Florence Habets, hydroclimatologist, research director at the CNRS and professor attached to the Ecole Normale Supérieure, explains that despite the rains, the drought continues. It underlines the need to preserve the resource in the long term, and therefore to redefine priority uses.
Is France still in a drought situation?
Yes, the water resource remains weak and the weather forecasts do not suggest any significant improvement before the end of the year. Beyond that, it is difficult to predict. We can even say that the current period is the most sensitive, because we are approaching the end of the low water levels [niveau le plus bas d’un cours d’eau]. At the end of the summer, unless it rains a lot, there are only groundwater tables – even if each one has its own dynamics – and the lakes that can feed the rivers. But they have already supported them a lot, their levels are very low, the speeds very limited. With a more stagnant low flow, the quality of the resource deteriorates.
We are experiencing a drought record on the scale of the last sixty years, with low rainfall aggravated by incredible temperatures. There is then a deficit of water vapor in the atmosphere which leads to a very high evaporative demand, which in turn accentuates the intensity of water stress.
What will happen if it doesn’t rain heavily this winter?
The catastrophic scenario would be a drought that lasts three or four years. We know it is possible: we have already observed it over periods of five or six years. Look at what is happening in California, for example. Preparation is essential to avoid going straight to disaster. It would be necessary to preserve strategic reserves of last resort – a mountain lake, an underground water table – for essential uses. But we must preserve them over the long term, not empty them for irrigation in the first dry season! Otherwise I don’t see how we can get out of it. The principle already exists, but these reserves contain enough to provide only eight or ten days of drinking water. They are rather designed as a palliative in the event of pollution.
Almost all departments of metropolitan France are still affected by prefectural orders restricting water use. Are these measures effective?
They are likely to be less so, because with the few rains in September, people see the vegetation green again, the question of saving water worries them less. However, it is especially now that the problems arise: the supply of drinking water is threatened in places. The western regions are still classified in red. Like those in northern France, they have been doing well until now thanks to recurring rains, but they are not well endowed with aquifers. This is why it is more difficult to get water in Lille than in Marseille or Montpellier.
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