When officials took count of the devastation, as many as 42 people had been killed in the Teesta basin, and 77 missing and presumed dead. Thousands had been displaced. Those who escaped did so with just the clothes they were wearing; they had no time to salvage anything else.
The hydropower dam over the Teesta was destroyed and the associated 1,200MW Teesta-III hydropower project submerged by the swirling waters in the disaster that rekindled an old debate: how safe are India’s dams?
Experts blamed what they call a Glacial Lake Outburst Flood, or GLOF, in the South Lhonak lake, for the disaster.
Glacial lakes sit atop or below a melting glacier and as they grow larger, they become more perilous. They are blocked by ice or sediment of rock and debris, and if the boundary breaks, waters surge down the mountains, flooding downstream areas. This phenomenon is known as GLOF.
It’s not as if the authorities had been caught totally unawares. As far back as 2015, glaciologist Anil Kulkarni had warned the Sikkim government about the formation of a lake in the South Lhonak glacier, which had been melting rapidly, and suggested that an early warning system be put in place to avert a disaster.
Kulkarni, a scientist at the Divecha Centre for Climate Change in Bengaluru-based Indian Institute of Science, was co-author of a paper that highlighted high risk posed to many settlements along Chungthang valley because of the construction of a hydropower dam over the Teesta river.
“The state government officials were part of this investigation and attempts were made to take some action to prevent a disaster. An early warning system was also installed,” Kulkarni said.
Obviously, this early warning system did not work on the night of 3-4 October.
A statement by the National Disaster Management Authority (NDMA) said excess rainfall, besides the GLOF, triggered the disaster. Sikkim has 10% or 750 of the country’s glacial lakes and 25 have been assessed to be at risk of GLOF.
The NDMA statement spoke of making assessments at two such lakes in September this year to develop an early warning system.
Debate on dams
Let’s delve deeper into the issue of dam safety.
Much of the 1980s and 1990s had been consumed by protests over the Russian (Soviet)-aided Tehri dam in Himalayas where some experts warned that an earthquake with the force of 10,000 Hiroshima-size atom bombs was waiting to strike, and the Sardar Sarovar dam in Gujarat.
The Sardar Sarovar dam, a part of the Narmada Valley project, became a centre of controversy because it meant displacing 100,000 tribespeople and peasants, sharecroppers and landless labourers from their ancestral lands.
India is the third most dammed country in the world, with 6,138 large dams in all. Any dam higher than 15 metres from its deepest foundation level is classified as a large dam. If it has very large storage, even a 10-metre high dam is called large.
But despite so many large dams, India has a rather poor record of dam safety. The country has a staggeringly large number of ageing dams and never has it decommissioned one so far.
An overwhelming 80% of India’s large dams are over 25 years old and 234 are over 100 years old, according to the latest data shared in a presentation by the ministry of jal shakti.
How are the 234 century-old dams kept safe? Are they safe in the first place? Some are over 500 years old!
Cumbhum in Andhra Pradesh was built in 1500, making it the oldest in the country at about 523 years. The two dams in Rajasthan, Swaroop Sagar and Udai Sagar, were also built in the 16th century (1560 and 1585, respectively). The dam in Dhamapur (Maharashtra) is 423 years old; dams on Magarpur and Pachwara Lake (Uttar Pradesh) are of 1694 vintage.
There had been 42 dam failures in India till September this year, according to a presentation by S.K. Sibal, chairman of the National Dam Safety Authority (NDSA). The failure of the Machchu dam in Gujarat in 1979 was the worst, in which 2,000 people perished.
According to the South Asia Network of Dams, Rivers and People (SANDRP), an informal network of organizations and individuals working on issues related to the water sector, the Bharudpura dam on Karam river, a tributary of the Narmada in Madhya Pradesh, faced a disaster after the dam was filled with water for the first time in August 2022—erosion of the dam wall was reported.
And there have been multiple dam failures and dam- induced floods in Madhya Pradesh, Tamil Nadu and Kerala. The Hirakud-induced floods in Mahanadi basin have affected several villages in Odisha and Chhattisgarh. There have also been several instances of unscientific operation of dams.
Not just older dams, most failures have actually involved “newly built dams, chiefly in the first 10 years,” according to NDSA’s Sibal.
The Chungthang dam was commissioned only in 2017. So, it wasn’t age that was responsible for its collapse.
The question is what can India do about the problem?
Anil Kulkarni said that not just South Lhonak, Himalayan glaciers in general have been receding and strict monitoring of lakes in states like Himachal Pradesh and Sikkim was necessary.
Should hydropower projects be located in the fragile Himalayan region at all?
“I have been recommending climate assessments in addition to environment impact assessments for such projects. I have said construction of hydropower stations in the Himalayan region should be avoided but if unavoidable, then GLOF assessment should be done beforehand and mitigation measures should be built into the project,” Kulkarni said.
