The Indian Space Research Organisation (ISRO) reported on Monday that over 27% of identified Himalayan glacial lakes have expanded significantly since 1984, with 130 of these lakes located in India. This observation is based on long-term satellite imagery analysis of Indian Himalayan river basins from 1984 to 2023, highlighting substantial changes in the glacial lake landscape.
According to ISRO‘s findings, out of the 2,431 lakes larger than 10 hectares identified during 2016-17, 676 have notably expanded. Detailed data reveal that 601 of these lakes expanded more than twice their original size, while 10 lakes grew by 1.5 to 2 times, and 65 lakes expanded by 1.5 times. Among the expanding lakes, 130 are situated within the Indian borders, distributed across the Indus, Ganga, and Brahmaputra river basins.
An elevation-based analysis showed that 314 of these lakes are located at altitudes between 4,000 and 5,000 metres, with another 296 situated above 5,000 metres. These lakes are categorised into four types based on their formation process: moraine-dammed, ice-dammed, erosion, and other glacial lakes. Most of the expanding lakes are moraine-dammed, followed by those formed by erosion.
Highlighting the significant changes, ISRO pointed out the Ghepang Ghat glacial lake in Himachal Pradesh’s Indus basin, which has increased by 178% in size from 1989 to 2022. Additionally, the risks associated with the Himalayan glacial lakes were evident in October when the South Lhonak Lake in Sikkim burst due to heavy rains, leading to the deaths of 40 people and 76 missing.
The study of glacial lakes is crucial, given their importance as freshwater sources and the potential risks they pose, such as Glacial Lake Outburst Floods (GLOFs). These floods occur when water breaches natural dams, causing devastating downstream impacts. The monitoring and analysis of these lakes, challenging due to the terrain, are facilitated by satellite remote sensing, which offers comprehensive coverage and detailed insights into climate change impacts on these critical water bodies.