On the morning of 26 August, the Himalaya delivered another warning. A cascade of geological triggers — their exact sequence still a subject of scientific debate — near the Langtang Lirung mountain, on the Nepal-Tibet border, sent a tsunami of ice, rock, water and debris down the Bhote Koshi and Trishuli valleys.

Settlements disappeared. Roads and bridges were swallowed. More than a dozen hydropower projects were damaged or destroyed, and hundreds of workers trapped at project sites.

Scientists now agree on the initial trigger for the cataclysmic event: a massive vertical section of a glacier (est. 100-200 million cubic metres) sheared off at an elevation of 5,200 metres and fell 1,200 metres into the valley below.

At Upper Trishuli-1, a 216 MW hydropower project under construction, workers had barely 40 seconds to run for higher ground after the flood wave arrived. The entrances to tunnels were sealed by debris. At one point, Nepal government data put the number of missing people at project sites at 934, though different agencies reported different figures as rescue operations progressed.

Parineeta Dandekar, senior researcher at the South Asia Network on Dams, Rivers and People (SANDRP), points out that nobody even knows how many people are working at these sites. There is no official count of contract labourers, casual workers and job seekers — an omission that looks really stark when disaster strikes — and yet the glossily produced environmental impact assessment reports usually paper over this detail.

The avalanche was a natural event, but the scale of human exposure and the loss of life and property and infrastructure built at great cost was not.

Only a year ago, on 8 July 2025, the Bhote Koshi-Trishuli valley was devastated by a major flood that damaged more than 10 hydropower projects. A year later, the same landscape was heaving under an even greater concentration of infrastructure........

© National Herald