Most often, this advice has been ignored because it entails costs, he added.
Mohammed Farooq Azam, glaciology expert and associate professor at Indian Institute of Technology- Indore, said that for GLOF hazards, the government should maintain “an updated inventory of all lakes.”
Azam warned that existing lakes are growing larger “and also new lakes are developing as glaciers are receding, leaving depressions which are filled with meltwater, leading to formation of new lakes or lake growth. The inventory of glacier lakes should be updated every five years so that we can estimate the water volumes in these lakes.”
Now, perhaps a little wiser after the north Sikkim disaster, the government may lend an ear to the glaciologists’ renewed entreaties for detailed climate impact studies and declaring a mountain regulation zone, on the lines of a coastal regulation zone, where large infrastructure projects would be regulated.
Kulkarni says the ministry of earth sciences was in the process of forming a committee to conduct a study of the climate impact of large infrastructure projects in the Himalayan region.
Should India build more dams, whether for generating hydro power or for other needs?
Azam says India is producing around 25,000MW energy from the dams on the Himalayan rivers alone, which is around 65% of the total hydropower potential of these rivers.
It will not be easy to find an alternative to damming the Himalayan rivers for securing India’s energy needs. Dams are also needed for irrigation and other water security purposes.
So alongside evaluating the climate impact of building new dams in ecologically sensitive areas like the Himalayan region, a critical component of dam safety has to be in-built special operating procedures in dam design that take care of eventualities like flash floods.
Disasters and ageing dams notwithstanding, India has no mechanism in place to assess the viable lifespan and performance of dams.
In response to a query from members of parliament during a meeting of the parliamentary standing committee on water resources, the Jal Shakti ministry said in March this year: “Dams in India are normally designed for approximately 100 years of useful age. The functional life of the dams decreases with progressive reservoir sedimentation concurrently reducing project benefits. There is no mechanism to assess the viable lifespan and performance of dams.”
The ministry also said no information/recommendation from the dam owners has been submitted for decommissioning of any of their dams.
In fact, Sibal of CWC laid the entire onus of ensuring safety of India’s dams on the state governments, public sector undertakings and private agencies.
A Jal Shakti ministry spokesperson referred to DRIP II and DRIP III schemes, which have been devised to enhance dam safety oversight. DRIP is an acronym for Dam Rehabilitation and Improvement Project. The Cabinet Committee on Economic Affairs approved DRIP II and DRIP III in October 2020.
DRIP aims to fully ‘rehabilitate’ 736 dams in 19 states by 2031. Rehabilitation includes treatment for reduction of seepage through masonry, improvement in dam drainage; treatment for cracking in the dam, improvement in the ability to withstand higher floods, etc.
Another senior ministry official said that dam safety was “close to the Prime Minister’s heart” and that after decades of inaction, the Narendra Modi government had brought in a comprehensive Dam Safety Act.
The Dam Safety Act of 2021 became effective from 30 December that year. According to an official statement, the Act provides a comprehensive framework for proper surveillance, inspection, operation and maintenance of all the large dams. The Act also provides for an empowered institutional framework for dam safety, both at the level of Centre and States and will help in standardizing dam safety practices across the country.
The official declined to provide any further details of the steps taken to make India’s large dams safe.
The parliamentary standing committee has noted that some of the dams were over 300 years old and despite the Jal Shakti ministry acknowledging that the lifespan of a dam is 100 years, none of the older dams had been decommissioned till date. The panel gave a three-month deadline to the ministry to apprise it of steps taken to nudge state governments to decommission dams that have outlived their lifespans and may pose severe threat to life and infrastructure.
Hot button issue
In any case, decommissioning of dams remains a controversial issue in India, points out Ranjan Panda, a water activist and convenor at Combat Climate Change Network, India.
“For one, India’s water policy is dominated by civil engineers who feel their work can pass the test of time. Policymaking does not involve stakeholders from diverse backgrounds, unlike in the US or Europe,” he said.
Then, there are powerful socio-economic concerns that prevent dam decommissioning.
“Dams create a new economy around them. Colonies develop around dams, making it very difficult for a country like India to shift ecosystems around dams to new sites. Mullaperiyar (Kerala) and Hirakud (Odisha) dams are examples,” Panda said.
In any case, decommissioning of dams is a time-consuming and laborious process. First, the government needs to conduct socio-economic and ecological impact studies and then earmark rehabilitation areas for the displaced people. Next comes a strategy for building an alternative water resource to offer livelihoods to the displaced population.
And nature has its own way of evening out things.
“The government has never decommissioned a dam in India but nature has. The GLOF event at the Chungthang dam over the Teesta has effectively meant that this dam has been decommissioned,” said Himanshu Thakkar, coordinator of SANDRP.