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How the Government Covered Up the Severity of Teesta Floods by Blaming Them on a ‘Cloudburst’

Himanshu Upadhyaya

In the early hours of October 4, hours before news broke of flash floods and a dam burst in Sikkim, social media users put out posts wondering what had happened. It was only much later in the day that news reports began trickling in that the severe floods had been triggered by a glacial lake outburst flood, known as a GLOF, in North Sikkim’s South Lhonak Lake.

The devastating flooding swept away the Teesta III dam around 62.35 kilometres ahead and damaged hydropower projects further downstream. The Teesta III dam is around half-a-kilometre downstream of the confluence of the rivers Lachen Chu and Lachung Chu near the village of Chungthang.

But for several hours on the day of the disaster, government media and disaster agencies continued to refer to the incident as a “cloudburst”, indicating a lack of clarity on what had actually happened. An analysis of publicly issued statements and posts shows that this confusion continued well until the next day, with the Sikkim chief minister’s office referring to the incident using terms such as “cloudburst-induced water surge”.

Such oversights raise questions about the monitoring lapses on the part of crucial government bodies such as the Central Water Commission as well as the National Disaster Management Authority. They also indicate a lack of coordination among government agencies as well as an established protocol to be followed in the event of catastrophes like a GLOF.

Warning signs and online posts

As early as 3.45 am that day, a few posts speculated that the Teesta dam had burst. Around 4.30 am, the Bharatiya Janata Party’s state spokesperson Kamal Adhikari warned of flash floods and said that the dam had burst. Tagging the prime minister and senior BJP leaders, Adhikari wrote that Sikkim was on high alert due to a cloudburst and the dam exploding. He added that people along the Teesta riverside, National Highway 10 and the towns of Rangpo and Singtam were being evacuated. “BJP head office filled with water,” he posted.

By 6 am, videos claiming to be from the downstream town of Rangpo and South Sikkim showing fast, heavy currents coursing through the Teesta river began circulating. Not knowing what had caused the flash floods, the posts conjectured that it had either been a cloudburst or a glacial lake outburst flood.

This confusion prevailed even at higher levels of the government, going by the communication issued. At 6.37am, Director of the Central Water Commission Sharad Chandra posted that there had been a lake outburst around midnight in Chungthang, North Sikkim, causing concerns in the catchment of the Teesta river. “Low lying areas such as Gazoldoba, Domohani, Bangladesh area may be affected,” he said.

But South Lhonak, where the GLOF occurred, is 49 km upstream aerially of Chungthang at an elevation of 5,200 metres. At Chungthang, the flooding triggered by the GLOF had swept away the Teesta III dam.

An alert journalist, Kamalesh Chowdhury from TV9 Bangla, sought more details from Chandra, asking: “Which lake? And why? Any primary hint?” The official handle of the Central Water Commission responded promptly saying, “Lhonak Lake, May be due to earthquake.”

Yet, the National Disaster Management Authority, in its alert issued at 6.30 am, said that a cloudburst was to blame for the floods: “Flooding of Teesta river basin has occurred due to cloudburst in the Northern part of Mangan district. All are advised to stay alert and avoid travel along the river basin.”

Lapses and oversights

Soon, academics and scholars in the field of geological studies and earth sciences began taking note of the incident. Rajeev Rajak, a doctoral scholar at Sikkim University’s Department of Earth Sciences, asked other researchers around 8am if anyone had access to recent satellite images.

Mauri Pelto, a veteran glaciologist from Nichols College in Massachusetts, United States, wrote back to Rajak with some images saying that the South Lhonak glacier, along with four others, had “significant moraine-dammed proglacial lakes”, which refers to dams formed by water accumulated from glaciers. Pelto wrote that a “GLOF was not necessary to cause this level of flooding” but it was too cloudy for images.

At 8.55 am, the official X handle of All India Radio, Regional News Unit at Guwahati, reported that there had been a “sudden cloudburst at Lhonak Lake in North Sikkim” and that a flash flood had occurred in the Teesta River in Lachen valley. Attributing information to “defence sources”, it said that some army establishments along the valley were affected and that efforts were on to confirm details. “Release of water from the Chungthang dam led to a sudden increase in water level up to 15-20 feet high downstream,” it said. “This has led to Army vehicles parked at Bardang near Singtam getting affected. 23 personnel have been reported missing.”

Though the GLOF occurred around midnight, government disaster and media agencies continued to put out incorrect and contradictory information about the incident for hours. Referring to the disaster as “release of water from Chungthang dam” plays down its severity and conceals factual details that the Teesta III dam was completely washed away that increased the severity of the flash floods, turning a natural disaster into a manmade one.

