Nepal disaster raises concerns about the threat posed by hanging glaciers in India and other parts of the Himalayan region. The event adds to the problem of glacial lake outburst floods in the Himalayas. In an interview with TNIE, leading authority on Himalayan snow and ice-cover events, Dr Anil V Kulkarni, a scientist at the Divecha Centre for Climate Change at IISc Bangalore, addresses the way forward to develop infrastructure in high-altitude areas.
Excerpts:
What do we know so far about the Nepal flash flood?
The recent flash flood in Nepal is primarily attributed to the collapse of hanging glaciers, which occur in high-altitude regions. An ice fall at the base of a mountain probably led to a massive landslide. The combination of the ice fall and the subsequent landslide led to a massive flash flood downstream. It also led to the formation of two lakes in the valley, which still pose a risk of flash floods.
Reports indicate that an ice mass approximately 2 km in length fell from a high slope into such a valley, causing rapid melting and triggering the initial wave of the flood.
Further, these glaciers are retreating and melting due to rising temperatures, 2 degrees Celsius in the Himalayas compared to the global average of 1.5 degrees Celsius. As a result, unstable ice masses accumulate on steep slopes.
Thus, the combination of climate change-induced glacier melting and the precarious nature of hanging glaciers has resulted in this devastating flash flood in Nepal.
Could we predict the damage caused by the breaking of hanging glaciers?
Currently, there is no technology available to predict disasters caused by hanging glaciers. Establishing an early warning system to assess the risks associated with hanging glaciers is a challenging task. These glaciers are often located on slippery slopes in steep regions, making it difficult for humans to access them. As a result, we do not yet have an effective early warning system.
To create an early warning system, we would need instruments placed on the glacier itself to measure changes in pressure. These measurements would then need to be linked to indicators downstream, such as specific soil conditions or other environmental factors.
Our research indicates that regions like Badrinath, which are at high risk, can implement measures to protect communities even if a glacier collapses. The critical question is that even if we can predict when a glacier is going to fail, the priority is to protect human lives rather than infrastructure. While it is important to safeguard both, our focus should be on creating infrastructure that can divert any potential flow away from human settlements, ensuring the safety of the community. This is the approach I believe is currently the most reliable.
Can we have technology to map hanging glaciers and assess their associated risks, similar to how we map glacial lake outburst floods (GLOFs)?
While we often focus on understanding GLOFs—largely because lakes form gradually and can be easily mapped using satellite imagery—hanging glaciers number in the thousands throughout the Himalayas. In our mapping efforts in Uttarakhand, we identified between 800 and 900 hanging glaciers. The actual number is likely higher in regions such as Nepal, Bhutan, Jammu and Kashmir, Himachal Pradesh, and other parts of the Himalayas and Tibet.
It is important to note that not all hanging glaciers pose a risk. However, the threat from these glaciers is expected to increase over time, primarily due to global warming, which is causing the Himalayan region to warm.
At the Indian Institute of Science, we have developed a technique to determine which portions of hanging glaciers are at risk of collapsing and identify the communities and infrastructure that could be affected. This work, conducted in Uttarakhand, is currently being transferred to the Government of India to help mitigate risks for mountain communities. Our technology makes it feasible to reduce these risks effectively.
Have such incidents happened in the Indian part of the Himalayas?
Yes, there have been similar incidents in the Indian part of the Himalayas. One notable event occurred in Uttarakhand's Rishi Ganga valley on February 7, 2021, when a flash flood impacted one or two hydroelectric power plants. This incident highlighted the risks and potential disasters that can affect both mountain communities and infrastructure in the region, making Rishi Ganga a significant case in understanding these threats.
Scientists say the breakup of glaciers may be a factor, but it cannot be the only cause of the flash flood. What could be the local effects that cause hanging glaciers to break?
There are various hypotheses regarding the incident, such as the possibility that a fall created a temporary dam, which was later breached. I find this case particularly unique. When this fall occurred, it generated a substantial volume of water, leading to a local earthquake with a magnitude of 5.2 on the Richter scale. Within two to three minutes, this water entered Nepal. One possibility is that there may have been a lake in the area where the material from the fall could have landed. However, satellite images indicate that there are no water bodies in the region along the path of the resulting flood. As of now, there is no evidence to suggest that there was another cause behind the event.
