All three major river basins of the Indian Subcontinent are experiencing some of their largest declines in ‘snow persistence’ — the fraction of time snow is on the ground after snowfall. The Hindu Kush Himalaya (HKH), of which these basins are a part, itself has experienced its third consecutive below-normal snow year in 2025, a new report released by Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD) on April 21, 2025, noted.
The Ganga basin, which recorded its highest snow persistence at +30.2 per cent in 2015, dropped to the 23-year lowest of -24.1 per cent in 2025. This would likely reduce flows in early summer, the report stated.
The Indus basin experienced a steep drop in snow persistence to -24.5 per cent in 2024, from a high of +19.5 per cent in 2020. This steadily dropped to its vicennial lowest of -27.9 per cent in 2025.
“In 2025, the basin recorded snow persistence anomaly at -16 per cent. This sustained deficit threatens early summer water supply for nearly 300 million people, calling for urgent water management strategies,” the analysis urged.
The Brahmaputra basin’s snow persistence peaked in 2019 at +27.7 per cent but steadily dropped to -27.9 per cent in 2025. This continued decline poses risks to hydropower generation and agriculture, especially in early summer, calling for integrated drought risk planning.
Snow persistence in the Tibetan Plateau — the source of many rivers of North India — plummeted from a +92.4 per cent in 2022 to -29.1 per cent in 2025. “These extreme changes highlight the plateau’s climate sensitivity,” the document noted.
The most alarming declines in snow persistence, according to the HKH Snow Update Report 2025 in the Mekong (-51.9 per cent) and Salween (-48.3 per cent) basins, followed by the Tibetan Plateau (-29.1 per cent), the Brahmaputra (-27.9 per cent), Yangtze (-26.3 per cent), and the Ganga (-24.1 per cent) basins.
Continued deficit of seasonal meltwater, in general, means lesser river runoffs and early-summer water stress, especially for downstream communities, already reeling under premature and intensifying heat spells across the region.
The report used a 23-year timeseries (from 2003 to 2025) of basin-scale snow persistence during the snow season between November and March.
In light of these findings, the report urges swift action: improved water management, stronger drought preparedness, better early warning systems, and greater regional cooperation. It emphasises that long-term resilience will depend on adopting science-led, forward-looking policies, and investing in seasonal water storage, efficient use of meltwater, and integrated water management strategies.