Hydrogeological situation on 1 February 2026
Across the northern two-thirds of France, with the exception of Brittany, and in southwestern France, recharging is happening at a relatively low pace. Groundwater levels are gradually decreasing, but remain satisfactory overall. The status of groundwater in northeastern France, however, is a greater cause for concern.
Rainfall events in December and January have had an impact on groundwater levels in southeastern France and in Corsica, which improved substantially, rising above normal levels.
Forecasts remain uncertain as they depend on rainfall in late winter and early spring. They are more favourable for groundwater in Brittany, southeastern France and Corsica, with higher-than-normal levels, but less favourable in northeastern France, with low levels.
Groundwater situation: a new map and more frequent bulletins
The BRGM groundwater status report, which is eagerly awaited by the public every month, is being revamped. It will now be published twice a month, and the map will have a new colour scheme to make it easier to read.
As of 1 July 2025, the comparative map between the current month and the same month of the previous year will also be reissued with the new colour scheme.
Map of aquifer levels in mainland France on 1 February 2026.
© BRGM
Evolution of the trends observed on piezometers from January 2025 to January 2026.
© BRGM
Trends
Recharging began between late August and September 2025 at many of the more responsive aquifers, with the exception of the Armorican Massif; it then paused in early October before resuming at the end of October and into November and December. Recharging of the less responsive aquifers began in October 2025 but failed to make much of an impact on the central part of the Paris Basin.
In January 2026, recharging was under way, with 56% of levels rising and 26% dropping (compared with 63% and 25% respectively in December). However, January rainfall failed to sustain this recharge.
Inertial aquifers
During autumn and winter 2025–2026, the Paris Basin and the eastern Artois region received less rainfall overall than usual. Recharging of the least responsive aquifers in the centre of the Paris Basin and eastern Artois was slow to start, with levels dropping or remaining stable. It resumed in January for the moderately responsive groundwater bodies around the edge of the Paris Basin. It continued only in the areas that received more rain and which harbour moderately responsive groundwater bodies, such as the marl chalk aquifers in western Artois and Champagne.
Recharging of the less responsive groundwater bodies the Rhône-Saône corridor began in October and November 2025. In January 2026, groundwater levels showed a rising trend. Recharging then slowed in northern France, the eastern Lyon and the Dijonnais regions.
Reactive aquifers
The recharge is under way only in the areas that received enough rainfall in December 2025 and again in January 2026. Peaks in groundwater flooding were observed from mid to the end of January in the Finistère basement, Morbihan and western Loire-Atlantique. Intense rainfall during the second half of December and from mid-January onwards was effective in recharging groundwater in the southern Massif Central, Roussillon, Languedoc and Corsica.
Groundwater levels in the rest of France are showing a slightly rising or stable trend. Recharging is slowing in southwestern France despite substantial cumulative rainfall in January. With below-average precipitation in December, dry soils prevented infiltration of effective rain at depth. In northeastern France, the trend is reversing following the lack of rainfall between November and January, with groundwater levels remaining stable or decreasing. Provence is showing contradictory trends, due to an uneven distribution of effective rainfall in December and January.
Comparison between 1 February 2025 and 1 February 2026
Map of France showing the state of the aquifers on 1 February 2025 (left) and 1 February 2026 (right).
© BRGM
Evolution of the situation observed on piezometers from January 2025 to January 2026.
© BRGM
Aquifer situation
At the end of summer 2025, groundwater levels were generally satisfactory for the less responsive and most of the more responsive aquifers. They then improved from September 2025, remaining stable thereafter from October to December 2025.
Groundwater levels in January 2026 were worse than in December, with marked variations from low to very high: the levels recorded at 40% of the observation sites were below monthly averages, 24% were comparable with monthly norms and 36% were above average (compared with 30%, 24% and 46% in December, respectively).
The situation was much better in January 2025, with 68% of groundwater levels above monthly norms. The 2026 levels are better in the more responsive aquifers that have seen the beginnings of a surplus due to recharge, such as in Brittany, southeastern France and Corsica.
Inertial aquifers
The levels in the inertial aquifers of the Paris Basin and Artois have been getting progressively worse since March–April 2025, which marked the end of the 2024–2025 recharge period. The very low recharge observed these last few months has had an impact on groundwater levels. In January 2026, the situation was generally good, with levels close to normal, but with differences appearing within the same water body. The Champagne marl chalk aquifer is the most affected, with low to very low levels recorded locally.
Groundwater levels in the Sundgau aquifers (southern Alsace) and those in the Rhône-Saône corridor range from close to normal to moderately low. The recharge started off well, but alternating dry and wet spells did little for effective rainfall infiltration and prevented long-term recharge.
Reactive aquifers
In January 2026 most aquifers across the northern two-thirds of France and in southwestern France experienced little to no recharge. Groundwater levels are thus decreasing in more responsive aquifers across the northeast and along a central strip, from the northern Aquitaine Basin to the Jura and northern Alps. In responsive groundwater bodies in the central and western parts of the Aquitaine Basin and in the eastern Armorican Massif, levels were maintained by effective rainfall in January.
Groundwater levels remain generally good, ranging from moderately low to moderately high. Locally contrasting situations can be explained by recharge events that have been unevenly distributed in time and place since September 2025. In northeastern France, groundwater levels are not very good, ranging from moderately low to low, due to the persistent lack of precipitation since November.
Only the more responsive aquifers in Brittany, southeastern France and Corsica have benefited from rainfall infiltration in late December 2025 and January 2026, showing substantial improvement.
