January 28, 2025
Introduction:
The Teesta-3 dam in Sikkim, which suffered catastrophic damage from a glacier lake outburst flood, is set for reconstruction. The flood resulted in loss of life and destruction of infrastructure. An expert committee from the Environment Ministry has proposed a new design that aims to enhance safety and operational efficiency. This new structure will be entirely concrete and will feature a spillway capable of managing higher water flow.
Background of the Disaster
- In October 2024, a glacier lake outburst flood (GLOF) led to the failure of the Teesta-3 dam.
- This incident caused extensive flooding and resulted in the deaths of at least 100 people.
- The flood was exacerbated by the inability to open the dam’s floodgates in time.
- The previous dam structure, a combination of rock and concrete, failed under the pressure of the flood.
New Design and Features
- The proposed new dam will be fully constructed from concrete.
- This change is intended to improve structural integrity.
- The new spillway will handle a peak flow of 19,946 cubic metres per second, three times the capacity of the old dam.
- This design modification aims to prevent future overtopping incidents.
Early Warning System Implementation
A key recommendation from the expert committee is the installation of an early warning system in the dam’s upper catchment area. This system will enable timely opening of the dam gates in the event of a flood. The aim is to provide sufficient warning to evacuate personnel and mitigate potential damage.
Financial Considerations
- The estimated cost for reconstructing the dam is ₹4,189 crore.
- This is in addition to the original project cost of ₹13,965 crore established in 2017.
- The financial implications of the new design will be carefully assessed against the expected benefits of increased safety and operational reliability.
Restoration Timeline
Most of the dam’s infrastructure, apart from the dam itself, remains largely intact. The underground powerhouse and electro-mechanical equipment can be restored within 10 to 12 months. The water conductor system has shown resilience against the flood, allowing for a relatively quick restoration of operations.
Safety Enhancements
To further enhance safety, plans are in place to relocate the dam control room to a higher elevation. This move aims to protect personnel during potential future flood events. The overall focus is on creating a more resilient infrastructure capable of withstanding extreme weather conditions.