Satellite Images Offer Clues to Causes of Glacial Lake Flooding

(from journal article: Field observations for glacial lakes: (a) the rapidly expanding Lake Longbasaba in 2012; (b) an areally increasing glacial lake at the Middle Rongbu Glacier near Mount Qomolangma (Everest) in 2008.)
(from journal article: Field observations for glacial lakes: (a) the rapidly expanding Lake Longbasaba in 2012; (b) an areally increasing glacial lake at the Middle Rongbu Glacier near Mount Qomolangma (Everest) in 2008.)

Satellites are now allowing us to track the behavior of icy glacial lakes on the Himalayan Mountains–in particular the conditions that lead to glacial lake outburst floods (GLOFs), which have become increasingly frequent in the region over the past 20 years.

Researchers from the Institute of Mountain Hazards and Environment and the State Key Laboratory of Cryosphere Sciences in China published a study in PLOS One in December of last year that catalogued data from lakes in the central Himalayas between 1990 to 2010.

The scientists, Drs. Yong Nie, Qiao Liu, and Shiyin Liu, used images from Landsat scientific satellites to count and measure glacial lakes in the region. As the longest running remote sensing project, Landsat has over 40 years of images available across the globe.

(from journal article: Distribution of glacial lakes in the central Himalayas)
(from journal article: Distribution of glacial lakes in the central Himalayas)

GLOFs – floods that occur when a lake dammed by a glacier or glacial moraine is released – are hazardous to communities located at elevations below the burst lake. Flooding and debris flows damage infrastructure, cause property loss, and can take lives, as GlacierHub has reported in prior posts. It is widely believed that rising temperatures due to climate change and reduced albedo of the ice from cryoconite (also known as carbon dust particles) are melting the glaciers at higher rates and causing lake volumes to rise, which in turn increases the risk of GLOF events. But the specific processes that lead to GLOF outbursts are not well understood.

By looking at lakes at four time points (1990, 2000, 2005 and 2010), at different elevations (from 3,500 to 6,100 meters), of different types (pro-glacial and supraglacial), and of varying sizes, the researchers were able to identify which lakes expanded faster and burst more frequently to understand which ones pose the greatest risk of GLOFs.

A GLOF from above in Alaska’s Kennai Peninsula (Travis S./Flickr, some rights reserved)
A GLOF from above in Alaska’s Kennai Peninsula (Travis S./Flickr, some rights reserved)

Overall, it was found that total lake surface area for the 1,314 lakes in the central Himalayas had increased over the 20-year period. Drs. Nie, Liu and Liu found that more lakes on the northern side of the central Himalayan range were expanding rapidly. They also found that pro-glacial lakes (lakes at the terminus of a glacier) grew faster than supraglacial lakes (lakes on the surface of the glacier). Some pro-glacial lakes are connected directly to glaciers while others are not, but those that were connected grew far faster. Additionally, larger pro-glacial lakes were likely to flood sooner than smaller ones and more changes to glacial lakes occurred at the altitudes between 4,500 and 5,600 meters.

The dynamics of alpine glacial lakes are complex, but this study could help communities monitor lakes at high risk of flooding and to create early-warning systems and disaster preparedness plans.

PAPER DOI: 10.1371/journal.pone.0083973.g002

GLOF aftermath in Peru ( Will McElwain/Flickr, some rights reserved)
GLOF aftermath in Peru (Will McElwain/Flickr, some rights reserved)

Flooded with memories in Nepal

Trail in Pharak. (Pasang Sherpa)
Trail in Pharak. (Pasang Sherpa)

I was born and raised in Kathmandu but Monzo has always been the place I call home. Monzo is where my paternal grandmother spent all of her life tending our fields and looking after our ancestral home. Monzo is also the place where my father was born and raised until he left for Kathmandu to attend school. I visited Monzo with my brothers every year during our school breaks.

From my village in Monzo in the Sherpa region in northeastern Nepal, we need to walk at least a day, depending on how fast we go, to get close to the glaciers higher up in the mountains. Because we can’t see the glaciers until we get closer to them, we don’t talk much about them. But we sometimes talk about glacial lake outburst floods (GLOFs).

In 1985, the year I was born, a high mountain lake, Dig Tsho, flooded. Although the flood came long time ago, I know about it from the stories I have heard throughout the years. My father always talked about it as we passed through the scars from landslides and the places where there were once villages, including my maternal grandmother’s natal village.

Rock painting in Khumbu. (Pasang Sherpa)
Rock painting in Khumbu. (Pasang Sherpa)

Often times, growing up, I would hear my grandparents say that some things are nomdok (inviting misfortune). Talking about bad experiences like the Dig Tsho GLOF was definitely one of them. It destroyed houses and fields, took lives and caused great distress. So, talking about GLOFs is not the most appropriate cultural thing to do from my grandparents’ perspective. But it is my hope that having conversations about them will let us prepare for an uncertain hazard-prone world of changing climate and bring us good karma in the long run.

