Lac des Brenets
|Lac des Brenets|
|The lake at high water level from the south-eastern (right) bank at Les Brenets|
|Tributaries||Doubs , Rançonnière|
|Places on the shore||Les Brenets , Villers-le-Lac|
|Altitude above sea level|
|Maximum depth||26 m|
international ( border between France and Switzerland )
The Lac des Brenets is an approximately 0.8 km² lake in the valley of the Doubs River in the Jura . The Doubs forms the border between Switzerland and France . In Switzerland it is named after the border town of Les Brenets on the south-eastern (right) bank. In France it is called Lac de Chaillexon after the hamlet Chaillexon opposite in the French municipality of Villers-le-Lac .
The lake is just over 4 km long and an average of 150 to 200 m wide. The mean lake level is.; the lowest point of the lake floor in the northern section of the lake reaches 724 m above sea level. M., which corresponds to a maximum depth of 26 m.
The lake is a natural reservoir of the Doubs, which in the shallow, partly swampy valley floor below Villers-le-Lac gradually transforms into a still wide body of water with many small turns. From the right the Rançonnière , which drains the high valley of Le Locle , flows into a branch of the lake. The initially flat banks change into steep banks the further down the valley you go. The lake, which is only 200 m wide, is deepened like a gorge into the heights of the Jura and has several large turns. The limestone cliffs form a specialty, some of which drop vertically into the lake at heights of 20 to 80 m. It is about 400 m from the lower end (northeast end) of the lake to the Saut du Doubs waterfall . The Lac de Moron reservoir connects almost immediately here.
The lake was created by a landslide that occurred around 14,000 years ago and dammed the Doubs, which had previously dug its bed here through erosion into the limestone layers of the Jura for millions of years . At the end of the filling of the valley cut over a length of about 400 m caused by the landslide, the dammed water in the Saut du Doubs falls back to the old valley floor. The depth of the lake at its end is about the same (26 m) as the height of the waterfall (27 m), which is an indication of the even height of the filling by the landslide.
In the hot and dry summer of 2018, more water seeped through the karst lake floor than flowed into it. The level of the Lac des Brenets fell seven meters, making the lake almost disappeared at the level of the village of Les Brenets. Shipping had to be stopped. The lake dried up almost completely by the end of October. On November 22nd, at 736.00 m above sea level. M. recorded the lowest level of this dry period. The lowest level ever measured was on October 5, 1906 at 734.66 m above sea level. M. measured.
Thanks to its natural beauty, the lake is a destination in the High Jura. In summer it is used for boat trips and swimming. During the winter it is regularly frozen over for several weeks, turning it into a huge ice rink.
- Captains without a Sea. SRF, September 22, 2018, accessed on September 29, 2018 .
- Captains Without a Sea (video). SRF, September 22, 2018, accessed on September 29, 2018 .
- Lac des Brenets: Swiss lake after months of drought only a trickle report by the daily DIE WELT of October 27, 2018, accessed on October 27, 2018
- Hydrological Yearbook of Switzerland 2018 (PDF; 8 MB) Federal Office for the Environment , 2019, accessed on August 10, 2019 .