Glacial Lake Outburst Floods

Glacial Lake Outburst Floods
Glacial Lake Outburst Floods

Glacial Lake Outburst floods (GLOF) occur when water contained in glacial lakes, which are dammed by glaciers or moraines (moraines are accumulations of glacial deposits, consisting of soil and rocks, that are left behind by moving glaciers) is released suddenly.

The release of these waters, when the weak structure of the “glacial” or “moraine” dams becomes incapable of withstanding the large hydrostatic pressure of the glacial lake waters which have accumulated behind these dams.


In the recent times, we have seen number of glacial lake outbursts, happening in India, with the most recent one happening in Ladakh. Infact in the recent times, given the effect of global warming and resultant climate change, there is an increasing tendency of the phenomenon. These outbursts cause large scale damage to life and property and has been classified as a potential climatological disaster by the National Disaster Management Plan, 2019.

The article explains the what Glacial Lake Outburst Floods (GLOF) are? followed by a short history of previous occurences , the steps taken by the government to combat this menace and the associated loopholes as highlighted by the National Disaster Management Authority (NDMA) task force report.

The adverse effects of climate change caused by global warming is posing some critical challenges for the Indian Himalayan Region (IHR). Rapidly increasing global temperatures have caused considerable impacts on the life cycle of the glaciers of the IHR triggering rapid meltdown of some large glaciers and consequent expansion of existing glacial lakes and formation of new glacial lakes. This large scale increase in the extent and numbers of the glacial lakes located in the IHR, coupled with the fact that the IHR is located in seismic zones IV and V, (which makes this region prone to earthquakes), long with a host of other environmental disturbances  like avalanche,  falling boulders etc. are making the glacial or moraine dams surrounding the lakes increasingly vulnerable to breaches, resulting in sudden and disastrous floods .

These floods may cause release of extremely large volumes of water, which may go upto about 15, 000 cubic metre per second, within a very small time interval. The time interval may range from minutes to days. These type of floods have the capacity to cause severe geo-morphological hazards, as it not only destroys all manmade structures located on the path of its flow but also result in death and irreparable  damage to human, animal  as well as plant lives. large scale damage to settlements, farmlands have also been reported , which have caused immense harm to the socioeconomic life of the people located in the areas affected by the floods.

Previous Occurrences of Glacial Lake Outburst Floods in India

Although many Glacial Lake Outburst Floods have hit the Indian Himalayan Region (IHR) in the past, and in particular the trans-Himalayan region of Ladakh, only a few have been documented. For example, in the year 1971 a Glacial Lake Outburst Floods had occurred in the Nyoma village located in the Chanthang area of eastern Ladakh. It had resulted in about 13 to 16 fatalities, another Glacial Lake Outburst Floods had occurred in Domkhar village, located in the Leh district of Ladakh in the year 2003. It had caused large scale destruction to farmland and infrastructure. However the most recent and extensively studied GLOF was the one that had occurred in the year 2014, due to the outburst of a glacial lake located in the Gya village of Ladakh. The flood had resulted in large scale destruction of the houses, fields and transport infrastructure of the village. The causes of the floods have been extensively studied and documented by experts, not only from India but also from abroad using the most advanced remote sensing technology.   Studies have revealed that the cause of the outburst was a little known and a unique phenomenon. Instead of a spillover as is expected in case of most GLOFs the debris  field of the glacier debris and water drained through the subsurface tunnels undeneth the moraine. Thus the moraine’s surface was not disturbed by the outburst.

Previous occurrences of Glacial Lake Outbursts Info 1
Previous occurrences of Glacial Lake Outbursts

Due to the presence of large number of glacial lakes Ladakh region is constantly under threat of Glacial Lake Outburst Floods events.

Besides Ladakh another region which have experienced large scale devastation due to Glacial Lake Outburst Floods is Uttarakhand. The flash flood that had occurred in Kedarnath ,on the month of June of the year 2013, was the worst natural disaster that have been experienced by the Indian sub continent since the 2004 Tsunami event. It had caused extensive damage  to life and property , with more than 5700 people being declared “presumed dead”, including the local residents and leaving lakhs of pilgrims and tourists stranded in the valleys leading to the hindu Chota Chaar Dham pilgrimage sites, for many days till they were being rescued by joint operations conducted by the  Indian Army, Indian Air Force, Paramilitary and National Disaster Response Force (NDRF), with aid from the local administrations .

Studies have revealed that the flash flood was caused by two events that had occured simulaneously: one being the excessive water and sediment accumulation in the Mandakini River and its surrounding channels, causing torrential volumes of water and glacial debris to move towards the Kedarnath Town thereby washing off almost the entire upper part of the town. The second event was the overflow and collapse of the moraine dammed Chorabari lake, due to hydrostatic pressure of the large volume of water that have accumulated in the lake due to the torrential rainfall and the meltwaters from a glacier located near the upper part of the lake.

Besides Ladakh and Uttarakhand states such as Sikkim and Himachal Pradesh are also areas which are under threat of catastrophic GLOF events owing to the increase in the number and volume of Glacial lakes in recent years owing to glacial retreats occurring due to global warming.

Government Measures to control the related devastations of GLOF s   

Recognizing the increased threat that is posed by the GLOFs in the IHR, the National Disaster Management Plan, 2019 has recognized GLOFs as a potential climatological disaster. Management of GLOFs has got two aspects: the first is to mitigate the principal cause of the floods i.e. global warming and the second is to manage the disaster itself through an effective disaster prevention and risk reduction mechanism.

