Snow persistence, the fraction of time snow remains on the ground, is significantly lower than normal in the Hindu Kush Himalaya this year, with serious implications for downstream communities’ water security. Leading experts from the International Centre for Integrated Mountain Development (ICIMOD), which publishes the annual Snow Update Report, warn water management officials to initiate drought management strategies and pre-emptive emergency water supply measures.
The report reveals that snowmelt, a critical source of water, contributes approximately 23% of the total water flow to 12 major river basins originating in the HKH region. However, its contribution varies significantly among rivers: the Amu Darya receives 74% of its flow from snowmelt, the Helmand 77%, and the Indus 40%.
Monitoring shows snow levels almost a fifth below normal across the region this year, with the west experiencing the most dramatic declines, where snow’s contribution to water supply is highest. The Helmand River basin, in particular, shows a dramatic fall in persistence at 31.8% below normal. This is the second-lowest level on record, with the lowest recorded in 2018 at a 42% reduction. Additionally, the Indus Basin has fallen to 23.3% below normal, marking its lowest level in 22 years, with the previous lowest being in 2018 with a 9.4% shortfall. The Mekong basin had the smallest variation, with snow persistence just around 1% below normal.
“We’ve seen a pattern of decreasing amounts and persistence of snow across the Hindu Kush Himalaya, with 13 of the past 22 years registering lower than normal seasonal snow persistence,” said ICIMOD Cryosphere Specialist Sher Muhammad, author of the Snow Update Report 2024. “This is a wake-up call for researchers, policymakers, and downstream communities: lower accumulation of snow and fluctuating levels of snow pose a very serious increased risk of water shortages, particularly this year.”
Miriam Jackson, ICIMOD’s Senior Cryosphere Specialist, emphasized the need for proactive measures. “We encourage relevant agencies to take proactive measures to address possible drought situations, especially in the early summer, update plans to accommodate water stress, and to notify communities of the risks.
“Beyond that, it’s clear that governments and people in this region need urgent support to help them adapt to changes in snow patterns that carbon emissions have already locked in. And that G20 countries need to cut emissions faster than ever before to prevent even more changes that will prove disastrous to major population centres and industries that rely on snowmelt in the mountains.”
In the Amu Darya River basin, seasonal snow persistence has reached its lowest point in the past 22 years, falling 28.2% below normal. The Brahmaputra River basin has also experienced significantly low snow persistence at 14.6%, compared to its lowest in 2021 at 15.5%. The Ganges River Basin showed the lowest snow persistence this year at 17%, contrasting with its highest in 2015 at 25.6%.
The report further highlights that the Irrawaddy River basin’s snow persistence remains slightly below normal at 2.4%, while the Mekong and Salween River basins show slight deviations below normal at 1.1% and 2.4%, respectively. The Tarim River Basin witnessed a significant decrease in snow persistence to 27.8%, the lowest in 22 years. The Tibetan Plateau’s snow persistence is below normal at 14.8%, and the Yangtze River basin saw a decrease of 13.2% below normal.
In contrast, the Yellow River basin saw an above-normal snow persistence at 20.2%, compared to its lowest in 2015 at 42.2% below average.
ICIMOD urges continuous monitoring and dissemination of snow information to manage the impacts of these long-term changes effectively. The organization calls for immediate action to address the water security challenges posed by this significant reduction in snow persistence, which could severely affect millions of people relying on these river basins for their water supply.