Drought in France: a hydrologist warns of a situation similar to that of 1976

With 93% of groundwater levels falling and more than 80 departments under water restriction orders, France is experiencing a drought that specialists are comparing to the historical episodes of 1976 and 2022. Yves Tramblay, research director in hydrology at the Institute of Research for Development, analyzes the causes and avenues for adaptation.

Three successive heatwaves since the beginning of summer, a persistent rainfall deficit, and increased water withdrawals: this combination has pushed French groundwater levels into a critical state. The French Geological Survey (BRGM) recently estimated that 93% of groundwater levels are declining, with the most vulnerable aquifers experiencing levels "well below monthly averages."

According to Yves Tramblay, a hydrologist at the French Research Institute for Development (IRD), soil moisture levels observed in early July are among the lowest ever recorded for this time of year. "It's highly likely we'll reach the critical levels of 1976," he predicts. That year, agricultural yields collapsed: down 30% for corn, down 17% for barley, and around down 10% for wheat.

The current situation, however, has a particularity. The soils had been adequately replenished with water during a peak in humidity recorded in February-March 2026, but three successive heat waves have caused massive evaporation. "The soils have a maximum infiltration capacity," the researcher points out. "All the excess runs off into the sea." The benefit of the rainy winter has therefore been largely negated.

The consequences are already being felt in the agricultural sector. Unions have warned of significant yield losses to come, and initial reports from the field indicate a possible drop in milk production of between 10 and 30%. Regarding the fires, Interior Minister Laurent Nunez indicated that some 32,000 hectares have been ravaged by flames since the beginning of the year, a figure already exceeding the total for the entire 2025 season.

Faced with these prospects, Yves Tramblay emphasizes the need to not separate adaptation from greenhouse gas emission reduction. "If we head towards a high-emissions scenario, the cost of adaptation risks being astronomical," he warns, referring to a trajectory that could lead France to adapt to more than four degrees of warming by 2100.

In the agricultural sector, the hydrologist questions the relevance of certain large-scale crops. Corn, a tropical plant with high water requirements in the summer, is grown extensively in the southern half of the country. "Does it make sense to grow corn on a large scale in France? We need to seriously consider this question," he says. He also cites the intensive drainage of agricultural land, such as that practiced in the Marais Poitevin, as a practice that has weakened the soil's capacity to retain water.

The debate surrounding mega-reservoirs, reignited by the examination of an emergency agricultural bill, has brought these tensions to a head. Tramblay is not opposed in principle to water storage, whether it involves dams, hillside reservoirs, or small-scale structures on a farm scale. But he refuses to see it as the sole solution. "Storage is presented as the one and only solution. Yet it's like keeping a system afloat that isn't necessarily sustainable and only benefits a few farmers. It's a way of avoiding having to fundamentally reform our production systems."

The researcher points to a disconnect between decisions made at the national level, where he considers the influence of agribusiness lobbies "disproportionate," and the realities observed locally. "Elected officials and government agencies are fully aware of the situation because they are in contact with stakeholders on the ground," he notes. It is at this level, he believes, that concrete solutions tailored to the specific geological and climatic characteristics of each region can truly emerge.