A week after the stormy episode which flooded the République district and caused serious damage, the Cannes Lérins Agglomeration presented, at a press conference, its strategy to combat flood risk reduction.
On September 23, in just half an hour, 50 mm of rain per m2 fell on Boulevard République and upstream on the hills of Vallauris, Cannet and Mougins, all falling on this sector of Cannes. in a bowl.
“The Boulevard de la République is located on the Foux watershed in Cannes and it has been completed in its current urban configuration since the 19th century”specifies the town hall.
A phenomenon which, if it had lasted longer, could have been similar to the episode of October 3, 2015.
The work paid off
To delay, therefore, the risk of flooding, numerous works and actions have been carried out since 2016. Which have produced the expected effect, since on September 23, in addition to material damage, no victims were recorded. “We have made a huge effort in this area to prevent and know what behavior to adopt, thanks to the training provided,” explains the mayor.
Regretting that no red or even orange vigilance was triggered (only a yellow vigilance was maintained). “It was enough for us to have known about this intensity and this concentration a quarter of an hour before for us to raise the alert straight away…”
The same day, Cannes town hall armed the crisis command post at 7 a.m. to monitor the storm. From the first rains, municipal and intercommunal teams mobilized to close the low points and activate the pumps at the intersection between rue de Cannes and avenue Frédéric-Mistral. SMS alerts were sent at 7:34 a.m. and 8:20 a.m. via Cannes Alerte to inform the population.
But it is also all the work carried out upstream which has paid off, notably within the framework of the Flood Action and Prevention Program (PAPI), still in progress, with 145 million euros of developments and operations over 18 years.
The Cannes Lérins agglomeration has notably protected, since 2016, numerous land plots at risk, in order to demolish regularly flooded homes and create a natural space, as was the case with the creation, in 2023, of the water basin. detention at Impasse Nouvelle.
La Frayère, from 14 to 25 meters
The maintenance of the valleys also plays a major role, in order to avoid ice jams: during a rainy episode, if the valleys are not maintained, we can have branches which block at the time of peak flow and then release 'all the water retained at once, causing waves.
The City reminds that 70 to 80% of the plots are in private domain, and that it requires individuals to maintain their valleys and waterways: in the event of non-completion after relaunch, the Cannes Lérins Agglomeration carries out the work and invoices them to the owners.
On September 23, “the valleys reacted very well. The recalibration of the spawning ground worked very well”rejoices David Lisnard, mentioning the completion of the first phase of widening of the La Frayère watercourse last July, making it possible to go from 14 to 25 meters in diameter, in order to allow a hundred-year flood to pass.
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