Devastating glacial lake outburst causes flash floods in Sikkim

On October 4th 2023, a devastating glacial lake outburst struck North Sikkim, sending shockwaves across the northeastern state. The lake outburst occurred in Lhonak lake in North Sikkim, resulting in a sudden and alarming rise in the water level of the Teesta River. Atleast 30 people have been reported missing in flash floods and 6 bridges have been washed away between Chumthang and Rangpo. This has severed crucial transportation links.
What is surprising is that scientists and experts had warned about this tragedy as early as 2003 when a series of dams were proposed on the Teesta river. The issue was raised again after the Joshimath tragedy in January 2023. Surrounded by potentially dangerous glacial lakes that can burst and cause floods any time, Sikkim is a ticking time bomb.
Break
Glacial lakes are formed by melting glaciers and sudden discharge of large volumes of water and debris from them is termed glacial lake outburst flood or GLOF. The inventory of glacial lakes in Sikkim Himalaya, prepared using temporal satellite data, shows the presence of 320 glacial lakes.
The situation in Sikkim has escalated further with damage to the Chungthang dam, causing a sudden overflow and a significant rise in water levels in the Teesta River. Eyewitnesses have reported a heavy inflow of muddy water in water bodies throughout the Mangan district.
In response to this critical situation, residents of Tista, Rangpho, Singtam, and other adjoining areas have been urged to evacuate their homes and relocate to higher-altitude regions for their safety. Authorities are actively monitoring the situation and coordinating rescue and relief efforts.
According to Gyatso Lepcha, an environmental activist in North Sikkim, both Sikkim and Joshimath are located in the eastern Himalayas and are facing the same challenges and predicaments. Apart from the dams, numerous pharmaceutical companies and rampant unnecessary road widening, smart city projects and congested urban planning are putting more pressure on the ecology, he added. “It is leading us to nowhere but environmental disasters.”
According to satellite mapping studies, 21 glacial lakes in Sikkim, including Gurudongmar lake and Kangchung lake, have the potential to cause dangerous outburst floods in the region.
Glaciers in the Himalayan region are considered as the freshwater tower of South and East Asia and are strongly affected by the ongoing climate change. However, Glacier retreat and mass loss have resulted in a rapid increase of unstable glacial lakes.
The impact of this glacial outburst in North Sikkim is a stark reminder of the vulnerability of the region to natural disasters, underlining the need for efficient early warning systems.

Down to Earth is Science and Environment fortnightly published by the Society for Environmental Communication, New Delhi. We publish news and analysis on issues that deal with sustainable development, which we scan through the eyes of science and environment.