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The South Lhonak lake in the Himalayan state of Sikkim experienced a devastating glacial lake outburst flood (GLOF) on the night of October 3. This event resulted in the loss of 42 lives, while 77 people still remain missing. The lake continues to pose a potential hazard, with scientists warning about its unstable conditions. This article aims to explore the significance, features, objectives, effects, and potential pros and cons of the South Lhonak Lake GLOF.
Significance of South Lhonak Lake GLOF
The South Lhonak lake is situated in North Sikkim at an altitude of 5,200 meters. It is one of the largest and fastest-growing glacial lakes in the region, making it an area of concern for several years. The recent GLOF highlighted the potential dangers associated with the lake and the need for effective monitoring and management of glacial lakes in the Himalayan region.
Features of the South Lhonak Lake GLOF
According to scientists, the GLOF was triggered by a slope failure along the lateral moraine on the lake’s left bank. The landslide material scraped the glacier terminus and hit the lake, creating an impulse wave that widened the lake’s outlet and resulted in a partial breach. The flood affected four districts, namely Mangan, Gangtok, Pakyong, and Namchi, impacting around 88,400 people in total.
Objectives of Understanding the Disaster
The primary objective is to understand the factors that led to the South Lhonak Lake GLOF and assess the potential risks associated with glacial lakes in the Himalayan region. By studying the disaster, scientists aim to provide insights into the role of climate change, rainfall patterns, and infrastructure planning in mitigating the impacts of such events. Furthermore, understanding the disaster can aid in developing early warning systems and disaster management strategies.
Effects of the GLOF
The GLOF resulted in the loss of lives, destruction of infrastructure, and damage to hydropower projects. The Teesta-III hydropower dam broke, leading to water from the damaged reservoir combining with the GLOF and causing further destruction downstream. Other hydropower projects, namely Teesta-V and Teesta-VI, were also impacted. Additionally, continuous landslides in the area pose a threat to downstream areas. The large deposit of sediments along the path of the flood adds to the risk of future disasters.
Pros and Cons
Pros:
– The disaster highlights the urgent need for improved monitoring and management of glacial lakes in the Himalayan region.
– The event provides an opportunity to study the impact of climate change on glacial lakes and the implications for future disasters.
– The disaster raises awareness about the potential risks associated with infrastructure development near glacial lakes.
Cons:
– The loss of lives and destruction of infrastructure are tragic consequences of the GLOF.
– The erosion of sediment caused by the flood may reduce the lifespan and efficiency of hydropower projects in the area.
– The continuous landslides and potential for future GLOFs pose ongoing risks to the affected regions.
Interesting Fun Fact
The South Lhonak glacier has been melting rapidly over the years, causing the lake to expand. In 1976, the lake area was only 0.20 sq. km, but by 2019, it had grown to 1.35 sq. km. This expansion is attributed to anthropogenic climate warming, indicating the close connection between glacial melt and climate change.
In conclusion, the South Lhonak Lake GLOF serves as a wake-up call for better management of glacial lakes in the Himalayan region. It underscores the need for accurate monitoring, disaster preparedness, and infrastructure planning. By studying these events, scientists can gain valuable insights into the impact of climate change and develop strategies to mitigate the risks associated with GLOFs.
Mutiple Choice Questions | UPSC – IAS
1. What is the South Lhonak lake?
a) A glacial lake in the Himalayan state of Sikkim
b) A lake in North Sikkim at an altitude of 5,200 m
c) One of the largest and fastest growing glacial lakes in Sikkim
d) All of the above
Explanation: The South Lhonak lake is a glacial lake located in the Himalayan state of Sikkim, specifically in North Sikkim at an altitude of 5,200 m. It is also one of the largest and fastest growing glacial lakes in Sikkim.
2. What caused the breach of the South Lhonak lake?
a) Excess rainfall and a cloudburst
b) Earthquake tremors
c) Landslides along the lateral moraine
d) None of the above
Explanation: The breach of the South Lhonak lake was caused by landslides along the lateral moraine on the lake’s left bank. This resulted in a partial breach and widening of the lake’s outlet.
3. What were the consequences of the glacial lake outburst flood (GLOF)?
a) 42 people died and 77 are still missing
b) Around 88,400 people affected in four districts
c) Damages to hydropower projects downstream
d) All of the above
Explanation: The GLOF resulted in the death of 42 people, with 77 still missing. It also affected around 88,400 people in four districts. Additionally, hydropower projects downstream, such as the Teesta-III, Teesta-V, and Teesta-VI, were damaged.
4. How did the cascade of events contribute to the disaster?
a) The dam of Sikkim’s biggest hydropower project broke, combining with the GLOF
b) Landslides along the path of the flood, including around the Chungthang dam
c) Large deposits of sediments posing a threat to downstream areas
d) All of the above
Explanation: The cascade of events leading to the disaster involved the breaking of the dam of Sikkim’s biggest hydropower project, which combined with the GLOF. There were also landslides along the path of the flood, particularly around the Chungthang dam. Furthermore, large deposits of sediments pose a threat to downstream areas.
5. What role did climate change play in the disaster?
a) The accelerated melting of the glacier contributed to the rapid growth of the lake
b) The lake’s rapid expansion weakened the permafrost holding the moraines
c) GLOFs are natural, but the rapid increase in the lake’s size is tied to anthropogenic climate warming
d) All of the above
Explanation: Climate change played a significant role in the disaster. The accelerated melting of the glacier caused the rapid growth of the South Lhonak lake. This expansion weakened the permafrost holding the moraines, contributing to the slope failure. Additionally, the rapid increase in the lake’s size is tied to anthropogenic climate warming.
Brief Summary | UPSC – IAS
A glacial lake outburst flood (GLOF) in Sikkim, India resulted in at least 42 deaths and 77 missing individuals. The South Lhonak lake breached due to a slope failure along the lateral moraine, causing an impulse wave and widening the lake’s outlet. The lake remains a potential hazard as it has not completely drained. Continuous landslides have occurred since the flood, and there is a risk of sudden water release downstream. The cause of the GLOF is disputed, with the government claiming a cloudburst while scientists analyze rainfall and earthquake data. The rapid growth of the lake is linked to climate change and the accelerated melting of the glacier.