Climate Change Increases Risk of Successive Natural Hazards in the Himalayas

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An international research team has concluded that the Sikkim flood disaster in the Himalayas in October 2023 was caused by some 14.7 million cubic meters of frozen moraine material collapsing into South Lhonak Lake, triggering a 20-meter flood wave.

An international research team has concluded that the Sikkim flood disaster in the Himalayas in October 2023 was caused by some 14.7 million cubic meters of frozen moraine material collapsing into South Lhonak Lake, triggering a 20-meter flood wave. The event is a striking example of the increasing dangers of climate change in high mountain regions.

An international study has investigated the causes and impacts of the devastating flood disaster in the Himalayas in October 2023, which destroyed large areas along and surrounding the Teesta River in Sikkim, India. A research team from nine countries, including researchers from the University of Zurich (UZH), analyzed the complex drivers, causes and consequences of this flood cascade and reconstructed the exact time of its onset.

On 3 October 2023, approximately 14.7 million cubic meters of frozen moraine material collapsed into South Lhonak Lake, triggering a tsunami-like impact wave up to 20 meters high. The subsequent glacial lake outburst flood breached the moraine and released approximately 50 million cubic meters of water – enough to fill 20,000 Olympic-sized swimming pools. The flood caused massive damage along the 385-kilometer-long valley, washing away some 270 million cubic meters of sediment and inundating infrastructure such as hydroelectric power plants on the Teesta River. At least 55 people were killed, and 70 others were reported missing.

Read More: University of Zurich

Flooding and destruction of Rangpo, over 130 km downstream of South Lhonak Lake (Photo Credit: Praful Rao)