Since World War II, the French coast has been caught between two waves. On the one hand, the natural phenomenon of erosion, which is amplified by global warming caused by human activities, is eating away at beaches and cliffs. On the other hand, man, because he has never wanted to live near the sea so much, has built massively on these spaces threatened by the ocean. This tension, which will only increase in the coming years, is at the heart of franceinfo’s # MontéeDesEaux project. “Today, we are paying for our reckless appropriation of the coastline. We wanted houses with their feet in the water, we have them”, summarizes Stéphane Costa, geographer, professor at the University of Caen and president of the National Strategy for Integrated Coastline Management.
>> This article is part of the special operation # MontéeDesEaux launched by franceinfo on the occasion of the COP26
To allow you to better visualize this phenomenon, franceinfo takes you to 18 places on the French coast, in mainland France and overseas, where the coastline often recedes, sometimes advances, threatening houses installed there over the past 50 years. These before-and-after images are available to you through the portal of the National Geography Institute, from aerial photographs taken between 1950 and 1965, then from photos taken between 2006 and 2010.
(Move the vertical line that appears in the middle of the photos to see the differences between the two periods.)
Hyères (Var)
In this Var commune, it is the peninsula of Giens which concentrates the concerns. The thin strip of land that connects it to the continent lost up to 37 cm per year on both sides between 1924 and 2011.
Le Grau-du-Roi (Gard)
This seaside resort is one of the places where the coastline advances. As can be seen in these images, the construction of the port allowed the sand to accumulate and the coastline to progress, up to 13m / year. A little further south, however, the coastline recedes.
Vias (Hérault)
This Hérault commune is a good example of the two opposing waves which assail the French coast. On the one hand, the houses are getting closer to the water, on the other, the beach is receding, up to 70 cm per year in places since 1935.
Biscarrosse (Landes)
In this seaside resort in the Landes, three buildings, the twin villas and a hotel, are built on a dune eaten away by erosion. The town hall is trying to negotiate the withdrawal of these homes, but the project is slipping, for lack of legal and financial tools. You will find more information on this situation in our report on the spot.
Lacanau (Gironde)
As in Biscarrosse, the beautiful sandy beach of this Landes seaside resort is eaten away by the Atlantic Ocean, with a marked decline of up to 1.75 m / year in places since 1957.
Soulac-sur-Mer (Gironde)
Famous for the tragedy of the Signal, one of the first buildings evacuated due to erosion in France, this village located at the exit of the Gironde estuary has experienced setbacks of up to 5 m / year since 1957 .
La Tremblade (Charente-Maritime)
Wedged between the Gironde estuary and the Maumusson sluice, two mouth areas where the coasts are particularly mobile, this Charente commune is experiencing significant movements, advancement and retreat of its coastline. The decline has reached 7.9 m / year since 1957.
Dolus-d’Oléron (Charente-Maritime)
Located on the west coast of the island of Oléron, this town, which has become urbanized in recent decades with the boom in tourism, is faced with the decline of its dune, behind which is a subdivision built below the level of the sea. On the spot, the question of how to defend oneself against the sea is the subject of lively debate, as Franceinfo will tell you on Friday October 29 in a report.
Lancieux (Côtes-d’Armor)
With its mostly granite coasts, Brittany is less exposed than the Atlantic coast to the onslaught of the ocean and to erosion. But some sandy areas, such as the southwest of the town of Lancieux can experience notable setbacks, up to 70 cm / year.
Gouville-sur-Mer (Manche)
Little spared by storms in recent years, this municipality in La Manche had to urgently consolidate, with riprap, its dune which protects two campsites and an oyster farming area. You will find more information on this situation in our report on the spot.
Etretat (Seine-Maritime)
Famous for its chalk cliffs, the small Norman village also suffers from the onslaught of erosion. The possible impacts of the rising water levels in the town are the subject of a virtual simulation which Franceinfo will tell you about on Thursday 28 October.
Ault (Sum)
Located south of the Bay of Somme, the town of Ault is faced with the nibbling of its chalk cliffs by the sea, up to 26 cm / year in places between 1947 and 2007. As in Dolus-d’Oléron, the The question of the defense of the village against the sea was the subject of bitter debates during the municipal elections as Franceinfo will tell you on Saturday, October 30.
Oye-Plage (Pas-de-Calais)
In this Pas-de-Calais village, an entire housing estate, visible in the center of the image, is built on the dune. For the moment, the coastline is advancing in this zone, up to 9 m / year in the east.
Ghyvelde (North)
An important part of this town, visible to the south of the dunes, is located below sea level. It is only kept out of water thanks to a system of pumps and canals, as franceinfo will explain to you on Thursday 28 October.
San Nicolao (Haute-Corse)
In Corsica, if the western coast suffers little from erosion, a large part of the eastern coast is threatened. This is the case for example in San Nicolao, where the decline is very marked, as you can see in this image.
Awala-Yalimapo (Guyana)
This Guyanese town holds the French record, with a decline of up to 65 meters per year. A particularly mobile coastline that it owes to its particular geographical location, between the mouth of the Maroni and that of the Mana. To adapt, it is revising its municipal map to displace 300 inhabitants as Franceinfo will explain to you on Saturday, October 30.
Le Prêcheur (Martinique)
Threatened both by the erosion of its beach and by mudslides descended from Mount Pelée, this town in northern Martinique wants to move to the heights, as Martinique La 1ère tells you in this article.
Sainte-Anne (Guadeloupe)
In Guadeloupe too, the coastline is receding. As Franceinfo will tell you on Saturday, October 30, the city of Sainte-Anne has started to set back certain activities, to raise them up: a school will soon be moving to reach a hill at an altitude of 70 meters.