What happens when we do not take any actions regarding warming? What will be affected at first? High mountains are most vulnerable to climate change, glacier melt being a significant concern. These melts result in one of the scariest disasters, GLACIER LAKE OUTBURST FLOODS (GLOFs).

Glacial Lake Outburst Flood (GLOF) is the sudden rise of the water retained in the glacial lake. It has always been an issue of public concern. 

Due to anthropogenic-induced interventions and natural causes to some extent, massive Glacial Lake Outburst Floods have triggered numerous sectors in our daily lives.

It is the primary cause of the dam failure entailing a glacial lake. Globally, multiple events concerning the Glacial Lake Outburst Floods (GLOFs) have occurred so far, as described in brief.

1. Dudh Koshi (Nare lake), Nepal

Dudh Koshi River aerial tour | Video Credit – Namaste World

On September 3, 1977, a massive, devastating catastrophe led by the Glacial Lake Outburst flood in Dudh Koshi of Nepal. The cause behind this critical event was the collapse of a moraine

The rapid water inflow caused Nare lake to destroy its end-moraine dam and discharge in the Imja river. And later, the flood moved towards the Dudh Koshi. 

Through investigation, the researchers predicted 4*10^5 cubic meters’ water released from the Nare lake. There was peak discharge of the water, roughly 800 cumecs. 

Almost all the bridges which covered the downstream valley were destroyed. Considerable accumulation of the debris flow as a cause of flood would be visualized with ease.

The Dudh Koshi valley was filled with debris flow even after the two years’ mountain hazard mapping by the reconnaissance group from the United Nations University

Three people were found dead and have mostly damaged the property of the human lives.

2. Dudh Koshi (Dig-Tsho), Nepal

one of the largest glacial lake outbursts in dig-tsho
One of the largest glacial lake outbursts in dig-tsho | Image Credit – Flickr

Dig-Tsho is considered one of the largest glacial lake outbursts as a cause of the end moraine of the Langmoche Glacier. It is located in the west part of Sagarmatha National Park. 

On August 4, 1985, there was massive catastrophic drainage of the Dig-Tsho due to the ice avalanche.

In the Nepal Himalayas, this glacial outburst flood is inferred as the largest moraine-dammed proglacial lake. It had affected almost 10 kilometers of downstream valleys, and four people lost their lives.

Most troublingly, it caused severe damage in the main trekking route of the Mt. Everest base camp. 

It severely influenced the trekking season. Due to the ice avalanche, a steep glacial surface was hit and suddenly fell into the lake. 

The heavy destruction of the dam and the glacial lake outburst impacted the channel across the lake.

It caused 6-10 million cubic meters’ water to drain from the lake within four hours. The water discharge had reached roughly 500 cumecs. 

The instability and even the landslides in the region cause severe hamper destroying all the area’s lives, natural beauty, and landscape.

The ice avalanche generated a wave roughly 5 m high, and within four to six hours, the lake drained almost completely. 

It had affected the almost completed Namche Small Hydropower Plant, thereby causing a loss of US$ 1.5 million.

3. The Lugge Tsho Glacial Lake Outburst Flood, Bhutan

1994 Lugge Tsho Glacial Lake Outburst Flood in Bhutan | Video Credit – Olivia Tyler

The Lugge Tsho Outburst Flood in Bhutan occurred on October 7, 1994 in the upper part of the Pho Chuu, covering the eastern tributary. 

The scientists and the researchers recorded the partial outburst of Lugge Tsho as the cause of this flood. 

Due to the ice melting, there was enormous hydrostatic pressure. In turn, the moraine dam failed, and there occurred the increment in the lake depth causing the Lugge Tsho Outburst Flood.

It devastated the East Pho Chhu Valley, a large number of houses in Chozo village situated at an elevation of 4000 m. The Thanza and Tenchey villages were entirely flooded. 

The glacial outburst flood also washed away the bridge which connected the two villages. The water swept and collected the large piles of the debris and the logs.

It has been revealed that the river returned to its original channels after breaching the river bank. 

It had affected several sectors such as water mills, pasture lands, bridges, paddy fields, and much more. Roughly 21 people lost their lives, with one dead body detected in Bangladesh.

Several fish species could not survive during a flood due to the muddy water, and they became graveyards within the flooded water. It took more than ten years to be in its original state to recuperate the fish population once destroyed.

The Lugge Tsho Glacial Lake Outburst Flood occurred at night. No person was available to warn the downstream valley; thus, Punakha suffered massive catastrophic damages. 

There seems to be a very high risk for the downstream valley people once the gigantic glacial lake outburst flood occurs.

