Himalaya's ‘hanging glaciers’ can cause higher disaster risks in Uttarakhand: Study

THe rapidly ever-changing mood has weakened swathes of the Himalayan glaciers and formed unstable chunks of water ice that string up away steep slopes and can snap, setting off a slew of environmental disasters in Uttarakhand, a new paper has found.The paper – led by the Indian Institute of Science, Indian Institute of Technology Bhubaneswar, and the Defence Geoinformatics Research Establishment – mapped 219 of these chunks, known as “hanging glaciers” in Alaknanda basin. These glaciers occupy steep slopes, with around 30% of them in the Upper Alaknanda basin, including areas such as Uttarakhand’s Badrinath, said the paper, published on Friday in Nature’s Natural Hazards journal. Rapid settlement growth increases disaster exposureThese hanging glaciers, coupled with a rapid rise in human settlements in the ecology in Alaknanda Basin, has increased the exposure of neighbouring populations and infrastructure to significant risks, especially glacier disasters.Analysis showed that settlements in the basin expanded 616% over the past five decades, contributing to a 57% drop in agricultural land and a 33% drop in barren land. Built-up surfaces are expected to increase from around 8,000sqm in year 2000 to about 152,000sqm by 2030. The number of people expected to be exposed to these risks is projected to grow from about 380 to 8,500 in the same period.Warming Himalayas accelerating glacier meltsGlaciers in high-elevation alpine environments are particularly sensitive to climate shifts. Warming in the Himalayas has exceeded the global average over the past two decades, shrinking glaciers and cutting off tributary glaciers from their “trunks”. These phenomena can spark off a cascade of disasters, such as the Dharali floods last year, which scientists attribute was triggered at least to some extent by unstable glaciers.“High-altitude regions of the Himalaya are experiencing major changes due to climate change...This investigation provides a unique dataset on hanging glaciers and potential regions which can be affected,” said Anil V Kulkarni, distinguished visiting scientist at the Divecha Centre for Climate Change, IISc. He added that the data is vital for planners to undertake systematic development and improve the safety of mountain communities.The Alaknanda basin contains around 848 glaciers distributed across sub-basins: Mandakini, Pindar, Mena Nala, Nandakini, Vishnuganga, Rishiganga, Dhauliganga and Girthiganga. The basin hosts several pilgrimage sites such as Kedarnath, Badrinath and Hemkund Sahib; major settlements including Joshimath, Chamoli, Tapovan and Mana; trekking routes like the Valley of Flowers, Roopkund and Nanda Devi Base Camp; and hydropower projects such as Vishnuprayag, Tapovan-Vishnugad and Pipalkoti, all located in close proximity to glacierised terrain.A 2023 paper reported 681 avalanche events causing over 3,100 deaths across High-mountain Asia over the past 50 years, including 60 that killed over 1,400 people in the Indian and Nepal Himalayas. The paper cited the 2015 Gorkha earthquake-triggered avalanche and the 2021 Chamoli rock-ice avalanche in Uttarakhand, as examples of disasters triggered by hanging glaciers. “Hanging glaciers have huge potential to induce indirect or secondary hazards. For instance, mass failure from hanging glaciers overhanging glacial lakes can result in surging of the lake’s water and breaching of its dam, leading to a glacial lake outburst flood,” said the paper.