Many waterways are less full and sometimes dry up before the start of spring, the fault of drought and low rainfall. Can the water come back into the rivers before the summer season?
The observation is clear: spring has not yet started that many streams, rivers and rivers are less full, and sometimes dry. The water level is extremely low in several southern regions and the images of the Garonne reduced to a trickle of water in Toulouse, those of the Canal du Midi or the Var Saint-Cassien lake at levels well below normal or the photos of the Loire which are still struggling to cover all these banks are worrying. Unfortunately, there is little chance of seeing the rivers and rivers regain their pre-drought level, as well as the groundwater which is just as dry, if not more.
At dawn in March 2023, about fifteen departments, mainly in the north and center of France, are observing very low water levels, while more than thirty others are also well below the usual averages according to info-drought data. To prevent the rivers from emptying further before the arrival of fine weather and the summer season, the month of March promises to be strategic even if it is already certain for meteorologists that the soils and rivers will not will soak up more water before next winter.
The general drop in the water level is inseparable from droughts, but the year 2022 was particularly dry in France, with a hot summer and clearly insufficient precipitation: -25% precipitation per month over the whole of France. year, according to the climatic bulletins of Météo-France. Special mention in May and July 2022 where the amount of precipitation fell by 63 and 84% compared to normal.
This lack of rain continued into February with the sad record of 32 days without rain. The month “was particularly dry and ended with a rainfall deficit of 75%”, explained the climatologist at Météo France Simon Mittelberger to franceinfo. But this dry weather in the middle of winter did not allow the ground, the rivers and the rivers to fill with water. And if the rain makes a timid return since the last week of February in some regions, the precipitation will not be enough. “We started from such a low and dry level, following last year’s drought, that it would have taken a clearly surplus winter” in rain to moisten the soil, notes the specialist.
It is no longer necessary to count on the rains or very little to see the rivers fill up again. The month of March, which marks the transition from winter to spring, is the last moment during which surface water and deep water can renew water stocks, after which the rains are absorbed by vegetation and feed the soil. and run off more than the water tables fill.
If precipitation is no longer a solution, there remains the mountain snows which melt in the summer and fill the waterways. But then again, snow has been scarce during the winter and peaks like glaciers have stored less water, water that may be in short supply this summer. And the snowy episode recorded in the last week of February from 1,300 meters above sea level will not be enough to reverse the trend.
If the drying up of rivers is due to lack of rain, is the lack of precipitation also due to drought? Not totally, it is rather one of the causes. The culprits are more climate change and its effects on weather patterns. If the winter was dry, it is largely the fault of the anticyclones which followed one another and for some were stationary above France, as shown by La Chaine Météo in mid-February.
The record 32 days without rain is linked to the presence of highs which blocked the lows, pushing them back to northern Europe
