The aquifer situation is highly satisfactory over a large part of the country, with 61% of levels being above monthly norms. However, the levels remain very low in the aquifers in the Roussillon area.
15 January 2025

Hydrogeological situation on 1 January 2025

In December 2024, groundwater recharge continued, with 67% of observation points showing an increase in levels. Only the aquifers in the south-east of France had levels that decreased.

The situation was highly satisfactory over a large part of the country, with 61% of levels being above monthly norms. The situation nevertheless remained worrying in the Roussillon area, where the aquifers continued to show low levels.

The trends and developments during this winter will depend primarily on the amount of rainfall. In January, the recharge should continue in the inertial aquifers as well as in areas with reactive aquifers that receive plenty of rainfall. However, if there is not enough rainfall, groundwater depletion could continue, causing the situation to deteriorate. The levels recorded at the end of 2024 suggest that satisfactory levels can be expected at the end of winter across much of the country.

Map of aquifer levels in mainland France on 1 January 2025.

Map of aquifer levels in mainland France on 1 January 2025.

Map drawn up by BRGM on 10 January 2025, based on data from the ADES database, acquired up to 31 December 2024. Data source: ADES database (ades.eaufrance.fr) / Hydroportail (hydro.eaufrance.fr) / Background map © IGN. Data producers and contributors: APRONA, BRGM, Conseil Départemental de la Vendée, Conseil Départemental des Landes, Conseil Départemental du Lot, EPTB Vistre Vistrenque, Parc Naturel Régional des Grandes Causses, Syndicat Mixte d'Etudes et de Travaux de l'Astien (SMETA), Syndicat Mixte pour la protection et la gestion des nappes souterraines de la plaine du Roussillon (SMNPR).

This map shows the global indicators reflecting the average fluctuations of the aquifers. They are based on point indicators collected at groundwater monitoring points (by means of piezometers).

The "Aquifer levels" indicator compares the current month’s figures with those of the same months in the entire record, i.e. at least 15 years of data and sometimes up to as much as 100 years of data. It is divided into 7 classes, from the lowest level (in red) to the highest (in dark blue).

The grey areas correspond to areas without unconfined aquifers, i.e. with an impermeable or semi-permeable layer above the aquifer, and/or sectors with a very low density of measuring points. This last case primarily concerns mountainous areas with small, heterogeneous aquifers.

The "Evolution of levels" indicator reflects the variation of the water level of the past month compared to the two previous months (stable, increasing or decreasing).

These global indicators reflect general situations and trends and do not take into account possible local disparities.

© BRGM

Evolution of the trends observed on piezometers from January to December 2024.

Evolution of the trends observed on piezometers from January to December 2024.

© BRGM

Groundwater trends

In rainy parts of the country with reactive water tables, the winter recharge period began in September 2024 and during October the recharge had generally started in all aquifers. Overall, the recharge was extremely dynamic in October, but slowed significantly in November.

In December 2024, the recharge was generally active: 67% of the points monitored recorded rising levels (46% in November).

The recharge resumed in December 2024, despite little rain. The levels in the majority of aquifers rose. The fact that the soil was moist, even saturated with water, meant that the rainfall was able to filter deep into the ground. However, the recharge slowed in areas with reactive aquifers that received little rain in November and December: aquifers in the Armorican Massif and in the north to the centre-west of the Aquitaine Basin.

Groundwater levels in the south-east of France either decreased or remained stable. These decreases can be explained by several factors. The aquifers in the Languedoc, south-eastern Massif Central, Provence, Côte d'Azur and southern Alpine valleys did not receive enough total rainfall over the past two months. Moreover, the precipitation that fell in the form of snow did not contribute to the aquifer recharge in the Alps and the Savoie foothills. Finally, the inertial water tables in the Bas Dauphiné, Haut Dauphiné and east Lyon area react slowly to meteorological events. Consequently, in December, they suffered from the lack of rainfall in November.

Comparison between 1 January 2024 and 1 January 2025

To see the change over a year, slide the cursor over the map.
Map of France showing the state of the aquifers on 1 January 2024.
Map of France showing the state of the aquifers on 1 January 2025.

Map of France showing the state of the aquifers on 1 January 2024 (left) and 1 January 2025 (right).

© BRGM

Evolution of the situation observed on piezometers from January to December 2024.

Evolution of the situation observed on piezometers from January to December 2024.

© BRGM

Groundwater situation

The 2024-2025 recharge period began between September and October with particularly high levels. Levels remained above monthly norms in November. However, the aquifers in the Roussillon area, the Hérault valley and on the south-eastern coast of Corsica continued to show very low levels.

In December 2024, the aquifer situation deteriorated slightly compared to November 2024, but remained highly satisfactory: The levels recorded at 17% of the observation points were lower than normal for the month; 22% were comparable with monthly norms and 61% were higher (compared with 15%, 20% and 65% respectively in November 2024).

