25-Oct-2023-Editorial

GLACIAL LAKE OUTBURST FLOOD IN SIKKIM KILLS MANY. HOW DOES A GLOF HAPPEN?

The Himalayan region faces an escalating threat of glacial lake outburst floods (GLOFs), as evidenced by the recent devastating incident in Sikkim. The precarious nature of these events, triggered by climate change-induced factors, necessitates a comprehensive approach to mitigate the risks and enhance early warning systems.

What is a glacial lake outburst flood?

A glacial lake outburst flood (GLOF) is the sudden release of water that has collected in former glacier beds.

These lakes are formed by the retreat of glaciers, a naturally occurring phenomenon that has been turbocharged by the warmer temperatures of human-caused climate change.

Glacier melt is often channelled into rivers, but ice or the build-up of debris can form what is effectively a natural dam, behind which a glacial lake builds.

If these natural dams are breached, large quantities of water can be released suddenly from the lakes, causing devastating flooding.

Early Warning Systems

Preparatory Measures:

The National Disaster Management Authority (NDMA) led a preparatory mission to install automated cameras and monitoring equipment at high-altitude glacial lakes.

Despite equipment failure at South Lhonak, successful identification of locations for sensors and mitigation measures at Shako Cho sets the stage for an end-to-end early warning system.

Event Analysis:

The tragedy in Sikkim underscores the challenge of predicting cascading events triggered by factors such as heavy rainfall, landslides, and glacial lake outbursts.

Monitoring equipment reported abnormally high temperatures, potentially linked to a massive rock/moraine collapse, emphasizing the need for a more nuanced understanding of the complex process chain.

Challenges in the Himalayan Region

Diverse Hazards:

The Himalayan region is susceptible to a myriad of hydro-meteorological, tectonic, climate, and human-induced mountain hazards.

Each requires distinct monitoring, mitigation, and early warning strategies, complicating the task of risk assessment.

Monitoring Complexity:

The multitude of glaciers and temporal variations in glacial recession pose challenges in monitoring and estimating the risk of GLOFs.

The National Remote Sensing Centre’s Glacial Lake Atlas highlights the enormity of the challenge, with 28,000 glacial lakes in three major river basins.

Mitigation Strategies

Global Efforts:

Various geo-technical solutions globally, including regulated discharge channels, drainage systems, spillways, and catchment dams, have been attempted for GLOF mitigation.

However, implementing these measures above 5,000 meters presents formidable challenges such as inaccessibility, harsh conditions, and logistical issues.

Risk Communication:

Downstream communities lack awareness of the risks posed by glacier melt and cascading hazards.

The short lead time for response intensifies the risk to life, property, and livelihood.

Integrating disaster and climate resilience principles into government policies and private investments is crucial for sustainable development.

Multi-disciplinary Effort

Integrated Approach:

Addressing the GLOF threat requires a collaborative, multi-disciplinary effort across institutions.

Remote sensing data from the NRSC, hydro-dynamic assessments by the Central Water Commission, and national guidelines from the NDMA play pivotal roles in understanding and mitigating risks.

Comprehensive Plan:

A GLOF risk mitigation plan, currently in the final stages of approval, emphasizes the installation of monitoring and end-to-end early warning systems at high-risk glacial lakes.

Governments and scientific institutions must unite, pooling resources and capacities, to enhance disaster risk reduction efforts and bring stability to the vulnerable hill communities.

Conclusion

The urgency to mitigate GLOF risks in the Himalayan region demands a proactive, collaborative approach. By enhancing early warning systems, understanding complex process chains, and implementing comprehensive mitigation strategies, stakeholders can reduce the impact of these disasters and safeguard the lives and livelihoods of the communities downstream.