Visite et présentation du barrage de Grosbois-en-Montagne

Grosbois is, with a capacity of 9.2 million cubic metres for a surface area of 105 hectares, one of the largest of all the Burgundy canal reservoirs. Built in 1838, it was consolidated in 1852. It is one of the deepest in the Côte d'Or, with a height of more than 20 metres at the level of the dam. It is located in the upper valley of the Brenne, at an altitude of almost 400 m. A 14 km long channel brings the water into the Pouilly basin, at an altitude of 378 m, which gives a slope of 0.16%. This channel crosses the very marked relief which separates the Brenne slope from that of the Armançon, through a 3.6 km long underground passage which leads to Soussey, where it collects the water from the Brionne before doing the same with two other streams downstream. In 1900, Grosbois received a "counter-reservoir" just downstream of its dam, intended to counterbalance the pressure exerted on it by the water reservoir. This second body of water contains 0.9 million cubic metres and is used for water sports, in addition to its role in regulating the Brenne.
An essential device for supplying the Burgundy Canal, it is also an emblematic element of the landscape and a place where protected species can be found. With a capacity of 8.6 million cubic metres, Grosbois was the largest of all the reservoirs on the Burgundy Canal until 1875, when it was enlarged.
Why and how did people decide to install an artificial water reservoir to feed the Burgundy canal ... on the other side of the hill?
Does the reservoir manage floods?
How does the counter-reservoir work and how can it be unique in the world?
How does a Burgundy Canal work and what are the different functions of the Grosbois-en-Montagne reservoir?
As the installations are non-electric, how does VNF manage this precious water resource at a time when droughts are adding up and the canal has closed earlier than expected in 2019.
To answer these questions, we will be helped by explanations from the dam operators.
Meeting point in front of the dam along the D905 at 16:00.
The visit lasts 2 hours and requires good shoes, to be covered and to have water in case of strong heat.
Free of charge, on registration.
Presentation limited to 25 people.