High-Altitude Lakes Expanding In Arunachal, Raising Flood Risk: Study

A new study has identified two high-altitude lakes in Arunachal Pradesh as being at high risk of triggering glacial lake outburst floods (GLOFs), while 36 others have been classified as medium risk, raising concerns about the state's vulnerability to such disasters.

The study, published in Discover Hazards, assessed 127 lakes across Arunachal Pradesh. It found that 89 lakes were at low risk, 36 at medium risk and two at high risk of a GLOF.

A GLOF occurs when water stored in a glacial or high-altitude lake is suddenly released, often after the failure of a natural moraine dam. According to the study, the medium- and high-risk lakes are concentrated in Upper Dibang Valley, West Kameng and Tawang, regions that are important not only for downstream settlements but also for hydropower infrastructure.

The researchers warned that the risk could increase further as glaciers continue to retreat and high-altitude lakes expand under rising temperatures.

The study also found significant changes in glacial lakes over the years. There were 24 potentially dangerous glacial lakes (PGLs) covering 110.72 hectares in 1988. By 2020, their number had declined to 22, but their total area had increased to 125.93 hectares.

Using multitemporal satellite data, the researchers observed a significant increase in both the number and area of glacial lakes in Arunachal Pradesh between 1988 and 2020, indicating that several lakes are expanding rapidly.

The researchers noted that earlier studies have linked the growth of glacial lakes to global warming and climate change. Rising temperatures have accelerated glacier melt across the Himalayas, leading to the formation of new lakes and the expansion of existing ones.

Arunachal Pradesh has a substantial concentration of high-altitude lakes, particularly in the Dibang Valley, Lohit, Tawang, Upper Siang and West Kameng districts.

Amid growing concerns over GLOFs in the Himalayan region, Union Home Secretary Govind Mohan on Thursday reviewed preparedness for glacial lake outburst floods and avalanches with Arunachal Pradesh and other Himalayan states and Union Territories.

With Arunachal Pradesh among the states vulnerable to GLOFs and snow avalanches, Mohan stressed the need for continuous monitoring of vulnerable lakes and avalanche-prone areas, faster warning systems and effective evacuation planning.