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The Rhône, a standard good heckled from upstream to downstream

This November afternoon, not removed from the Swiss border, the Rhône has an air of excellent nature. Its waters, swollen by latest rains, are clean and serene, masking the wooded shores with a swaying movement. All the things is calm on the reservoir of the Génissiat dam (Ain), which was the biggest construction in Europe when it was commissioned in 1948. Right here, we all know higher than elsewhere: the river is a “frequent good” par excellence.

As a result of water is an important useful resource, but additionally as a result of the river gives immense companies to individuals, such because the irrigation of agricultural land, navigation and vitality manufacturing. In France, the Rhône produces the equal of the electrical energy consumption of 5.6 million French individuals every year.

Nonetheless, these companies have important impacts and entice generally contradictory pursuits, from upstream to downstream, which have to be reconciled. That is additionally the opposite dimension of a “frequent good”: its administration have to be collective, organized in session and with out forgetting anybody. In Génissiat, or extra precisely on the borders of France and Switzerland, the place the Rhône defies borders, we give substance to this concept. And to be trustworthy, we do not have a lot selection.

Concrete illustration with sediment administration, one of many greatest challenges for dam managers. The truth is, rivers are usually not solely made from water; in addition they carry huge plenty of clay, sand and silt, which, over time, accumulate on the foot of the reservoirs. On the Swiss facet, about thirty kilometers from Génissiat, it’s estimated that 350,000 m3 of sediments are deposited every year on the Verbois dam. If nothing is completed, in case of flooding of the river, the slums of Geneva threat being flooded.

“Empty the bathtub”

“You need to empty the bathtub!” », summarizes Jérôme Barras, director of hydraulic manufacturing on the Geneva Industrial Providers (GIS), which manages this dam. Till 2012, this delicate operation, referred to as “looking”, was carried out by the Swiss, who didn’t have the identical laws as France. Besides that, that 12 months, the operation went mistaken. “There was a mix of opposed elements, acknowledges the director. We had been finishing up work and the quantity of sediment was essential, as a result of it was the primary hunt for 9 years. »

Downstream of the operation, in Génissiat, it’s amazement: far too excessive portions of suspended solids pour at excessive velocity on the dam, straight from Verbois. In locations, the degrees attain 49 g/l, when French laws impose a mean worth of… 5 g/l. “At these charges, we’ve a form of liquid mud”, describes Jean-Michel Olivier, analysis engineer on the CNRS, specialist within the ecology of the Rhône. “We discovered many fish silted up on the banks, trout, pike, barbel… An ecological catastrophe”, remembers the scientist.

“It was an electrical shock, on the Swiss facet and on the French facet, says Laurent Tonini, territorial director of the higher Rhône on the Compagnie Nationale du Rhône (CNR), whose concession on the French a part of the river has simply been renewed. We mentioned to ourselves that we needed to sit across the desk. »

No extra query of managing these operations on their very own; from 2014, a sustained dialogue is going down to seek out, from 13 eventualities, a standard administration technique. “With out session, there are misunderstandings, tensions between industrial gamers, and abruptly between nations”, helps Jérôme Barras. As for the authorities, that is additionally the conviction of François Pasquini, director of the water ecology division on the Geneva cantonal water workplace: “It’s essential to have a shared imaginative and prescient, as a result of these operations have an effect so far as Lyon! »

Widespread guidelines

Since 2016, the protocols have modified. Widespread guidelines have been established, on either side of the border, to restrict the impacts: partial – and never full – decreasing of the water within the reservoirs, a restrict of 5 g/l of suspended solids , joint monitoring and knowledge change. “Because of this two-year dialogue, we’ve moved from distrust to belief,” assures Laurent Tonini. “Hyperlinks are created, we perceive the constraints of the opposite, whether or not we’re upstream or downstream”, provides François Pasquini, on the Swiss facet. The final operation of its form passed off in Could 2021: round 400 individuals mobilized to permit the evacuation with out injury of a couple of million cubic meters of sediment and to guard Geneva from the wrath of the river. With higher managed results on the atmosphere.

“With these sedimentary operations, there may be all the time injury to ecosystems, that are fairly tough to evaluate, nuance Jean-Michel Olivier. However we’ve made progress. » For this scientist, extra typically, “the attention of the ecological worth of the river” has come a good distance, with shared goals, between the CNR, the State and the water companies, round a standard good with a number of challenges. On the Savoie fishing federation, Fabrice Piatek agrees. Nonetheless, the fisherman is lucid: “Vitality manufacturing is very strategic, and this difficulty continues to return first. »

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and me and me and me…

After 5 years of steady progress and a document 12 months 2021, France now has 3.2 million personal swimming swimming pools. And it is not over: in accordance with the order books of pros, the French have already determined to construct 230,000 further inground swimming pools by the tip of 2024.

This enthusiasm makes France the main European marketplace for personal swimming swimming pools and the second on this planet behind america. Nonetheless, the messages encouraging individuals to save lots of water are multiplying. On August 25, 2022, 78 departments had been positioned in a drought disaster scenario, with a ban on filling their swimming swimming pools. A scenario that ought to grow to be regular by the 2040s.

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