GLOF part 1– A threat present and real: Indian summary (VIDEO)

Posted on | augustus 10, 2011 | No Comments

GLOF Part I On August 4, 1985 the Dig Tsho (Tsho-lake), in the western section of the Sagarmatha (Mt. Everest) National Park, Khumbu Himal, Nepal breached the moraine releasing 8 million cubic meters of water that rushed downstream. The lake burst destroyed the Namche Small Hydel Project on its wake and claimed 5 lives. The world record holder, Apa Sherpa, who scaled Mount Everest for the 21st time in May 2011, narrowly escaped to save his life but his native village of Thame was completely washed away.

This was not just another natural disaster and don’t get spoofed by the low casualty statistic (in India we have grown stoic to news of loss of life in hundreds every few months). This was a forewarning of a chain of imminent such great disasters whose cause and reason have been studied and understood by scientists rather well. In scientific parlance this is known as GLOF or Glacial Lake Outburst Flooding. GLOFs are believed to be connected to climate warming. The real bad news is:  the Himalayas are warming faster and higher than the global average. As the temperatures in the Himalayas soar, the glaciers retreat leaving behind molten water filled lakes, moraine dammed and precariously holding huge amount of waters in very unstable geo-morphology.

Don’t you think it will be a somewhat disturbing sight if you come back to your mountain home after a couple of decades and find a lake where, in your childhood, you used to run or fly kites? Take Lake Imja for example. In 1960 there were a few small ponds where presently the lake stands storing 38.5 million cubic meters of water on a fragile balance high up at 5000 m altitude. This is a potential candidate for an oncoming GLOF.

These lakes are just not supposed to be there.

Warming TrendThis malady is not unique for Himalayan people. Glacial lake outburst floods have long been known to occur in different parts of the world. In 1941, an outburst flood destroyed the city of Huaraz in Peru killing 4,500 people (Lliboutry et al. 1977). Outbursts from a glacier-dammed lake in the Swiss Alps in 1968 and 1970 triggered debris flows and caused heavy damage in the village of Saas Balen. The 1968 event eroded about 400,000 cubic meters of debris (Horstman 2004). But in the Himalayas this assumes a threat of catastrophic proportions as the Himalayas has the greatest concentration of glaciers out of the Poles. More importantly the HKHR or Hindu Kush Himalayan Range in 4 countries, namely India, Pakistan, Bhutan and Nepal the threat increases multifold on account of population, urban penetration in higher altitudes, struggling economies invested with considerable infrastructure in the mountains and poor to non-existent integrated management of water resources.

The reason why India stands out as one of the most Climate threatened countries is this. A vast swathe of the Himalayan Mountains  lies  in  India  with  a large  number  of  glaciers  in  the States  of  Jammu  and  Kashmir, Himachal Pradesh, Uttarakhand, Sikkim and Arunachal Pradesh. These glaciers and  others  which  lie  across  India’s  borders sustain the major Indian river systems of the Ganga,  Brahmaputra,  Indus,  Sutlej,  Beas, Chenab, and other water bodies, ensuring a year-round water supply to millions of people downstream. The  Indian  Himalayan  region  is  home  to over  7,000  glaciers  covering  an  area  of  8,500 km. They play a crucial role in shaping and influencing the environmental conditions in India.  Siachen, Gangotri, Zemu, Milam, Bhagirath, Kharak and Satopanth are  some of the important glaciers located in the Indian Himalayan region. Around 968 glaciers drain into  the  Ganga  basin  in  Uttarakhand,  over 4,660 glaciers feed the Indus, Shyok, Jhelum and  Chenab  river  systems,  the  Ravi,  Beas, Chenab and Sutlej river systems are fed by 1,375 glaciers, and 611 glaciers drain into the Tista and Brahmaputra basins, and contribute between  50  and  70  percent  of  their  annual discharge. Most of these glaciers are retreating and their overall dimensions are diminishing. Studies conducted on different Indian glacier systems over the past two decades indicate an average annual retreat rate of between 2.6 metres and 40.5 metres.

In India, the state of Himachal Pradesh is the most vulnerable to the GLOFs. Ironically, Himachal Pradesh is one the smallest Indian states with remarkably high indicators of human development and growth with high literacy rates, bountiful natural resources and a distinct physiographic identity. Almost 50 percent of the population lives in three of the state’s twelve districts:  Kangra,  Mandi  and  Shimla. Around  7.54  percent  of  the  total  population reside, in the three least populated districts of Lahaul and Spiti, Kinnaur and Bilaspur. It is within Shutlej basin and Himachal Pradesh  Himalayas,  there  are  2554  glaciers, with  156  glacial  lakes,  16  of  them  being potentially dangerous. Kinnaur is particularly threatened as it lies just at the downstream of Tibetan Shutlej and it is speculated that there are as many as 24 glacial lakes in Tibet that are potentially dangerous for Kinnaur and Himachal Pradesh. In the

1997 floods, six bridges were washed away in the Sutlej basin and Kinnaur district was completely cut off. The year 2000 and 2005 (Parechu river lake  burst  in  Tibet)  especially  caused  heavy destruction of livelihood, infrastructure and loss of life in the basin, particularly in Kinnaur and the eastern part of Shimla districts. Two most problematic glacial lakes to keep careful eye on are Shutlej_gl 7 and Shutlej_gl10 (as per ICIMOD inventory).

Studies after studies confirm that almost all glaciers of Indian Himalayas are leaving glacial lakes with increasing intensity, which in fact is corroborating with the intermediate effects of long term Climate Change by majority of Climate scientists. Though IPCC’s mistaken report about a definitive year of predicted complete loss of Himalayan Glaciers earned a lot of criticism, it does not require a rocket science to see the damaging effects of GLOFs over a few decadal scales:

  1. Enormous loss of property, infrastructure and life that can cripple the local as well as national economy.
  2. Huge ecological losses those are common after natural disasters and related resource crises.
  3. Worsening stress on national water cycles and downstream effects like lesser navigability in ice fed rivers of Ganga and Brahmaputra.

As a professional I feel that any grand engineering intervention to prevent this is an utopian idea in Indian context – the scale is simply enormous beyond any feasible engineering solution.

What then are we to do in the face of such real and present danger? I shall come back on human response to such threats in India, which I assure is a mind blowing story of indomitable spirit and innovation of humanity. As a teaser, I leave this.

Ants can eat a dead elephant when jackals give up- An old Indian proverb.

 This post is a small tribute in appreciation of the ‘Iceman’ Chewang Norphel.


  1. ICIMOD article: Formation of Glacial lakes in Hindu Kush Himalayas and GLOF Risk Assessment.
  2. GLOF – Risk Reduction in the Himalayas Project A UNDP-ECHO Initiative 

This coverage was first published at Climate Himalaya.

AUTHOR: Pabitra Mukhopadhyay
E-MAIL: mukhopadhyay.pabitra [at]


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