A 2026 scientific study by researchers from Nagaland University and Cotton University has assessed the changing lake landscape of Arunachal Pradesh and identified two lakes at high risk of Glacial Lake Outburst Floods. The study used satellite observations for 1988–2020 and applied the Analytic Hierarchy Process to screen GLOF risk.

Key Highlights of the study 

The Eastern Himalayas are warming rapidly, causing glacier retreat, snow-pattern changes and the formation or expansion of high-altitude lakes.

• The number of unconnected glacial lakes increased from 136 in 1988 to 205 in 2020, an increase of 69 lakes.
• Their combined area, however, declined from 1,363.96 hectares to 1,215.57 hectares.
• Most newly formed lakes were concentrated around 4,000–5,000 metres above mean sea level. 
• Out of the wider lake inventory, 127 lakes were assessed for GLOF risk.
• 2 lakes were classified as high risk, 36 as medium risk and 89 as low risk.
• The two high-risk lakes are located in West Kameng and Upper Dibang Valley districts. 

What is a Glacial Lake Outburst Flood (GLOF)?

• A GLOF occurs when water stored in a glacier-fed lake is suddenly released, often because of the failure of a moraine dam or other triggers, causing massive downstream flooding.
• A GLOF can be triggered by earthquakes, heavy rains and ice avalanches.
• Based on their formation process, there are four categories of glacial lakes i.e. Moraine-dammed, Ice-dammed, Erosion, and others.
• Such floods can rapidly carry water, rocks and sediment downstream, damaging settlements, roads, bridges and hydropower infrastructure.

How was risk assessed?

The researchers used the Analytic Hierarchy Process, a multi-criteria decision-making method.

The most important factors were:

• Rate of lake expansion, because rapid expansion can increase water pressure and moraine-failure risk.
• Distance from glaciers, because nearby glaciers can generate ice or rock avalanches capable of triggering an outburst.
• Other factors included lake volume, depth, elevation, slope and distance from settlements. 

Why does it matter for Northeast India?

The Eastern Himalayas are highly sensitive to climate change. A GLOF originating in Arunachal Pradesh can travel rapidly through downstream valleys, affecting communities and infrastructure.

The study therefore calls for:

• Continuous satellite and ground-based monitoring of vulnerable lakes.
• Early-warning systems for downstream communities.
• Regular hazard and risk assessments as lake conditions change.
• Protection and climate-resilient planning of roads, bridges and hydropower projects.
• Greater community preparedness and evacuation planning.

Prelims Takeaway

Remember: The study concerns Arunachal Pradesh → Eastern Himalayas → 1988–2020 satellite assessment → 127 lakes screened → 2 high-risk, 36 medium-risk and 89 low-risk lakes. 

Exam Hook — Prelims Question

Consider the following statements:

1. Glacial Lake Outburst Floods can result from the failure of natural moraine dams.
2. Rapid expansion of a glacial lake can increase its GLOF risk.
3. The Analytic Hierarchy Process can be used for multi-criteria GLOF risk assessment.

Which of the statements given above are correct?

Answer: 1, 2 and 3.

One-line wrap: Climate change is turning the changing Himalayan cryosphere into a growing disaster-management challenge for downstream Northeast India.