The devastating floods along the Nepal-Tibet border have once again exposed the extreme vulnerability of the Himalayan region, where earthquakes, avalanches, glacier instability, landslides and intense rainfall can combine to produce cascading disasters within hours.
The reported magnitude 4.4 earthquake along the Tibet-Nepal border, followed by a major movement of ice, rock, mud and water, has drawn fresh attention to the region’s geological fragility.
But the disaster also raises a broader question for a region divided by political boundaries but connected by the same mountains and river systems: can Himalayan disasters really be managed within national boundaries, or does the region need “science without borders” to detect, understand and respond to risks before they cross into downstream countries?
Importantly, experts caution against directly connecting the Nepal floods to China’s planned 60,000-MW Medog hydropower project on the Yarlung Tsangpo. The immediate disaster and the proposed dam are separate issues. Yet the event has renewed scrutiny of what a mega-project of such unprecedented scale could mean for downstream countries when it is located in one of the world’s most seismically active mountain regions.
What triggered the Nepal floods?
The flooding followed a sudden movement of a huge volume of water and debris near the Nepal-Tibet border. Initial reports pointed to an avalanche or ice avalanche, while an earthquake-triggered event was also examined.
According to Prof. Naresh Chandra Pant, former Professor in the Department of Geology at Delhi University, available satellite imagery suggests that a large section of glacier broke and entered the valley system.
It looks like as if a big part of a glacier broke down and entered into the valley system.
Pant said the event involved much more than ice.
When it broke, it wasn’t just ice; along with the ice, there was a rather large quantity of rock slide—both rock and mud were present.
However, one major question remains unresolved: where did the enormous quantity of water come from?
Pant said that, based on the information available to him, there was no evidence of an artificial lake having formed upstream of the Nepal-China border. A cloudburst could potentially generate large volumes of water within a short period, while another possibility is a Glacial Lake Outburst Flood (GLOF).
But he said the available evidence did not show the lake buildup normally associated with such an event.
Instead, Pant suggested that glacier instability linked to warming could have contributed.
I would consider it as a warning of global warming, as an event which is generated by the melting and softening of a large glacier segment… As soon as it mixed with the water, the melting was accelerated, and that led to the generation of water.
At the same time, he stressed that this remains a hypothesis rather than a definitive explanation.
It is not a very 100% convincing argument even to me, but as far as I see, it looks like that only right now
His broader assessment is deliberately cautious:
I am a little conservative always till such time the science is not added up. It will take some time to work this out.
(Representative image)
Why does this bring Medog back into focus?
The Medog Hydropower Station, also known as the Motuo project, is planned on the Yarlung Tsangpo in Tibet, close to the river’s Great Bend around Mount Namcha Barwa.
With a proposed capacity of around 60,000 MW, the project would be the world’s largest hydropower facility by installed capacity.
The strategic significance comes from what happens to the river after it leaves Tibet.
The Yarlung Tsangpo enters Arunachal Pradesh as the Siang, flows through Assam as the Brahmaputra and eventually reaches Bangladesh.
That makes China the upper-riparian country and India and Bangladesh downstream states.
The concern is not simply that China could “switch off” the Brahmaputra. The river receives substantial additional water from rainfall and tributaries after entering India.
The bigger question is whether a project of this scale could influence the timing and pattern of upstream flows, sediment movement and downstream river conditions.
Does an active fault make Medog unsafe?
The project’s location has also attracted geological scrutiny.
Chinese geological researchers have identified the Paizhen Fault in the project region and highlighted concerns about tectonic activity, landslides and slope instability.
For a project spread across difficult Himalayan terrain, seismic risk does not concern only the main dam structure. Reservoir slopes, tunnels, roads, bridges and other associated infrastructure could also be exposed to earthquakes and secondary hazards such as landslides.
But an active fault does not automatically mean that a dam will fail.
Pant stressed that major dams are designed with seismic risks in mind, pointing to India’s experience with projects in earthquake-prone areas.
Potential engineering risks are always there.
