Lac de Saint-Laurent
The Lac de Saint-Laurent (German: Saint-Laurenter See ) was a reservoir in the Romanche valley in the French Alps that was created at the end of the 12th century by a landslide , which triggered a disaster when the barrier broke.
Formation of the lake
On August 10, 1191 , after heavy rains in the Oisans, the slope of the Romanche valley slipped and blocked the course of the river with a natural barrier about 1 km upstream of the town of Livet , so that an extremely large lake was formed. According to various calculations, this stretched over 15 to 20 km in length to Le Bourg-d'Oisans (which was then called Saint-Laurent) or beyond, had an area of up to 22 km² and around 340 or up to 660 million m³ storage volume. The resulting reservoir was called Lac de Saint-Laurent or Lac d'Oisans.
The catastrophe in the Romanche valley
The barrier broke 28 years later on September 14, 1219 in a strong storm. Due to a large influx of water, the dam broke at 10 p.m. and the dammed lake emptied. A tidal wave tumbled down the Romanche valley to the mouth of the Drac and on to the Isère . Grenoble was largely spared from the first wave because at that time it had not yet expanded to the Drac. But in the Isère a backwater developed, which cut off the escape route for the fleeing people. Half of the population in Grenoble was killed in the floods and there was great destruction. Today models are shown in a museum that explain the phenomenon.
Coordinates: 45 ° 6 ′ 49 " N , 5 ° 57 ′ 26" E
literature
- 1219: la catastrophe du Lac d'Oisans, in: L'Histoire , No. 103, September 1987, pp. 86-88.
- Claude Marche: Barrages: crues de rupture et protection civile , 2004.
Web links
Individual evidence