SOUTH LOHNAK LAKE DISASTER (Syllabus: GS Paper 3 – Disaster Management)

Context: Recently, the breach of South Lhonak Lake in the Himalayan state of Sikkim led to a devastating glacial lake outburst flood (GLOF) that affected four districts, resulting in the tragic loss of at least 42 lives, with 77 individuals still unaccounted for. 

• The Sikkim government has been claiming that the GLOF was triggered by a cloudburst. In fact, Sikkim State Disaster Management Authority’s daily reports on deaths and damages continue to call the flood “cloudburst induced”.

Role of Climate Change

• In 1990, the South Lhonak glacier measured 6.4 km in length, but a research article published in 2021 revealed that by 2019, it had shrunk by approximately 1.3 km and its area had decreased by about 0.96 sq. km.
• Back in 1976, the South Lhonak Lake occupied a mere 0.20 sq. km, as reported in a research article from 2018. However, as the glacier continued to diminish, the lake expanded significantly. 

Glacial Lake Outburst Floods (GLOFs)

• About: Glacial Lake Outburst Flood (GLOF) is a type of flood that occurs when a glacier-contained water body is suddenly released.
• Causes of GLOF: GLOFs happen when the natural dam formed by a glacial lake fails, allowing the stored water to flow rapidly. GLOF can be triggered by several reasons, including earthquakes, extremely heavy rains and ice avalanches.