Pace of melting snow sparks water worry | Latest News India

Snow melted in the Ganga basin at the fastest rate in more than two decades this year, data from the International Centre for Integrated Mountain Development (ICIMOD) showed on Monday, raising the spectre of heat stress and water shortages in summer months and adverse impact on agriculture.

The snow persistence – the fraction of time snow remains on the ground after snowfall and measured using data from Terra and Aqua satellites – in the Ganga basin was 24.1% below normal, the lowest in 23 years, said the ICIMOD annual snow update.

Last year, snow persistence stood at 20.4% below normal in what was a normal monsoon year in what was a normal monsoon year.

ICIMOD data also showed that snow persistence over the Brahmaputra basin also fell to its lowest of 27.9% below normal this year. In comparison, it stood at 15.7% below normal last year.

Together, the data from India’s two largest river basins raised concerns over heat stress downstream, water shortages in early summer, adverse impact on hydropower generation and agriculture, especially in early summer among others, for the country.

“The cumulative impact of these persistent deficits is likely to result in substantially reduced river runoffs and increased potential for early-summer water stress, particularly affecting vulnerable downstream communities already grappling with intensifying heat waves,” the organisation said.

Measuring snow persistence is crucial for understanding water availability for the long Indian summer, because snowpacks act as natural reservoirs that feed rivers. Around 10 to 15% of the Ganga and Brahmaputra’s flow is snow fed.

On average, seasonal snowmelt contributes about a fourth of the total annual runoff of rivers in the Hindu Kush Himalayan (HKH) region , with the share gradually rising from the rivers in the east to those in the west.

ICIMOD’s annual snow update reports provide year-wise analysis of seasonal (November-March) snow persistence since 2003. In 2023, the Ganga basin snow persistence stood at 13.6% below normal and the Brahmaputra at 10.7% below normal. In 2022, these numbers were 26.4% and 13.9% above average respectively.

“This could lead to early drying of mountain springs and increase in forest fire season. Moreover, streams originating from snow regions might experience reduced runoff; however in high altitude glaciated streams, it can get compensated by additional glacier melt. It can cause more negative glacier mass loss, affecting overall glacier health,” said Anil V. Kulkarni, glaciologist and distinguished visiting scientist at Divecha Center for Climate Change, Indian Institute of Science.

Across the Hindu Kush Himalayan region, snow persistence dipped to a 23-year low of 23.6% below normal, underscoring a “significant and growing threat” to the water security of nearly two billion people in the region, ICIMOD said.

The organisation also said 2025 marked the third consecutive year of below-normal seasonal snow across the Hindu Kush Himalayan region, which is the origin for 12 major river basins. Between 2003 and 2025, the region experienced 13 below-normal snow years, the body added.

“Carbon emissions have already locked in an irreversible course of recurrent snow anomalies in the HKH. To tackle this regional snow crisis and the challenges it creates for long-term food, water and energy resilience, we urgently need to embrace a paradigm shift toward science-based, forward-looking policies and foster renewed regional cooperation for transboundary water management and emissions mitigation,” said Pema Gyamtsho, ICIMOD’s director general.

The report said the most alarming declines in snow persistence were in the Mekong (-51.9%) and Salween (-48.3%) basins, followed by the Tibetan Plateau (-29.1%), the Brahmaputra (-27.9%), Yangtze (-26.3%), and the Ganges (-24.1%) basins.

“We are observing such deficit situations occurring in continuous succession. This is an alarming trend. While our findings give a broad picture across the region, each must act based on the specific conditions of their river basins, particularly where seasonal snowmelt is the major water source,” said Sher Muhammad, Remote Sensing Specialist at ICIMOD and the lead expert for Snow report 2025.

He said the level of deficit in snow persistence in the western river basins – such as Helmand , Amu Darya and Indus– was less this year compared to the last year, the eastern river basins faced deficits up to 50% below normal.