What is GLOF? Which caused catastrophic floods in Sikkim killing 30 people so far. Read to know more

Copy edited by Lipika Roy

After the glacial lake outburst flood (GLOF) occurred at the Lhonak Lake in the Chungthang area of North Sikkim and caused a flash flood in the Teesta river basin on Tuesday night at least 30 people died and over 100 others, including 22 army personnel, are still missing.

The powerful floods caused by the GLOF completely destroyed vital infrastructure, roads, and houses while threatening people’s lives, and livelihoods in the Himalayan state.

In this article, you will find what GLOF is, why it occurs, how disastrous it can be, what factors contribute to the occurrence of GLOFs and how it can be dealt with.

What is Glacial Lake Outburst Floods (GLOFs)?
The sudden release of water from glacial lakes causes devastating natural disasters that are called “glacial lake outburst floods” (GLOFs). For the protection of sensitive areas and populations, it is necessary to comprehend the causes, methods, and contributing variables that contribute to GLOFs.

The natural dams that hold back glacial lakes and are made of ice, rock debris, or moraine collapse or are breached, resulting in flash floods of exceptional magnitude. The melting of glaciers in high-altitude regions is usually what causes these glacial lakes to emerge.
It becomes problematic when the water builds up in depressions that are frequently blocked by glacial debris or ice dams.

How do GLOFs occur?

GLOFs are caused by a number of factors, the main one being the increased glacier melting brought on by the increase in global temperatures. Glacial lakes grow in size as a result of the glaciers feeding water into them as they melt.

Another reason is ice dam failure, which occurs when the amount of water in these lakes exceeds the capacity of the natural dam, which is frequently made of ice or moraine. When this happens, the dam may weaken or shatter, releasing a torrent of water downstream.

Another major factor is various triggers, such as earthquakes, avalanches, or landslides, which can induce ice dam failure.
The release of water can be abrupt and disastrous once a GLOF has been started. Rapidly flowing down valleys, the massive amount of water gains deadly power.

In addition to their rapidity, floods are very dangerous because they transport boulders, debris, and sediment downstream. This creates a catastrophic force that can destroy villages, agricultural land, and infrastructure.

Is the cloudburst in Sikkim related to October 3 Nepal Earthquake?

There are speculations that the 6.2-magnitude earthquake that struck Nepal the day before may have caused the eruption.
It could be the reason because earthquakes shake loose the ice or debris, weakening the dam and causing it to give way.

Factors contributing to the occurrence of GLOFs?
In recent years, the frequency of GLOFs has increased due to a number of factors, such as:

1. Climate Change: As the earth’s climate warms, glaciers melt more fast, causing glacial lakes to enlarge and become unstable.
2. Glacier Retreat: In the downstream regions, additional rock and debris can accumulate and create unstable natural dams when glaciers shrink and retreat, exposing more of these elements.
3. High-Risk Zones: Infrastructure and residences close to glacial lakes are particularly vulnerable to GLOFs. The threats are made worse by the rapid urbanization and development of these areas.
4. Monitoring and Early Warning: Inadequate monitoring and early warning systems in many affected areas limit the ability to predict and respond to potential GLOFs.

Threat to India

In the Himalayas, 25 glacial lakes and water bodies have witnessed an increase in water spread area since 2009 posing a huge threat to Sikkim, Assam, Arunachal Pradesh, Jammu and Kashmir, Ladakh, and Himachal Pradesh.

Also Read: Sikkim flash floods: 30 dead, search for 22 army personnel continues