Winter drought: the worrying situation of French groundwater

Europe 1 with AFP 6:25 p.m., March 13, 2023

An "unprecedented" and worrying situation: the water tables of the whole of France are at the end of the winter "degraded" and below normal, which suggests a probable drought in the coming months, estimates Monday the Bureau of Geological and Mining Research (BRGM), which calls for vigilance.

For February, "all the groundwater shows levels below normal and 80% of the levels are moderately low to very low", indicates the BRGM.

The areas of the Rhone corridor, Limousin, Causses and the Roussillon plain are particularly affected, displaying "red" levels and "very low" water tables.

"We have already experienced a situation with many more red dots" at that time, in 2012 and 2017, "but what is unprecedented is that all of France is affected", underlined Violaine Bault, hydrogeologist from BRGM , during a press conference.

"Great uncertainty" for the next few months

The month of February, which according to Météo-France was the 4th driest in France since 1959 with in particular a record series of 32 days without precipitation between January 21 and February 21 and an overall deficit of precipitation exceeding 75%, was particularly damaging, with a "brutal stoppage of charging", notes Violaine Bault.

At the end of this month, the levels are "generally down" on the reactive aquifers - the most sensitive to rain - and this while the 2022-23 recharge period began "one to two months late" and "remains in deficit".

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For the next few months, the BRGM reports "great uncertainty".

The evolution of trends "will depend mainly on rainfall", adds the geological institute, which however considers that "the reconstitution of stocks by spring remains difficult to envisage on the reactive aquifers showing very low levels".

Does this mean that the summer of 2023 will be worse than that of 2022, already marked by an exceptional drought?

Recharging could resume in certain sectors in March but "the next rains will probably have little impact", insofar as from April onwards, the resumption of vegetation will absorb most of the water.

A need for heavy rains

"There at the beginning of March, it rains, but it must first moisten the soil before allowing really deep infiltration", notes Violaine Bault.

A process all the longer as the dryness of the soil is already particularly marked, according to Météo France, which reports a situation at the end of February which corresponds to that of mid-April or even mid-May for certain sectors.

The BRGM also points out that the rains in autumn and winter, an essential recharge period for the reconstitution of stocks, were "very insufficient to compensate for the deficits accumulated during the year 2022".

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So if it does not rain heavily in the coming weeks when Météo France announces for the next three months temperatures probably warmer than normal, "we risk having all of France affected by water restriction decrees" , believes Violaine Bault.

A plan to improve water management in France

Currently, 14 departments are already on alert or on alert, according to the official Propluvia website.

The government is preparing to launch a plan to improve water management in France.

It will be published "in a few days", promised Saturday the Minister of Ecological Transition Christophe Béchu.

This plan, supposed to draw lessons from the historic heat wave of the summer of 2022, "is very comprehensive, it includes around fifty measures, it deals with sobriety, quantity, quality, financial means, governance “, added the minister.

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To preserve groundwater, the BRGM has outlined ways, such as de-impermeable the soil to promote water infiltration or recharge the groundwater with "unconventional" water, including treated wastewater.

It is also possible to limit withdrawals.

"Saving water with every little gesture that saves water can count," says Violaine Bault.