Chamoli flash flood: A wake-up call

Print edition : March 12, 2021

A general view of the damaged Dhauliganga hydroelectric power project in Chamoli district of Uttarakhand on February 10. Photo: PTI

Path of debris after hill slope failure. Photo: NTPC-THDCIL Survey Report

Path of debris after hill slope failure. Photo: NTPC-THDCIL Survey Report

The lake after river damming at the confluence of the Rishi Ganga and its tributary. Photo: NTPC-THDCIL Survey Report

Geologists and glaciologists see the recent landslide and flash flood in Uttarakhand as part of inevitable natural processes given the fragility of the Himalayan region, but affirm that close monitoring and study of such processes are crucial to preventing the recurrence of disasters that result in significant human cost.

On February 7, around 10 a.m., a landslide, the trigger of which was unknown, crashed into a lake formed in the past in the Nanda Devi Sanctuary in Uttarakhand, resulting in a flash flood bearing mud and other debris that hurtled down the steep slopes and claimed at least 56 lives and two hydroelectric power projects. One of the projects was already in commission and the other was under completion. At the time of filing this report, 149 persons were still reported missing and feared dead, a good number of them migrant workers who were on shift duty. Had it not been a Sunday, the toll would have been higher since senior staff and engineers too would have been on duty.

Frontline spoke to leading geologists and glaciologists, whose collective opinion was that such natural processes were inevitable given the fragility of the Himalayan region but close monitoring and study of such processes was crucial to preventing disasters occurring downstream at huge human cost.

The possible cause

A helicopter survey by a team of glaciologists, geologists and technical personnel from the Wadia Institute of Himalayan Geology (WIHG) submitted a preliminary report on the possible causes of the disaster. According to the survey of the Rishi Ganga Valley (Nanda Ghonghati Glacier), a copy of which is with Frontline, a huge rock mass got dislodged along with snow and ice at an elevation of 5,000 metres, 10 kilometres from the confluence of the Rishi Ganga and Dhauliganga rivers. The area affected by the slide was approximately 300 m long and 80 m wide. “Large amounts of moranic debris also slid from this zone,” the survey report said. A derivative of the term ‘moraine’, moranic refers to accumulated and unconsolidated debris.

The lake into which the parts of the glacier crashed “may have been formed in the past due to falling debris and slope failure”, according to the preliminary report issued by the Director (Project), NTPC Limited, and the Director (Technical), Tehri Hydro Development Corporation Limited.

Also read: Himalayan tragedy in Uttarakhand

The preliminary conclusion of the report was: “The huge failure of the wedge might have triggered due to lubrication of various joints/planes by melting of snow and ice, including the weight of the overlying glacier. This wedge of approximately size of 100x30x80 m slid down from approximately 2,000 m with further failing en route mass containing nearly 300,000 cubic m of material and bursting the supposedly previously formed lake in the past and triggering the flash flood.”

Formation of new lake

The survey also reported that in the downstream part, a “large lake had been created in the right rivulet of the Nanda Ghongati nalla due to the blockage of the mouth of the rivulet by approximately 60 m high debris, requiring immediate attention”. Information about the formation of a river and a possible second flooding was not initially shared in the public domain, for reasons unknown. The matter came to light only after a geologist, Dr Naresh Rana from HNB Garhwal University trekked up to those parts, took videos and shared images of the lake. Dr Rana had worked on neotectonic studies in the Alaknanda Valley for his Ph.D thesis. His Ph.D supervisor, Dr Navin Juyal, a geologist associated with the Physical Research Laboratory, Ahmedabad, had suggested that he make a physical visit to the site.

Dr Juyal said that the Nanda Devi Sanctuary was a protected area considered very sensitive since 1980. There was zero human interference there, he said. “To say that the disaster was caused by human anthropomorphic intervention would not be correct. This was a purely natural process in the valley,” he told Frontline.

According to him, the Rishi Ganga gorge was one of the most difficult gorges in the world. In 1935, the British geologist Tillman discovered it; he attempted to reach it but had to take a different route. Local residents believe that the gorge, surrounded by eight peaks, is a fortification of the Goddess Nanda. Dr Juyal, who belongs to Uttarakhand, said that in a region with so many glaciers, it was natural that there would be avalanches too. Winter temperatures were on the rise and glaciers were very sensitive to temperature changes, he pointed out.

