More than 6,000 homes and business premises would be threatened by the decline of the coastline linked to erosion by 2050, according to an “objective and probable” scenario carried out by Cerema unveiled this Friday by the Ministry of the ecological transition. Vendée would be one of the five French departments most affected, while 500 municipalities at risk have been identified across the French coast by the government. Update with Olivier Dalmasso, mayor of Saint-Vincent-sur-Jard, one of only two Vendée municipalities (with La Tranche-sur-mer) listed among the 242 vulnerable French municipalities according to the latest decree of July 31, 2023.
How does coastal erosion manifest in your territory?
We have two and a half kilometers of coastline and we have two typologies: a strip with a rocky base where erosion is relatively weak, and another a little more sandy where it manifests itself in a more pronounced way. But the particularity of our commune is that the main risk of marine submersion occurs at the level of a dune located in the neighboring commune of Longeville. Erosion at this location is very strong. The dune has receded by around fifteen meters over the past ten years. The shrinkage is even estimated at four meters since October alone after the passage of three successive storms. It is clearly visible to local residents and walkers.
Are homes threatened in the short term?
Fortunately, no, not immediately. But if the Longeville dune were to disappear, several houses would be directly exposed in Saint-Vincent. There are also some houses in Longeville protected from the waves by private walls. When there are stormy events, water already enters the gardens.
What means of protection do you have?
Faced with the deterioration of the dune, it was decided to carry out emergency work: we added sand and pebbles to reconstruct it. It will slow down the erosion, even if we know that it is not sustainable. Apart from this emergency work carried out by a joint union, we have no protection system. We are currently thinking about one-off systems to limit flooding during high tides. Above all, we are working with the State on the most effective strategy to pursue. Certainly, these are not the same issues as in Sables-d’Olonne where actions have already been taken to protect around 2,500 homes on the embankment. But we still have remarkable sites, the Clemenceau house for example, which must be preserved.
What exactly do you expect from the State?
Our inclusion on the list of 242 municipalities subject to erosion has, for the moment, not brought any significant change. So we expect to be truly recognized and to be treated with special attention. We need to anticipate things, to have reliable data. How many homes would be affected if the dune were to disappear? How much rehousing will be necessary? We don’t know exactly at the moment. Financial support is also expected. The budget of a municipality like ours will obviously not be enough to deal with this problem. From my point of view, this must be the subject of national solidarity.
Is awareness of the consequences of erosion complete today?
The population understands what is happening. Residents talk about it regularly, they will see the consequences after each storm. I don’t see any major concerns yet, but they too are waiting for information and transparency. This is why we are going to organize a public meeting on the subject in mid-May. As for coastal elected officials, I have the impression that the issues are understood. There is solidarity, we all work together. Now, we haven’t yet gotten into the hard part of the actions. There will inevitably be difficult decisions to make, we know that.