“It’s not every day that Morlaix discovers its river”: an unprecedented and colossal project against flooding

“He’s one of the only Papi

of France which results in a solid solution, both scientifically and financially. It enters the operational phase. This is a rare opportunity. » This Thursday, November 28, 2024, Jean-Paul Vermot, president of Morlaix community and mayor of Morlaix (29), a town regularly affected by flooding, announced the launch of urban studies and consultation around the “La Rivière de Morlaix” project. “. A unique project. Colossal.

Remodeling and reopening of galleries

Concretely, this large-scale work will be of three types. First, the remodeling of the Jarlot underground gallery and the creation of a new section in that of Queffleuth, to facilitate the flow of water. Then the reopening of the main gallery, 1,200 m long and 6.50 m wide, between the kiosk, the convergence point of the two rivers, and the Charles-de-Gaulle roundabout. And this in order to improve the evacuation of this bowl. Finally, a reprofiling of Places Cornic and De Gaulle, to make them concave, is planned. The goal: to contain excesses.

“We now know: flooding in Morlaix is ​​caused by the saturation of the galleries. This is the heart of the matter,” insisted Clément Le Saux, Papi project manager within An Dour, the public water authority. The studies and modeling carried out gave, says Jean-Paul Vermot, “exceptional results”. They indicate that these actions will make it possible to avoid 80% of the damage from thirty-year floods (having a risk in 30 of occurring each year); 50% on 50-year floods. Such a device would have made it possible to practically “erase” the floods of the winter of 2013-2014.

Cheaper and more effective than dams

However, additional actions will be carried out upstream. But without resorting to the construction of dams on this 200 km2 watershed. Because it's more expensive. And less effective. “This option would have cost €32 million. For one euro invested, we saved €0.96 in damage over 50 years,” explained Clément Le Saux.

The reprofiling and reopening solution, which has the advantage of being “static”, that is to say with low maintenance costs, amounts to €22 million, excluding urban redevelopment (for one euro invested, savings in damages will be €1.26 over 50 years). The State will cover half of this amount to be refined. Because today's prices can change in proportions that are difficult to control. Other partners could abound. The remainder will be financed by the Gemapi tax.

First works in 2028

The first shovels are expected in 2028. After three years of consultation orchestrated by Brest Métropole Aménagement (BMA), at the scale of the agglomeration, which begins on December 7 and 8. This will be the time needed to design the Morlaix of tomorrow. Organize things, too. And reassure. Because if some work carried out in the galleries will have no impact on the surface, others will inevitably cause difficulties (commerce, parking, traffic, etc.). Even if they will be sequenced.

For what duration? We don't know yet. “But we want to make this open construction site an event, a vector of attractiveness in itself,” indicated Jérôme Plouzen, deputy for town planning. And the municipal elections of 2026 will change nothing. “There are projects that go beyond the scope of a mandate. This is the case with this one. It’s not every day that Morlaix discovers its river,” concluded Jean-Paul Vermot. The train has started, it will not stop. Morlaix will discover its river well.