The situation was slightly better than last year, in December 2023, when only 56% of the levels observed were above monthly norms. Some aquifers had higher levels than in 2023. Aquifer levels in the south east and Corsica, for example, were better than in 2023. The state of the aquifers in the Paris Basin, Sundgau and Rhône-Saône corridors improved gradually over the last 12 months. However, other aquifers had lower levels than in December 2023, notably in the Artois Basin, and the reactive aquifers in the northern two-thirds of the country and in the south west. It should be noted, however, that levels were exceptionally high at the end of 2023 in some of these aquifers.

In December 2024, the situation of inertial aquifers continued to improve very slowly, but overall remained similar to that in November. The aquifer levels in the Artois and Paris Basins were generally moderately high. They were even high to very high in the upstream sections (east and south) of the Paris Basin. The level in Sundgau aquifer (southern Alsace) has been moderately low since June 2024, due to its very high degree of inertia. The levels in the inertial aquifers of the Rhône-Saône corridor ranged from normal to moderately high, and although local situations varied, no observation point recorded low to very low levels. 

As regards reactive water tables, the situation did not change from the previous month in most cases. The levels deteriorated in areas that received little rainfall over the past two months: north and west of the Armorican Massif, north and centre-west of the Aquitaine Basin, south of the Massif Central (basement), Languedoc coast, Provence and Côte d'Azur.

The situation in reactive aquifers remained highly satisfactory over a large part of the country, with levels generally being in line with monthly norms or high. The levels in the reactive aquifers in the basement formations of the south-eastern Armorican Massif and in the Jurassic limestone aquifers from the Brenne to the border of the Poitou region remained very high, despite receiving only light rainfall over the past two months. A few rare observation points had very high levels reaching 20-year highs, but these situations remained exceptional and localised. This was notably the case in a few observation points in the Jurassic limestone aquifers in the Berry region and in the Tertiary-formation aquifers in the basins of the Armorican Massif.

The impact of the lack of rainfall over the past two months was particularly felt in the aquifers in the Languedoc, Provence, Côte d'Azur regions and in Corsica. In these areas, the situation was less satisfactory than elsewhere, with moderately low to near-normal levels. Some local situations remained difficult, with low levels recorded in the Provence aquifers and very low levels in the aquifers along the south-eastern coast of Corsica. However, satisfactory levels, ranging from moderately high to very high, were recorded on the eastern coast of the Côte d'Azur, on the north-eastern coast of Corsica and in Cap-Corse.

Finally, rainfall in late autumn and early winter had a beneficial effect on the alluvial aquifer of the Aude, which has recorded moderately high levels since November 2024, after nearly 3 years of sub-normal levels, particularly in its upstream section. That being said, the precipitation in the Pyrénées-Orientales region was insufficient to offset the rainfall deficit accumulated over the past 3 years. Levels remained very low in the Roussillon plain and low in the Corbières Massif.

Several aquifers had surplus stocks, with high to very high levels, compared to the levels recorded for December in previous years:

  • The situation in the semi-inertial and inertial aquifers in the upstream (east and south) section of the Paris Basin has gradually improved over the past year, with high to very high levels recorded in December 2024; 
  • The reactive aquifers in the basement formations of the south-eastern Armorican Massif and in the Jurassic limestone formations from the Brenne to the border of Poitou region have remained at very high levels since May 2024;
  • The levels recorded in the reactive aquifers in the Combraille basement, under the Millevaches plateau and in the Jurassic limestone formations of the Berry region were high.

The situation was unfavourable in several aquifers with moderately low to very low levels compared to those recorded for December in previous years:

  • The situation remained fragile in certain localised areas, with low to very low levels in the aquifers in the coastal plains of southern Corsica (eastern plain and Rizzanese plain); 
  • The situation of the aquifers in the Roussillon multilayer formation and the karst limestone of the Corbières Massif remained critical, with low to very low levels.

Aquifer recharge: 3 questions to provide a better understanding of the process


 

Groundwater levels vary throughout the year, from high levels in winter (when vegetation does not absorb rainwater) to low levels in summer (the traditional depletion period).

The fate of rainfall varies greatly depending on the time of year and the condition of the ground surface on which it falls. Usually, the groundwater-recharge period takes place from early autumn (September-October) to early spring (March-April), a six-month period during which vegetation is dormant (with low evapotranspiration) and rainfall is generally more abundant. If the winter is dry, groundwater recharge is very low.

From spring through summer, rising temperatures coupled with the regrowth of vegetation and thus increased evapotranspiration, limit the infiltration of rainfall into aquifers. Between May and October, unless there are exceptional rainfall episodes, aquifer depletion usually continues and levels will keep decreasing until the autumn.