In January 2026 groundwater levels in the Finistère basement, Morbihan and western Loire-Atlantique were high to very high. Flooding in January was caused by soils being saturated, leading to heavy surface runoff and river flooding. This was made worse in some cases by high tidal coefficients, which prevented rivers from flowing out to sea. Mid-January groundwater levels were not high enough to contribute to flooding. But high levels at the end of January likely made river flooding worse. Gradual groundwater drainage towards valleys probably contributed to prolonging and extending the flooding.
Intense rainfall events in December and January contributed effectively to groundwater recharge in southeastern France and Corsica. Some groundwater levels are still close to normal, due to a slower response, such as in Roussillon and Valras-Agde, or to unevenly distributed rainfall, such as in the Bas-Rhône and Durance Basins. Alluvial aquifers along the Languedoc and Corsican coastlines have responded quickly to rainfall from mid-January, with high to very high levels. They then may have contributed to river flooding either through groundwater emerging above the ground surface or draining into rivers, or indirectly by saturating soils, thus preventing rainfall infiltration. Flooding from karstic springs was also observed on the southern edge of the Massif Central, contributing to the flooding of various rivers. Groundwater levels in karst aquifers had already increased in December, so that intense rainfall in January failed to have an impact on these already high levels. Rainfall drained away quickly in these responsive areas, without groundwater being able to slow down the flows.
Aquifers with surplus water
Several aquifers showed particularly high levels, from high to very high, compared to those recorded for January in previous years:
- Groundwater in the southern Massif Central and Corbières basement and karst limestone and groundwater in alluvium deposits in the coastal valleys of Languedoc experienced significant recharge events during the second half of December and in January;
- This significant recharge in December and January has led to high levels in alluvial aquifers and tertiary formations along the Corsican coastline.
Aquifers with low water levels
Several groundwater bodies show worse levels, from moderately low to low compared to those recorded for January in previous years:
- The 2025–2026 recharge for aquifers in northeastern France is poor, with levels decreasing to moderately low to low;
- Jurassic limestone and basement aquifers in the northeastern part of the Armorican Massif remain affected by low levels of effective rainfall since autumn.
Key figures
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56.00%of levels increased
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36.00%of levels were above monthly averages
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40.00%of levels were below monthly averages
Forecasts
The Météo-France seasonal forecasts for February, March and April 2026 predict higher temperatures than usual across the whole of France. No clear scenario has emerged concerning rainfall.
Groundwater trends and changes over the next few weeks will depend exclusively on rainwater infiltration, and so on cumulative precipitation, and the response times typically associated with individual groundwater bodies.
Less responsive aquifers
Groundwater levels in less responsive aquifers depend on the level reached during the previous low-water period and on cumulative effective rainfall over the whole of the recharge period.
Over the next quarter, recharging is expected to continue for the less responsive groundwater bodies in Sundgau, southern Alsace, and the Rhône-Saône corridor, with the slow infiltration of winter and early spring rainfall. The forecast for the end of winter is relatively good. However, the end of the recharge period remains uncertain, as well as the forecast for summer 2026.
The forecast is fairly optimistic about the lack of drought at the end of winter for the less responsive aquifers of the Paris Basin, where groundwater levels are currently close to monthly norms. However, recharging is expected to remain low in February for most of the less responsive aquifers in the Paris Basin and eastern Artois, due to persistent dry weather in January. The forecast is less optimistic and uncertain for the summer of 2026, especially if recharging remains low.
More responsive aquifers
Forecasting for more responsive aquifers is often difficult, because groundwater levels mainly depend on recent rainfall infiltration. Groundwater levels for the summer of 2026 will depend on whether there is an abundant winter recharge continuing into the spring. This would push back the time when the levels start to drop again. Forecasts are more optimistic for aquifers showing levels well above normal, than for those with levels below normal. However, deficits or surpluses can be absorbed in a matter of weeks. The later into the recharge period the forecast is made, the more reliable it is.
With regard to the more responsive aquifers with levels ranging from high to very high, seasonal forecasts are optimistic. But they remain uncertain for the longer term, because levels depend on cumulative rainfall. Groundwater levels in Roussillon and Languedoc are expected to improve, however, compared to the four previous summers.
Forecasts are relatively pessimistic for the northeastern aquifers, which were showing low levels in January 2026. It will only be possible to return to above-normal levels by the end of winter if there is significant and well-distributed rainfall before mid-spring and vegetation regrowth.
It should be noted that some levels within the deep Pliocene aquifers in Roussillon remain very low, and that they are very likely to stay this way in 2026. It seems unlikely that there will be a sustainable replenishment of these less responsive groundwater bodies.
At the end of January, levels in alluvial, karst limestone and basement aquifers in Brittany, Languedoc and Corsica remained high to very high, which means that groundwater or karst flooding may occur in the short term. If rainfall is abundant in February, levels in these very responsive aquifers could rise again, leading to flooding and overflowing.
Basement and alluvial groundwater will then play a direct role by flooding valleys and lower areas or by flowing into rivers that are already full. It will also play an indirect role if for example the water table is high and the subsurface is saturated, as this will reduce rainfall infiltration into the ground, causing rainwater to run off and flow straight into rivers. Groundwater will then worsen surface runoff and river flooding.
Saturation of the karsts will lead to rapid flows towards temporary outlets, such as springs and rivers. This will lead to increased runoff and river flows downstream of catchments.
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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.
Aquifer recharge: 3 questions to provide a better understanding of the process
How do aquifers fill up and how do they empty?
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.
Why do some aquifers recharge faster than others?
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.
Inertial and reactive aquifers: what are they?
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.
© BRGM
Map drawn up by BRGM on 6 February 2026, based on data acquired up to 31 January 2026.
Data source: ADES (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.