.  In San Sebastian, the promenade was completely destroyed and the road collapsed leaving a huge crater, and in Santander several vehicles were lifted up and carried across the road by the waves, one ending up embedded into a hotel.  Then, in January 2009, a continuous stream of very intense low pressures pushed the average wave height for that month above twenty feet.  The sustained wave heights resulted in extreme erosion along the coasts of France and Spain.  Tourist beaches were ‘robbed’ of valuable sand, and coastal urbanizations were destabilized everywhere.  I am writing this in early winter 2009, and so  far the sand has not yet returned. 

When these events occur, the natural coastline simply moulds and flexes a little, adapting itself to the energy without the slightest hint of tragedy, while our roads, walkways, shops and houses always fail miserably.  So what the hell are we doing putting them there in the first place?  Are we in some kind of territorial battle, laying claim to a thin strip of land bordering the ocean, to stop it being invaded by the ocean itself?  Do some people think that when a storm comes the sea knocks down our defences and advances into ‘our’ territory? Is all that concrete supposed to be some sort of territorial marker?

Even in modern textbooks you still see terms like these:

·         Protection of our coasts

·         Maintaining coastal property lines

·         Coastal property being threatened

·         Erosion mitigation strategies such as retreat and relocation

This kind of almost-military terminology implies that we somehow own that narrow strip of land, and that the sea, our ‘enemy’, is coming to take it from us. 


Why does the water ‘invade’ us?

When large waves reach the coast, why don’t they stop when they encounter sea walls, promenades, piers and breakwaters?  Even when the waves break a long way out from the shore, why does the water at the shoreline surge over onto parks, walkways, roads, shops and hotels? 

Well, sometimes, the tide can be a big influencing factor.  If a large swell coincides with a very high tide then this will move the breakpoint and, hence, the force of the waves, closer to the land, which will allow them to cause more damage.  But the tide on its own isn’t enough.  There are two other factors that combine to greatly enhance the height of the water.   These are wave-induced set-up and infragravity waves.

Wave-induced set-up is where the water literally ‘piles up’ on the shoreline due to the action of the breaking waves.  Broken waves (but not unbroken ones of course) carry vast amounts of water towards the shore, on the surface, in the form of lines of whitewater.  This water eventually finds its way back out to sea again in rips and undertows; but first the water is pushed up against the shore by the force of the waves, holding it up there and causing the surface to slope upwards towards the shoreline.  As a result, the water level is pushed up sometimes several metres higher than high-tide level, which means it will probably start to encroach upon man-made structures.  Logically, the amount of set-up increases as the offshore wave height increases.

Infragravity waves are very long period, almost tsunami-like waves, which cause the entire shoreline to move in and out on scales much greater than those of the normal waves.  Just like most tsunamis, they are so long that they don’t break.  Instead, they just surge in and out, sometimes several hundreds of metres, with periods of many tens or even hundreds of seconds.  The result is a further increase in the height of the water at the shoreline, but this time on a periodic basis. This is even more frightening for the local population because large masses of water sporadically and unpredictably invade ‘their’ territory.  And of course, the bigger the offshore wave height, the bigger the infragravity waves. 

 

The coastline: a mini-Gaia

During the days following some of the severe events of 2008 and 2009, I was able to check the after-effects along some of my local beaches.  In many places I was astounded when I saw how far the sea had reached.  Massive surges of water had snaked their way through gaps in the dunes, across fields and into the woods, and had completely flattened grassy areas and left debris hundreds of metres inland and, in some cases, completely out of sight of the sea.  The morphology of the beach was completely changed, and so were some of the dunes. There was sand were there hadn’t been before, and rocks exposed where sand had been.

Overall, I could see that the coastline had eroded.  Movable material had been displaced from the land to the sea.  But I knew that it hadn’t really ‘hurt’ the coastline itself; the damage – if you could call it that – was not permanent.  No ecosystems had been permanently altered, no species had been wiped out and no permanent damage had been done to the soil or the Earth’s crust.  It made me think how a simple system of dunes, sandbars, grass and trees is actually far more resilient than some clumsy concrete structure built by humans.

The reason for this is simple.  It is because all the components of the system – not only the ‘solid’ ones like the sand and the dunes, but also the energy fluxes like the weather, the storms and the waves – evolved together to function in harmony with each other.  The beach is not fighting the sea, and the sea is not fighting the beach.  They are both working together. 

In fact, according to Gaia Theory, first proposed by James Lovelock about 30 years ago (and, in a similar way to Darwin’s Natural Selection, probably destined not to be fully accepted until he is long gone), every component of our planet is evolving in close step with every other component.  The planet is a vast intertwining of feedback loops between the animals, plants, bacteria, the atmosphere, the rocks, the ocean and everything you can think of, including us.  The coast, then, is a kind of ‘subset’ of the Living Planet, a kind of mini-Gaia which regulates itself but is also intrinsically linked to the rest of the planet. 

So, what’s the solution to our coastal problem? Well, I don’t have the definitive answer, but I believe that a change of attitude would help a great deal. Obviously the best way to stop man-made coastal structures being washed away by the sea is to not put them there in the first place. Of course, this is easier said than done, especially if the structures were built tens or even hundreds of years ago, or if there are people living in them. But we know so much more now that we did a few years ago, and a change of general philosophy would be a good starting point. Instead of believing that we are somehow separate from the other elements that make up the planet, and somehow superior to them, we need to realize that we are a just another part of Nature, just like the sea, the rocks, the plants, the fish, the dunes and the weather. If we insist on trying to fight with Nature, we are, in a way, fighting with ourselves.