Kathmandu, July 10, 2025 — A devastating flood that swept through Nepal’s Bhote Koshi River this week, killing at least nine people and leaving over two dozen missing, was triggered by the draining of a supraglacial lake in China’s Tibet region, according to the International Centre for Integrated Mountain Development (ICIMOD).

The torrent struck on Tuesday, sweeping away infrastructure including the iconic Friendship Bridge, a key link between Nepal and China, and devastating nearby settlements and construction sites. Among the missing are at least 19 people, including six Chinese nationals working on the Beijing-funded Inland Container Depot project.

China’s state-run Xinhua news agency reported that 11 people are also unaccounted for on the Chinese side of the mountainous border, underscoring the transboundary impact of the disaster.

Lake Drainage Cited as Trigger

Experts from ICIMOD, based in Kathmandu, have identified the source of the flood as a supraglacial lake situated north of the Langtang Himal range in Tibet.

“This is based on preliminary analysis of satellite imagery,” said Sudan Maharjan, a remote sensing analyst and glacier expert at ICIMOD. The satellite data indicates that the rapid drainage of the lake led to a sudden outburst flood, which surged downstream into the Bhote Koshi River basin.

Supraglacial lakes form on the surface of glaciers, particularly those covered in debris. They begin as small meltwater pools but can rapidly grow, merge, and eventually burst under pressure—especially under the influence of rising global temperatures.

Worsening Climate Crisis in the Hindu Kush Region

“This kind of event is increasing at an unprecedented pace in the Hindu Kush Himalaya region,” noted Saswata Sanyal, another official at ICIMOD. He emphasized the need for deeper investigation into the growing chain-reaction disasters triggered by climate change.

The Hindu Kush region—spanning eight countries including Nepal, India, China, and Pakistan—is particularly vulnerable to climate-induced hazards such as glacial lake outburst floods (GLOFs), landslides, and extreme weather events.

The June–September monsoon season routinely causes widespread destruction in Nepal. This year, the early monsoon rains have already claimed at least 38 lives or left individuals missing since May 29, according to Nepal’s National Disaster Relief, Reduction and Management Authority.

Urgent Call for Regional Cooperation

As rescue and recovery efforts continue, with the Nepalese Army airlifting stranded residents from the Bhote Koshi region, calls are growing for better cross-border monitoring and early warning systems to manage glacial and hydrological risks in the Himalayas.

“This is not just a national issue; it’s a regional crisis that requires coordinated response and long-term resilience planning,” said an ICIMOD spokesperson.

The tragedy highlights the urgent need for countries across the Hindu Kush region to invest in sustainable environmental strategies, improved infrastructure, and real-time data sharing to prevent further loss of life in the face of a rapidly changing climate.