Nepal’s mountain tsunami: The 200-km trail of water, rock and destruction

Nepal’s flash flood death toll has reached 469 , with nearly 1,000 people missing in Nepal and neighbouring Tibet after a glacier collapse unleashed torrents of water, mud and debris. Rescue operations continue, but authorities warn that debris-blocked rivers and rising lakes could breach, triggering another potentially devastating flood.

The disaster began when an estimated 600-metre-wide section of a glacier broke free from an altitude of around 17,000 feet, plunging into a valley and triggering a cascading mass of water and rock that swept nearly 200 km downstream within hours.

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The surge wiped out settlements along riverbanks and left hundreds dead, while damaging roads, hydropower infrastructure and facilities at a key Nepal-China border crossing.

Glacier break triggered massive surge

The Lhende Khola, which originates in Tibet and flows south, marks the international border between Nepal and China. It is also a tributary of the Bhote Koshi river in Nepal.

The glacier chunk plunged into the valley, damming the river until the pressure became too much, creating the surge that travelled downstream.

Hydropower projects, workers affected

As the flood moved through the Bhote Koshi river valley, settlements, road sections and hydropower works were affected.

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At Mailung, the Hydel Project was among the infrastructure hit. Scores of hydropower workers in the area were also reported missing.

Key Nepal-China trade hub damaged

The flood reached Gyirong Port-Rasuwagadhi, the border checkpoint between Tibet in China and Nepal and a key hub for movement of goods between the two countries.

Border posts and facilities on both sides were destroyed, along with electricity and communications infrastructure. Roads were washed away, while the Nepal-China bridge was also damaged.

Settlements along the flood’s path

Syabrubesi was among the settlements affected as the surge moved downstream.

The flood’s path also extended through locations including Betrwati Bazaar, Muglin Bazaar and Devighat, leaving a trail of destruction across settlements and infrastructure along the river system.

The scale of the event stretched from a glacier high in the mountains to hydropower projects, roads, settlements and a major cross-border goods route, underscoring the breadth of the damage caused within just a few hours.

(With TOI inputs)