Any claims made at this stage are likely speculative. We do know that a portion of a hanging glacier fell approximately 1.5 to 2 km into a deglaciated valley. This triggered a significant flash flood originating from that valley, which is what we have been able to observe through satellite images.
How much time does it take to form a deglaciated valley? Has this process become faster in the past few decades?
Glacier melt is a prolonged process that typically takes hundreds of years, but its impacts are now becoming increasingly evident. One reason for this heightened awareness is the significant increase in human activity in mountainous regions. More people are travelling for pilgrimages in high-altitude areas, and extensive infrastructure is being developed, including hydropower stations and roads. These projects require security and have led to a substantial amount of human movement in these fragile environments.
A notable example of this impact is the Rishi Ganga disaster. A hydropower plant located just a few kilometres from glaciated terrain was affected when a glacier fell. This incident not only damaged the nearby hydropower plant but also had cascading effects on another hydropower station downstream. As we expand our activities into previously uninhabited high-altitude regions, we are feeling the consequences more acutely.
Therefore, it is crucial to remain vigilant regarding development activities in these sensitive areas.
Has the thinning of glaciers increased the threat from hanging glaciers?
The thinning of glaciers has nothing to do with the effects of hanging glaciers. Both processes pose risks and are related to climate change.
In the case of Nepal, there is a glacial system. The glacier is the main body. Then, along with that, there are tributary glaciers; in addition, there are hanging glaciers. This means that those hanging glaciers do not contribute ice to the main glacier, but only contribute water.
So, in this particular case in Nepal, there is a glacial system. The glaciers have main bodies, along with tributary glaciers and hanging glaciers. This means that the hanging glaciers do not contribute ice to the main glacier, but only contribute water. They melt, and the water flows into the already melted, deglaciated valley.
What can India learn from this experience?
The key lesson we should take from this disaster is the need for increased caution when undertaking development activities in mountainous regions. The fragile landscape of the higher-altitude Himalayan region undergoes various processes, snow accumulates, melts, water flows, glaciers form, and glaciers erode, making it delicate and prone to disruption. As such, we must be very careful about engaging in extensive development activities at these high elevations.
Historically, after extensive development along coastal areas, the government established a Coastal Regulation Zone to mitigate risks. A similar regulatory body is necessary for high-altitude regions above 3,000 metres. We could create a High Altitude Mountain Regulation Authority to oversee development activities, specifically as we build roads, hydropower plants, and pilgrimage centres. This would help reduce vulnerabilities within these communities.
Furthermore, it is essential to approach development activities in these areas differently. For example, while environmental reports are typically conducted for hydropower projects to assess their effects, we must consider the reverse: how climate change impacts these hydropower plants. This shift in perspective is crucial for adapting our development practices in these vulnerable regions. In conclusion, there is significant potential for us to rethink our approach to development in the Himalayas, ensuring we protect both property and lives.
Following the study on hanging glaciers by IISc, the NDMA, along with the Ministry of Water Resources, Ministry of Earth Sciences, and IISc scientists, discussed how to address the threat. What measures are being prepared?
After the Rishi Ganga Valley disaster, the Government recognised the urgent need to address this issue critically. We developed a mapping technique using satellite images to identify hanging glaciers. Additionally, we created models to understand which portions of these glaciers might collapse and which areas would be affected by such an event.
This work was carried out for the entire Uttarakhand region, and some of the reports have now been submitted to the Ministry. They are currently engaged in detailed discussions about specific hanging glaciers, such as those near Badrinath, to identify remedial measures to protect local communities.
While the temple itself is not at risk, the surrounding areas, where significant development has occurred, are likely to be impacted if a hanging glacier were to fall. Therefore, we are exploring various remedial strategies to protect the region. This ongoing work has led to many discussions, and we hope the government will take appropriate action soon.
There are reports that China has not shared timely information related to disasters. How do you view the neighbouring country's record of helping its neighbour prepare for or provide early warning of threats?
I don't know whether there is an agreement between Nepal and China, or between India and China, on sharing data on rivers and other matters. I'm not aware of it. There may be some data sharing, but in this case, people are complaining that it wasn't shared.
A government-to-government agreement is required to share the data. But in this particular case, if you really understand, the time between the disaster and its arrival in Nepal is not much. It's only a couple of minutes. Within that time, it has come. So, in this particular case, whether China will be able to warn Nepal or not, I don't know, essentially. Otherwise, we should have an agreement with various countries to share this risk.