At 10.08 am, the New Delhi-based think tank, South Asia Network on Dams Rivers and People, tried to bring some anomalies to the attention of Chandra, the Central Water Commission director. The think tank pointed out that the Teesta river in Sikkim was in “extreme flood” but the Central Water Commission’s official websites put up posts about water inflow hours after safety levels had already been breached. But there was never a reply. Now, the think tank has put out a detailed report analysing how the Central Water Commission’s flood monitoring and forecasting system had failed.

On the day of the disaster, the Central Water Commission’s Flood Forecast handle put out its first alert at 11 am on October 4 warning of an “extreme flood situation” due to the Teesta river at Melli in South Sikkim district. Minutes later, it put up another post with details of the water level at Khanitar in East District of Sikkim.

But by then, the flash floods had already caused devastation in these areas and the floodwaters had reached downstream towns in northern Bengal, beyond the Sikkim-West Bengal border. Residents along the Teesta river bank further downstream had to be moved to higher ground. Referring to the incident as a “flash flood” is misleading as it conceals the devastation that was compounded due to the dam being swept away.

By midday, images of the destroyed dam had begun circulating on social media and messaging platforms. Sikkim Express had reported by then that the Teesta III hydropower dam was in “dire condition” following the flash floods in the Teesta river. “The dam has been completely damaged, with a substantial portion of it being washed away by the flood,” it said. Across social media, video clips were circulating of the surging floodwaters and damaged portions of National Highway 10.

Himalayas at risk

By afternoon that day, glaciology and mountain hazards specialist Ashim Sattar asked on X if the flash floods in Teesta River basin had been triggered by a cloudburst or GLOF. Sattar posted links to two studies, which he was a part of, highlighting that the Teesta III hydropower dam at Chungthang was at a high risk of GLOF. Glaciologist Pelto responded soon after pointing out that there are several proglacial lakes in the basin with South Lhonak being the largest. “Middle Lhonak, Changsang, E.Langpo and Jongsang being younger as well,” wrote Pelto.

Around this time, the Indian Space Research Organisation issued its satellite image-based study of South Lhonak Lake. Its analysis clearly shows how the size of the glacial lake had increased between September 11 and 28 – from approximately 162.7 hectares to 167.4 hectares. This points to a possible lapse or oversight in the monthly monitoring of South Lhonak Lake by the Central Water Commission.

The Indian Space Research Ogranisation’s analysis does not explicitly state that the size of the lake had increased. It merely points out that in the October 4 image obtained from its satellite at 6am, “The Lake is Burst and about 105 Hectares area has been drained out (28 September 2023 image versus 04 October 2023) which might have created a flash flood downstream”.

At 10pm that day, the National Disaster Management Authority finally issued a press release stating that the sudden surge in the Teesta river appeared to have been a “likely combination of excess rainfall a GLOF” in South Lhonak Lake. It said the Central Water Commission’s monitoring stations revealed that the first surge of water was 19 metres above the maximum level at Sangkalang at 1.30 am and four metres above the maximum water level at Melli at 4 am.

If the Central Water Commission was aware of a sudden surge in the Teesta River, it is not clear why it took so long to issue clear information about the incident. It also raises worrying questions about the lack of preparedness or foresight to deal with disasters of such kind.

For years now, several scientific studies and assessments have warned that the Himalayas are at risk of GLOFs, yet, little has been done to prepare for such disasters. In fact, only in February 2021, a glacier collapse in Chamoli district of Uttarakhand had triggered flash floods that killed an estimated 150-200 people and damaged a hydropower project. Increasingly warm global temperatures and erratic weather and rainfall are speeding up the melting of glaciers across the Himalayas.

The disaster in Sikkim is only the latest in a string of related incidents. But it must serve as an urgent reminder at all levels of the state and Central governments that the fragile condition of the Himalayas as the effects of climate change escalate will pose a continued and imminent danger to residents of India’s hill states.

(Himanshu Upadhyaya is faculty member at Azim Premji University, Bengaluru. Opinions are that of the author and are not endorsed by and do not reflect the views of Azim Premji University. Courtesy: Scroll.in.)

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‘Ticking Time Bombs’: Sikkim Floods a Reminder of Why Locals Opposed Dams in the Himalayas for Years

Vaishnavi Rathore

In the early hours of October 4, a flash flood ravaged North Sikkim. The hurling waters washed away Sikkim’s largest hydropower project, the 1,200-MW Teesta III, escalating the damage downstream in districts of Gangtok, Namchi, and Pakyong. Thirty-three people have died and 105 are missing, according to the latest update by Sikkim state disaster management authority on the evening of October 8.

