Every summer, dozens of French departments have dry throats: they suffer from drought and are affected by water restrictions. The water tables are almost empty, the streams dry, the cornfields and the meadows arid …
However, thanks to a rainy fall and winter, the groundwater will return to pleasant levels before the arrival of the warmer seasons. A relief for the world of agriculture and livestock, and not only. We explain it to you.
Where does the drinking water come from?
The domestic water we use comes from the natural environment. Raw water is obtained in part (38%) from so-called “surface” waters (lakes, streams, etc.) but mostly from groundwater (62%).
Before reaching us, it is collected by collection, sent to a drinking water production plant and treated in several stages. Drinkable, it is distributed to consumers and, after use, is collected through the sewage network to take it to wastewater treatment plants before returning it to nature.
Since groundwater is our main source of drinking water, it is an essential resource for human consumption.
Where does the groundwater come from?
Groundwater literally falls from the sky: it comes from precipitation that reaches the basin drained by a watercourse and its tributaries. Some of this rainwater seeps into the ground through pores and crevices in the rocks. We are talking about the phenomenon of infiltration.
Then, by the magic of gravity, the water flows deeper to form a sheet, in which we can find different types of water. These underground water tables are hidden in sedimentary basins (Paris basin, Aquitaine basin, Rhone valley, etc.), mountain ranges (Alps, Pyrenees, Armoric massif, central massif, Corsica, etc.) or in the valleys crossed By rivers or streams.
Why is the groundwater level dropping?
The level of a water table depends on the amount of water that enters the water table by infiltration and the amount that leaves it.
When it rains or snows heavily and low temperatures prevent precipitation from evaporating, the recharge rate of groundwater is higher than that of pumping – the level will rise. When it’s the other way around, it will fall.
The favorable period for filling the water table is, therefore, between the months of October and March. A good reason to rejoice in all these clouds over our heads and go, why not, sing in the rain …
Three levels of water use restrictions
To save this resource, the restrictions on the use of water can be of three levels:
– Alert: reduction of extractions for agricultural purposes of less than 50% (or prohibition up to 3 days a week), measures that prohibit the operation of valves, nautical activity, prohibition at certain times of watering gardens, green spaces, fields golf, to wash your car.
– Enhanced alert: reduction of withdrawals for agricultural purposes greater than or equal to 50% (or closure greater than or equal to 3.5 days a week), greater limitation of withdrawals for watering gardens, green spaces, golf courses, car washes,. … until certain levies are prohibited.
– Crisis: cessation of non-priority rates, including rates for agricultural purposes. Only samples that allow the exercise of priority uses (health, civil security, drinking water, sanitation) are authorized.
There is also a “zero” level, called “drought monitoring”: this involves informing and encouraging people to save water (take quick showers, reuse water for irrigation), as well as professionals (recycling cleaning water, etc. ), farmers, municipalities, etc.
Please note: any violation of the mandatory water restriction measures in the event of a drought alert is subject to a fine of up to 1,500 euros, or even 3,000 euros in the event of a repeat offense.