Written by Aaitijhya Goswami
Edited by Kashish & Emil Koch
It was a regular night in the bustling valley of Sikkim, where tourists from all around India came each year to enjoy the scenic views of the snowy peaks that the state had to offer. Everything was quiet in the darkness of the night, except for the monotonous ebb and flow of the Teesta River. As usual, the town slumbered in peace as the late evening darkened into midnight. Suddenly, their reverie was broken by a loud rumbling noise, as if a huge chunk of a mountain had broken apart and fallen into the stream, followed by a sudden surge in the flow of water, and its gush down the valley began to sound more terrifying. When the residents looked out of their balconies, they were horrified by the sight that lay ahead of them in the eerie darkness of the mountains.
On October 4, 2023, a glacial lake outburst flood was produced by severe rains that forced the glacial South Lhonak Lake in Sikkim, a state in northeastern India, to overflow its banks. Before the Teesta III Dam's gates could be opened at midnight, the flood arrived at Chungthang, devastating the dam in a matter of minutes.
A cloudburst in early October 2023 caused Sikkim to receive more than twice its typical amount of rainfall; on October 3 and 4 alone, the state received five times its regular amount of precipitation. A flash flood resulted from the South Lhonak rupturing its shores. Satellite images from the Indian Space Research Organisation'sRISAT-1A show that the lake's surface area shrunk by more than a hundred hectares. Based on a warning from the Indo-Tibetan Border Police at midnight, the operators of the Teesta III Dam at Chungthang rushed to open the dam's gates but were too late; the flood quickly destroyed the dam, as well as the bridge to its 1200MW hydroelectric powerhouse, which went underwater.
Following that, the River Teesta's downstream water levels increased by fifteen to twenty feet, submerging a large portion of the districts of Kalimpong Cooch Behar Jalpaiguri and Darjeeling in West Bengal and Mangan Gangtok Pakyong and Namchi in Sikkim. The flood continued into Bangladesh, affecting hundreds of communities in the Char and Teesta River basins. Parts of National Highway 10 collapsed, cutting off the north of the state, including the capital Gangtok, from the rest of India and causing the collapse of fifteen bridges. There were 3,000 tourists stuck all around the state. Teesta Bazaar, Chungthang Dikchu Singtam Rangpo Melli, and other towns and cities sustained significant damage.
The flood was deemed a disaster by the Sikkim government, and ₹48 crore ($5.76 million) in disaster relief funds were given by the national government of India. The National Disaster Response Force and the Indian Army are involved in the ongoing relief operations. 2,400 people were evacuated from flood-hit areas, and 7,600 others were in relief camps. 10,000 more were evacuated in West Bengal.
Fourteen people were believed to be trapped inside the tunnels of the destroyed Teesta III Dam; a 60-strong team of the NDRF - including scuba divers - was assembled to rescue them.
At least 40 people were killed and 22 injured, while 75 were reported missing as of 6 October. Of the missing were 23 Indian Army personnel, of whom seven were subsequently found dead and one rescued alive. One of the dead soldiers was found floating in the Teesta in Nilphamari, Bangladesh; the Border Guard Bangladesh handed over the body to the Indian officials through a flag meeting. One child was killed and six injured in the neighboring state of West Bengal when a mortar shell carried downstream from Sikkim exploded after being picked up by locals.
The South Lhonak Lake is a moraine-dammed lake fed by the meltwater of the Lhonak glacier. It was first seen in CORONA satellite images from 1962 as a supraglacial lake. Landsat MSS images show that it became a separate lake by 1977, with a surface area of 17 hectares. In four decades, as the glacier retreated 1.9km, the lake swelled, covering nearly a hundred hectares by 2008. It was identified as potentially being at risk of causing glacial outburst floods, and in 2018, pipelines were carried up by yaks and installed to pump water out of it.
Before the flood, scientists and authorities were working on an early warning system for glacial floods that was to be eventually installed at the South Lhonak Lake.Sentinel-1A images from 28 September 2023 showed the lake covering an area of 167.4 hectares. Many leading Indian environmentalists cited the rapid melting of the glacier in the past few decades to be the major cause of the sudden flash floods. The lake's volume has increased 10-fold in the past 40 years, as per the detailed study of satellite images, and despite many warnings from different climate bureaus, the matter was ignored by both the state and central government. This incident served as a wake-up call for both the Indian central and state governments to take sterner measures as glacier floods become more and more devastating each year and claim thousands of lives, apart from the property damage worth billions and the destruction of livelihood and income of millions of people in the hill region. These Himalayan glacial floods are a warning sign for the world to shift the greener methods of lifestyle and prevent greenhouse emissions and global warming.
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References
India, H., & India, H. (2023, October 17). The Hans India. The Hans India. https://www.thehansindia.com/news/national/centre-shared-no-data-on-natural-calamities-with-himalayan-states-in-10-years-says-parl-panel-report-830595. Accessed on 10/25/2023.
What is National Disaster Response Force? NDTV.com. https://www.ndtv.com/india-news/what-is-national-disaster-response-force-467984. Accessed on 10/25/2023.
Wikiwand - National Disaster Response Force. Wikiwand. https://www.wikiwand.com/en/National_Disaster_Response_Force. Accessed on 10/25/2023.