Three months before a wall of water, mud and rock killed hundreds after tearing down a Himalayan valley bordering Nepal and China, officials and experts from both countries met in Kathmandu to discuss the risk of exactly this kind of disaster.
At the meeting on 27 May, 10 Nepali officials and around a dozen Chinese counterparts, including representatives from Tibet, discussed strengthening cooperation on monitoring and responding to floods, weather and glacier hazards, according to an agenda prepared by the Nepali side and seen by Reuters. Participants called for joint risk-reduction measures, including inventories of glacial lakes and hazard mapping.
Two Nepali officials told Reuters they did not receive as much information as they had hoped for on glacier risks and water levels following that meeting, and said they feared insufficient data sharing could hamper the country's ability to anticipate and prepare for major disasters. Sauhardra Joshi, a hydrologist at Nepal's Flood Forecasting Division who attended the meeting, said Nepal wanted advance notice of early movements in glaciers in the area, adding "we would want to know a bit early."
No official or expert has blamed either side for the disaster, which is expected to cost the equivalent of a tenth of Nepal's annual economic output to recover from. Nepali officials say the priority now is deepening cooperation with Beijing. China's foreign ministry said the two countries have maintained sound cooperation on meteorology, water resources and disaster prevention, adding that Beijing would continue supporting Nepal's relief efforts.
China says data-sharing has been timely
Last week's disaster began with the sudden collapse of a glacier in Nepal's Langtang mountain range, triggering a flood that has killed more than 900 people, with almost 5,000 still missing on both sides of the border. It remains unclear what data, if any, China held on the condition of glaciers in the area before the collapse.
Fan Xuanmei, director of the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection at Chengdu University of Technology, told China's state-run China Daily that such failures were extremely hard to detect in advance. Potential source areas often sit above 5,000 metres, where field monitoring is difficult and satellite observation can be limited by snow cover and steep terrain.
At the May meeting, Chinese representatives said they lacked the mandate to sign an agreement meeting Nepal's requests and proposed further talks, according to Binod Parajuli, another Nepali government hydrologist. China's embassy in Nepal said the two sides had made "substantial progress" at the meeting on cross-border disaster information sharing, and rejected criticism from Nepali social media users that Beijing had failed to provide adequate warning, saying monitoring hazards in the remote Himalayan region posed major challenges for Chinese and international experts alike.
Nepal raised similar concerns a year earlier, officials said, though experts and officials cautioned that slow progress on data sharing was not a significant factor in the latest disaster. Parajuli said China had begun sharing heavy rainfall forecasts for Tibet over WeChat and email a month ago, but that similar advance data was not yet provided for avalanches, water levels or landslides.
Timeline to disaster
Twelve days before the flood, China's World Meteorological Centre told Nepali officials by email, seen by Reuters, that a monsoon depression was forecast for the area between 14 and 19 August, warning of the potential for landslides and flash floods. China's embassy said Beijing had shared information, including monitoring data on a lake formed by debris from the collapse.
The episode highlights the difficulty of monitoring and forecasting hazards in a region where geopolitical rivals, including China and India, control remote mountainous areas holding vast reserves of ice and snow above densely populated South Asian plains. Austin Lord, an environmental anthropologist and senior fellow at the Washington-based Stimson Center who supports Nepal's government on disaster and climate risk management, said a lack of bilateral cooperation was not a significant factor in Nepal's response, though he noted the system between the two countries remains poorly developed, adding that Chinese scientists "have much greater resources for monitoring than those on the Nepal side."
The speed of the flood underscored the value of early-warning systems, Parajuli said. At around 8.32am Nepal time last Wednesday, the deluge tore through a border crossing in Tibet as people tried to flee, according to surveillance footage that has become a defining image of the disaster. Twenty-six minutes later, Parajuli received a call from the head of Nepal's National Disaster Risk Reduction and Management Authority alerting him to flooding on the Trishuli river. His team found that a border monitoring station had stopped transmitting data, and downstream stations also went silent, leading them to suspect the equipment had been swept away. After confirming the flooding with local authorities, Parajuli's team issued a public alert to mobile phone users at 9.13am.
A landscape reshaped
At least four monitoring stations were destroyed as the flood surged 168km downstream from the Nepal-China border, carrying an estimated 57.4 million cubic metres of water, more than half again the normal volume, according to a Nepali government assessment. The floodwaters dislodged large boulders, swept away buildings, damaged 19 bridges and around 40km of highway, and knocked out more than 10% of Nepal's power-generation capacity, the Stimson Center said.
Keshav Prasad Baral, from Tupche village around 25km downstream of the border, described the moment the flood hit, saying "it wasn't water, it was a huge gush of mud coming straight at us." He said he tried to grab his wife's hand but she was swept away.
Preliminary assessments by Nepali authorities found the disaster began when part of the glacier broke away and crashed to the valley floor hundreds of metres below, unleashing high-speed flash floods. The glacier chunk responsible carried an estimated 5 million cubic metres of ice and rock, according to Basanta Raj Adhikari, director of the Centre for Disaster Studies at Nepal's Tribhuvan University.
The Hindu Kush Himalayas, home to hundreds of millions of people from Afghanistan to Myanmar, hold the largest volume of ice outside the poles, with more than 63,700 glaciers covering close to 56,000 square km, an area almost the size of Croatia, and storing up to 5,700 cubic km of ice. Glacier melt is accelerating as snow cover declines and snowfall grows more erratic, according to a 2023 study by the International Centre for Integrated Mountain Development, which projects rising risks of flooding and landslides for mountain communities already contending with erosion and sedimentation.
Nepal's authorities now plan to work with China on research and monitoring systems for avalanches and glacial lake outbursts, Parajuli said. His department intends to propose a data-sharing agreement with Beijing modelled on Nepal's existing arrangement with India, seeking more frequent updates on precipitation and river levels rather than high-precipitation forecasts alone. Nepal wants data every 10 minutes, he said, so that authorities "can warn our people, save our people."
Source: Reuters