He added:
The reason is that the structural drawings and safety measures implemented far exceed the potential earthquake risk.
This distinction is important. The existence of geological hazards is a reason for rigorous risk assessment; it is not, by itself, evidence of an inevitable catastrophe.
Why does the “water bomb” argument persist?
Arunachal Pradesh CM Pema Khandu expressed serious concerns about China’s plan to build the Great Bend Dam on the Yarlung Tsangpo River.
“The issue is that China cannot be trusted. No one knows what they might do. Setting aside the military threat from China, it seems to me that this is a far bigger issue than anything else. It is going to cause an existential threat to our tribes and our livelihoods. It is quite serious because China could even use this as a sort of ‘water bomb’,” CM Pema Khandu said.
Strategic expert Dr. Brahma Chellaney takes a significantly more critical view of the Medog project.
Reflecting on the latest Himalayan disaster, Chellaney wrote:
The Himalayas are the world’s most seismically active major mountain range, with a record of triggering devastating earthquakes.
He argued that the latest event demonstrated how even a moderate seismic event can generate cascading consequences.
Chellaney described China’s continued construction of Medog as:
China’s folly in persisting with the construction of the world’s largest dam in the middle of the Himalayan seismic zone.
He further called the project:
A water bomb in the making, which could drown India’s northeast and wreak havoc farther downstream in Bangladesh.
The phrase is a strategic warning rather than an established scientific prediction. There is no evidence that China intends to deliberately use Medog to flood India.
The underlying concern is about upstream control, geological risk and the absence of a comprehensive India-China water-sharing treaty.
Importance of ‘science without borders’
For Pant, the most important lesson from the Nepal disaster lies beyond the immediate question of the dam.
The Himalayas may be divided among several countries, but their natural systems are not.
The world is growing into a very isolationist context… But nature does not recognize those boundaries.
A glacier in one country can feed a river in another. A landslide can alter downstream flows. An unstable glacial lake can threaten communities across a border.
That makes scientific information itself a form of disaster protection.
Pant argues that countries need to move towards “science across borders” and “science without constraints across borders.”
He illustrated this with the example of a dangerous glacial lake upstream.
If there was a glacial lake somewhere upstream that could suddenly burst, pre-warning for people outside that nation would have been very important.
Such warning systems, he said, can work only through cooperation:
This comes only from cooperation. This comes from science across borders, science without constraint across borders.
His conclusion is broader still:
That is what is the need of the hour—thinking beyond our geographic boundaries and thinking rationally.
Is India’s Siang project a counter to Medog?
India’s proposed 11,000-MW Siang Upper Multipurpose Project is frequently viewed through the strategic lens of Medog.
Pant, however, rejects describing it as a direct counter-project.
No, it is not a counter to that because we are downstream.
According to him, India is developing the project for its own requirements and to utilise its hydropower potential.
That does not remove the project’s own environmental and geological questions. A major project in Arunachal Pradesh would also have to contend with seismicity, steep terrain, biodiversity, sediment flows and impacts on local communities.
In the Himalayas, China controls the upper reaches of rivers that feed not just India but also Bangladesh, Nepal and Vietnam.
What does Nepal tell us about Medog Dam?
The Nepal floods do not prove that China’s Medog project caused the disaster. Pant is clear that the two should not be connected.
That is a separate issue altogether. It is not related to this particular disaster
But the event has demonstrated the speed at which Himalayan hazards can cascade, from ice and rock to mud, water and flooding.
That is precisely why the Medog debate cannot be reduced to whether a dam will or will not fail.
The more difficult questions concern what happens during an extreme event, how quickly it is detected, how reliable upstream information is, and whether downstream countries receive enough warning to act.
In that sense, the central lesson from the Nepal disaster may not be about proving a link between a flood and a dam.
It is about recognising that the Himalayas function as one interconnected geological and hydrological system, even when the countries sharing them do not.
And that makes Pant’s formulation particularly relevant: “nature does not recognize those boundaries.”