He said: “But it doesn’t happen overnight. It happens over a period of time, the detachment of the ice, surface melting, etc. I was there a few days before the incident in Raini village, on February 3, 4 and 5. This was the same village where the Rishi Ganga project got washed out in 2013 and now once more. This winter was completely dry compared to last winter, so when there was some light snowfall, people were happy now because their wheat crop last winter had failed owing to low rainfall. When it snowed here, it must have snowed a little more in the high altitudes. Water must have percolated through the dry soil on the surface of the snow. February 6 was a very hot day and the ice possibly melted.”

Dr Juyal added: “There are lots of crevasses inside the glaciers. If there is snow on top of a crevasse and it melts, it lubricates and expands; coupled with gravity, the crevasse must have collapsed. That a crevasse broke is a fact. Along with it, the dry part melted. Debris was generated. The avalanche occurred with the breaking of the crevasse.”

Also read: The 2013 tragedy in Uttarakhand

There are two glaciers—Raunthi, the bigger one, and Nanda Koti. The Raunthigad river is formed at the confluence of the two and meets the Rishi Ganga river after about 20 km. Dr Juyal said: “When the crevasse collapsed, the sub-stratum glacier bodies which contain water broke. The phenomenon happened between 4,000 and 6,000 m. The ridge height of the glaciers is more than 6,000 m. We had an image of huge boulders on the channel flow. They acted as a dam. When the small river hit the confluence of the Rishi Ganga, which flows in the centre of the Nanda Devi park, one part flowed downstream and the other upstream. The upstream part blocked the Rishi Ganga and the flow downstream created the havoc.”

He expressed surprise that none had bothered to look what had happened to the Rishi Ganga. There were sorties in the area but no reports were coming out. Dr Juyal and some other experts said that the magnitude of the sediment must have been such that the Rishi Ganga got blocked. He said: “It was then that Naresh Rana went, but for two days he was stalled at Joshimath and not allowed to go through. He reached on February 7 itself. As it was a protected forest area, he did not get permission. He finally got transported across and then trekked with locals. He is the one who revealed that water was accumulating. Why they did not make it public is a mystery. But there is no danger of bursting.”

He added: “The slope is very gentle and the sediment loose and unconsolidated. The river will fill up with sediments once the summer sets in. It will recede and fill up at the same time. But then we never know. The Himalayas are full of surprises. A monitoring system should be set up there by the administration. If Naresh Rana can go without any support, it is not impossible.”

Strain on higher Himalayas

Several geologists are of the opinion that the Himalayan region is under tremendous strain because of climate change and there should not be any intervention in the higher Himalayan region, which witnessed a lot of glacial advancement in the past and has left behind a lot of sediment up to heights of 2,500 m.

Dr Juyal said: “In our language we say it is not only sediment limited but transport limited. As and when there is a trigger mechanism, the impact of this mobilisation and [water] not allowed to flow downstream can cause havoc to man-made formations. There should be a rethink on the carrying capacity of the higher Himalayas keeping in mind that the glaciers are very sensitive to change in temperatures. Any increase in the air temperatures can have critical effects.”

According to him, the 2013 disaster was also the result of a similar trigger. He said: “We told the Supreme Court as well. The peak died down after three to four hours. In 2007, when the IPCC report came that the Himalayan glaciers would disappear by 2035, it was considered a hoax. The Government of India constituted a committee on glaciers and I was a member of that committee. We were told to identify 10 million glaciers and were supposed to generate quality data. A centre for glaciology was set up in the Wadia Institute. It started in 2008 and was closed down in 2020.”

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Dr Juyal said that the need of the hour was honest monitoring. He added: “When the glacier recedes, the water melts and one has to monitor, as disaster will strike if the barrier breaks. In Bhutan, local citizens are involved in monitoring such events. There is a remote sensing centre in Dehradun, so why were they not able to tell us about the formation of the water build-up? We should have a dedicated centre working on all the glaciers. Monitoring the glacier lakes in very important. Every State has a disaster mitigation centre. This is applied science. There has to be coordination between scientists and the administration.”

Raini village

Raini village was where the Chipko movement activist Gaura Devi stayed in the jungle all night in the 1970s, protecting the forests. Residents of the village had objected to the Rishi Ganga hydroelectric power project. Perhaps aware of the topography, villages were located in the middle ranges. That was one reason why loss to human life in habitations was minimal in Raini and nearby villages, although homes were damaged.

