Although the risk of drought is high in summer, FranceInfo regularly publishes several updated maps and graphics to monitor groundwater levels and river flows.
Much of France is at risk of drought as summer approaches. After a particularly dry winter, water tables were unable to replenish sufficiently and as few as 28 sectors presented the risk of summer drought by mid-May.
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To follow the evolution of the phenomenon, several indicators are closely examined, and special services are drawn up every month. List of water resources. Francinfo offers you to follow a constantly updated selection of these measurement tools, such as groundwater level, river flow, number of dry streams, precipitation, soil moisture… using infographics and maps.
Two-thirds of the groundwater table is below normal
Where are we? As of May 31, 71.1% of groundwater levels were below normal, according to calculations by France Info, based on data from the Bureau of Geological and Mining Research (BRGM), a French public agency of reference. The situation is comparable to 2022 on the same date and the worst in the last five years. Earlier in the year, the discovery was even more alarming: in February, groundwater tables reached an average of 80% below their normal recharge levels. An exceptional deficit, which is somewhat reduced with rainfall, but not across the territory.
Last Updated: June 1, 2023
Why is this indicator important? Groundwater is the vast natural reservoir from which nearly two-thirds of the water we consume comes from. Their status is closely monitored: when the situation is considered more critical, decisions on restrictions on water use are taken into account, especially by the provinces. If necessary, individuals, farmers or businessmen should limit or stop their withdrawals.
How did FranceInfo calculate this figure? Franceinfo BRGM relies on a list of 297 measurement points that it uses to produce its monthly groundwater level analysis bulletins. For each measurement point – called a piezometer – a monthly Standardized Piezometric Index (IPS) shows whether the groundwater level is below or above normal on a given date.
River flow is below average
Where are we? As of May 29, nationally, 88.7% of river gauging stations reported a flow rate below the average for the years 1990-2020, according to Franceinfo calculations from public data. The situation is tense in the southern part of France, especially in areas like the Pyrenees-Orientales along the Mediterranean coast, where there has not been enough rain for weeks. In some rivers, particularly in the northwest, such as Brittany, flows have decreased less and remain above historical averages.
Last Updated: June 1, 2023
Why is this indicator important? The flow of rivers is an important indicator to assess the availability of surface water and to adapt it for domestic, agricultural, industrial uses or energy production. At the local level, prefectures define watershed flow thresholds below which restrictions on water use must be taken.
How did franceinfo create this map? River flows are measured in real-time, across hundreds of rivers, by various regional departments of environment, planning and housing (Dreal). These data are centralized by the Central Hydrometeorological Service (SCABI). It can be accessed on its website. Franceinfo relies on a list of 1,300 measurement points and is used in monthly analyses. Waterways may be missing from this map. One is because they are not measured by public bodies; The fact that they contain many facilities (such as dams) limits the interest of their flow analysis; Or because their data history does not allow them to average between 1990 and 2020.
Now some streams are dry
Where are we? In the last ten days, only 3.4% of observed streams have dried up. These were mainly based in Mediterranean departments such as the Gard or the Herald. In the areas where observations were made, 95% of streams had visible flow.
Last Updated: June 1, 2023
Why is this indicator important? While the Schapi data measures the flow of rivers and streams, the National Low Water Observatory (Onde) is interested in smaller waterways, mostly streams. L’Onde makes visual observations of the state of water bodies, which makes it possible to anticipate situations of scarcity for human use and the range of impacts on aquatic fauna and flora. Formal measurements are carried out from June to October. In May, only one-time measurements are carried out that do not concern the whole of France.
How did franceinfo create this map? Onde and OFB conduct visual monitoring of a stream at least once a month. In order not to include in the map observations that are very old and particularly subject to change depending on rainfall, franceinfo only keeps observations made in the last ten days.
