episodes of frost, floods, droughts
Over the years, the annecy lake was subject to the vagaries of the weather. Episodes of frost, floods or even drought, the jewel of Annecy has not always been just a nice quiet watering place. While the cold spell seems to be settling in Haute-Savoie in this month of January 2023, we will avoid you going back to the vagaries of Lake Annecy.
Frost episodes on Lake Annecy
Over the centuries, Lake Annecy has frozen over many times. In 1573, it was possible to cross between Duingt and Talloiresas well as between Veyrier-du-Lac and Sévrier. An estimated 2,000 people crossed the lake on foot that year, during the months of January and February. The thaw will not begin until February 16.
The winter of 1879-1880 was probably the harshest. The cold then sets in from November, before intensifying in December and January. The average temperature drops to -10°C, the mercury reaching -17°C on January 27, 1880. Faced with the magnitude of this cold snap, the plane trees in the rue d’Albigny split.
At the beginning of February, the people of Annecy take out their ice skates and perform in Duingt Bay to take advantage of the frost. Temperatures will not begin to warm until February 20.
The other episodes of freezing of the Lac d’Argent took place in: 1681, 1682, 1684, 1709, 1789, 1799, 1891, 1927, 1963, 1956 or even in 2012. Be careful however, it remains extremely rare for the lake to freeze in its entirety. It’s actually almost impossible. This is explained by its surface area of 28 km² and its average depth of 40 meters. The water in Lake Annecy averages around 6°C in winter.
Episodes of deadly cold weather
These episodes of extreme cold were deadly. In 1895, for example, the roadmenders working on the departmental road between alexander and Bluffing discover a dead man, completely frozen. It was Deronzier, a farmer returning from a burial in Villaz. Instead of going through Alex, the poor guy decided to take a faster trail. Following a misstep, Déronzier fell and, numbed by the cold, he was unable to get up. This is how the roadmenders found him.
The floods of the lake
Lake Annecy has also experienced many floods over the years. The normal level of Lac d’Argent is set at approximately 446 meters above sea level, or 0.80 centimeters. Among the floods having the most impact, we find that of 1711.
The month of January, very cold, means that a large amount of snow is present at altitude. But from February 8, heavy rain fell on the city of annecy. The waters of the lake rise and the first floods applied at the level of the Paquier.
Between February 15 and 28, the rain does not stop. It was then that the lake reached its highest level: 3.10 meters. The waters continue to grow and communications are suspended across Annecy.
Faced with the magnitude of the flood and the force of the water, some buildings cannot resist. We are thinking in particular of the Cordeliers tower, located at the junction of the Notre-Dame canal and the Thiouas well as the collapse of part of the hospital cemetery.
In order to limit the risk of flooding as much as possible, work was carried out from the end of the 19th century. The shores of the lake are raised and a system of valves is installed in order to control and regulate the flow of the Thiou.
1914 and the great flood
Another flood that will have marked Annecy, that of 1914. It is also nicknamed the “great flood” and called oceanic. On August 6, heavy rain fell on the lake. In one night, the height of the lake increases by 1.01 meters. It was then that Albert Crolard, general councilor of the department for the canton of Annecy, asked that the Thiou be scoured regularly. It will also highlight the need to disadvantage buildings, increase the flow of the Vassé and rebuild the Morens bridges.
And if the work is done well, it will not always be enough to prevent flooding. Proof of this is in 2012, when Silver Lake rose 20 centimeters due to melting snow combined with heavy rainfall.
© France 3 Auvergne-Rhône-Alpes
Lake Annecy and drought
Lake Annecy is also known for periods of drought. The latest is in 2018. In that year, the water level decreased by about 70 centimeters. On the Pâquier esplanade, there is no longer the possibility of sitting on the pontoons in order to have your feet in the water. To find water, you have to walk several hundred meters. We will have to go back to 1947 to find such a drastic reduction in the lake.
1906, a year with little rainfall
Another year marked by a severe drought, 1906. Rainfall was then very poor and the withdrawal of the lake was all the more consequent. Indeed, the shore retreats more than 150 meters from its usual location.
During the summer, the animal watering hole on Avenue d’Albigny is dry. To swim, it is necessary to walk several hundred meters. However, this is not the first time that the lake has been in bad shape. He said to the elders that the situation had already occurred in 1854 and 1857.