Workers Hopes Still High During Adverse Weather: Runoff Persists

In the aftermath of the Lonza river blockage, authorized officials in Ferden reported an initially controlled draining of the rapidly accumulated water. The feared deluge or debris avalanche, which could endanger additional villages in the Lötschental valley, has yet to materialize, said Christian Studer of the Natural Hazards Office during a press briefing. Nevertheless, potential hazards continue to exist.

Preliminary channels have started to form, providing a glimmer of optimism that the water is finding a viable path, according to Studer. Drone footage demonstrates a shallow trickle of water on the approximately two-kilometer-long debris cone, while water additionally flows further down the Lonza riverbed. This suggests that water is also infiltrating the two-kilometer-long accumulation of debris.

Immediate dangers for the communities farther down the valley appear nonexistent, as experts reported no immediate perils during helicopter overflights approximately 1,500 meters above sea level in the Lötschental valley, canton of Wallis. However, predicting how the unstable debris cone will evolve remains challenging, with an estimated nine million cubic meters of material on the valley floor.

While Studer does not anticipate rapid melting of the material at this time, approximately one-third of it is believed to be ice from the Birsch glacier. Potential hazards persist, particularly concerning further collapses at the Kleine Nesthorn above 3,000 meters, which instigated the disaster. The terrain's steepness amplifies the risk of additional debris flows, and rainfall remains a concern, according to Studer, with inclement weather forecasted for the region beginning Sunday.

On Wednesday, after several days of rockfalls around 3,000 meters above sea level, the underlying Birsch glacier broke off and tumbled into the valley in massive volumes of rock and debris, completely obstructing the Lonza riverbed. The village of Blatten, home to around 300 residents, was mostly buried under the debris. Early last week, the residents were successfully evacuated. One local resident who was in the disaster area on Wednesday remains missing.

Swiss President Karin Keller-Sutter expressed shock following a helicopter flight over the disaster area, stating, "The total erasure of an entire village is incomprehensible." She pledged extensive support for the affected residents. Residents in the neighboring communities of Gampel and Steg, located approximately 20 kilometers downstream from Blatten, have experienced cautious relief as the situation has improved, but the risk endures, according to Stéphane Ganzer, a member of the canton of Wallis government.

The municipalities of Gampel and Steg have been asked to pack necessary items for a potential evacuation, should a flood wave or debris flow from the disaster area push down the valley. Situated between Blatten and Gampel, Ferden boasts a dam and retention basin, which have already released water in the hopes of curbing additional flooding. A debris retention facility may also be established in the lake formed by the blocked water from the flooded houses to ward off future blockages.

Cleanup efforts remain on hold, as the terrain remains unstable, and both people and machines risk collapse. The Swiss army stands ready to initiate cleanup operations as soon as conditions improve. Preliminary operations may commence soon at the margins of the disaster area, according to Studer. The lake contains significant debris from the inundated homes, which may require a debris retention facility to prevent future blockages.

The environmental science community is closely monitoring the climate-change impacts on the weather patterns, as the weather forecasting for the region predicts rainfall, which could potentially exacerbate the unstable situation in the Lötschental valley.
As a result of the Lonza river blockage, the science of weather-forecasting takes on renewed importance, with experts predicting potential further collapses at the Kleine Nesthorn above 3,000 meters, which poses a risk of additional debris flows.
The study of environmental-science, particularly in relation to climate-change and weather patterns, is crucial in understanding the potential risks associated with the unstable debris cone formed by the Lonza river blockage, which contains approximately one-third ice from the Birsch glacier.