The Sikkim chief minister’s office has called the disaster an “unexpected natural calamity”. The National Disaster Management Authority said the sudden surge was the combined effect of excess rainfall and a glacial lake outburst flood, or GLOF, at the South Lhonak glacial lake. GLOFs can occur when lakes formed due to melting glaciers breach their capacities, either due to sudden heavy rainfall or their natural embankments giving way after landslides or earthquakes.

Sikkim nests 694 glacial lakes. South Lhonak, situated at 5,200 metres above sea level, is one of the 21 lakes identified by a 2021 scientific study as “potentially dangerous with a high outburst probability”.

But local activists and environmental experts point out that the damage caused by the glacial lake outburst flood was compounded by the presence of a string of dams in the Teesta river basin. The flood emanating from the lake destroyed the structures of three dams downstream, unleashing the water stored in their reservoirs, exacerbating flooding and damage.

Activists say they had warned the authorities that building dams in an earthquake-prone region like Sikkim was dangerous. A 2020 report by the National Disaster Management Authority, while comparing potentially critical lakes in the Himalayan region, had noted that the “threat to hydropower is the highest in Sikkim”. Specifically, the government knew the dams built on the Teesta river were under threat from the South Lhonak lake.

“We had been raising our voices for a long time against building a series of dams along the Teesta,” Mayalmit Lepcha, a member of the Affected Citizens of Teesta, a local advocacy group, and resident of Dzongu, told Scroll. “Teesta III had already stored tonnes of the water in its reservoir, so when the flash flood occurred, it came down with much more intense force.”

An official from the Central Water Commision conceded that the dams had intensified the damage in this instance. “If there is a series of dams, a cascading effect happens downstreams in flash flood scenarios,” he told Scroll.

Officials Scroll spoke to emphasised the need for more effective monitoring of glacial lakes to prevent future disasters. But environmental experts said the lessons go much deeper. “We know that the Himalayan region has tectonic activity. We know that the rivers here also carry huge amounts of silt. We know Himalayan region has historically had many cloud bursts,” said Amitangshu Acharya, a lecturer at the Netherlands-based IHE Delft, an institute for water education, who has spent four years working on water governance in Sikkim.

The government is aware of these uncertainties, said Acharya. “Why have we constructed dams which are essentially mine fields on the river bed?” he said. “These are ticking time bombs.”

Why dams made it worse

Sikkim currently has five existing hydropower projects along the Teesta basin, 15 that are upcoming and 27 more in the pipeline. Of these, at least three suffered damage in the October 4 flooding, said the Union Ministry of Power. The Teesta phase III project, commissioned in 2017, was the first to bear the brunt of the floods and was washed away. Downstream lay the Teesta V, whose bridges and power station were submerged. The floodwaters then barrelled down to the 50 MW Teesta VI, which was under construction, sweeping away bridges and a powerhouse while two cranes are missing.

Teesta III was a run-of-the-river project, which diverts the river flow from a high point to use the kinetic energy for turning turbines instead of creating a reservoir. But the dam still had a reservoir capacity of 5.08 million cubic metres.

“The dam already had water in its reservoir, and when the lake burst, silt and debris came along the water, and the dam could not hold [the water],” said Vimal Khawas, professor at Jawaharlal Nehru University’s Special Centre for the Study of Northeast India. Khawas has worked on hydropower and disasters in the eastern Himalayas and taught previously at Sikkim University.

Infrastructure like dams act as barriers, whereas earlier, the pathway for the floods to go through the valley used to be clear, said Khawas. Apart from the series of dams, people have also settled along the river beds further obstructing the flow of water, he said.

Sikkim has witnessed GLOFs earlier as well, but the damage was limited, he said. According to Khawas, hydropower has “definitely played a role in maximising the disaster”. “We may call the GLOF and cloudburst natural, but the disaster that has happened after the breaking of the dam is entirely human made,” said Khawas.

Lepcha of the Affected Citizens of Teesta said that they had raised environmental and cultural concerns – the Teesta river has cultural significance for the Lepcha community – while opposing the dam in the Sikkim High Court. But the court in 2010 dismissed the matter while noting that project authorities had undertaken requisite action such as conducting an environmental impact assessment and obtaining forest clearance.

Red flags ignored

Between 2003 and 2021, there have been several efforts to collate information about glacial lakes in Sikkim. In all such inventories, South Lhonak was identified as a glacial lake at risk of outburst.

One reason was its fast rate of growth. Due to the melting glacier, the area of the lake increased by almost six times from 17 hectares in 1977 to 99 hectares in 2008. “[The] last time we saw the glacier in September this year, it was 165 hectares,” said Tashi Chopel, the district collector of Pakyong district.

Rising global temperatures have caused increased glacial melt in the Himalayas. Between 1960 and 2000, estimates based on satellite imaging show that the Himalayas lost 13% of their glacier area and are extremely vulnerable to climate change.