4. Glacier-dammed lake 3 Outburst Flood in Switzerland

Around 1968, Glacier-dammed lake 3, Outburst Flood, occurred in Switzerland, thereby causing heavy destruction in the village of Saas Balen. 

The glacial flood outburst massively eroded roughly 400,000 cubic meters of debris. The research reveals that it is equivalent to around 1000 detached family houses. 

The same lake was burst for the second time in the year 1970. Since the glacial lake outburst occurred twice, it indicates the hazardous situation of the lake. 

It requires the utmost attention to research widely and carries the necessary actions to prevent it from worsening in the coming days. 

5. Nanda Devi Glacier Lake Outburst Flood, Uttarakhand, India

Nanda Devi Glacier Lake Outburst Flood, Uttarakhand, India
Nanda Devi Glacier Lake Outburst Flood, Uttarakhand, India | Image Credit – India Today

A glacier burst triggered by a Nanda Devi glacier led to a catastrophic flash flood in Sumna village of Chamoli Garhwal district, near the India-China border of Uttarakhand, India, on February 7, 2021. 

The residents near Alaknanda and Dhauliganga rivers had to be evacuated several kilometers away.

It caused massive devastation basically in the high mountainous regions. Additionally, the outburst flood caused direct damage to the two hydropower projects known as the Rishi Ganga Hydel Projects and NTPCS’s Tapovan-Vishnugad Hydel projects.

The rescue teams discovered that many laborers working in the tunnel (road construction activities) would have been trapped there for several hours or even days. 

The great cause behind this catastrophic bursting of the glacial lake is the continuous massive snowfall in the region. Over 150 people were recorded missing and took the lives of over 200 people. 

There was an enormous flood in the Dhauli Ganga river, making the whole region fragile in terms of the ecosystem.

Besides this, another cause of this devastating glacier lake outburst flood in Uttarakhand of India was the avalanche that fell roughly 27 million cubic meters of rock and the glacier from nearby Ronti mountain. 

In the past, the snow used to occur in winter and the floods in the monsoon in that region, but surprisingly, the event took place during February. It may be due to the climate change-induced effects in the glacier lake.

6. Lemthang Tsho Glacial Lake Outburst, Bhutan

The Lemthang Tsho glacial lake Outburst event occurred in the Gasa district of the north-western part of Bhutan on July 28, 2015. 

Due to the moraine dam associated with the lake and the mother glacier at the foreground, this glacier lake is predicted to be one of the 24 potentially dangerous glacial lakes.

The significant cause behind this devastating glacial lake outburst was the sudden collapse of the ice scarp from the upper supraglacial pond. 

Rising in the lake water and increment in the hydrostatic pressure caused the outflow discharge at an extensive rate and later increased the erosion with outlet widening.

Such a catastrophic event led to the damage of four larger bridges and one care of the agricultural land. The 148 pieces’ timbers piled up along the riverbed were washed up. 

Around 1 km of the trail was damaged resulting from the flash flood. It has been estimated that the net loss of this catastrophic event was 0.976 Nu. Million.

The other effect behind this event was the loss of a 14 km stretch between Kohina and Gasa. 

The harsh climate and the barren steepness would have impacted the downstream valley due to the sediments’ increased accumulation and transportation from one region to another. 

Glacier melting seems the great cause to occur, this event stressed by several researchers

Conversion of the grazing land to debris accumulation, hillslope erosion may be frequent once such an event is likely to happen once and again.

7. Ghulkin Glacier Lake Outburst, Pakistan

Ghulkin Glacier Lake Outburst, Pakistan
Ghulkin Glacier Lake Outburst, Pakistan | Image Credit – Research Gate

Ghulkin Glacier Lake was an outburst in Karakoram, Pakistan, in the year 2008. The colossal cause of this event was the moraine collapse. 

It had caused several damages to the land and the infrastructures of the Ghulkin village. 

The glacier lake flooding severely impacted the Karakoram highway in the upper Hunza valley of northern Pakistan on a massive scale.

Since there was a rockfall in 2005, the residents depicted that there might be an increase in the debris accumulation mainly in the coming years. Unfortunately, the glacial lake triggered flash flood-impacted. 

During the May and June of 2008, the three glacial lake outbursts occurred, signifying a giant disaster in Pakistan history.

Among the three events in 2008, Ghulkin Glacier Lake Outbursting on May 25 and June 14 was the largest. 

Immediate impacts entailed a loss of livestock, agricultural lands, and cattle sheds. Apart from these, this disaster affected four irrigation channels. 

These irrigation channels resulted in drought in Borit village in 2008 after massive glacier lake outbursts hit the Ghulkin village. 

The glaciologists support that the terminus overrode the terminal moraine on the northern side.

Once there is channel choking caused by the boulders through the moraine, there may be variation in the channel flowing of the river, thereby influencing the associated valleys and the regions. 

