Glacial lakes are water bodies that form near, underneath, or on melting glaciers. As these lakes expand, their risk factor increases because their boundaries are usually made up of unstable ice or loose rocks and debris. If these boundaries fail, it results in a massive outpour of water that cascades down the mountains, potentially causing destructive floods in the regions below. This phenomenon is known as a Glacial Lake Outburst Flood, or simply, a GLOF.
What Causes Glacial Lake Outburst Floods (GLOFs)
- There are two types of glaciers: normal glaciers and hazardous glaciers. Normal ones, also known as land terminating glaciers, release water harmlessly. However, hazardous glaciers pose a threat as they can lead to Glacial Lake Outburst Floods (GLOFs).
- These hazardous glaciers have a bowl-shaped region filled with water. If the water volume in this bowl, or lake, increases too much, the moraine wall, which is made up of debris left by the moving glacier, can burst. This results in a sudden, massive release of water.
- Several events can cause a GLOF. A major earthquake can destabilise the moraine, leading to an outburst. Other triggers can include a snow avalanche or landslide entering the lake and displacing water.
- Glacial lakes are typically found in steep mountain regions. This makes them vulnerable to landslides or ice avalanches that can displace water, cause the natural dam to overflow, and result in a flood downstream.
- A tragic illustration of a GLOF happened in 2013. In Uttarakhand’s Kedarnath, flash floods and a GLOF from the Chorabari Tal glacial lake led to the loss of thousands of lives.
- Climate change and increased human activities on glaciers are considered key factors contributing to GLOFs.
The Increasing Risk Of GLOFs In Indian Himalayas
- The Himalayas are facing an escalating risk of Glacial Lake Outburst Flooding (GLOF).
- Numerous GLOFs have occurred in the Himalayas over time, resulting in substantial damage and loss of life.
- The most recent event took place at Lhonak Lake in Sikkim.
- The Himalayas house around 2,000 glacial lakes, and over 200 of these are susceptible to outbursts.
- There are a host of reasons why the threat of GLOFs in the Himalayas is on the rise.
- Himalayan glaciers are melting rapidly due to global warming, shrinking by 20 metres each year.
- This rapid melting increases the likelihood of Glacial Lake Outburst Floods (GLOFs).
- Some glaciers are predicted to disappear in just a few decades.
- In regions like Jammu, Kashmir, and Ladakh, glaciers are the primary source of water.
- In June 2013, unusual heavy rainfall occurred in Uttrakhand. This caused the Chorabari glacier to melt and the Mandakini river to overflow.
- The resulting floods caused widespread damage in Uttarakhand, with the Kedarnath valley being the most severely affected.
- The flood resulted in over 5,000 fatalities.
- GLOFs are not a new occurrence. They continue to pose a significant threat to communities, infrastructure, and the natural environment in downstream areas.
- A study published in 2020 named ‘Glacial Lake Outburst Flood (GLOF) Hazard, Downstream Impact, and Risk over the Indian Himalayas’ was conducted by Saket Dubey and Manish Kumar Goyal. Both of them are from the Indian Institute of Technology in Indore.
- They discovered that the Indian Himalayas have many glacial lakes.
- These lakes can be dangerous for people living downstream.
- If a GLOF (Glacial Lake Outburst Flood) occurs, it could lead to terrible disasters.
- These disasters could have a catastrophic impact on the socioeconomic conditions of these communities.
- Populations living less than 20 kilometres downstream from a glacial lake face a higher risk.
- It’s crucial to monitor and plan for these areas to prevent potential casualties.
- Even though the Western Himalayas haven’t historically experienced many Glacial Lake Outburst Floods (GLOFs), the situation has changed over the past 30 years.
- Numerous lakes have formed in this region, and each carries an outburst potential.