although it rained at the beginning of the year, the water surface was dry

ENVIRONMENT – Dry rivers, water that no longer flows from the taps, thirsty plants: a picture of the summer drought of 2022 marked France. This winter, the heavy rain episodes that fell at the end of December and from the beginning of the week with the storms Gérard and Fien will assure us of water reserves for the summer. And again…

Unfortunately, this bad weather does not appear to be enough to raise groundwater levels, which are currently very low. “The same scenario for summer 2023 as for 2022 is being enacted”, anticipate with HuffPost David Labat, research professor at Paul Sabatier University in Toulouse.

Water restrictions in the middle of winter

Remember: the extreme tenderness of late 2022 has caused a waterspout in France. Between December 31 and January 2, a month of rain falls in Brittany, for example. And in the Alps, continuous rains have melted what little snow remained on the slopes. The start of 2023 is not to be missed as it falls on January 10, in just 24 hours, the equivalent of three weeks to one month of rain in the Pyrenees mountains.

However, the water table is therefore at a level “ worrying » in most parts of France, as warned, in its last monthly bulletin published January 13, the Bureau of Geological and Mining Research (BRGM).

” The groundwater level in December was unsatisfactory. Indeed, the rains infiltrated during the autumn are grossly insufficient to compensate for the deficit accumulated throughout 2022 and to improve the groundwater situation in the long term.” continue BRGM, considered as « weather tablecloth “. A public body that also calls itself “quite pessimistic” water availability in 2023.

Neither Gérard nor Fien will allow the aquifer to be refilled

On 16 January, four departments were still placed on drought alert (Ille-et-Vilaine, Jura, Lozère and Savoie) and eight departments were on alert or high alert, a law that accompanied water restrictions (Oise, Deux-Sèvres , Ain , Isère, Lot, Tarn-et-Garonne, Haute-Garonne and Pyrénées-Orientales), according to the government website Propluvia.

But hurricanes Gérard, then Fien, which hit France in the last few days with similar rainfall, couldn’t they change the situation? Unfortunately not, answered David Labat. “When you have a hurricane, there will be soil saturation. Just like a sponge: once it’s saturated, it can’t absorb any more water. »

” Therefore there is no vertical flow of water which allows it to recharge the aquifer “, continued the researcher from Paul Sabatier University. “The principle is the same as that of a summer storm: you can have 300 millimeters of water in a few hours with no effect on the water level”, further support professors in hydrology.

What is clear, when such bad weather occurs, instead of seeping in, the water actually overflows and causes flooding. Wednesday, January 18, Landes and Pyrénées-Atlantiques, where heavy rain is expected, are also still being placed on an orange alert by Météo-France for “rain-flood”.

Another two months to reverse the trend

In addition to this counterproductive bad weather, the extreme softness of late December-early January makes it impossible to accumulate sufficient snow stocks. This stock usually fills dams that regulate low water flows (seasonal dips in rivers, Editors note) during the summer”, determine which researchers expect very dry soil and very low flow for July-August 2023.

The same worrying observation was made by Pierre Pannet, deputy director of BRGM during a press conference held in mid-January. If rain continues to be rare in 2023, “ we will arrive at a much worse situation than we found ourselves in late summer 2022” when almost all metropolitan departments are experiencing water restrictions.

If the groundwater situation in France is currently less favorable than it was at the end of the 2021-2022 winter, there is still two months to reverse the trend. For this, there is no magic recipe: ordinary rain is needed. “In February and March, we need 20 to 30 millimeters of rain every two weeks,” still support David Labat. After April, it would be too late, because with the spring water pointing at the tip of its nose, the rain would be absorbed by the growing vegetation and would leave no groundwater droplets behind.

The “water” action plan is drawn up by the government

Regarding plants, the water situation is also very worrying in the Aude and Pyrénées-Orientales where “ the soil moisture index is close to 0. Yes, zero, in January “, as noted agroclimatologist Serge Zaka, in a message posted on his Twitter account. The rain that occurred since January 15 and 16 was not “not enough to fill in gaps but will remove the flora and fauna in the first centimeter of soil”somewhat relativistic researchers.

Facing 2022 which is the hottest year recorded in France with a rainfall deficit close to 25%, the government is currently drawing up an action plan. “water” for 2023. It aims to “reducing water consumption and optimizing withdrawals, better reusing wastewater and accelerating reduction of leakage in water networks”. Details of the measures will be announced on January 26 in Rennes during the local water management meeting.

“ The government no longer has a choice: we must enter an era of water tranquility”, still abundant David Labat. Hydrologists recall that with climate change, record droughts will continue to double. “A year like 2022, very deficit, had a chance in 20 years of happening in the 80s, today this probability increases to one in five. »

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