The danger of an outburst at the South Lhonak lake damaging hydropower projects had been flagged at a 2021 meeting of the standing committee on water resources. There, a representative of the Centre’s Department of Water Resources, River Development and Ganga Rejuvenation, observed that glacial lakes “have created problems for all the hydel projects which were being constructed in the upper region” of the Himalayas.

The Central Water Commission official confirmed that project developers are well aware of such lakes in their catchment area and it is unlikely that they were caught off guard by events like these. The official, who did not wish to be identified, said that developers calculate the effect such glacial lakes could have and accommodate for possible damages. It is based on this awareness that they design the dam, he added.

But, in its environmental impact assessments for the dam, Teesta Urja Ltd, a state government enterprise that was later named Sikkim Urja Ltd, did not include these risks. In 2006, the Affected Citizens of Teesta had filed an appeal in the National Environment Appellate Authority, the body that preceded the National Green Tribunal. The petitioners had argued that the environmental impact report for Teesta III did not include any environmental risk assessment, like earthquakes and GLOFs, despite the project being based in the Eastern Himalayas that are “prone to several environmental risks”.

“We had been raising the issue of melting glaciers at a high speed and that they might burst,” Lepcha said, who has been a part of the opposition to hydropower development in the region for the last 17 years. “We had said that if that happens, with the series of dams built in Teesta, it will create havoc.”

Now, unfortunately, that has happened, said Lepcha.

Previously, the Teesta III hydroproject had also suffered damage due to an earthquake measuring 6.9 on the Richter scale in September 2011. The quake had triggered 1,196 new landslides, Indian Space Research Organisation scientists found in a 2015 scientific study . Using pre-and post-earthquake satellite images, the scientists found that the landslides had severely affected several roads and hydro projects in the region. Apart from resulting in the deaths of 16 workers, the earthquake had also caused severe damage to official buildings, workers’ colonies, tents and approach roads of Teesta Phase III hydro project.

“The developers then knew that they were making the dam in a seismologically active zone, and what damages it could cause, yet they continued,” said Lepcha. “Today, the costs are borne by us, the indigenous communities living here.”

Scroll telephoned the office of Sikkim Urja Ltd multiple times but officials were not available for comment.

Despite these risk factors, Acharya pointed out that dams are a profitable business, spurring heavy construction in the region. “Dams are basically sponges for private capital,” he said. “The long gestation period of dams allows private investors to incur long term investments with high returns,” said Acharya. “That explains the number of dams, not our development needs.”

Gaps in glacial lake monitoring

Research also shows that despite several reports highlighting the risks of GLOFs in Sikkim, not enough was being done to monitor the situation.

The first glacial lake inventory of the Himalayan region showed that there were more than 2,000 such lakes that spanned more than 10 hectares. But, a 2017 report by the Comptroller and Auditor noted that since 2011, only 477 of these were being monitored, as pointed out by Himanshu Upadhyay, a professor at Bengaluru-based Azim Premji University.

Sikkim’s South Lhonak lake was on the radar since 2016, when a sensor to monitor water level and pipes were installed to facilitate siphoning, or removing of excess water. In September this year, Pakyong’s district collector Chopel had been part of a multi-disciplinary team that surveyed the South Lhonak lake.

The team included officials from the National Disaster Management Authority, the Sikkim State Disaster Management Authority, the Indian Space Research Organisation, the Geological Survey of India, the Swiss Agency for Development and Cooperation and others.

“They had put an all weather station, and in the next phase they were going to put an early warning system,” said Chopel. “Unfortunately, the lake burst before that.” He admitted that while the siphoning was ongoing, it was not effective enough to prevent the sudden disaster.

Since much of the monitoring is done through satellite imagery, only spatial monitoring, which checks the size of the lake, is possible. “For now, we do not have the technology to do real time monitoring,” said the Central Water Commission official.

He said that the monitoring of this data is done on a monthly basis and it is then shared with “all concerned authorities”, such as the National Disaster Management Authority and state authorities. On keeping dam officials in the loop, the official said that it is arbitrary, depending on “if we have their contacts”, and that information is largely sent to state authorities that take further action.

Those familiar with the region’s geography say merely raising questions about the lapses in dam and water governance isn’t enough. Official admissions of inadequate monitoring with the promise to improve such factors gives the “sense that they are doing something about it”, said Acharya. “But what we really need to ask is why we have so many dams along the Teesta.”

(Vaishnavi is a climate and land reporter with Scroll.in. Prior to that, between 2019 and 2022 she worked as an environment lead with The Bastion, a development journalism portal based in India. Courtesy: Scroll.in.)