 The state of Sikkim within India | |
| Date | 4–5 October 2023 |
|---|---|
| Location |
|
| Cause | Outburst of the South Lhonak lake due to heavy rainfall |
| Deaths | 92+ |
| Property damage | 15 bridges, one hydroelectric dam destroyed |
On 4 October 2023, heavy rains caused the glacial South Lhonak lake in Sikkim, a state in northeastern India, to breach its banks, causing a glacial lake outburst flood. The flood reached the Teesta III Dam at Chungthang at midnight, before its gates could be opened, destroying the dam in minutes. Water levels downstream in the River Teesta rose by up to 20 feet (6.1 m), causing widespread damage.
It was the deadliest flood in the area after the 1968 Sikkim floods when around 1000 people were killed.
Background
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 (42 acres). In four decades, as the glacier retreated 1.9 kilometres (1.2 mi), the lake swelled in size, covering nearly 100 hectares (247 acres) by 2008. It was identified as potentially at risk of causing glacial outburst floods, and in 2018 pipelines were carried up by yak and installed to pump water out of it. Sentinel-1A images from 28 September 2023 showed the lake covering an area of 167.4 hectares (414 acres).
Before the flood, scientists and authorities were working on installing an early warning system for glacial floods from the lake.
The flood
In early October 2023, a cloudburst caused Sikkim to receive more than double its normal rainfall; between 3 and 4 October alone, the state received five times the usual precipitation. The South Lhonak burst its shores, causing a flash flood. Satellite images from the Indian Space Research Organisation's RISAT-1A show that the lake's surface area shrunk by more than 100 hectares (247 acres). 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 1200-MW hydroelectric powerhouse, which was submerged.
Water levels downstream in the River Teesta subsequently rose by 15 to 20 feet (4.6 to 6.1 m), flooding many areas in Mangan, Gangtok, Pakyong, and Namchi districts in Sikkim, and Kalimpong, Cooch Behar, Jalpaiguri and Darjeeling districts in West Bengal. The flood also went onwards to Bangladesh, where it affected hundreds of villages along the Teesta River and Char areas.
Fifteen bridges across the state were washed away, and the north of the state, including the capital Gangtok, was cut off from the rest of India as parts of National Highway 10 collapsed. Three thousand tourists were stranded across the state. Towns and cities like Chungthang, Dikchu, Singtam, Rangpo, Melli, and Teesta Bazaar were very heavily damaged.
Relief operations
The government of Sikkim declared the flood a disaster, and the Indian central government released ₹48 crore ($5.76 million) in disaster relief funds. Additionally, the state government announced an ex-gratia compensation of ₹4 lakh ($4804) to the families of those who died, as well as an immediate payment of ₹2,000 ($24) to those in relief camps. The National Disaster Response Force and the Indian Army are involved in the ongoing relief operations. Two thousand four hundred people were evacuated from flood-hit areas, and 7,600 others were in relief camps. Ten thousand 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 National Disaster Response Force — including scuba divers — was assembled to rescue them.
Casualties
 | This section needs to be updated. Please help update this article to reflect recent events or newly available information. (October 2023) |
At least 40 people were killed and 22 injured, while 75 were reported missing as of 6 October. By 18 October, 92 were confirmed dead, with more bodies being retrieved. Among 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 neighbouring state of West Bengal when a mortar shell carried downstream from Sikkim exploded after being picked up by locals.
Notes
- Based on an exchange rate of 1 USD = 83.26 INR as of 6 October 2023
References
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- "Meer lichamen gevonden na overstromingen en dijkdoorbraak India, 74 doden". NOS (in Dutch). 9 October 2023. Retrieved 9 October 2023.
- Babu Govindha Raj, K.; Remya, S. N.; Vinod Kumar, K. (10 February 2013). "Remote sensing-based hazard assessment of glacial lakes in Sikkim Himalaya". Current Science. 104 (3): 359–364. JSTOR 24089638. Archived from the original on 14 May 2023. Retrieved 6 October 2023 – via JSTOR.
- Singh, Jyoti (2018-09-26). "Glacial lake flood keeps disaster managers on toes in Sikkim". BusinessLine. Retrieved 2023-10-06.
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- ^ Choudhury, Subrata Nag; Ahmed, Aftab (2023-10-06). "Death toll rises to 40 after glacial lake flooding in Indian Himalayas, dozens still missing". Reuters. Archived from the original on 2023-10-06. Retrieved 2023-10-06.
- ^ "Sikkim flood | 10 dead, 22 army men among 82 missing as flash flood wreaks havoc; PM Modi dials CM Tamang". The Hindu. 2023-10-04. ISSN 0971-751X. Archived from the original on 2023-10-06. Retrieved 2023-10-06.
- ^ "Indian soldier's body found in Teesta handed over to BSF". Dhaka Tribune. 6 October 2023. Archived from the original on 7 October 2023. Retrieved 6 October 2023.
- ^ "Sikkim: Race against time to save 102 missing in India floods". BBC News. 2023-10-05. Archived from the original on 2023-10-05. Retrieved 2023-10-06.
- ^ "Sikkim flash floods: Centre approves release of Rs 44.8 crore in funds". The Economic Times. 2023-10-06. ISSN 0013-0389. Retrieved 2023-10-06.
- "Sikkim flood: Toll rises to 25, search on for 143 missing people; CM Tamang announces Rs 4 lakh ex-gratia". Deccan Herald. Archived from the original on 2023-10-10. Retrieved 2023-10-07.
- "Sikkim floods: NDRF faces great unknown in bid to save 14 trapped in tunnels". Hindustan Times. 2023-10-06. Archived from the original on 2023-10-05. Retrieved 2023-10-06.
- Lama, Prawesh (2023-10-17). "As Sikkim rescue op winds down, the search continues for local hero". Hindustan Times. Retrieved 2023-12-02.
- "Sikkim Flash Floods Updates: One out of 23 missing Army personnel rescued". Hindustan Times. 4 October 2023. Archived from the original on 4 October 2023. Retrieved 4 October 2023.
- "Sikkim flood: Death toll rises to 25; 'explosive, firearms' warning issued". Hindustan Times. 2023-10-06. Archived from the original on 2023-10-06. Retrieved 2023-10-06.
| Floods in 2023 | |
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| Africa | |
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| ← 2022 floods· 2024 floods → | |
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