Snow-rock landslide near China blocked river, debris lake formed, then burst: What may have caused Nepal's deadly flood

Nepal's disaster management authority on Wednesday said a snow-rock landslide near the Nepal-China border may have triggered the deadly flash flood in Rasuwa.

The authority said that an initial study based on the analysis of satellite images by Planet Labs indicates that a glacier-inclusive flood occurred in the Lhende River due to a snow-rock landslide that took place on the Nepal-China border, approximately 20 kilometers northeast of the Nepal-China Rasuwagadhi border crossing.

The disaster has killed at least 98 people, while the number of missing tourists has risen to 579.

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What May Have Triggered The Flood

The deadly flash flood originated near the Nepal-Tibet border after an avalanche or landslide caused a sudden surge in the Lhende Khola, which flows into the Bhote Koshi river.

The Kathmandu Post reported that an ice avalanche may have blocked the river and led to the formation of a temporary debris lake. The lake then burst, sending a sudden rush of water and debris downstream.

Binod Parajuli, chief of the Department of Hydrology and Meteorology's Flood Forecasting Division, said preliminary satellite images received from Chinese authorities showed debris blocking the river about 20 km upstream of the Miteri Bridge.

"An icefall and landslide can be seen," he said, according to the Kathmandu Post. "An ice and debris lake formed and then burst. A dam was formed."

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The large amount of debris carried by the released water made the flooding more destructive, Parajuli said. "If it had been only clear water, it would not have caused this level of destruction. But once the debris mixed with the water, the depth increased significantly."

Rijan Bhakta Kayastha, a climate researcher and professor at Kathmandu University, said that there was information that an ice avalanche from the Nepal side blocked the Lhende river. "An earthquake also occurred on the Tibetan side around the same time."

The US Geological Survey recorded a magnitude 4.4 earthquake in Tibetan territory at 8:37 am, about 47 km north of Gosainkunda.

Kayastha said it could take several days to determine whether a glacial lake also burst. The possibility is being considered because similar glacial lake outbursts have occurred in the area.

A similar flood hit the Bhote Koshi river on July 8, 2025. Nepal's Department of Hydrology and Meteorology later concluded that a glacial lake outburst had caused flooding in the Lhende River near the Nepal-China border.