A fisherman on the Indus river in Jamshoro, Sindh, Pakistan. The snow persistence in the Indus Basin dropped to 23.3 per cent below normal, the lowest level in the past 22 years. iStock photo
The Indus, Ganga and Brahmaputra basins experienced a below-average snow persistence, recording a decrease of 23, 17 and 15 per cent between November 2023 and April 2024, compared to historic observations during 2003-2023, according to a new report.
The report analysed data on snow persistence from 2003 to 2024 and found it to be significantly lower than normal in the Hindu Kush Himalaya (HKH) this year, the ICIMOD Snow Update Report 2024 stated. Snow persistence is the fraction of time that snow remains on the ground.
This below-average anomaly threatens water availability in early summer this year, requiring governments to activate drought management strategies.
The 2024 trend follows a pattern of decreasing amounts and persistence of snow across the HKH. Thirteen of the past 22 years have registered lower than normal seasonal snow persistence, ICIMOD cryosphere specialist Sher Muhammad, author of the Snow Update Report 2024, said in a statement.
“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,” Muhammad added.
The frozen water in the HKH is a critical source of freshwater for approximately 240 million people living in the region, while also benefiting around 1.65 billion individuals living downstream.
Snowmelt contributes roughly 23 per cent of the total water flow of 12 major river basins that originate high in the HKH.
The report compared the persistence of seasonal snow in November 2023-April 2024 with historical records.
Their analysis showed that the snow levels were almost a fifth below normal across the region this year, with the west witnessing dramatically low levels. The snowmelt in the west also contributes the highest water supply to rivers.
The report also highlighted a trend of decreasing below-average snow persistence from east to west in the HKH region.
The snow persistence in the Indus Basin dropped to 23.3 per cent below normal, the lowest level in the past 22 years. This level surpassed the previous low in 2018, with a 9.4 per cent shortfall.
The Brahmaputra river basin also experienced below-normal levels this year. In 2021, it experienced the lowest seasonal snow persistence, dropping below its average at 15.5 per cent.
The Ganga river basin, which also experienced a record low in 2024, has seen significant fluctuations in the past 22 years. The previous low in 2018 had the lowest snow persistence at 15.2 per cent, while the highest of 25.6 per cent was recorded in 2015.
The Helmand river basin shows the most dramatic fall, with snow persistence reaching 31.8 per cent below normal. In 2018, it recorded a 42 per cent decline. The Helmand river originates in the HKH region before flowing into southwestern Afghanistan and eastern Iran.
The Amu Darya river basin, too, faced its lowest snow persistence, recording a 28.2 per cent cover below normal. The Amu Darya is one of the longest rivers in Central Asia.
The Irrawaddy river basin, which has seen fluctuations in the last 22 years, also saw a slightly below-normal snow persistence with a value of 2.4 per cent. The Irrawaddy is a major river in Myanmar.
“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,” Miriam Jackson, ICIMOD’s senior cryosphere specialist emphasised the need for proactive measures, said in a statement.
The report recommends governments effectively communicate the situation and update water management plans to prepare for water stress.
It also added that drought response strategies are important to organise relief activities during emergencies to ensure a clean water supply.
Further, promoting rainwater collection from the upcoming rainfall for irrigation and other relevant activities could help, it stressed.
The report called for collaboration among countries sharing transboundary rivers to update their water management laws to ensure long-term resilience to climate change.
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