New Delhi: A new study has raised concerns over the growing threat of glacial lake outburst floods (GLOFs) in Arunachal Pradesh, identifying 38 high altitude lakes at medium to high risk of such events.
Researchers assessed 127 lakes across the state and classified 89 as low risk, 36 as medium risk and two as high risk. The lakes facing greater risks are concentrated in the Upper Dibang Valley, West Kameng and Tawang regions, where downstream communities and important hydropower infrastructure could be affected.
A GLOF occurs when water stored in a glacial or high altitude lake is suddenly released, often following the failure of a natural moraine dam. The resulting flood can carry huge quantities of water, rocks, sediment and debris downstream, potentially causing widespread damage.
Satellite data examined by researchers showed a significant increase in both the number and area of lakes across Arunachal Pradesh between 1988 and 2020. The number of mapped lakes rose from 1,487 to 1,985, while their combined area increased from 7,921.95 hectares to 11,134.51 hectares.
Non glacial lakes recorded the sharpest expansion. Their number increased by 498, while their combined area grew by more than 3,200 hectares. Glacial lake patterns varied, with proglacial lakes becoming larger despite a slight decline in numbers, while unconnected glacial lakes increased in number but declined in total area.
Most newly formed lakes were located at elevations between 4,000 and 5,000 metres, pointing to significant changes in the higher reaches of the eastern Himalayas.
Researchers identified lake expansion and proximity to glaciers as key factors influencing GLOF risk. Rising temperatures and glacier retreat are contributing to the formation and enlargement of high altitude lakes.
The study warned that rivers originating in these basins eventually feed the Brahmaputra system, meaning a GLOF could affect areas far downstream through sudden flooding, heavy sediment deposition and unstable river channels.
Researchers have called for continuous monitoring, updated risk assessments, early warning systems and greater community preparedness to reduce the potential impact of future flood events.
