Warning signs seen before Nepal glacier collapse

Disaster Preparedness

Satellite pictures show water in the glacier moved faster before it fell, according to experts from ICIMOD.

In short:

A quick safety check by world scientists asks if better planning could have saved many workers at several power sites.

Satellite pictures show early clues of the slide, like a change on the glacier’s surface.

Experts say we need better early alerts in risky places, looking beyond just the project area.

A fast safety check by global scientists says there were early clues of the slide, seen in satellite pictures of the glacier’s surface.

First findings by HiRISK on Aug 28 ask if better planning could have saved many workers trapped after deadly floods on Wednesday.

Jakob Steiner, a report co‑author and geologist advising Nepal on mountain risks, told ABC early warnings for workers were very weak.

In the last ten years, China and Nepal built many high‑altitude roads, dams, tunnels and power plants near the border.

Many of those works were hurt by the huge flash flood that ripped through the valley last Wednesday.

Missing people now total over 3,900, with at least 1,000 confirmed dead.

Hundreds of missing workers are thought to be Nepali, Chinese and Indian builders on roads, dams and tunnels by the Trishuli River.

On Monday Nepal said about 933 workers were thought trapped at about six power sites.

So far about 300 workers have been rescued from a collapsed Upper Trishuli tunnel.

Satellite pictures show early warning signs

In May, Nepal and China experts met in Kathmandu to talk about disaster risk in the border area, Reuters reported.

They talked about floods, glacier dangers, and how to watch and respond, according to Nepal’s meeting agenda.

The group asked for joint steps to cut risk, like watching glacial lakes and mapping danger zones.

Jakob Steiner says satellite watching could help scientists spot risks over huge mountain areas.

But the HiRISK report says no early warning system for glacier danger was set up in the area yet.

“Because the slide moved so fast, normal warning systems would give little time and likely not be enough to evacuate at the Rasuwagadhi border checkpoint,” it said.

“Further down, with ten‑minute warnings or more, good systems could have saved many lives.”

The HiRISK paper was written by experts from the Asian Mountain Academic Alliance, the Stimson Center and China’s Institute of Mountain Hazards and Environment.

When experts looked at satellite pictures days before the glacier fell, they saw some early clues of the slide.

The report says one clue was a change on the glacier’s surface.

Before and after photos show the glacier breaking away, from Planet, Landsat 9 and HiRISK.

Satellite data suggest water in the glacier moved faster before it fell, a sign something was shifting inside and rocks were becoming unstable.

August 24 satellite pictures also showed meltwater turning brown, and scientists saw a crack growing into the rock slope days before the slide.

Mr Steiner said AI‑helped satellite watching could help scientists find risks over huge mountain areas.

“This is where we need to spend more money,” he said.

“There are thousands of glaciers in High Mountain Asia, so we need solutions that can be used everywhere.”

“We can’t say … nobody knew.”

For scientists studying the Himalayas, floods like last week’s have become more common in the past ten years.

In July last year, a glacial lake burst sent flood water through the Nepal‑China border checkpoint, destroying roads and a bridge linking the two nations.

It killed at least nine people.

A photo of the Gyirong port taken just days before the slide‑triggered mudslide was shown (RedNote: Makaqiu).

Last Wednesday the Gyirong port was hit again by flood water and was completely flattened this time.

Similar events happened in earlier years.

A rock‑ice slide hit the same spot in July 2024, and an earthquake‑triggered ice slide hit in April 2015.

“All these events together in the same place is worrying, and we call that a multi‑hazard event,” said Mr Steiner, who surveyed the valley.

Satellite pictures show where the July 2024 and April 2015 rock‑ice slides happened (Planet, Landsat 9, HiRISK).

Mr Steiner said past disasters should have warned us, and officials must be asked why very little was done to prepare.

The ABC sees the damage and rescue work happening in Nepal’s hardest‑hit areas.

Chinese Ambassador Zhang Maoming told NTV that Nepal and China can learn a lot from how they responded to this disaster.

“China and Nepal must work harder together on disaster prevention, mitigation and emergency management, and keep improving our ability to react to natural disasters,” he said.

The ABC asked Nepal’s Foreign Ministry, the Nepal Electricity Authority and the Chinese embassy in Canberra for comment.

Workers need more protection

China helped build at least four hydro‑electric dams and tunnels about 35 km downstream from Gyirong port.

Three of them – Upper Trishuli‑1, Upper Trishuli‑3A and Upper Trishuli‑3B – were badly damaged by the flood, and rescue work continues.

In total, 12 power plants and a solar farm – about 10 % of Nepal’s working capacity – were shut down; seven were damaged or destroyed, the report says.

Mr Steiner said each project had detailed environmental and risk studies, but it was unclear if they were fully followed.

He said workers were more exposed because they lived in camps close to the power sites.

He added that, with hundreds in each “cave” and natural danger, early warnings were still very weak.

He said after the 2025 rock‑ice slide he met local leaders and pushed for ongoing staff training and for disaster agencies to watch early warning signs.

But he said no money had been put into those abilities yet.

“To be honest, there was a lot of talk but very little action,” he said.

He said both Nepal and China must do more to keep construction workers safe in the area.

Risk beyond project borders

While experts agree early warning systems are valuable in the Himalayan valley, they admit little can be done at the project‑management level.

Arnold Dix, an Australian geologist and engineer, is helping with Nepal’s rescue at the collapsed Trishuli‑3A tunnel.

He guessed flood water moved over 160 km per hour, leaving only about ten minutes to act.

“People were in the camp; ten minutes is not enough to run to the tunnels, which were more flood‑resistant,” he said.

Rescue teams work at a power tunnel site in Rasuwa district (Reuters: Naveen Srivastava).

Professor Dix said looking back, other safety steps could have been added.

“We could make access points to underground caves. We could build something man‑made to slow down huge energy,” he said in two sentences.

“But right now, I’m just scratching my head.”

Professor Dix said the design of Trishuli‑3A looked sound and already considered some risks.

He said last week’s flood was “like a bomb” in its impact.

Rescue workers near the Trishuli 3A power tunnel (Reuters: Nepal Prime Minister’s Office).

Tunnel expert Chris Cooper, also helping with rescue, said planners must think about risks outside the project area.

“When you design a project, you know the yearly flood level and build for the worst flood you expect,” he told ABC’s The World.

He said what happened on the Trishuli River was catastrophic, and he doubts any project considered that risk fully.

Going forward, Mr Cooper said better monitoring and cross‑border data sharing are needed between countries.

See more ABC coverage in your search results

Pratique d'écoute

Pratique d'écoute