June 2021 ranked among the five wettest months of June over the period 1959-2021 and July is also starting off on a good footing.
Enough to fill our water tables to the brim?
Not really.
"The summer rains are mainly captured by the vegetation", responds to the Bureau of Geological and Mining Research (BRGM).
However, these abundant rains have meant that groundwater has not been used much so far over a large part of the metropolitan area and, on July 1, the level of these underground reserves was generally favorable for the BRGM.
Still, a prolonged drought could quickly change the situation, while Météo France still expects a drier and hotter than normal summer.
Especially around the Mediterranean, where the situation is already much less favorable.
It won't come as a surprise to those who have wiped out rain after rain in recent weeks.
June 2021 ranks among the five wettest months of June over the period 1959-2021, Météo France indicated in its hydrological situation bulletin published last Thursday.
Blame it on very frequent and very active rain and storm passages "which were not very localized as one can get used to with this type of episodes but which, on the contrary, concerned a large part of the country, says Michèle Blanchard, climatologist at Météo France.
From Hauts-de-France to New Aquitaine as well as from the Grand Est to the north of Auvergne-Rhône-Alpes.
💦 WATER BALANCE ▶ ️ As of 07/01 ◀ ️
June ranks among the 5⃣ wettest months of June over 1959-2021.
The soils became humid except in the south of Occitania, the Mediterranean arc and Corsica where the drought was accentuated.
🔎Full reporthttps: //t.co/wRn2lUhXsx pic.twitter.com/rphVi2XFBB
- Météo-France (@meteofrance) July 8, 2021
Up to more than 200 mm of precipitation
“On average, over the country and over the month, the excess rainfall was 50% higher than normal [calculated over the period 1980-2021], continues Michèle Blanchard. We expected 70mm of rain, we got 102.2. »But, in some places, the accumulations of precipitation reached 200 to 250 mm, from the Allier to the Lot, from Vienne to the north of the Gironde, on the Jura Massif, the north of the Alps as well as, very locally, on Seine-et-Marne, Haute-Marne, the south of the Vosges and Burgundy. With records broken here and there. Especially in Hauts-de-France, reported France 3.
And then, to this wet month of June, we must add May, also well watered, just as is, for a large part of the metropolis, this first part of July.
In recent hours, on Twitter, Météo France warned against an increase in the rains in the departments of the North-East.
The rains will intensify in the coming hours in the departments of the North-East in #vigilanceorange, sometimes taking on a stormy character with 15 to 30mm in a short time, then remain constant all next night, even tomorrow morning in Alsace ▶ ️ https: / /t.co/CSYEovTI83 pic.twitter.com/wvshJf9zDn
- VigiMeteoFrance (@VigiMeteoFrance) July 12, 2021
Summer rains that only slightly reach the water tables
We could also see the glass half full and tell ourselves that all this fallen water shelters us from the drought for the rest of the summer to come, the forecasts of Météo France still counting on the months of July, August. and September drier and warmer than normal over much of France. It missed. "At this time of the year, the rains which infiltrate the soils, even abundant, have little impact on the level of the water tables," explains Violaine Bault, hydrogeologist at the Bureau of Geological and Mining Research (BRGM), the national geological service in charge of monitoring groundwater. Much of it is captured by growing vegetation, which therefore drinks a lot of water. The rest must first cross the ground, very dry in May because it had not rained for three months then.Very little water therefore reaches the aquifers, not in sufficient quantity in any case to fill the emptying of the latter towards their natural outlets. Rivers, oceans, wetlands… ”
Result: the latest BRGM map summarizing the state of the groundwater on July 1, published on Monday, is dotted with triangles pointing downwards, indicating that the groundwater level is generally falling. Nothing unusual at this time of year. The heavy rains of recent weeks are not without positive consequences. "They have allowed, in many sectors, that this drop in level is slower than usual," continues Violaine Bault. Quite simply because we had less to use the groundwater to water crops, gardens, fill swimming pools, etc. The streams are also at a higher level than usual in relation to the water tables, so the emptying is slower. "
State of the groundwater tables on July 1, 2021
📉 the trends are downward for the majority of water tables.
Usual observation at this time of year.
Find the detailed bulletin with new data: ➡️https: //t.co/BlZJOaoUih#eau pic.twitter.com/DsV8c41igF
- BRGM (@BRGM_fr) July 12, 2021
An overall satisfactory level of groundwater ... for the moment
Add to this an autumn-winter 2020-2021 marked, for the second year in a row, by a strong groundwater recharge over a large part of the territory, and you obtain a situation on July 1 that is generally satisfactory in terms of the hydrological situation. in a city.
With levels close to normal over a large northern and western part of the territory, indicates the BRGM.
Sometimes even high in the Aquitaine basin.
But it is only for this region that the BRGM considers that "the situation should remain satisfactory during the summer".
Elsewhere, even when the water tables are currently in the green, "the situation can deteriorate rapidly during the summer in the event of a prolonged meteorological drought", indicates Violaine Bault.
“The most reactive water tables that we have in metropolitan France - those in particular in the Armorican massif (Brittany) and the central massif (Limousin and Auvergne) - take five to six weeks to go from a green level as we have today at a level that is starting to turn orange-red, ”she explains.
Much more complex situation on the Mediterranean rim
The Mediterranean rim, the Alps and the Pyrenean foothills, for their part, face the summer in a less favorable situation. “These regions have already been very little affected by the June rainfall,” begins Michèle Blanchard. In the PACA region, for example, the accumulations of precipitation were 50% lower than normal. We expected 60 mm of rain, there were 32. ”Violaine Bault goes back even further to the famine around the Mediterranean. “The region experienced significant precipitation at the end of September and the beginning of October until it caused flooding,” she recalls. Then, they had hardly anything during the whole winter. It fell in May, but that was not enough to reload the water tables. "
On the Mediterranean coast, the water tables thus show a "low level", indicates the BRGM, which expects the state to deteriorate further during the coming weeks. The situation could become tense in certain sectors, he said in his bulletin published on Monday. "The level of the water tables is also moderately low in Corsica, even if the situation is a little more contrasted according to the sectors, specifies Violaine Bault. It has rained on the reliefs in recent weeks, in particular. "
Be that as it may, these regions in the south of France “will have to be watched closely,” continues Violaine Bault.
In particular, always, on this Mediterranean coast where the water tables are very often requested in the summer because of the influx of tourists that this region receives.
"Drought" prefectural decrees have already been taken to curb the solicitation of water tables.
All the Mediterranean rim and the Rhone corridor are already placed in vigilance [information and encouragement of individuals and professionals to save water].
In the Var, the Bouches-du-Rhône, the Hérault, the Eastern Pyrenees, the Haute-Garonne, several sectors have even been placed on alert, with water use restrictions already in force.
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