Lethal Flooding from Previously Flagged Glacial Lake Overwhelms Indian Communities

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A high-altitude glacial lake in India’s northeastern Himalayas, known as Lhonak Lake, breached its banks, resulting in the failure of a significant dam and unleashing devastating floods through various towns. State authorities, scientists, and environmental advocates had warned of the lake’s perilous nature years ahead of the catastrophe.

As reported on Friday, the deluge has resulted in at least 31 confirmed deaths and necessitated the evacuation of thousands of residents.

The flooding initiated in the early hours of Wednesday after Lhonak Lake overflowed due to an intense downpour. The waters surged into the Teesta-3 dam—Sikkim’s largest hydroelectric facility—fracturing its concrete structure and then inundating towns in the Lachan Valley, causing severe destruction to infrastructure and human life.

This event marks another fatal flooding incident for northeastern India, which has experienced a year characterized by extraordinary monsoon rains. In nearby Himachal Pradesh, flash floods and landslides claimed nearly 50 lives in August, while unprecedented rainfall in northern India resulted in over 100 fatalities in a span of two weeks in July.

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Built six years ago as part of India’s effort to expand its hydropower capabilities, the Teesta-3 dam had been the subject of controversy since its inception. Critics, including local activists, argued that the increasing extremities in weather due to climate change make dam construction in the Himalayas inherently risky. They further contended that the dam lacked sufficient safety precautions.

The Sikkim State Disaster Management Authority had, as early as 2019, categorized the lake confined by the dam as “highly vulnerable” to floods that could wreak havoc downstream, posing risks of flash floods capable of breaching dams.

No comments have been received from the dam’s operating agency or local entities tasked with dam safety, despite requests made on Friday.

Recent studies in 2021 indicated that Lhonak Lake has been experiencing rapid water level increases, primarily due to accelerated glacier melting attributed to climate change. The rising waters and the lake’s steep surrounding terrains have compounded the likelihood of catastrophic floods.

Costing $1.5 billion and taking nine years to complete, the Teesta 3 hydropower project had a capacity of 1,200 megawatts, sufficient to supply electricity to approximately 1.5 million homes in India. It became operational in 2017.

Authorities have been criticized for not implementing early warning systems, despite knowing the risk posed by overflowing glaciers. India’s National Disaster Management Agency announced plans on Friday to establish real-time alert systems at 56 known at-risk glacial lakes across the country.

Himanshu Thakkar of South Asian Network for Rivers, Dams and People asserted that the government failed to heed the lessons from a 2021 dam failure in Uttarakhand that led to 81 deaths, allowing a similar calamity to unfold.

Despite legislation passed in 2021 mandating emergency planning for dams, the Teesta-3 facility is not under safety surveillance by India’s principal dam regulator, the Central Water Commission.

In a statement, Gyatso Lepcha, General Secretary of Affected Citizens of Teesta, warned that similar disasters could occur with other dams and called for a comprehensive safety review of all dams in the state.

While the exact cause of Wednesday’s breach remains undetermined, experts cite the potential influences of intense local rainfall and a 6.2 magnitude earthquake in nearby Nepal.

Over 2,000 individuals have been rescued since Wednesday’s events, according to the Sikkim State Disaster Management Authority, which also reported the establishment of 26 relief camps to accommodate more than 22,000 displaced people.

Search and rescue operations are ongoing for nearly 100 missing individuals, including 22 soldiers, as per the Sikkim state government.

Despite the growing risks attributed to climate change, India’s federal government plans to increase the nation’s hydroelectric capacity by 50%, targeting 70,000 megawatts by 2030.

Floods and landslides are recurring phenomena in India’s Himalayan region during the monsoon season, with scientists indicating an increase in frequency due to global warming affecting glacial melts.

Last month, dam failures in Libya, triggered by Storm Daniel, caused extensive damage to the city of Derna.

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Reported by Arasu from Bengaluru, India.

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Frequently Asked Questions (FAQs) about Lhonak Lake flooding

More about Lhonak Lake flooding

• Sikkim State Disaster Management Authority 2019 Report
• National Disaster Management Agency’s Future Plans
• 2021 Study on Lhonak Lake Water Levels
• Indian Federal Dam Safety Law of 2021
• Teesta 3 Hydropower Project Overview
• Recent Flooding Events in India
• Climate Change Impact on Himalayan Region
• Extreme Weather and Dam Safety Concerns
• Affected Citizens of Teesta Organization Statement
• South Asian Network for Rivers, Dams and People Report