David Dehenauw (IRM) on the floods: “I was convinced that something serious was going to happen”

The head of the scientific weather forecasting service at the IRM retraced the chronology of the forecasts issued by the institute since Monday, July 12.

AAdded Friday morning by the parliamentary flood investigation committee, David Dehenauw, head of the weather forecast scientific service at IRM, retraced the chronology of forecasts issued by the institute since Monday, July 12. Forecasts and warnings which turned out to be correct, he defended, pleading nevertheless for a “closer” cooperation with the regional administration which could notably involve the creation of a “risk center for natural disasters. “.

“On the morning of Monday July 12, we consult several models which already give enormous quantities for Wednesday July 14, with 150 mm announced locally south of the Sambre-et-Meuse groove. We know then that what normally falls in two months will fall in two days. It is already alarming, ”detailed David Dehenauw.

On Tuesday, the Belgian models are more precise than the European model, which still revolves around 150 mm. The MRI, on the other hand, evokes peaks at 190 mm in the Hautes Fagnes, to which are added the risk of thunderstorms. The alert turns orange and the phones start to heat up.

“We have started to receive a lot of calls, in particular from the Flemish hydraulic service which is concerned,” continued the head of the IRM. “Flanders decides to make a first warning public. I was convinced that something serious was going to happen. In my entire career, I had never predicted so much precipitation. I then go out of my skills a bit by telling the air that this is not the time to go camping, ”he added.

The next day, the red alert – which can only be issued 12 hours before the events – is finally launched. This is the third since 2017: the first two concerned the heat waves of the summer of 2019 and 2020.

“On Wednesday morning, two models confirmed more than 100 mm in Liège. With what had already fallen, we arrive at 200 or 250 mm. Finally, in Jalhay, we will arrive at 270 mm ”, added David Dehenauw.

It was also this Wednesday, when it was already raining heavily, that the first telephone contacts took place with the hydrological service of the Walloon administration. “We worked well together, but we could have closer cooperation”.

Towards a risk center for natural disasters

In this context, a risk center for natural disasters could see the light of day. “We may lack a level with specialists who could gather information and transmit it directly to the provinces and municipalities”, concluded David Dehenauw before answering questions from parliamentarians.

These mainly focused on the 12-hour deadline for issuing a red alert, “a matter that deserves deep thought”; on contacts between the administration and the SPW; on the EFAS alerts “that we do not receive at the IRM” and on the declarations of the Walloon Minister of Climate, Philippe Henry, according to whom it rained more than what was expected. I have a lot of respect for him. He is an intelligent man but his statements surprised us, ”finally admitted Mr. Dehenauw.

Friday afternoon, the commission will resume its work with the hearing of Philippe Dierickx, the director of hydrological management at the Public Service of Wallonia.


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