Arunachal Pradesh's Glacial Lakes: A Growing Threat of GLOF
Rising Concerns Over Glacial Lakes in Arunachal Pradesh
32 are considered high-risk and require active mitigation
Guwahati, Sept 11: Arunachal Pradesh is home to 197 glacial lakes, with 32 identified as high-risk and in need of immediate attention, according to renowned river expert Prof Nayan Sarma.
Prof Sarma explained that both Arunachal Pradesh and Bhutan are situated in the Eastern Himalayas, an area particularly susceptible to climate change. The rapid melting of glaciers has led to the formation of numerous unstable proglacial lakes, posing threats to areas downstream.
Key river systems facing risks from Glacial Lake Outburst Floods (GLOF) include Tawang Chu (Mago Chu) and Dibang in Arunachal Pradesh, as well as Punatsang Chhu and Kuri Chu in Bhutan. The Kameng Chu (Mago Chu) in Tawang district is particularly at risk due to the melting Khangri glacier.
Recent studies have identified unstable proglacial lakes at elevations of 16,500 feet near the Khangri glacier. High-risk lakes in the Mago Chu basin have expanded over the past decade, with the National Disaster Management Authority (NDMA) categorizing them as potentially hazardous. The Kameng Chu is referred to as the Jia Bharali River in Assam.
A satellite analysis from 2026 indicated that the Sanhapo Glacial Lake in the Mago Chu basin has grown significantly, increasing from 56 hectares in 2016 to 89 hectares, raising alarms about potential GLOF events.
In Bhutan, the Punatsang Chhu Basin has shown vulnerability due to historical incidents like the 1994 Lugge Tsho outburst, alongside critical lakes such as Thorthormi Tsho. The Punatsang Chhu, which features two hydropower dams, is known as the Sankosh river in Assam.
The glaciers in the northern mountains are vital for seven major river systems in Bhutan, including Amo Chu (Torsa), Wang Chu, Punatsang Chhu, Mangde Chu, Chamkhar Chu, Kuri Chu, and Drangme Chu. The hydropower generated from these rivers contributes approximately 40% of Bhutan’s national revenue, primarily through exports to India.
The Kuri Chu and Drangme Chu, along with Tawang Chu from Arunachal Pradesh, converge into the Manas river in Assam, raising significant concerns for the river's safety in the event of a GLOF from these high-altitude sources.
Prof Sarma emphasized the importance of monitoring and mitigating GLOF risks through the integration of real-time satellite technology, field sensors, and structural engineering to safeguard communities downstream.
Utilizing high-resolution satellite imagery and Interferometric Synthetic Aperture Radar (InSAR) is crucial for monitoring the growth of glacial lakes and detecting any potential failures in moraine dam walls. Synthetic Aperture Radar (SAR) is particularly effective for tracking glacial movements, as it can penetrate cloud cover and darkness, allowing for continuous monitoring even during adverse weather conditions.
Additionally, Automated Weather Stations equipped with solar-powered units can be installed near high-risk lakes to monitor meteorological changes, temperature fluctuations, and local water level variations.