Guwahati: A new scientific study has warned that climate-driven changes in the high mountains of Arunachal Pradesh are increasing the risk of glacial lake outburst floods (GLOFs) - sudden and potentially devastating floods caused by the failure of glacier-fed lakes.
The research, conducted by scientists from Cotton University and Nagaland University, analysed satellite data to assess changes in glacial lakes across the eastern Himalayas between 1988 and 2020.
Published in the journal Discover Hazards, the study highlights how rapid warming and glacier retreat in the Eastern Himalaya are reshaping the region's fragile mountain landscape and creating new flood hazards for downstream communities.
The researchers - Nabajit Hazarika, Vimha Ritse, Amenuo Susan Kulnu and Latonglila Jamir - found significant changes in the number and size of lakes in Arunachal Pradesh over the past three decades.
Their analysis revealed that the number of non-glacial lakes increased by 498, the total lake area expanded by more than 3,200 hectares, and many new lakes have formed at elevations between 4,000 and 5,000 metres above sea level.
These changes are closely linked to glacier retreat and rising temperatures, which cause meltwater to accumulate and form new lakes in high-altitude regions.
To assess the flood threat, the scientists evaluated 127 glacial lakes using an analytical model that considers factors such as lake expansion, proximity to glaciers and surrounding terrain.
The results showed that two lakes were classified as high risk, 36 lakes as medium risk and 89 lakes as low risk.
The study notes that lakes that are rapidly expanding and located close to retreating glaciers pose the greatest danger.
Glacial lake outburst floods occur when natural dams made of ice or loose moraine suddenly collapse, releasing massive volumes of water downstream. Such floods can destroy infrastructure, wash away bridges and roads, and threaten villages located along mountain rivers.
Across the Himalayas, several GLOF disasters in recent decades have highlighted the growing risks associated with climate change and glacier melt.
The researchers say the findings underline the need for continuous monitoring of glacial lakes in Arunachal Pradesh, which lies in one of the most climate-sensitive parts of the Himalayas.
"As many rivers originating in the state flow into Assam and other downstream regions, any large GLOF event could have serious impacts far beyond the high mountains," the researchers noted.
The study calls for improved early-warning systems, detailed lake monitoring and risk mapping to reduce the potential impact of future glacial lake floods.
As climate change accelerates glacier retreat across the Himalayas, scientists warn that understanding and tracking these high-altitude lakes is becoming increasingly critical for disaster preparedness in the region.
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