Glacial lake outburst monitoring at Plaine Morte

Challenge

The Plaine Morte is a plateau glacier at the mountain Wildstrubel in the Bernese Alps, Switzerland. The flat glacier drains mainly towards the north over the river Trüebbach and through the touristic village of Lenk. Several glacial lakes are formed every year in the same places: the Faverges, Vatseret and Strubel lakes. During spring and the summer months, the snow melts rapidly which fills up the lakes. Lake levels rise quickly and the lakes can reach an alarming size. Eventually, the lakes drain through a subglacial system which is still not fully understood. Lake drainage can occurr rapidly with a flood-like discharge or the lake drains over several days at elevated water levels of the river Trüebbach).  In 2011, a major glacial lake outburst flood occurred. Subsequently, it was decided to monitor the lakes and the discharge river, Trüebbach, the during the summer months.

 

Solution

In order to warn the community in the event of a significant drop in water levels and an associated flood wave, we installed four monitoring stations for community of Lenk in 2012: three lake stations including webcams to measure lake levels and a river station to measure discharge rates of Trüebbach. We apply pressure probes to measure the water level of the lakes from underneath and radar gauges mounted across the river to measure its level. The station’s webcams record lake images several times a day and transmit the images and level data continuously to the Geopraevent online data portal. Authorized users can observe the lake status remotely anytime via online data portal. The exceeding of a certain sink rate or discharge level triggers the alarm and immediately informs the municipality as well as the responsible person at the canton of Berne.

Since 2018, only Lake Faverge and Trüebbach are being monitored. The other lakes (Vatseret and Strubel) are much smaller and currently form irregularly. Currently, they are not regarded as problematic and do not require monitoring any more.

Monitoring station at Faverge lake with webcam, pressure probe, solar cells and data communication device. 

Time lapse images of Faverge lake 2014: The lake drains completely within three days without causing a flood wave at Trüebbach. 

 

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Plaine Morte

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