20 years ago, the Gard under water: “Today, the consequences would probably not be the same”


Florence Vaysse is Météo France’s territorial reference for Languedoc-Roussillon. It details the changes in terms of forecasting and monitoring since the tragedy of 2002. Twenty years ago, floods in the Gard caused 22 deaths and considerable damage. Regarding the weather, what has changed since then? Lots of things. In the field of tools we benefit first: there have been great technical improvements. Radars have improved, as well as satellite images or digital models, thanks to more and more powerful computers… So forecasts are more accurate. Also, in 2002, we were just at the beginning of the weather watch, which was created in 2001 following the storms. of December 1999 and the floods in the Aude. What is it about ? The surveillance is designed to inform citizens and public authorities in case of dangerous phenomena in the next 24 hours, direct communication to the general public. In 2002, there were no smart phones and no notifications… Since this tragedy, surveillance has advanced as events unfolded. More parameters are taken into account. The heat wave watch, for example, was put in place in 2004 in the wake of the summer disaster of 2003. In 2006, a flood watch was created, separate from the rain watch: a great development in terms of prevention. For each event, we provide feedback for continuous improvement. Here, we take stock of the episodes that have impacted us in recent days. General public: how to get information As Florence Vaysse reminds us, in 2002 no one had a smartphone in their pocket. “In the Météo France app, everyone can subscribe to alerts by entering their geolocation to be immediately informed of the watch in the Gard or at their holiday spot, for example via a notification.” But it invites the general public to go further, to benefit from more precise elements. “When we are alert, everyone can easily go to see the constantly updated monitoring bulletin, which gives more localized information than at departmental level.” On the website: www.vigilance.meteofrance.fr. Precisely: these recent episodes have been quite localized, while Météo France’s surveillance is reported at a departmental level. Isn’t that too broad? Surveillance has been designed at departmental level since its inception because it is the most relevant scale for our institutional interlocutors, starting with the COD (departmental operational center, the crisis management tool available to the prefect, ed.). By the way, I remind you that if Météo France calls for vigilance, it is the prefecture that decides on the alerts and sets them in motion… As for this week’s episodes, it was about the so-called V cells, which produce stationary storms. In this case, the models are able to predict a storm situation, but have great difficulty in predicting the onset and duration of the stationarity… For heat waves, for example, which can affect 10 or 15 departments , there is a little uncertainty, we see them coming. But these Mediterranean storms are so small and fast-moving that they scatter through the cracks in the models. But beyond departmental monitoring, we produce continuous monitoring bulletins, accessible to everyone with, as soon as we can, more details and localized data. People sometimes have the feeling that there are more and more alerts… Because more parameters are taken into account. But also because in our region, according to studies, the frequency of Mediterranean episodes and their intensity have increased. There is consensus on an increase of more than 20% in 50 years and future projections still point in that direction. If it happened today, would the 2002 rains cause less damage or death? I can’t answer you. There would have been, upstream, more fluid information for the general public. Since then, more information campaigns have been carried out about the risks and behaviors than have not been done. And there’s also the impact of the work and the developments, which I don’t know how to assess. If it’s impossible to say, I think the consequences probably wouldn’t be the same. In the future, the increasingly violent episodes “What is exceptional about the phenomenon of 2002, in addition to the record rainfall, is the importance of the very extensive surface area affected”, remembers Florence Vaysse. More than 5,000 km2 (almost the entire Gard department) received rainfall above 200 mm, the maximum approaching the incredible figure of 700 mm. “In the last few days, the scientist continues in comparison, we have recorded bands of very heavy rain, intense but localized.” Question: Could the great flood of September 8-9, 2002 happen again? “Yes, it will happen again, she answers without hesitation. But it will be this autumn, in 20 years or in 50 years: we don’t know.” Climate projections do not lead to optimism: if they promise “little change in annual accumulations at the end of the 21st century” (source: climat HD, on meteofrance.fr), so-called exceptional phenomena will become more frequent. and more violent in the future. It’s getting hotter and hotter! Ditto side dryness and heat. Since the creation of the Nîmes-Courbessac weather station in 1921, the 40°C threshold had been exceeded three times in 80 years, between 1921 and 2000. It was exceeded 10 times in 20 years from 2001 to 2022, including nine times after 2017. and… three times this summer of 2022 alone! “Records for the driest or hottest periods will become the average after 2050,” announces Florence Vaysse. Although political measures made it possible to significantly reduce CO2 emissions, warming will continue in Languedoc-Roussillon, observe the climatologists of Météo France. “It could exceed 5°C in average annual temperature by the end of the century compared to the period 1976-2005.”
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