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Context

On January 27, 2025, an expert committee constituted by the Ministry of Environment, Forests and Climate Change recommended a proposal to rebuild the Teesta-3 dam on the Teesta river in Sikkim.

About Teesta-III Chungthang hydroelectric dam

Original 1,200 MW Teesta-III Chungthang hydroelectric dam was destroyed in a flash flood, triggered by a Glacial Lake Outburst Flood (GLOF) from the South Lhonak Lake, which washed away the 60-metre-tall concrete dam, claiming around 100 lives.

Failure of Dam & Global warming

• Reducing albedo
• Accelerating melting of ice - Global warming and rise in the global average temperature accelerates the melting of ice and glaciers, this leads to the rise in the water levels.
• High rate of glacial retreat
• Rise in glacial lakes - As per the Central Water commission, the number of glacial lakes in Himalayan region grew by 10.8% from 2011 to 2024.
• Black Carbon Deposition
• Unstable Geological Formations

Concerns

• Insufficient Model for Capturing the GLOF Dynamics
• Risk Assessment Limitations
• Seismic and Landslide Risks
• Flawed Clearance Process
• Unpredictable Disaster Patterns
• Potential for Greater Destruction
• Erosion and Sediment Transport
• Engineering Limitations
• Flaws: IIT Bhubaneswar, IISc Bangalore, and ITBP studies highlight flaws in GLOF modeling.
• Challenges in Climate Predictions: Climate models struggle to predict extreme rainfall accurately.
• Limitations of Engineering Solutions: US experts argue, “Engineering cannot solve climate change; retreat is inevitable.”
• Need for Risk-Focused Decision-Making: Priority should be risk mitigation, not just economic viability.

Suggested Measures: 

• Development and implementation of a robust Early Warning System (EWS) for flood alerts in the river catchment.
• Construction of concrete gravity dam, a design that relies on its own weight to bear loads.
• Shifting Focus: Shift focus to small-scale hydro projects with less risk.
• Strengthen Early Warning Systems: Improve early warning and monitoring systems.
• River Basin Management: Implement effective river basin management.
• Disaster-resilient infrastructure: Build disaster-resilient infrastructure.
• Risk Assessment: Develop a clear risk assessment framework with safety thresholds.
• Conduct thorough environmental impact assessments (EIA)

About South Lhonka Lake

• A glacial lake in North Sikkim.
• Formed due to the retreat of Lhonak Glacier.
• The National Remote Sensing Center showed a 40% increase in its size over the past three decades.

About Teesta River

• Originates from the Tso Lhamo (lake) in North Sikkim.
• Flows through Sikkim and West Bengal in India then enters Bangladesh & merges with Brahmaputra river (known as Jamuna in Bangladesh).
• The total length is 414 km. 
• Tributaries are Ranget, Lachung, Lachen and Dikchu rivers.
• Hydropower project: Teesta-III, Teesta-IV and Teesta-V dams in Sikkim.
• Teesta water sharing treaty with Bangladesh has been pending between the two countries for over a decade.

• The decision to rebuild the Teesta-3 dam highlights the complex intersection of energy needs, environmental risks, and socio-economic considerations.
• While the project promises renewable energy and economic benefits, its location in a geologically unstable, climate-sensitive region raises serious concerns.
• As climate change continues to amplify risks, infrastructure planning must evolve beyond commercial viability to prioritize resilience, risk reduction, and sustainability.
  

Sources:

THE HINDU