Le Figaro Nice
LE FIGARO. - Three successive Mediterranean episodes brought down quantities of rain rarely recorded on the Côte d'Azur in one month. In Nice alone, 400 millimeters of water were recorded, which is already more than in the entire year of 2023. How do you view this situation?
Matthias PALUSZKIEWICZ. -
The bad weather of 2019, storm Alex of 2020, storm Aline of October 2023 and these latest rainy episodes demonstrate a recurrence of increasingly intense weather events.
This is what I have observed after being in my position for five years, but it is something that was already true before.
On the other hand, at this time of year, it is the first time - on a personal level - that I have been confronted with a phenomenon of such magnitude.
Is the Alpes-Maritimes department, from a geological point of view, capable of absorbing all this rain?
We had two years of drought in 2022 and 2023, which caused a buffer effect at the start of the events.
However, the geology remains very varied in the department, due to the coastal context on one side and very high altitude on the other.
Soils therefore react differently to water inputs, which explains, for example, why there are many more landslides in the middle and hinterland areas.
However, on the coast we have municipalities like Nice which are also subject to these hazards.
At the moment, we are also carrying out studies on the phenomenon of “ground movements” in the commune of Mandelieu-la-Napoule.
Even several days after the bad weather, numerous landslides were recorded in various places in the department. Should road users still worry about this?
One of the factors that causes a landslide is the accumulation of water in the ground.
However, as long as it does not drain, the risk of sliding persists.
It is the same with falling blocks and landslides.
Furthermore, the reaction of the ground is much slower than that of watercourses, where we speak of flash and torrential floods.
In any case, zero risk does not exist and even less so on mountain roads.
However, road managers, whether the department, the metropolis or even Escota for the A8 motorway, have the mission of protecting these major axes against these dangers, and they do it very well.
The danger is the alternation of extremes, between scorching summers and very rainy seasons, which poses enormous problems in terms of “ground movement”.
This shortens the periods between potentially very dangerous events.
Matthias Paluszkiewicz
Exactly, how can we act to counter, or even anticipate, landslides?
Unfortunately, it is very difficult to anticipate this hazard.
The ground can give way in one place and not ten meters later... It is impossible to intervene everywhere.
For missions that depend on the DDTM and in particular the division that I represent, we develop plans to prevent the risks of ground movements.
This involves mapping very exhaustive areas exposed to these hazards.
Once the risk has been assessed, this gives areas of different colors on which prescriptions are issued, particularly with regard to constructions.
The entire department is not covered but we endeavor to map the most sensitive municipalities.
We also call on design offices which travel through the municipalities with this risk assessment mission.
By cross-referencing these field phases with known historical data, we derive a hazard which, when combined with an issue, creates the risk.
Are there more risks in terms of land movement today than before?
Necessarily, yes.
The climate change context in which we find ourselves brings new challenges.
The danger is the alternation of extremes, between scorching summers and very rainy seasons, which poses enormous problems in terms of “ground movement”.
This shortens the periods between potentially very dangerous events.
A recurrence which can also be a threat and which needs to be taken very seriously.