Steep gorges amplified deadly mudslide along China-Nepal border, experts say

A mudslide that tore along the China-Nepal border and struck Gyirong Port in southwest China's Xizang Autonomous Region on August 26 was made far more destructive by the steep, narrow Himalayan gorges, said Sudan Bikash Maharjan, a remote-sensing analyst at the Kathmandu-based International Center for Integrated Mountain Development.

The debris flow, triggered by a glacier collapse in Nepal, surged at exceptional speed and carried enormous force, the analyst told China Media Group. 

Sediment and boulders, picked up as the ice-rock avalanche plummeted down to the Bhote Koshi River and into the Trishuli River, breached riverbanks, wreaking havoc along roughly 100 kilometers of the river corridor in Nepal.

Hydrological observations from the International Center for Integrated Mountain Development (ICIMOD) show that water levels on the Trishuli River at Galchhi rose by as much as 9 meters within 30 minutes, while levels at Malekhu increased by 7 meters. Several monitoring stations along the Trishuli were reportedly damaged or washed away.

ICIMOD researchers are continuing to analyze hydrological, seismic, remote-sensing and field data to better understand how the disaster developed and assess the risks facing downstream communities in Nepal.