France has just gone through an episode of winter drought, which follows long months of rainfall deficit. If the fate of the summer of 2023 has not yet been decided, it would take an abnormally rainy month of March to compensate for the current situation.
Can France still escape the lack of water this summer? “If it rains as it usually rains regularly in the spring, we won’t have any problems since we won’t need to take water from groundwater or waterways”replied the Minister of Agriculture, Sunday February 27, in “Le Grand Jury” RTL-LCI-Le Figaro. Marc Fesneau, however, recalled and defended the first measures taken in five departments (Ain, Isère, Bouches-du-Rhône, Var and Pyrénées-Orientales), “restrictions of anticipation if we don’t have enough rain“.
>> Drought: which five departments are already affected by water restrictions?
Whether precipitation was on average below the average for nine of the last twelve months compared to the normal recorded from 1991 to 2020, the rain can still contribute to recharging the water tables. “The difficulty is if we continue to have weather like this, that’s what we need anticipate”, admitted Marc Fesneau. Because the groundwater recharge period takes place between September and the end of March. Beyond this window, several factors hinder the absorption of rainwater by the soil: the mild temperatures, which facilitate evaporation, and the assimilation of water directly by the plants, then in full growth.
A “normal” rain should not be enough
In his latest report (PDF document) drawing the three-month trend, dated Tuesday, Météo France noted that “the hotter than normal scenario [était] privileged for spring, while no trend emerges for precipitation”. On Friday again, the organization was under “uncertainties” as for the following week. On the other hand, it is certain that it would take a particularly rainy month of March to make up for the rainfall deficit of the last few months.
During this recharge season, normal average precipitation over France is 583.7 mm. With one month left before the end of this season, the average rainfall for the whole country is 435.1 mm. Gold, “if it rains as usual”as the minister said, it is unlikely to see an average of 148.6 mm fall on France by the end of March.
Usually, the month of March is indeed less rainy than November, December or January. According to Météo-France, the average precipitation for this month, in France, is thus 67.1 mm, far from the approximately 150 mm which would allow the year 2023 to record “normal” rainfall over the whole of the country. countries at the end of the charging season.
A month of March rainy enough to allow France to “catch up” with its rainfall deficit has only happened once since 1959, the date of the start of the Météo France surveys. It was in March 2001: 169.7 mm of precipitation then fell on France.
Already very dry soils
Moreover, “we started from such a low and dry level, after last year’s drought, that we would have needed a clear winter surplus” to moisten the soil again, forecaster Simon Mittelberger told franceinfo on Tuesday. Because the problem of this 2022-2023 season is not just a story of meteorological drought. According to Météo France, the soil humidity rate also posted a figure below the daily median throughout the month of February, which ended with a rate corresponding to a normal situation in mid-April. On March 2, it equaled the record low of March 2, 1992, namely a humidity level of 0.75.
As with rainfall, this is an average for France, which does not reflect certain territorial inequalities: some regions are more seriously affected by drought than others. Similarly, the state of filling of groundwater and the uses and needs related to this water resource differ from one place to another. Finally, no one is able to predict whether the summer will be as hot and dry as the previous one.
To prepare for the possibility of a new drought, the Minister for Ecological Transition and the Secretary of State for Ecology, Christophe Béchu and Bérangère Couillard, will meet with the prefects on Monday March 6, “to anticipate and prevent the risk of drought throughout the territory”. This progress report should make it possible to share with them the lessons learned from the summer of 2022, according to those around the ministers. And to prepare for a new dry summer, still hypothetical, but worrying.