This monsoon, North Bengal is paying the price for last year’s Sikkim floods

In October last year, when a breach in the South Lhonak glacial lake in Sikkim swept away a hydropower project on the river Teesta, the effects were felt downstream in West Bengal’s Kalimpong district.

Nawang Doma Bhutia, whose home in Melli, Kalimpong, overlooks the Teesta, felt lucky to have survived.

The 45-year-old remembers several homes being washed away as debris from a broken dam, silt and water barrelled down because of the glacial outburst lake flood, or GLOF, on October 4, 2023.

A few days after the floods had subsided, Bhutia and other residents in this area on the border of West Bengal and Sikkin noticed something alarming – the riverbed had risen. “Earlier, the river used to flow about 20-25 feet below our house. But it had clearly gone up after the flood.”

Activists, district administration officials and residents attribute the rise to deposits from last year’s massive floods.

“The amount of debris which was brought down by the GLOF was phenomenal,” Praful Rao of Save The Hills, a Kalimpong-based non-governmental organisation, told Scroll.

The flood had broken the Chungthang dam or the Teesta Phase III hydropower project, 60 km from Melli, as well as several bridges and a power station. “Besides trees, trunks and branches, the heavier debris which we cannot see now would also include metal from the many bridges swept away, vehicles, boulders and parts of homes, which must be buried deeper in the sand.”

This year, as the monsoon brought heavy rains and triggered landslides in northern Sikkim, Bhutia and other residents were put at greater risk.

“For eight months now, we have been living in fear, watching the river level go up,” said Bhutia. “But since June 13, we have not been able to sleep because with the rains in Sikkim, the water can enter our houses anytime,” Bhutia told Scroll.

The water did enter her neighbour Arshad Mansuri’s 70-year-old home on June 19. Ansari and his family members were shifted out of his home into a relief camp, along with 70 other families, officials in the district administration said.

“The rise of the riverbed is abnormal and unprecedented, and very concerning for us,” Krishnendu Bhowmick, chief engineer of the North East Division of West Bengal’s irrigation department, told Scroll.

A lake bursts, a river bed rises

When lakes formed from glacial melt overflow, either due to sudden heavy rainfall or damage to its embankments because of landslides or earthquakes, the effects can be dangerous.

The GLOF disaster in Sikkim, which killed 179 people, was worsened by the presence of a network of dams in the Teesta basin, many of which were wrecked by the surging waters from the lake.

“It deposited huge amounts of sand, silt, gravel, boulders into the Kalimpong catchment,” said Vimal Khawas, professor at Jawaharlal Nehru University and a researcher on hydropower in the eastern Himalayas. “Because of this silt accumulation, the riverbed has risen by 15 to 20 feet.”

Activists, officials and residents Scroll spoke to pointed out that the increase in elevation is most evident in a 40-km stretch of Teesta, beginning from Rangpo, where the river enters Bengal from Sikkim.

This includes the hilly settlements of Rangpo, Melli, Teesta Bazaar and 29th Mile, which are located along National Highway 10. Around 6,000 people live and work in the area, said local residents and government officials.

Kalimpong district magistrate Balasubramanian T told Scroll: “We estimate that the riverbed has increased by 10 feet at places like Teesta Bazaar, Melli and 29th Mile because of siltation caused by the wreckage of the Chungthang dam.”

Already flowing at high levels, the river has swollen even more from the heavy rain in Sikkim in the last few weeks, said Khawas. Between June 13 and June 19, Sikkim received 230 mm of rain, 93% more than the normal, according to data from the India Meteorological Department.

The volume of water has gone up in the river and is threatening to enter hundreds of houses. “All these habitats, located along the national highway and the river, are all either totally or partially underwater,” Khawas said.

The Teesta Bazaar area, for instance, was completely submerged, and several families had to be moved to relief camps.

Kalimpong was nearly cut off from Darjeeling for several days, as the road connecting the two cities of North Bengal via Teesta Bazar went under water. “The water level of the river was 25 feet below the road before the October flood,” said Yowan Thapa, a 47-year-old resident of Teesta Bazaar. “But now the waters of the river have reached the road.”

District magistrate Balasubramanian admitted that houses are at risk in the area and the highway unsafe to travel because of cracks and erosion of National Highway 10. “The 40-km stretch along the river is a major challenge and we are addressing it,” he said. “Cracks have developed on the highway at different points.”

However, he denied that there has been extensive damage from this year’s rains so far.

