Episode 2: Marine submersions and coastline erosion
An unavoidable risk of flooding
100 % : is the probability of marine submersion in the Mediterranean over the next 35 years, according to a recent publication in the journal Pure and applied geophysics.
L'Indépendant article on the risk of a tsunami
The last tsunami to cause damage in France was on 16 October 1979, when a deadly wave hit Antibes, killing 12 people. Since then, urbanisation of the coastline has intensified: seaside campsites have replaced tents and caravans with mobile homes, transforming these areas into veritable hotel complexes.
The article in France Info takes a closer look at these risks with seismologist Pascal Roudil, head of the Tsunami Warning Centre (CENALT), who points out that the gentle slope of the seabed near Perpignan could amplify the height of the waves.
Detailed explanation of the risk of a tsunami in the Mediterranean
Prevention and insurance issues
The primary objective of the CENALT is to alert the population in the event of an imminent risk. Some infrastructures are equipping themselves with platforms to protect against tsunamis, but the question of the resilience of the installations remains. Insurers, for their part, are incorporating these risks into their models and increasing premiums, or even refusing certain contracts.
On 2 February 2021, a full-scale tsunami prevention exercise was organised in Sanary under the aegis of the prefecture of the southern defence and civil security zone.
Video of the tsunami prevention exercise
Replay of the show C à Vous from 19/01/2024
UNESCO is also working to set up a warning system to protect coastal populations.
Coastal erosion and rising sea levels
Climate change is exacerbating the phenomenon of flooding, particularly through rising sea levels. By 2050, an estimated 413 French campsites will have more than 80 % of their surface area at risk, with a high concentration in the Vendée, Charente-Maritime and Hérault regions.
CEREMA report on coastal erosion
Map of coastline erosion in the Mediterranean
Some scientists are adopting even more alarmist forecasts, considering factors such as the subsidence of coastal soils due to the pumping of groundwater in urban areas.
Article on rising water levels in the Occitanie region
Study on the acceleration of rising sea levels in the Mediterranean
A danger exacerbated by storms
In the previous episode, we explored the risks associated with Mediterranean storms. However, storms can also generate waves capable of crossing the coastline and invading inland areas, particularly if a dyke breaks.
National Coastline Observatory
Conclusion
The Gulf of Lion is on the front line when it comes to climate risks. Flooding due to Mediterranean episodes and marine submersion due to rising sea levels and storms are no longer exceptional events, but recurring threats. Adapting infrastructures and prevention policies is becoming a necessity to limit human and economic losses.
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