Groundwater flows at different rates depending on the porosity (percentage of gaps/cracks in the rock) and permeability (capacity to allow water to circulate, i.e. interconnectivity between these gaps/cracks) of the aquifers. The larger the gaps and the more interconnected they are, the faster the water will flow, for both refilling and depletion.

It takes a given volume of water different periods of time to travel the same distance, depending on the kind of rock formation:

  • a few years in a porous formation,
  • a few months in a cracked formation,
  • and a few days, or even a few hours, in a karst formation.

The impact of the winter recharge varies according to the cyclic nature of the aquifer, i.e., its reactivity to rainfall infiltration.

We refer to aquifers that are:

  • reactive (when they are composed of sand, gravel, karst limestone or weathered granite formations). These aquifers are characterised by their rapid reaction times: they can recharge during heavy summer rainfall, but are also highly sensitive to drought. Their levels can therefore vary very quickly over the course of the same season.
  • inertial (when composed of chalk, non-karst limestone, sandstone formations). Their reaction times are slow. They can have multi-annual cycles, meaning that they require a long period to recharge or empty.
Cyclicity of aquifers in mainland France.

Cyclicity of aquifers in mainland France.

© BRGM

Cyclicity of aquifers in mainland France. © BRGM

Forecasts

The Météo-France seasonal forecasts for the months of January, February and March 2025 predict higher-than-normal temperatures across the country and drier-than-normal conditions in the south of France and Corsica. No clear scenario has been established concerning rainfall for the rest of the country.

Until spring and the regrowth of vegetation, the trends and changes in aquifer situations will therefore depend on the amount of rainwater infiltration, and hence the total rainfall, and the reaction time of the aquifers (reactivity/inertia).

After the lack of rainfall in November and December 2024, the levels in the country's aquifers will probably be affected if the month of January is also dry. In this case, the depletion of the aquifers would resume, resulting in lower water levels, and the situation could continue to deteriorate. The inertial aquifers would take longer to be affected, but the recharge would likely slow down and then cease, if the lack of rainfall continues. On the other hand, if there are normal to excessive amounts of rainfall, the recharge will continue. In this case, the state of the aquifers would remain stable or even improve (rapidly in areas with reactive aquifers that receive a lot of rain, but more slowly in the inertial aquifers).

Longer-term forecasts continue to indicate that virtually all the areas around the country in which groundwater levels are currently above monthly norms are unlikely to be affected by a winter drought.

The situation of the inertial aquifers in the Artois region, Paris Basin, Sundgau (southern Alsace) and Rhône-Saône corridor should continue to improve slowly or remain stable over the coming weeks. The levels in spring 2025 will probably be satisfactory, close to or above the seasonal norms.

In the case of reactive aquifers, the seasonal forecasts remain uncertain and their levels will depend on the total rainfall. Over a large part of the country, the generally positive start to the winter recharge means that we can expect to see satisfactory levels at the end of winter. As regards the aquifers that had below-normal levels in December 2024, their levels could potentially return to above-normal levels, if there are significant, well-distributed episodes of rain over the coming months. However, the situation in reactive aquifers could also deteriorate rapidly if there is insufficient rainfall. The groundwater levels in the summer of 2025 will depend on whether there is an abundant winter recharge continuing into the spring. This would push back the start of the depletion period.

It will be more difficult for aquifers in the Roussillon plain, which had very low levels in December, to reach normal levels in Spring 2025. It is difficult to imagine the aquifer reserves in the Roussillon region reaching above-average levels by spring 2025 or being replenished in a lasting manner over the coming months.

In view of the lack of rain over the last two months, there is less likelihood of any short-term risk of flooding due to rising groundwater levels in reactive aquifers. As regards the inertial aquifers of the Artois Basin and Paris Basin, this type of risk remains possible in late winter and early spring, if rainfall totals over the next few months are greater than average. Certain aquifers in the Paris Basin had high to very high levels in December and could reach historically high levels during the winter. Close monitoring is recommended in the following areas over the coming weeks: 

  • Semi-inertial Turonian chalk marl aquifer in the Champagne, Burgundy and Gâtinais region;
  • Semi-inertial Tertiary limestone and sand aquifer in the Brie Tardenois region.

Next groundwater tables status report

Our groundwater report is now published every month, in the middle of the month.

The next issue will be published in mid-February 2025.

Groundwater monitoring network, Pyrénées Orientales

State of groundwater: monitoring by BRGM

Groundwater is a widely used resource: in metropolitan France, it accounts for nearly two-thirds of drinking water consumption and more than one-third of agricultural water consumption. It is also widely used in the industrial sector. Groundwater tables depend on cyclical recharges.

BRGM monitors groundwater levels and quality in mainland France. Discover the actions carried out by the French geological survey and the resources and databases available on groundwater in France.

Press contact

Avatar du BRGM
Press relations office
Phone: +33 (0)2 38 64 46 65 / +33 (0)6 84 27 94 14