7 Oct 2023

Sikkim Disaster: Toll Mounts To 56; What Led To Catastrophe? Were Warning Signs Ignored?

The tragic disaster in Sikkim, which claimed the lives of at least 56 individuals and left over 100 others missing, did not occur without prior warning signs. 

The number of people who died due to floods has mounted to 56. Of these, 26 bodies were found in Sikkim and 25 bodies were found in different areas of Jalpaiguri district of West Bengal. 11 army personnel are also among the dead. While about 102 people are still reported missing, the number of injured has also increased to 26.

The state government said that the rescue operations were underway but the process was slowed down due to bad weather and damaged infrastructure.

Over 22,000 have been affected by the calamity

Over 22,000 people have been affected by the calamity. Approximately 3,000 tourists, including foreigners, are stranded in various parts of Sikkim.

NH-10, a key road connecting Sikkim to the rest of India, has suffered damage. This can impede rescue and relief efforts.

According to official data, 2,011 people have been rescued so far. Those affected by the calamity have been moved to relief camps in the state. 

At present, teams of many departments of the state government including Army, NDRF, SDRF, Sikkim Police are engaged in searching and rescuing the missing people.

This flood washed away the Chungthang Dam built on the Teesta River producing 1200 MW electricity, whose investment cost was about Rs 25 thousand crores.

Disaster did not strike unexpectedly

But disaster did not strike unexpectedly. Over the past decade, government agencies and researchers had repeatedly issued alerts regarding the risk of devastating glacial lake outburst floods in Sikkim.

The most recent cautionary message, pertaining to the Lhonak Lake in North Sikkim, was issued in 2021, but unfortunately, all these warnings went unheeded. Then, on a fateful Wednesday, disaster struck. A cloudburst possibly occurred over the lake, setting off flash floods within the Teesta River basin. This catastrophic event had a profound impact, affecting the lives of over 22,000 people.

Glacial Lake Outburst Floods are a significant concern

Glacial Lake Outburst Floods (GLOFs) are a significant concern in regions like Sikkim, where the topography and climate contribute to the formation of such potentially dangerous lakes. 

South Lhonak Lake is situated in the far northwestern region of Sikkim at an altitude of 5,200 meters (17,100 feet) above sea level. The lake has formed primarily due to the melting of the Lhonak glacier. Glacial lakes like this are formed as glaciers retreat due to rising temperatures on account of global warming, and they can pose significant hazards as they store large volumes of water.

The size of South Lhonak Lake is rapidly increasing due to the continuous melting of the glaciers that feed it. As glaciers melt, they contribute water to the lake, leading to its expansion. This growth can have significant consequences.

South Lhonak Lake is susceptible to GLOFs

The fact that South Lhonak Lake is one of 14 potentially dangerous lakes susceptible to GLOFs underscores the need for continuous monitoring and risk assessment. 

In regions with a high concentration of glaciers, such as the Himalayas, the impact of climate change on glacial retreat and the formation of glacial lakes is a significant concern. GLOF events can have devastating consequences on local communities and ecosystems, making it essential to study and manage these natural hazards effectively.

High outburst probability for a glacial lake

National Remote Sensing Centre and ISRO Study in 2012-2013 identified a high outburst probability of 42 percent for a glacial lake. The specific lake is not mentioned, but it implies a significant risk of a GLOF event in Sikkim region.

An expedition led by Sonam Wangchuk of the Students' Educational and Cultural Movement of Ladakh raised concerns about the potential for a GLOF event. To mitigate this risk, high-density polyethylene pipes were installed to drain water from the glacial lake.

South Lhonak Lake was identified as potentially dangerous 

A 2021 Study published in journal Elsevier identified South Lhonak Lake as potentially dangerous with a high outburst probability. It noted significant glacier recession in recent years, which has increased concerns about the potential hazard posed by the lake, especially considering the densely populated downstream areas and infrastructure.

The study highlighted the glacier had receded approximately 2 km in 46 years from 1962 to 2008 and retreated another 400 m from 2008 to 2019. This raised concerns about the hazard potential of this lake, as the downstream valley is heavily populated with numerous settlements and infrastructure. 

Overall, these findings and reports highlight the ongoing efforts and concerns related to GLOF events in certain regions of India, emphasizing the importance of monitoring and mitigation measures to protect communities and infrastructure in these areas.

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