Understanding Glacial Lakes:

• Glacial lakes are substantial bodies of water typically found near, on top of, or beneath glaciers.
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• These lakes primarily form due to glacial processes, including the melting of ice and the accumulation of meltwater within depressions or basins formed by glacier movements.

Concept: Glacial Lake Outburst Floods (GLOF):

• A Glacial Lake Outburst Flood (GLOF) refers to the sudden and often catastrophic release of water from a glacial lake, usually caused by the breach or failure of natural dams that contain the lake.
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• GLOFs commonly occur in glacier-rich regions, where meltwater accumulates within depressions or basins created by glacier movements.

• These events can have severe and far-reaching consequences for downstream communities and ecosystems.

Causes: Various Triggers for GLOFs:

GLOFs can be instigated by multiple factors, including:

1. Melting Glaciers: Rapid glacier melting due to rising temperatures can increase the water volume in glacial lakes.
2. Avalanches: Snow or ice avalanches can impact the lake, dislodging ice and debris into the water.
3. Earthquakes: Seismic activity can destabilize natural dams or trigger avalanches.
4. Rainfall: Heavy rainfall can contribute additional water to the lake and weaken natural dams.
5. Volcanic Eruptions: Volcanic activity can lead to rapid glacier melting and the formation of glacial lakes.

Destruction and Impact:

GLOFs bring about several adverse consequences, including:

1. Flooding: Rapid and extensive flooding in downstream areas with a quick rise in water levels.
2. Infrastructure Damage: GLOFs can harm or destroy roads, bridges, buildings, and farmland.
3. Loss of Life: GLOFs often result in human casualties and harm to livestock and wildlife.
4. Environmental Harm: Floodwaters and debris severely affect natural environments, such as forests, wetlands, and river ecosystems.

Notable GLOF Incidents:

• Historically, GLOF events have led to significant loss of life and infrastructure damage.
• The tragic 2013 flash floods in Uttarakhand’s Kedarnath stand as a stark reminder of the devastating consequences of GLOFs, exacerbated by a GLOF event originating from the Chorabari Tal glacial lake, resulting in the loss of thousands of lives.

The Vulnerability of South Lhonak Lake:

1. Glacial Melting: Rising global temperatures accelerate glacier melting in the Sikkim Himalayas, including the glacier feeding South Lhonak Lake, increasing its water volume and vulnerability to GLOFs.
2. Glacial Lake Expansion: South Lhonak Lake’s size has significantly increased over the past five decades, primarily due to glacier retreat and melt, heightening its vulnerability.
3. Seismic Activity: The region surrounding South Lhonak Lake is prone to seismic activity, which can destabilize natural dams or trigger avalanches, potentially leading to GLOF events. Past earthquakes in the area further increase this risk.

Government Initiatives:

1. To mitigate the risk associated with South Lhonak Lake, the Sikkim government, in collaboration with various agencies, including the Sikkim State Disaster Management Authority and Sikkim’s Department of Science and Technology and Climate Change, took proactive measures in 2016.

2. They decided to syphon off water from the lake using an innovative approach. Under the guidance of innovator Sonam Wangchuk, authorities installed three eight-inch-wide and 130-140-meter-long High-Density Polyethylene (HDPE) pipes to extract water from the lake.

3. This initiative successfully extracted 150 liters of water per second, reducing the lake’s water level and mitigating the risk of a potential GLOF.

The Path Forward: Warning and Mitigation:

1. Lake Monitoring: Regular monitoring of glacial lakes to assess changes in water levels and natural dam stability.
2. Early Warning Systems: Implementing systems to detect and warn downstream communities of potential GLOFs.
3. Infrastructure Development: Constructing protective infrastructure such as dams or diversion channels to manage floodwaters.
4. Land-Use Planning: Implementing land-use planning and zoning to restrict construction in high-risk areas.

Conclusion:

The recent calamity in Sikkim underscores the imminent threat of GLOFs in the Himalayan region.

While government initiatives are commendable, continued monitoring, research, and disaster preparedness are vital to safeguarding vulnerable communities in the face of expanding glacial lakes and the looming specter of GLOFs.