A TEAM of geologists and glaciologists did an aerial survey of the Nanda Devi glacier area after the flash floods in Chamoli district of Uttarakhand on February 7. A preliminary survey revealed that a huge rock had dislodged itself from a peak, which resulted in an avalanche that fell on a probable waterbody and created an artificial dam. This ‘dam’ breached and water cascaded down, causing flash floods. The trigger for the phenomenon was deemed unusual as the disaster had occurred in the cold season, and two, it was not preceded by heavy rainfall or any seismic activity.
Dr Kalachand Sain, Director of the Dehradun-based Wadia Institute of Himalayan Geology (WIHG), an autonomous institute of the Department of Science and Technology, Government of India, has advanced specialisation in the fields of inversion modelling, and processing and interpretation of geophysical data. He told Frontline that given the fragile nature of the Himalaya, the phenomenon was not unusual. He said a nodal centre for the study of glaciers and better coordination between the Himalayan States were required to mitigate and prevent such disasters.
Excerpts from the interview:
What was the possible cause of the flash floods and the factors that led to the disaster?
Our [WIHG] scientists have gathered information. It seems that a heavy mass of rock from a height of 5,000-6,000 metres fell onto a hanging glacier. This seems to have created an artificial dam near the Raunthi stream. There was glacier melt. When water accumulated, a good amount of pressure was generated. Whenever there is some form of depression, it is possible that small bodies of water are created. We have not come up with evidence to say that a glacial lake had burst. Some queries have pointed towards some underlying waterbody. Our team was of the opinion that an artificial dam was created in the up slope, which breached, and water and debris came down as a flash flood. Because of the avalanche, the dam was created. Then all the snow melt from the valley accumulated. It is a narrow valley, there might have been some accumulation of ice, debris, etc. We have to study where the water came from. It is not clear if it was from snow melt from the valley that had accumulated over a period of time, but the artificial dam could not withstand the pressure and it burst. It was a narrow gorge through which the water went down; the width of flowing water expanded and the level of debris increased. There must have been some trigger to cause the fall of the rock mass from that height, but we have not got any evidence. Water might have accumulated from snow or there must have been some other source or sources of accumulation. Our scientists have not found any evidence of a glacial lake in the region so far.
What was the time span and the sequence of events that led to the disaster?
The rock that fell from that height was already in a weakened state. It must have occurred over a period. It went through some freezing and thawing process. At that height if there was a rock mass and a hanging glacier, glacial melts can occur. Water must have percolated inside and, in a frozen state in winter, must have expanded in volume and developed a crack or accelerated cracks. Over a period, we do not know whether it was 50, 100, 150 or 500 years ago, but the process of weakening has happened over time coupled with general global warming. From which date do we consider global [climatic] changes is also a question. There was snowfall before the event and some increase in temperature must have resulted in a snow melt and created a slippery plane inside the rock formation. The remaining mass in the slope region must have got detached from the main rock. When it got detached it must have fallen on the hanging glacier, which also broke. It fell, rolled down and scraped soil, vegetation and formed an artificial dam.
Also read: Himalayan tragedy in Uttarakhand
We are not able to categorically state in how many hours all this happened. It did not happen over three days or three hours. It could have happened the same day. The flood came at 10 a.m. on February 7. So the phenomenon happened before that. Probably it was of recent origin. The material that was found in the water did not appear as if it had accumulated for many days. It is possible that it accumulated over hours. Once that amount of water and debris went down, damage was bound to occur.
When is the last time that such a phenomenon occurred in the region? Is it likely to happen again?
It is difficult to say unless we monitor. It will be too early to say this phenomenon will occur in this region or other regions. But we cannot say it will not happen again. There are 10,000 glaciers in the entire Himalayan region and 1,400 in Uttarakhand alone. We must analyse and prevent it from occurring.
Is monitoring a major challenge given the topography of the region? Surely other countries that face similar challenges have worked out some mechanism.
It is a challenge because of the difficult terrain. We depend on huge quantities of data as the area is large. Remote sensing data are the first option. But they must be validated by ground observations. This means they must be physically verified. There are limitations as one cannot go everywhere. Weather stations can help; some assessment can help. Nothing is impossible, but it is tough. It is not like in the plains. Lots of effort and support—monetary, machinery and human resource—are needed.
When such a disaster takes place, should not there be a vision to mitigate human losses? A detailed project report normally does not contain details of glaciology.
Yes, whenever such activity takes places, a committee of experts assesses the vulnerability of the region and the impacts. This is generally done by area experts. It is a collective opinion. In the Himalayan region, many aspects are involved. Apart from the general inhospitable terrain, landslides, earthquakes and glacial lake outbursts can occur. Yet, there is fertile soil in some places to meet the food requirements and there are rich sources of drinking water, too.
Also read: Uttarakhand: State of paralysis
From the health, energy and water security point of view, the Himalaya is a great resource. A detailed impact assessment and glacial impact studies are required. Many States are connected to the Himalaya. If each State takes charge of the glaciers in its area, much can be done to understand the processes of glaciology and glacial impact. A central nodal agency is required. Locally, a team should be created to study them on a regular basis.
Countries with hydel projects in mountainous areas must be conducting glaciology studies. Why is it difficult to undertake such studies here?
Our glaciers are different from the Arctic and Antarctica glaciers. They get impacted only by climate change. Our glaciers get affected by climate change and because they lie on a tectonically complex region. This region affects glacier behaviour. We need to look beyond the surface and see what is happening underneath. The Himalayan range is 2,500 kilometres long and 300 kilometres wide. It involves mammoth and specialised work.
We will be able to reveal much more after we collect more data. The second challenge is how to propagate what we have found in order to prevent the next disaster. These are natural processes. Governments, at the Centre and in the States, should come out with a full plan. The Central government’s support is necessary. Information collected in each Himalayan State should be assessed and reassessed. This should be coordinated by some Central organisation. The main objective of scientific knowledge is to help minimise loss of life and property.
Are there any similarities between this incident and the Kedarnath disaster of 2013?
The Kedarnath tragedy was caused by multiple factors. There was heavy rainfall, a cloudburst and a glacial lake burst. It collected a lot of debris. There was inundation on both sides. Some 6,000 people died, 5,500 villages were destroyed, and two lakh people were displaced. In this case, heavy precipitation was not there. There was no weather report about rainfall. We did not find any glacial lake; but some colleagues have suggested there might be a hidden lake. Once we collate all the data, we will be able to come to a conclusion.