Lonza River in Switzerland Resumes Flow After Landslide

The Lötschental region in Switzerland has temporarily averted another disaster following a significant glacial collapse earlier this week. The Lonza River, which had been blocked by a massive debris cone, has now carved a new path down the valley. Fortunately, the anticipated flood wave did not materialize, although the water now carries remnants of the recent catastrophe.

The municipalities of Gampel and Steg have informed residents that heavy machinery will be deployed to ensure the safe discharge of water and debris. Authorities emphasized the importance of maintaining a smooth flow of sediment and driftwood through the riverbed of the Lonza within the villages.

Water contaminated with sediment is currently flowing downstream. The precautionary draining of a reservoir at the Lonza in Ferden, located below the affected area, is now being reversed as it begins to fill up again. The hydropower plant operator has been directed to release additional water as needed to capture larger quantities flowing downstream. However, due to the high sediment content, the water cannot be utilized for electricity generation as initially planned.

The risk of a mudslide remains a significant concern. If the Lonza River carries debris and other materials down from the debris cone, the reservoir in Ferden is expected to mitigate the impact. Otherwise, the villages downstream, particularly Gampel and Steg, could face potential hazards. As the Lonza approaches its confluence with the Rhône River, it flows through narrow concrete channels that could overflow rapidly during heightened water levels. Continuous monitoring systems are in place to track conditions around the clock.

The region faced considerable strain after the landslide, which originated from unstable rock at approximately 3,000 meters elevation. The collapse occurred on Wednesday afternoon, sending vast quantities of ice, rock, and debris crashing down into the valley. The village of Blatten is largely buried under meters of debris, although the approximately 300 residents were evacuated prior to the event. Concerns remain about further collapses in the danger zone.