Apart from the hilly areas, large amounts of sludge and debris have also been deposited at the point where the Teesta river enters the plains of North Bengal in Sevoke. “Low-lying areas here are getting frequently inundated,” said Bhowmick, the chief engineer.

The effect on dams

The rising river bed also has implications for the network of five hydropower projects on the Teesta basin in Sikkim run by the National Hydroelectric Power Corporation.

At least two of those projects in Kalimpong – Teesta Low Dam III and Teesta Low Dam IV – could not operate for a few months after the GLOF last year, experts said.

“When the river came down from Sikkim to West Bengal and entered Teesta Low Dam III, most of the debris got deposited in that reservoir,” Himanshu Thakkar, who is the coordinator of the South Asia Network on Dams, Rivers and People.

As a result, even before the monsoon arrived, the water level of Teesta was alarming, he said. “It had climbed close to the road. So, all the signs were very much there,” Thakkar said.

The administration and NHPC authorities should have opened the dam gates so that the debris could have flown further downstream, Thakkar said. “And where it cannot flow down, the NHPC should have dredged the reservoir,” he said. “That would have helped reduce the accumulated silt and the water level. They obviously didn’t do that, and that's why there is a much higher water level upstream from the dam.”

Chief engineer Bhowmick said the Jalpaiguri irrigation department is carrying out a morphology study of the Teesta river following the disaster in Sikkim in the Laltong Basti and Chumuk Dangi areas – further downstream of Melli and Teesta Bazaar – to assess how much the riverbed has changed. The report is expected to come by next month. “We are thinking of dredging the river but we haven’t decided yet,” he said.

Poor disaster management

Both Bhutia and Mansuri told Scroll that it is the first time in living memory that the Teesta river has come so close. “Hundreds of households are displaced and the state government is nowhere to be found,” said Mansuri.

The residents of Kalimpong blame the tardiness of the local administration for their plight. Several pointed out that the West Bengal government did not even declare last year’s flood in Kalimpong as a disaster and continue to be lax about helping those affected.

Arjun Chetry, a panchayat member of Melli, said that homes of about 70 families were washed away last year on October 4. “The Bengal government has given only Rs 75,000 per family,” Chetry said.

In contrast, the Sikkim government disbursed cheques of Rs 1 lakh each from the Chief Minister’s Relief Fund to those whose houses were damaged in the flash flood. It also announced two housing schemes for those who lost their homes in the disaster.

Residents complained that the disaster management of Teesta basin in Kalimpong left a lot to be desired.

According to Praful Rao, in November, residents had written to the Centre asking for a team of experts to study the behavior of the river as it was flowing close to the national highway. “After five months, the monsoons have come and nothing has been done,” Rao said. “It is a pity that we wasted a lot of time.”

Khawas, too, alleged that policymakers and local politicians have ignored the problem. The Gorkhaland Territorial Administration, a semi-autonomous council which included the districts of Darjeeling and Kalimpong, has little expertise in disaster management, he added.

Long-term effects

Experts pointed out that the rise in the riverbed poses several risks in the future.

Rao feared that the populated areas of Kalimpong would continue to get flooded whenever it rains, with the river flowing at a higher level.

“The rise in the riverbed will also threaten livelihoods as the Teesta river bank is a source of income for many,” said Khawas.

From eco-tourism to rafting to fishing to low-intensity sand mining, many families depend on the access to the river and its banks to earn a living. “All these will be affected as the river banks are now under water,” said Khawas.

He suggested that the authorities should draw up a plan for the complete relocation of all habitations in a 200-300 metre stretch from Rangpo to Sevoke as a “disaster risk reduction exercise”. “This would be the only permanent solution to ensure human security in the area,” he said.

Several residents, such as Bhutia, complained that they are paying the price for the “development in the name of dams” in Sikkim. Mansuri added: “The water would not come down with this intensity before the dams were constructed. Even fishes in this part of the river have died after the dams were built. If the government does not give this attention, the highway will not last too.”

Activists and experts pushed for coordinated action from Sikkim, West Bengal and the Gorkhaland Territorial Administration.

“This is a Teesta valley disaster not a Sikkim disaster,” Rao said. “A comprehensive solution has to be found for the entire basin, rather than sections of the valley, and that too based on political allegiances.”

Khawas added: “The construction of dams and railway tunnels in Sikkim needs to be seriously evaluated for the overall safety of the Teesta basin, including Bangladesh.”