Hanging Glacier Collapse Triggers Nepal Flash Floods; India Reviews GLOF Preparedness

The Himalayas are among the world's youngest and most tectonically active mountain systems, formed by the ongoing collision of the Indian and Eurasian tectonic plates. This geological youth produces steep, unstable terrain prone to seismic activity, landslides, and mass-wasting events. The range hosts more than 63,000 glaciers across the Hindu Kush-Himalaya (HKH) region, covering approximately 48,000 sq km in the Himalayan range alone and another 18,000 sq km in the Karakoram. Researchers have mapped over 5,000 glacial lakes across the Himalaya, of which roughly 500 are classified as hazardous or significantly hazardous. As global temperatures rise — at rates considerably faster than the global average in the HKH — glaciers are retreating, permafrost is thawing, and glacial lakes are growing in number and volume, raising the risk of sudden catastrophic releases.

The transboundary character of Himalayan rivers is central to understanding disaster risk. Rivers such as the Bhotekoshi, Koshi, Gandak (Narayani), Karnali, and Trishuli originate in the Tibetan Plateau, cut through Nepal's mid-hills, and enter the Indo-Gangetic Plain, making Bihar, Uttar Pradesh, and other Indian states chronically vulnerable to upstream events. India and Nepal share transboundary river systems governed by the Gandak Treaty (1959) and the Kosi Agreement (1954, revised 1966), but real-time hydrological data sharing and joint early-warning systems remain underdeveloped. India's institutional framework rests on the Disaster Management Act, 2005, which established the National Disaster Management Authority (NDMA), State Disaster Management Authorities (SDMAs), and District Disaster Management Authorities (DDMAs). India is also a signatory to the Sendai Framework for Disaster Risk Reduction 2015–2030, which prioritises proactive risk reduction over reactive relief — a shift that has been slow in practice.

The Bhotekoshi corridor in Nepal's Rasuwa and Nuwakot districts is one of the most hazard-exposed transboundary corridors in the region. It carries the Araniko Highway, the Gyirong (Kerung) Port — a key Nepal-China trade crossing — and the Nepal route of the Kailash Manasarovar Yatra, which crosses into Tibet at the Rasuwagadhi–Gyirong border point. The concentration of trade, pilgrimage, and hydropower infrastructure in this high-gradient valley makes any glacial or flood event here a multi-dimensional crisis.