La Rochelle is hosting this Tuesday the European Water Forum imagined on the initiative of the Charente-Maritime farmer and EELV MEP Benoît Biteau.
Associations, scientists, trade unions and European politicians intend to debate this “common good”, its uses and its good governance.
"Le Parisien" spoke with hydrologist and researcher Emma Haziza, one of the speakers at this meeting and a specialist in climate issues in the face of the risk of flooding.
In Charente-Maritime as in Deux-Sèvres, pro and anti-basins are torn on the question of the storage of water intended for the intensive irrigation of crops.
What do you think of this solution?
Emma Haziza.
The pro-basins claim that water is extracted from rivers and rivers to supply these reserves.
This is false, in fact: the water is mainly taken from groundwater, in an underground environment, before being stored on the surface, in the open air, and treated with chlorine.
This creates evaporation.
Between 20 and 40% of the water is lost.
The pro-basins claim to capture an overflow of water in winter but this is not hydrologically logical.
The primary user of water remains the natural environment.
Wetlands like the Marais Poitevin are necessary, they in turn generate new rains, new loops in the water cycle.
I am in favor of small hill reservoirs that collect rainwater by runoff, but opposed to groundwater collection, a Californian model of water management that benefits only a few.
Read alsoIn Charente-Maritime, a trial against the backdrop of the water war
In New Aquitaine, groundwater recharge could drop by 30 to 50% by 2030 under the effect of global warming.
The average flow of rivers would drop by 20 to 30%.
Do these figures, put forward by the region to support its “water strategy”, seem reliable to you?
This trend is confirmed everywhere in France. In reality, the deadline is now 2025. Things are accelerating as shown by the latest data, in particular those supported by the IPCC, the Intergovernmental Panel on Climate Change. By dint of pumping in the layers, they become fragile. Their level of balance drops until they dry up. But it takes nearly 10 years for a slick to recover, provided you give it the opportunity...
Only 9% of rainwater reaches groundwater.
In Charente-Maritime as in the former Poitou-Charentes region, the aquifers are currently being recharged.
But this is a sham situation, linked to particular weather conditions in France in 2021. The previous four years, from 2017 to 2020, have all set historic drought records…
A drinking water catchment was closed in Clavette in January 2021 following the discovery of pollution 130 times greater than the regulatory limit for chlortoluron, a herbicide.
The Agglomeration of La Rochelle has since initiated a reflection to widen the perimeters of protection around these catchments.
The repurchase of land is one of the avenues put forward.
Is this a good solution?
Yes, it works very well.
The fact of converting agricultural land by buying it back or renting it out clearly improves the quality of the water and that of the catchments.
This system should be developed everywhere in France in order to protect the most fragile areas.
And that would save us from spending crazy sums on the treatment of drinking water and depollution...