Swiss glaciers 1850–2100

The Giétro flood

Ice from the Giétro Glacier dammed the valley. When the dam gave way, 20 million m³ of water reached Martigny in 90 minutes.

Date1818-06-16
Water released≈ 20 million m³
Deaths≈ 34
To Martigny1 h 30 min
Distance33 km

In the cold years before 1818, ice avalanches from the Giétro Glacier piled up in the gorge of the Drance near today’s Mauvoisin dam. The cone of ice blocked the river, and a lake grew behind it through the spring.

Villagers dug a tunnel through the ice to lower the lake. On 16 June 1818 the dam failed, releasing about 20 million m³ of water. The flood front reached Martigny, 33 km downstream, in about 1 hour 30 minutes and Lake Geneva after 6 hours 30 minutes.

Around 34 people died. The flood destroyed 38 houses, 336 other buildings and 17 bridges. It remains the deadliest glacier-related flood in Swiss history and an early case study in glacial hazards.

The Giétro Glacier in 1818, painted by Hans Conrad Escher von der Linth.
The Giétro Glacier in 1818, painted by Hans Conrad Escher von der Linth. Escher von der Linth · Public domain · Wikimedia Commons
The lake at Mauvoisin after the ice fall from the Giétro Glacier, 1818. From Philippe-Sirice Bridel’s account.
The lake at Mauvoisin after the ice fall from the Giétro Glacier, 1818. From Philippe-Sirice Bridel’s account. https://www.helveticarchives.ch/detail.aspx?id=1551172 · Public domain · Wikimedia Commons

Glaciers

Sources

Sources

  1. Ancey et al. (2019). Hydraulic reconstruction of the 1818 Giétro glacial lake outburst flood. Water Resources Research. agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019WR025274
1895: The Altels ice avalanche →