Mentor’s Comment:  On July 8, 2025, Nepal experienced a major Glacial Lake Outburst Flood (GLOF), which triggered a flash flood along the Lende River, destroying a China-built friendship bridge and disabling four hydropower plants, cutting off 8% of Nepal’s power supply. This catastrophe highlights the growing threat of GLOFs due to glacial melt from rising temperatures in the Himalayas. The incident has raised concerns over the lack of trans-boundary early warning systems, particularly between China and Nepal. It also drew attention to India’s vulnerability, as the Indian Himalayan Region (IHR) contains 7,500 glacial lakes, many at high risk of GLOF due to climate change, poor monitoring infrastructure, and lack of early warning systems. India’s National Disaster Management Authority (NDMA) has responded by launching a national programme targeting 195 at-risk glacial lakes, focusing on hazard assessment, early warning systems, risk mitigation, and community engagement.

Today’s editorial analyses the major Glacial Lake Outburst Flood (GLOF) in Himalaya region. This topic is important for GS Paper III (Environment) in the UPSC mains exam.

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Let’s learn!

Why in the News?

Recently, Nepal faced a major Glacial Lake Outburst Flood (GLOF), which led to a sudden flash flood along the Lende River.

What are their transboundary risks in the Himalayas?

• Trans-boundary Nature of Risk: Glacial lakes in upstream countries (like China) can cause floods that affect downstream nations (India, Nepal, Bhutan), often without early warning. Eg: In July 2024, a GLOF from a Tibetan lake caused destruction in Nepal’s Rasuwagadhi hydropower project, without prior alert.
• Lack of Data Sharing and Early Warning: There is minimal real-time data exchange between neighbouring countries on glacial lake status, making risk management difficult. Eg: Nepalese authorities received no early warning from China before the 2024 GLOF incident.

How has climate change increased GLOF frequency in the IHR?

• Accelerated Glacier Melting and Lake Formation: Rising temperatures are causing rapid glacier retreat, leading to the formation of new, unstable glacial lakes. Eg: The Milam Glacier in Uttarakhand has shown rapid retreat, increasing the size and number of proglacial lakes, raising GLOF risk.
• Extreme Precipitation Events: Climate change has intensified rainfall patterns, which can suddenly overfill glacial lakes and cause breaches. Eg: The Gya GLOF (2014) in Ladakh was triggered after heavy rainfall, damaging bridges and roads downstream.
• Increased Landslide Activity due to Warming: Thawing permafrost and unstable terrain lead to landslides that can fall into lakes, displacing water and triggering GLOFs. Eg: In 2013, a landslide into a glacial lake in the Chorabari Glacier near Kedarnath amplified the devastating flood.

What measures has India taken for GLOF mitigation?

• Early Warning Systems (EWS): India has installed EWS to detect rising water levels and trigger alerts for timely evacuation. Eg: An EWS was deployed at South Lhonak Lake in Sikkim, where a GLOF occurred in October 2023.
• Remote Sensing and Satellite Monitoring: ISRO and NRSC use satellite imagery to monitor glacial lakes, assess risks, and track expansion trends. Eg: Monitoring of glacial lakes in Ladakh, Uttarakhand, and Himachal Pradesh through Bhuvan portal.
• Risk Mapping and Vulnerability Assessment: Under the National Mission on Sustaining Himalayan Ecosystem (NMSHE), high-risk areas are identified for focused action. Eg: Studies in Kinnaur and Chamoli districts identified vulnerable lake systems.
• Drainage and Engineering Interventions: Controlled draining and structural measures are used to reduce lake volume and prevent overflow. Eg: Risk reduction work at Tsho Rolpa Lake (Nepal) near the Indian border was supported as a model for replication.
• Community Awareness and Preparedness: NDMA and state disaster authorities conduct training, drills, and awareness drives in high-risk areas. Eg: Mock drills in Uttarkashi (Uttarakhand) and Kullu (Himachal Pradesh) to prepare locals for GLOF events.

What are the gaps? 

• Early Warning Systems (EWS): India lacks robust systems for GLOFs, including real-time sensors, automated sirens, and communication tools. This was evident in the Chamoli disaster (2021), where early alerts could have saved lives.
• Community Preparedness: Awareness and preparedness remain low in high-risk zones. Most villages in Sikkim and Uttarakhand lack formal evacuation protocols or disaster response training.
• Transboundary Coordination: Weak cooperation with neighbouring countries like China hampers data sharing on glacial lakes and rivers, affecting early action in downstream regions such as Arunachal Pradesh.
• Infrastructure Resilience: Critical assets like bridges and hydropower dams are not designed to withstand GLOF surges. The Chungthang dam breach (2023) exposed this structural vulnerability.
• Scientific & Technical Capacity: India lacks adequate glaciologists, risk modelers, and remote sensing experts. Agencies like NDMA depend on fragmented satellite data without reliable ground validation.

Way forward: 

• ​​Strengthen Early Warning Systems (EWS): Deploy real-time monitoring equipment like automated sensors, satellite-based surveillance, and AI-driven forecasting tools in high-risk glacial regions. Ensure last-mile communication through mobile alerts and sirens to reach remote communities.
• Enhance Regional and Local Preparedness: Promote transboundary data sharing with neighbouring countries for upstream glacial lake information. Simultaneously, build community-based disaster preparedness through mock drills, localized evacuation plans, and training programs in states like Sikkim, Uttarakhand, and Arunachal Pradesh.

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