In Gironde, the effectiveness of anti-hail generators undermined by the violence of storms

More than a hundred anti-hail generators are deployed in Gironde. But the effectiveness of this technology seems to reach its limits when faced with particularly violent stormy episodes, like the one that hit the department on June 20.

In the aftermath of the storms which severely damaged crops, homes and vehicles, the question arises of how to fight hail. In Gironde, the Adelfa association, the departmental association for the study and fight against atmospheric plagues, has been working on the subject for more than sixty years.

It has set up a technological system in the department, making it possible to reduce the size of hailstones, and therefore their consequences. One hundred and thirty eight generators are thus placed throughout the department.We work with nearly 300 volunteers, explains Dominique Fedieu, mayor of Cussac-Fort-Médoc and president of Adelfa. These are warned by the national headquarters of the association, itself in conjunction with forecasters, when the network must be put on alert..

Four hours before the arrival of the stormy episode, the volunteers will then turn on the generator, which will burn a liquid, made up of 97% acetone and 3% silver iodide. A solution diffused in low concentration, and harmless to the environment, according to the association. Once ignited, it rises into the sky and allows the hailstones to split. “Small hailstones become rain, medium ones become small and large ones become medium“, summarizes Dominique Fedieu.

If the president of Adelfa is formal about the effectiveness of the technology, which has been proven many times over, he recognizes its limits. This Monday, the activation of the device did not prevent the formation of hailstones several centimeters in diameter.

The forecasters had correctly estimated the risk, and the network was in operation. But Monday’s hailstones formed in the Gulf of Biscay, and we have no offshore generators. So it fell directly on the coastal towns.

Dominique Fedieu, president of Adelfa Gironde

Source: France 3 Aquitaine

Among the factors to consider in measuring the effectiveness of the technology: the violence of stormy episodes. The one that swept over Aquitaine on Monday was particularly intense, associated with winds exceeding 100 km / h in places. “We have a device that can reduce the size of hailstones by 50 to 70%. But 5cm hailstones that turn into 2.5cm hailstones will still do enormous damage, emphasizes Dominique Fedieu. Himself a winegrower, he wants to be realistic: dIn some cases, we have no satisfactory solution to offer.”

We must remain humble: in relation to certain violent behaviors, our prevention system is not adapted. It has its limits, just like the anti-hail nets put in place in certain arboreal farms, and which have been torn away by the power of the winds.

Dominique Fedieu, President Adelfa Gironde

Source: France 3 Aquitaine

The president of Adelfa also recognizes that the system, financed by the department, local authorities and the federation of fine wines, would benefit from being improved, in particular by extending its coverage. “We cannot deploy new posts overnight, we also need to find volunteers to hold the posts. And that’s where we are a little limited”, continues the winegrower, who would like the State, or even the insurance companies, to become financially involved in the deployment.

No generator is set up in the municipalities of the Bordeaux metropolitan area. A failure in the system, believes Dominique Fedieu, who wants to believe that the significant damage observed on June 20 on farms, homes and vehicles in the municipalities of Saint-Médard en Jalles, Eysines or Le Taillan-Médoc, will change the situation. “It can encourage us to have a collective response, and to be concerned about it”, he hopes. “It doesn’t make any noise, it takes up little space, it would be quite possible to install it on the mainland“.

Contacted the president of Bordeaux Métropole, excludes any installation of short-term generators. “We have no project of this nature, replies Alain Anziani. This is a question that has never been addressed in the debates of the metropolis.
If it became frequent and there were major disasters for our farmers and our market gardeners, perhaps we would review our position, but today, the question is not posed in these terms”, he maintained.

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