The mystery of the disappearing beach…

What exactly is the problem? Grains of sand (sediment) are not amalgamating sufficiently with the beach; it is slowing emptying and shrinking. Every wave is a new threat to the sand’s peaceful existence; each wave rips grains from the shore and drowns them in the destructive swell. This marine erosion affects cliffs and rocks and nibbles at the precious summer tourist territory… it’s a natural phenomenon.

Well, not really that natural. In theory, some algae (like seagrass in the Mediterranean) play a “fixing” role on the grains of sand. It is the same principle as those of plants and shrubs that stop earth from sliding on a slope. This is what happens under dunes where the grass is hidden and also on all the world’s beaches. But chemical products, global warming and the excessive collection of dead algae are all reasons that prevent organic matter from doing its job.

If it were up to the sea, it would reclaim its rights and swallow up the beach slowly but surely, grain of sand by grain of sand, to remodel the shores to its own taste. But seashore towns do not share this point of view… Marine erosion is a threat to our beaches, but what about the homes and shops near the shore? Their foundations are more fragile and will breakdown sooner or later. To offset the sea and her threat to the beaches, we need to find ingenious ways of making the sand stay put.

Some believe that we should put another layer of sand down every year before the holiday season begins. It is an expensive, temporary and unecological solution; the artificial sediments will strangle the local marine flora and only mask the problem.

We could also build “groynes”. Have you ever wondered what those rocky jetties are every 200 metres along the beach? They are there to keep the sand in place. The groyne or dyke breaks the flow and inertia of the waves which then do not have the power to move the sandbanks.
Unfortunately, the problem still exists between the dykes…

One new solution has been tested on the beaches of Sables d’Olonne since winter 2000: Ecoplage. It is a clean, silent and environmentally friendly solution which as well as fixing the sand in place actually helps bring grains of sand back to the beach! Truly miraculous…
How does it work? Three months are required to dig a ditch in the beach; then drains are installed connected to a powerful pump that aspirates all the water collected in the sand. Once dry, the sand solidifies as normal and does not move.
And the collected water? Well, it is clean because it has been filtered by sand and so can be returned to the sea or used to fill seawater swimming pools. Even more interesting: imagine another system whereby the water can be treated and desalinated…

At Sables d’Olonne they have managed to recuperate 15 metres (in width) and 50cm (in height) of beach since the installation of Ecoplage. Which is enough for plenty of sandcastles when you consider that the installation is completely invisible to sunbathers as it is buried 2 metres beneath the surface. Ecoplage has also been installed at Saint-Raphaël and Villers-sur-Mer, and is currently being studied for many other coastal areas.

Text : Nathalie Jouat
Photos : Ecoplage