Winter drought: can the situation still be reversed?

Yanis Darras 6:00 p.m., March 02, 2023

A blue sky and few clouds on the horizon.

Since mid-January, France has hardly experienced any episodes of rain.

Worse, the country recorded its longest period without significant rain since records began, with almost 32 days without precipitation.

A catastrophic record, when winter is the only time for groundwater to recharge and ensure the water supply in summer, when the rain is rarer. 

As a result, the situation is difficult in France.

The Geological and Mining Research Bureau (BRGM) was worried about the level of the water tables in January and said it was quite pessimistic about the availability of water in 2023. And for good reason: "We came out of the summer of 2022 with particularly dry soils, especially in certain regions where we had reached, in the heart of summer, records of low humidity in the soils", explains the climatologist, Research Director at the Research Institute for Development, Françoise Vimeux .

A deficit...

A dry summer, followed by a mild autumn which slowed down the humidification of the soil by maintaining evaporation, specifies the climatologist.

And the presence of an anticyclone over the country from the first weeks of the year, "high pressures which act a bit like a shield against the masses of humid air which generally arrive at us during this season from the Atlantic Ocean" , did not help things, underlines Françoise Vimeux. 

Thus, the rainfall deficit in February 2023 should reach or even exceed 50%, warns Météo France.

But it is not impossible that the situation will change in the coming weeks, before the end of the groundwater recharge season, at the end of March, temper the climatologists.

"If the situation is to be reversed, it must be done in the coming weeks, as long as the vegetation is dormant", specifies Françoise Vimeux.

Because once the vegetation has returned, "the water will no longer be able to infiltrate deep to fill the groundwater", because it will be captured by the plants, she continues. 

... but which can still be reversed, under conditions

So, to compensate for the lack of water over the last six months, it should rain the equivalent of 14 days in Paris (i.e. 95.5 mm of water), the equivalent of 16 days in Dijon (108 mm) or again, the equivalent of 24 days of rain in Toulouse (137 mm of rain).

Figures two to three times higher than seasonal normals for the month of March, warns the newspaper Le Parisien. 

"We have already observed very dry ends of winter and beginnings of spring, as in 2012 for example, when we experienced a very short winter, but which was followed by an exceptionally wet month of April with precipitation almost twice as high as usual", explains Simon Mittelberger, climatologist at Météo France.

"This made it possible to avoid the installation of a drought in spring and summer", he continues, stressing that the soils "reacted very quickly". 

Further episodes of rain are expected in the coming days.

It remains to be seen whether this precipitation will be sufficient, or whether the prefects will have to quickly take measures to limit water consumption in the territories most affected by the drought.