Dr Juyal said: “We are not against hydel projects at all. But don’t touch the higher Himalayas. We are the ones who advocated that we should have run-of-the-river schemes but we are realising that such schemes are effective in the lower Himalayas. But it should not be bumper to bumper. We cannot impound water in such huge quantities higher up. The entire Tehri town has got submerged. Hydel projects are such lucrative ventures. The lifespan of a project is 30 years and there is a lot of scope to make money.”

According to him, the entire town of Joshimath was located on a landslide deposit. One tunnel boring machine was still stuck below Joshimath town. The entire State was sitting on a time bomb, he said, and expressed surprise that there was talk of restarting the power project soon. R.K. Singh, the Minister for Power, has ruled out scrapping of NTPC’s Tapovan Vishnugad project.

Dr D.P. Dobhal, a glaciologist formerly associated with the Wadia Institute, told Frontline that the cause of the flood was possibly a snow avalanche from a hanging glacier. “There are different kinds of avalanches. Sometimes it is just in the form of powdered snow. This was a hanging glacier. It was standing almost vertical. There is a lot of tectonic activity going on all the time. There are some similarities between the Chamoli disaster and the 2013 Kedarnath devastation. In Kedarnath, on June 17, an avalanche triggered by heavy rain fell into a lake resulting in flash floods that caused the complete decimation of the town itself and a huge number of casualties. In the Chamoli case, when the avalanche fell, it created a sub-layer glacial lake. There are lots of loose material left behind by a glacier. All that forms part of the debris.”

Asked whether it was difficult to monitor the area, he said very good remote sensing technology was available. Sometimes, potential avalanches could be prevented by breaking up rock formations. A nodal agency was required for this work. There is the possibility of preventing some loss of life, if not much.

Dr Dobhal said: “When a project is planned, the impact of glaciers is not factored in. Take up any detailed project report, you won’t find any mention of the role of glaciers. It is felt that glaciers are too far and will not have an impact. But when a disaster occurs, the distance gets breached. The entire event must have occurred within three to four days.”

According to him, a lot of dust was generated first and people were taking photographs and shouting warnings. But within minutes, it reached downstream. As there was no monitoring at those heights, the disaster happened. It was a combination of topography and climate. He said: “The approach to those routes is very difficult. There are 14-15 glaciers almost 5 km long in Nanda Devi North and Nanda Devi South. There are a lot of logistics issues involved. I have spent 30 years working on glaciers. In the Alps and the Andes, there are helicopters that drop scientists and pick them up after the study. They put up stations in the areas itself. We do it all manually. It has to be teamwork and a combination of all sciences. There is no doubt there is a lot of work happening but it has to be a combined effort.”

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Dr Dobhal said that in the entire Himalayan region, there are 16,000 glaciers. He added: “In the inner Himalayas, there are 9,027 glaciers. In Uttarakhand, there are 1,000 glaciers; in Himachal Pradesh there are more, 14,000 or so. There had to be some knowledge of how much water is being stored in the upper reaches that had the potential of causing damage downstream.” The glaciers in the Alps are at low altitudes and high latitudes but the Himalayan glaciers are at high altitudes and low latitudes, which made them dangerous.

In a paper titled “Glacier changes and associated climate drivers for the last three decades, Nanda Devi Region, Central Himalaya,” jointly authored by six scientists including Dr Dobhal and Manish Mehta of the WIHG, eight glaciers were studied to measure their temporal and spatial variability towards climate change. The Nanda Devi group of glaciers fall within the upper Rishi Ganga catchment (a tributary of the Dhauliganga) that is dominated by “Higher Himalayan rugged topography with high elevation ridges adjacent to deep glacial valleys”.

The Nanda Devi peak is at an elevation of 7,817 m. The glaciers of the upper Rishi Ganga catchment area contain thick layers of debris, according to the study. Mapping showed that the eight glaciers under study had “significantly receded” during the past 37 years, between 1980 and 2017, attributable to a combination of decreased precipitation and increased temperatures.

Dr Manish Mehta, who was part of a five-member team sent by the WIHG to study the causality of the disaster, said that glaciers and their boundaries could be mapped with manual delineation and satellite imagery. He added that “solid precipitation” also needed to be monitored regularly.

