The new Cévennes episode has been gradually taking place since Saturday. It is this Sunday when it settles the most and causes significant precipitation in the sector of the Cévennes massif and the departments below, in particular Lozère and Gard. Hérault, Ardèche and Aveyron are also affected.
But if this region is the wettest, the entire Mediterranean is affected by precipitation. In the case of Roussillon, in the Pyrénées-Orientales and Aude sector, this is very good news. This part of the country is suffering from a historic drought which is beginning to be counted in years.
Meteorologist Guillaume Séchet notes that Roussillon could thus be watered by more than 50 mm of rain by Tuesday, the equivalent of 50 liters per square meter. This amount would correspond to an average of one month of rain. Additional precipitation could occur from the second part of next week, which would increase the total.
As noted by the Geological and Mining Research Bureau (BRGM) in mid-April, the water table level is good in almost all of France, sometimes with levels significantly higher than normal. The Pyrénées-Orientales, Aude and Hérault are exceptions. Part of Alsace is also in this situation, but the area concerned is significantly smaller.
Regular rains since late fall have contributed to this situation. But Roussillon benefited little or nothing from it, with showers often passing nearby. However, the current rains will primarily benefit the vegetation because it is not in a dormant period this season. But if the accumulations become significant, the water tables will also benefit.
The Weather Channel specifies that between three weeks and a month of water has already fallen since Friday in several areas. Ardèche, Lozère and Gard were well watered. This intensity is characteristic of Mediterranean episodes which are defined by sudden and intense rains in a limited area.
The most remarkable local variation is the so-called Cévennes episode due to the relief of the Cévennes massif which favors the stagnation of clouds and therefore a strong accumulation of precipitation. Mediterranean episodes generally form in the fall, but 2024 is an exceptional year since this weekend’s precipitation constitutes the seventh such episode since February.
The risk of flooding will also increase with continued rainfall. Vigicrues, the organization responsible for the level of watercourses, is not sounding the alarm for the moment. “The rain intensities will remain moderate, but the episode will be lasting, which could lead to significant accumulations. The hydrological reactions generated should, however, be moderate in the watersheds. » Most of the watercourses in the area are already placed on yellow alert (level 2 out of 4).
More than the intensity, it is therefore the duration which will be the determining factor for possible significant floods. After a calm which gradually sets in on Monday, new precipitation should set in from Tuesday. They could last until Friday.
