The Glacial Lake Outburst Flood (GLOF) in portions of Lhonak Lake, Mangan District, which caused the rise of water levels with very high velocities downstream along the Teesta River Basin in the early hours of October 4, 2023, has caused severe damage in Mangan, Gangtok, Pakyong, and Namchi Districts.
The lake outburst in portions of Lhonak Lake in North Sikkim caused a rise in water levels with very high velocities near about 15m/sec, crossed the CWC Melli site measuring 227 m, near about 3m above Danger Level, at 0600 am.
According to the Central Water Commission (CWC), the flood occurred at midnight on October 3, 2023. Simultaneous flood forecasts for both India and Bangladesh were made at 0600 hrs and 1400 hrs. The river Teesta is flowing below the warning level at CWC Domohani FF Station. The water level at 0600 hrs is 84.83m and is expected to cross its warning level within 6 hours.
Similarly, around 1 a.m. on October 4, 2023, the major flooding of the Teesta River was reported from Chunthang. Likewise, by 2:30 pm, the flood had reached the lowlying areas of the remaining districts, causing serious destruction to public properties and public infrastructure. The communication network under Mangan District surrounding Chungthang and its pheriphery has been affected. Districts sprung into action and immediately initiated the evacuation of the people from the lowlying areas.
Further, the SDRF team from the State Home Guard and Civil Defence, Gangtok, and NDRF Pakyong has already been deployed in the affected areas.
Climate Change Triggers Catastrophic events
According to ICIMOD Newsletter, Pema Gyamtsho, Director General, The International Centre for Integrated Mountain Development (ICIMOD) said: “Sadly, this is the latest in a series of deadly flash-floods that ricocheted across the Hindu Kush Himalayan region this monsoon, bringing the reality of this region’s extreme vulnerability to climate change all too vividly alive.”
Globalization and climate change have an increasing influence on the stability of fragile mountain ecosystems and the livelihoods of mountain people. The International Centre for Integrated Mountain Development (ICIMOD), is a regional knowledge development and learning centre serving the eight regional member countries of the Hindu Kush Himalaya – Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal, and Pakistan – and based in Kathmandu, Nepal. ICIMOD aims to assist mountain people to understand these changes, adapt to them, and make the most of new opportunities, while addressing upstream-downstream issues.
As per the newsletter, ICIMOD’s HIWAT application has recorded exceedingly high precipitation, exceeding 100millimetres within the last 24 hours in the vicinity.
Arun B Shrestha, Senior Climate Change Specialist, ICIMOD, said: “Information is fragmented, but it appears heavy rainfall from a Bay of Bengal low-pressure depression triggered the disaster. This seems like another unfortunate example of cascading hazards.”
Miriam Jackson, Senior Cryosphere Specialist, ICIMOD observed that such extreme events increase in frequency as the climate continues to warm and takes us into unknown territory.
As per the report received from the SSDMA, the following damages have been reported from the districts:
(i) Mangan District: Chungthang cut off due to the Toong Bridge collapse. Phidang Bridge collapsed. Four pucca houses at Phidang were washed away. Two houses at Dikchu were washed away. Houses along the river line are in danger, and two GREF labourers are reported missing at Sangkhalang, as per information received from GREF sources and one person missing from Phidang.
The GREF Crusher Plant and Old Police Barrack have been washed away at Toong, and four people have been reported missing.
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(ii) Gangtok: Four injured have been taken to Singtam Hospital. 25 people have been rescued by SDRF, more rescue is underway.
(iii) Namchi district: LD Kazi Bridge washed away. Indreni Bridge washed away. A relief camp was set up at Namphing Sai Mandir. As of now, 500 people have been kept in the relief camps, and permanent relief has been set up at Pranami Mandir.
(iv) Pakyong district: Two minor injuries, one dead in West Bengal, and one person is under observation at Rangpo PHC. 23 army personnel have been missing and one person has been rescued at Bardang.
Jakob Steiner, High Mountain Asia hazards and hydrology expert and fellow of ICIMOD’s Himalaya University Consortium said: “It is possible that strong permafrost degradation in the vicinity of the lake may have destabilized the dam, which may have then failed upon an exceptionally strong rainfall event.
Downstream, a hydropower structure was ripped away, further contributing to the massive impact that has resulted in yet more loss of life and damage to homes and infrastructure in what has been just a devastating monsoon season in the mountains of the Hindu Kush Himalaya.
Tragically, what we’ve seen this summer in terms of flash floods is likely to pale in comparison with what’s to come unless we limit temperature rise.”
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