8. Jinwuco Glacial Lake Outburst Flood, Jinwuco of Tibet, China

Jinwuco Glacial Lake Outburst Flood occurred in eastern Nyainqentanglha, Jinwuco of Tibet on June 26 in the year 2020. 

The huge cause of this flood was the occurrence of a debris landslide from a steep lateral moraine. 

The researchers associate this event with the anthropogenic-induced climate change effects. 

During the incident at the dam side, there was a peak discharge of 5602 cubic meters per second on average. 

The south Asian monsoon-associated torrential rainfall was estimated to trigger such a devastating event in Tibet of China.

During the event, ten residential houses were destroyed. 43.9 km of the road that connects Zhongyu township government seat to Yigacun has been washed away. 

There was the washing of six steel bridges, one suspension bridge, and one associated concrete culvert. 

Roughly 3.15 ha of the artificial grassland was destroyed, entailing the forage lands. 9.07 ha of forest was reserved for the soil, and the water conservation project was hampered. The glacier lake outbursting led to around 7.7 km of flood.

Most troublingly, 25 corrugated pipes and Yoga view Project accounting for 8.4 million were flooded completely. 

The impacts, as mentioned earlier, have created severe influences in the farmland, forest, grasslands, and physical infrastructures such as roads and bridges.  

9. A rockfall induced Glacial Lake Outburst Flood, Upper Barun Valley, Nepal

Serene View of Upper Barun Valley
Serene View of Upper Barun Valley | Image Credit – Flickr

On April 20, 2017, dangerous flooding triggered by the glacial lake outbursting occurred in the remote Barun Valley in the eastern part of Makalu-Barun National Park. The debris accumulation had dammed the floodwaters and reached the Barun Bazaar village.

Outbursting of the lake threatened multiple downstream villages, including Dining, Phaksinda, Lumningtar, and Chetabesi. 

It displaced roughly ten families from their original homes. Since the dam failed immediately, it threatened to hamper 80 families residing nearby the area.

The glacial lake-induced flood formed two-three kilometers in length and a 500 m wide lake at its confluence attached with the Arun river. 

The government recently approved the Upper Arun hydropower project, which was too threatened by a rockfall-induced Glacial Lake Outburst Flood in the upper Barun Valley of Nepal.

There was massive destruction of the extensive pastures and the forest lands. The study lamented the deaths of 24 yaks and dzo (a yak-cattle crossbreed). 

Most surprisingly, there was an erratic flood channel, and when the flood reached downstream, the flood channel became more uniform.

10. Gay Glacial Lake Outburst Flood, India

Gay Glacial Lake Outburst Flood
Gay Glacial Lake Outburst Flood | Image Credit – The Hindu

Glacial Lake Outburst Flood hit a gay village in Ladakh of India on August 6, 2014. The cause of this Glacial Lake Outbursting was ice cores thawing in the moraine

Despite an elevation at 5400 m, the Gya lake almost covers the ice even during summer. 

The flood entirely damaged the channel constriction with several pillars. There was damage to the irrigation canal and the small footbridge. 

Roughly 4000 square meters of the cultivated land situated in the orographic right side was too eroded. Partly damaging occurred in the two watermills. 

Over 2 m depth of the flood in the village has devastating impacts basically in the motorable concrete bridge.

Gay villagers in 2014 who faced the Gya Glacial Lake outburst flood reveal that the rise in the lake water may be increment due to the tunnel blockage or the effects of climate change

Additionally, the results of the heatwave increment may have caused the meltwater increase in the glacial lakes so far.

Concluding Remarks

Glacial Lake Outburst Flood seems a severe matter. Once it hits the downstream valley at both spatial and temporal scales, it holds for the massive destruction of various sectors. 

All these Glacial Lakes Outburst Flood was the crucial cause of the ice avalanches, moraine dam, increment in the lake water level as a cause of heatwave increase. 

These glacial flood outbursts provide us with an insightful lesson to halt the climate crisis issues and prepare ourselves before the glacial lakes bursting incident occurs. 

Heavy investment in the research targeting the glacial lakes, emergency preparedness, and the adaptation practices to such disasters looks pretty substantial in the coming days and building a sustainable nation. 

Kalpana Ghimire holds a post-graduate degree in Environmental Science from Nepal. She possesses numerous research experiences working in water pollution, community forestry, environment conservation status, and wildlife ecology. She was an internee in the Department of Environment (EIA monitoring and auditing section) under the Government of Nepal. Kalpana Ghimire is an avid traveler, an enthusiastic wildlife researcher, and has a huge passion for working in the environment sector. She loves far traveling to the natural areas, conducting field wildlife research and reading the novels.