Is it true that 3000 liters evaporate every second from Lac du Der?

Straddling the departments of Marne and Haute-Marne, Lac du Der is an artificial lake created 50 years ago. Managed by Seine Grands Lacs, it regulates the flow of the Marne, a tributary of the Seine. It is also a great Source of biodiversity.

Lac du Der is a reservoir lake with an area of ​​4,800 hectares, which can store 350 million m3 of water .

On the Terre de Champagne-Ardenne show page on the France Bleu radio website, we received this question from Cécile: “In summer, how much water evaporates from Lac du Der?”

To answer this question, we went to meet Jerôme Brayer, operations manager at EPTB Seine Grands Lacs.

Listen: 3 minutes to find out everything

Explanations and details in the report to listen to via the player on this page.

Is it true that 3000 liters evaporate every second from Lac du Der?
Olivier Cattiaux and Jérôme Brayer from Seine Grands Lacs © Radio France
Lac du Der in Champagne

For further

The Der-Chantecoq reservoir lake was commissioned in 1974. This artificial lake’s mission is to strengthen the flow of the Marne by low water and reduce the risk of flooding downstream.

It is the most important of the works managed by the EPTB Seine Grands Lacs. Its action is determined by the rhythm of the seasons:

  • In winter and spring : the waters taken from the Marne and Blaise upstream of Saint-Dizier flow by gravity to the reservoir lake via a supply canal (11.9 km for the Marne and 5.2 km for the Blaise). This water taken constitutes a reserve for low water. During periods of flooding, additional samples are taken to limit the risk of flooding downstream.
  • In summer and autumn : the water previously stored in the reservoir lake is returned to the rivers to avoid too low a flow. For this purpose, a 3 km restitution canal, starting from the lake, restores water to the Marne to the west of the village of Arrigny. A restitution channel
    1 km also allows water to be returned to the Blaise to the east of the village of Sainte-Livière.

Its management

Low flow support, which in principle takes place from the beginning of July to the end of October, can provide an average of 30 m³/s additional flow support in Marne for an average natural summer flow of 7 m³/s in Saint-Dizier. During floods the structure can drift up to 375 m³/s in Marne and 33 m³/s in Blaise, or almost 80% of the maximum known flow rate. The reservoir lake thus limits flooding in the departments of Haute-Marne and Marne, as well as in the valleys of the Marne and the Seine, up to the Paris metropolitan area.

Key figures

  • 4,800 hectares: total surface area of ​​the work
  • 349 million m3: filling capacity
  • 20.3 km: earth embankments with a maximum height of 20 m
  • 2,900 km²: controlled watershed

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Report to listen to via the player at the top of the page


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