But, for Régis Leymarie, deputy delegate Normandy from the Coastal Conservatoryto intervene, to resist does not make sense: “The cost/benefit ratio is not favourable. The costs are colossal. In any case, in places where there are no human issues, it is better to support the phenomenon, and, for example, to move a coastal path. We have to relearn that the coastline is a mobile interface. The man of the 20th century has forgotten it!”
We have to relearn that the coastline is a mobile interface. The man of the 20th century has forgotten it!
Stéphane Costa agrees, and gives the example of the Ault-Onival sector, north of Dieppe. In the 1970s, a reinforcement was placed there on the cliffs. “The municipality has been in debt for forty years, but the cliff is breaking apart again, it is going to collapse. So, we can totally decide to protect a place but it will only be temporary. We’re just giving ourselves time to retreat.”
Coastal erosion is catching up with urbanization
Coastal erosion is now catching up with urbanization which has come a little too close to the shore, summarizes the professor. Villages are already threatened, such as Criel-sur-Mer, in France. Or Happisburgh, England. In 20 years, 35 houses have been submerged there.
Paradoxically, the erosion of the cliffs provides them with natural protection: the eroded materials feed the beaches, which protect the foot of the cliffs. “Sediments are the best protective buffer against the onslaught of swells” confirms Stéphane Costa.
However, for a long time, astronomical quantities of sand were extracted on the European coasts, for construction, for roads. This has therefore contributed to the weakening of our coasts.
An acceleration of the reversal speeds
But the erosion of the cliffs is obviously the result of a multiplicity of factors: runoff, infiltration, alternating freeze/thaw, the attack of the sea at the foot of the cliffs, the evolution of the roof of the water table inside the cliff.
And, even if it is still only a scientific hypothesis, it should intensify: “Attack from the sea is believed to be the most important factor. However, it will increase with the rise in sea level due to climate change. We therefore imagine that there will be an acceleration in the speed of retreat of the cliffs.
The resilience capacity of coastlines and ecosystems, we see it every day.
Faced with this, Régis Leymarie, from the Conservatoire du littoral, wishes to recall that, with regard to natural spaces, forms of adaptation are possible: “The resilience capacity of coastlines and ecosystems, we see it every day.”
This article was first published on April 16, 2021.