The Bureau of Geological and Mining Research has alerted to the unsatisfactory situation of groundwater in France.
The groundwater situation in France “has deteriorated and is unsatisfactory”, alerted Monday, March 13 the Bureau of Geological and Mining Research (BRGM), the French national geological service. While all of them are currently below normal, after an exceptional drought last year and a long period without significant rain, especially in the first quarter, the situation raises fears of another dry summer in the territory.
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“If spring and summer are as dry as last year, we risk having restrictions on the use of water throughout France”, alerted Violaine Bault, hydrogeologist at BRGM, during a press conference. Franceinfo explains why specialists on the subject are alarmist.
Because the tablecloths are dry
“All the groundwater shows levels below normal and 80% of the levels are moderately low to very low”alerts the BRGM in its bulletin on the situation on March 1st. “What is new since the start of recordings is that all of France is affected. We have low levels throughout the country”adds Violaine Bault.
Four sectors are particularly affected: the Rhône-Saône corridor from Burgundy to Bas-Dauphiné, the Roussillon plain, the Causses and Limousin.
Because the current rains do not compensate for the lack
Fortunately, the soils have been moistened by the rains of the past few days. “We went from a record situation for the start of March to a normal situation for the season”, describes Simon Mittelberger, climatologist at Météo France. With the exception of the Paca and Languedoc-Roussillon regions and the axis running from Normandy to the Grand-Est, the soil situation has therefore “much improved”as shown in this map comparing the soil moisture index in France on March 6 and 13.
However, to sufficiently recharge groundwater tables for the summer, “very above normal rains”, insists Pierre Pannet, Deputy Director of Territorial Actions at BRGM. These precipitations thus only have the effect, for the moment, of rewetting the soil, without penetrating to the underground water tables. Same problem for the storms that occurred during the night of March 13 to 14. “It’s not ideal for seepage of water through the soil to the aquifers. We need more long-lasting disturbances with less heavy rains. There, the water will run off and feed the courses of ‘water”commented for franceinfo Frédéric Long, forecaster at Météo France.
Because spring is likely to be hot
Furthermore, Météo-France writes in its three-month trend bulletin that a “warmer than normal scenario is preferred for spring”. Warmer temperatures, boosted by human-induced climate change, will decrease the amount of water that can infiltrate the soil. In effect, “the water will evaporate more”, begins to explain Simon Mittelberger. In addition, with an early spring, the growth of vegetation starts earlier and comes, to develop, “to draw water from the ground”adds the climatologist. “These plants will be [en outre] much more developed and predisposed, if there is frost in April, to suffer damage”Serge Zaka finally anticipated, agroclimatologist at ITK and administrator of the Infoclimat association, in January on franceinfo.
Because the snowpack is not sufficient to irrigate the soil
Finally, the snow cover of the mountain ranges is low. “The state of the snowpack is very deficient, even close to the lowest record values for the Alps”, details Simon Mittelberger. This lack which risks limiting the water supply in the spring. The snow constitutes a stock of water which irrigates the nearby regions during the melting. “It will have an impact on certain groundwater in Provence or around the Pyrenees”, warned the BRGM during its press conference. And if snowfall has whitened the peaks in recent days, “it did not allow us to return to a normal level for the season”laments the climatologist.
Another element has dried up the water resources coming from the massifs over the years: the melting of the glaciers due to global warming. “In the Pyrenees, (…) they will disappear in ten to twenty years”, warned in January on franceinfo the glaciologist of the CNRS Etienne Berthier. In the Alps, “they will persist longer, but in 2100, our projections indicate that there would remain at best about fifteen percent of their mass”, he continued. And until then, the mass of water flowing from it each year will decrease.