Government Measures to control Info 3
Government Measures to control

The government of India has taken concrete steps to address both the above two aspects. In order to address the issue of global warming the Government of India committed to increase its renewable energy capacity through its Intended Nationally Determined Target of installing 175 GW of renewable energy capacity by 2022. Prime Minister Modi in UN Climate Action Summit in September 2019 announced a revision of the target to 450 GW. This has been done  to adhere to the global emission targets, of the 2015 Paris Climate Deal,which will limit the increase in the global temperatures to below 2°C below the preindustrial levels.

To address the second issue the National Disaster Management Authority (NDMA), which is the nodal authority responsible for disaster preparedness and risk reduction at the national level, created in accordance to the Disaster Management Act 2005, has given a set of guidelines to generate public awareness on various aspects of  glacial hazards in India and to outline the suitable actions that are required to be taken to reduce the reduce the risks to lives and socio economic infrastructure  that are  associated with these hazards.

Increased threat that is posed by the GLOFs info 2
Increased threat that is posed by the GLOFs

 These guidelines are designed with the objective of improving the administrative responses, drawing on the international best practices and to bring the scientific capabilities and infrastructure of the nation to eliminate the potential losses that may arise from these hazards.

Ministry of Jal Shakti (MoJS) and The Central Water Commission(CWC) has been designated as the nodal Ministry and Agency respectively for conducting studies on Glacial Lakes and GLOFs. A national centre of excellence, by the name, Centre for Glacial Research, Studies and Management (CGRSM) will be established by the MoJS under the umbrella of National Institute of Hydrology (NIH), located in Roorkee for conducting research studies in collaboration with different premier national as well as international institutions. It will be  fully autonomous in its functioning and will have its own independent budget.

The NDMA has also submitted a proposal to the Central Government to launch a Comprehensive National GLOF Mitigation Project (CNGMP), which will have multiple aims and objectives like assessment and mapping of risks and vulnerabilities of different areas in IHR to GLOF events, reduction in severity of GLOF events, establishment of robust monitoring and Early Warning Systems (EWS) , capacity development, implementation of R&D programs etc.

Besides these NDMA guidelines some states have adopted some unique and scientific approach to prevent GLOFs from occurring. For example, the Government of Sikkim Government in partnership with Ladakh-based NGO, Students’ Educational and Cultural Movement of Ladakh (SECMOL) have started a project to siphon off excess water from the South Lhonak Lake located in the North-Western part of  Sikkim, using high density polyethylene pipes. The South Lhonak lake is one of the 14 glacial lakes in the Sikkim Himalayas  which have been identified as potentially susceptible to catastrophic GLOF events. Records also show that this lake also has a long history of bursting.

Lacunae  as has been seen in development of a holistic set-up to deal with GLOF

If we take into account the large scale widespread loss of life and property during the recent GLOF events such as the disaster in Kedarnath  (2013), clearly shows that lacunae exists in the present disaster management mechanisms of India especially when GLOF comes into picture.

As a matter of fact some of these gaps  have been identified in a  NDMA task force report published recently. Let us discuss a few of them:

Firstly , the construction plans of the present infrastructure especially those located in the IHR region have shown extremely poor adherence to the established  building standards and design codes of India. This has led to a lot of unplanned and unregulated developmental activities in this region like for example construction of poorly engineered or even unengineered roads and poor or even lack of proper drainage  facilities in some areas. These things are collectively increasing the hazard risks due to GLOF events in these areas. It is quite evident that there is a lack of  proper monitoring mechanism to monitor the adherence of development activities to the established design standards and building codes.

Secondly, the building bye laws , which are legal regulations with regards to the design and construction aspects of buildings do-not adequately cover all natural hazards, for example the “Model Building Bye-laws – 2016”, which was put forward very recently by  the Ministry of Housing and Urban Affairs (MOHUA), have no specific mention of GLOF events even though other natural hazards which are happening frequently in different parts of India like earthquakes, landslides, cyclones etc. are included.

Also, as far as land use planning  is concerned, there are no widely accepted guidelines or recommendations with regard to areas prone to GLOF in India.


Also See: Himalayas for dealing with water crisis in India


Wayforward and Conclusion:

Looking at these abovementioned loopholes in the GLOF Disaster mitigation mechanisms, it is quite evident that a robust “techno-legal” framework is necessary so as to reduce the risk, to life and property, associated with GLOF events in the IHR. The NDMA taskforce is of the view that any such framework, when conceived, by the competent authority must take into account the following three aspects:

(i) The framework must include a  “Himalaya GLOF Mitigation Policy based on the latest building standards/regulations at central/state/ local level.”

(ii) It should also include “a Himalaya GLOF Mitigation Strategy which will focus on implementation and strict enforcement of laws/ regulations and accountability”

(iii) Lastly it should have the provisions for demarcating “no habitation/construction zone in the GLOF hazard area as determined from robust and up-to-date hazard and risk mapping studies across the Indian Himalayan Region.”

To implement the abovementioned aspects and to restrict unsustainable development in the IHR, the NDMA task force have urged the central government in its report document to bring in necessary changes in the laws and codes associated with development activities (like for example National Building Code (NBC)-2016, Model Town and Country Planning Bye-laws (2016) etc.). More specifically the report document suggests taking into account the guidelines given by NDMA with regards to management of different types of disasters.

As planning and development is a state subject according to the seventh schedule of the Indian Constitution, the document has urged the various state governments to also make the necessary modifications in their planning legislations, so that the competent authority as designated by the central government, may notify them of the respective regulations for land use management in areas which are prone to risks of GLOF events.

The task force has also recommended launch of large scale mass awareness campaigns with regard to GLOF events.


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