He told Frontline: “It is not possible to delineate all glaciers manually in the Inner Himalayas. But we don’t have a nodal agency to study glaciers. A centre was set up once but discontinued. Glaciers are a very good natural resource. The Himalayas are very young and very fragile as compared to the Alps and others. Being young, the rock mass is very loose as compared to other mountain ranges. These processes will happen but we can prevent the calamity from happening. We can only mitigate the losses downstream. It is preventable.”

It was an unusual phenomenon for such a huge quantity of water to accumulate in the winter, he said. Remote sensing and satellite imagery could have shown the accumulation of water. The Indian Space Research Organisation (ISRO) runs an institute of remote sensing in Dehradun that monitors all disasters, but a dedicated nodal agency to study glaciers is required.

The human cost

According to Rajinder Negi, trade union leader and State secretary of the Communist Party of India (Marxist), nearly 206 people were missing. He had visited the disaster site along with members of the Centre of Indian Trade Unions (CITU). He said that 136 workers from the NTPC Tapovan project, all members of the CITU, 56 workers from the 13-megawatt Rishi Ganga Project and 12 persons from the village were missing. Only 12 persons had been rescued so far, he said. “The rest are missing and they could be dead,” he added.

There are four tunnels at the Tapovan project. People in only one tunnel could be saved. The distance between the two projects was just 5 km. Rajinder Negi said that had it not been a Sunday, the “company people” would have died, referring to managerial and senior technical staff. And more workers would have died had they not been on strike in a machine fitting area downstream on the Tapovan site, he added. “Water entered the ground floor completely,” he said.

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Kundan Singh, a resident of Raini village, had objected to the projects and the cutting down of trees. “We are angry that there is no alarm system, no satellite system to warn people. It was one scientist from Garhwal University who found that water was accumulating upstream. The people have a right to know.” Rajinder Negi said: “Our union president, an electrician, lost three persons from his family. He would also have died had his wife not called him over to help her. She was across the river.”

Some 13 gram panchayats got disconnected from the district headquarters and several small bridges were damaged. Some 40 labourers from a nearby village were also trapped in the affected region, unable to head back as they were cut off. Homes in Raini and Tapovan villages were also damaged. Rajinder Negi said that a large number of workers were migrants from Uttar Pradesh, Himachal Pradesh, Jammu and Kashmir, Bihar and Jharkhand.

He said that while NTPC had announced a compensation of Rs.20 lakh for the next of kin of those who died, the State government announced only Rs.4 lakh. “We have objected to the small amount as in 2013, Rs.5 lakh was given to each family for the Kedarnath tragedy,” he said.

In the 2013 cloudburst, the Rishi Ganga project was destroyed; the private contractor died in the disaster. But that project was restarted.

Rajinder Negi claimed that there were two different “wage rates” in the area, one that applied in State hydel projects and another applicable in Central government projects. He also said that the State rates were very bad and that workers were not given a tunnel allowance despite the risks. In Central projects, only the company staff who worked in the tunnels received the allowance; those employed by the contractor did not. “There is a lot of risk working in the tunnels. There are poisonous gases that are emitted sometimes but there is little protection for workers. We have demanded that there should be laws for workers’ protection in State hydel projects. In Himachal Pradesh, it was after a long struggle that workers in hydel projects were paid such allowances,” he said.

Also read: 'My fight was to save the Himalayas'

According to Rajinder Negi, local residents were not preferred for employment as much as people from outside the State. He said: “The locals will unionise, so people from outside the State are preferred. But now locals are also demanding that they be employed as they have lost their lands to the projects. Some are getting employed.” But the employment generated did not have any long-term benefits for the workers. It was an added irony that in the protected sanctuary, local residents were not allowed to pick wood from the forest areas but hydel projects were allowed. “It is a big question here,” he added.

The ironies do not end here. In February last year, the NITI Aayog commissioned a study to evaluate the far-reaching economic impacts of “green verdicts”. The objective of the study was ostensibly to sensitise the judiciary on the economic impact of judgments. While the outcome of the study is yet to be revealed, the practical impact of natural disasters such as the one witnessed in Uttarakhand on February 7 with huge human cost is there for all to see. The core of the problem is not the lack of domain knowledge of the topography but the disdain for human lives and the lackadaisical approach to ecological matters.