After finishing high school in Nepal, I left the country to continue my education. Several years later, I returned to the Sherpa region to conduct research for my dissertation at an American university. During that time, I asked my aunt—actually a friend of my parents from Monzo who I called “aunt” –whether I could interview her about her experience with the Dig Tsho flood. She agreed to talk with me, but at first did not remember the event. She had not spoken about the big flood with anyone for many years, because it had happened far in the past, and there was no need to recall those stressful moments of her life. But when I persisted in asking about the big flood that came many years ago when she was young, she opened up. She was with her mother in their potato field weeding the bean plants when she heard loud noises that sounded like the thunder that lightning produces.

Rock painting in Pharek. (Pasang Sherpa)
Rock painting in Pharek. (Pasang Sherpa)

She said, “I remember the villagers calling us to come up and see what was going on on the other side of the Dudh Koshi [the major river in the region]…It was like a movie. People were running up the hill as the water below engulfed trees and rocks…so fast.”

Unlike other villages in Pharak in the central part of the Sherpa territory, Monzo is not close to the Dudh Koshi, which is fed by the mountain glaciers up north including Dig Tsho to the left and Imja Tsho to the right. So, my aunt and her family were safe but they were terrified by the experience. After the flood, her family and neighbors took shelter under a giant rock and stayed for several hours. Under the rock, they cooked potatoes, shared tales of what they saw and heard. They returned home only when the night came.

Planting potatoes. (Pasang Sherpa)
Planting potatoes. (Pasang Sherpa)

Nowadays, many people in the Sherpa region talk about the potential Imja GLOF. We have heard about the expanding Imja Tsho and the destruction it could cause to our villages. Most of this information comes to our villages from the media, the scientists and NGO sponsored projects that organize workshops there. When there is heavy monsoon rain, my maternal grandmother and her children, my uncles and aunts, worry about the rising water levels in the river. They live in Thumbuk, a village below Monzo, which is close to the river. The discussions about Imja Tsho flooding that have now spread throughout the villages leave the villagers more with a sense of dread than with a feeling of preparation.

Several years ago, my uncle and his wife found themselves running for their lives along with other villagers after they received a phone call from their friends in a different village that told them the Imja Tsho was flooding. This was later found to be a rumor spread by some people from Khumbu, a much higher Sherpa area close to the Imja Tsho. They were alarmed by a recent information-sharing workshop that discussed the potential Imja GLOF and showed its likely path of destruction, including several middle-elevation Pharak villages that would be directly affected. Among the people who fled was a young mother with her newborn child. They found refuge in their wet potato field on that cold, rainy night. The great discomfort that they experienced brought to mind my grandparents’ concern that talking about misfortune was nomdok. Even well-intentioned discussions can create misunderstanding, confusion and fear, and lead to harm that might otherwise be avoided.

This guest post was written by anthropologist Pasang Yangjee Sherpa of Penn State.  If you’d like to write a guest post for GlacierHub, contact us at glacierhub@gmail.com or @glacierhub on Twitter. 

 

In Kyrgyzstan, not all glacier lakes are monitored equally

https://www.flickr.com/photos/depenbusch/14244010047/in/photostream/
Two people riding horse in Ala Archa National Park, about 40km south of Kyrgystan’s capital Bishkek. Glacier lake levels in the mountains surrounding the city are monitored by the government, especially considering that lake outbursts are on the rise. (Thomas Depenbusch/Flickr)

As the temperature rises and glacial lakes grow, the Kyrgyzstan government is monitoring some glaciers while neglecting others.

Kyrgyzstani officials are closely studying the 18 growing glacial lakes on the Adygene Glacier to predict glacial hazards. Since these glacial lakes are located above Kyrgyzstan’s capital, Bishkek, glacial lake outburst floods could potentially flood the valley, endangering a million people.

As glaciers are retreating, glacial lakes are growing and forming. This poses the risk of a glacial lake outburst, a kind of megaflood that occurs when dams holding back glacier lakes fail. Incidences of glacial lake outbursts are increasing. In 2007, the United Nations Environment Program classified floods from glacial lakes as the largest and most extensive glacial hazard with the highest potential for disaster.

The rock-dammed Ala-Kul lake in the Terskey Alatau mountains. (Evgeni Zotov/Flickr)
The rock-dammed Ala-Kul lake in the Terskey Alatau mountains. Floods from glacial lakes are the largest glacier-related disaster.(Evgeni Zotov/Flickr)

An additional threat comes from the underground ice plugs that dam these lakes. These plugs thaw slowly, feeding water into the Ala-Archa River. But a sudden melting could create an outburst of water and develop into a large, destructive mudslide and debris flow.

In recent history, glacial lake outbursts have already impacted Central Asia. In 1998, one such event claimed more than a hundred lives in Batken Province in western Kyrgyzstan. In 2002, an outburst at Tajikistan’s Pamir Mountains claimed 23 lives. In both cases, early warnings of floods were not available. If a similar disaster occurred on the Adygene Glacier, many thousands of lives could be claimed, since the capital downstream is densely populated.

Today, the Kyrgyzstani government is closely monitoring the glacial lakes above Bishkek and preparing organized emergency plans for evacuation. The government has allocated $15 million to build a drainage channel and automatic monitoring stations. When the sensors detect a critical increase in the water level, they trigger alarms in the valley to warn people to flee to safer ground away from the river valley.

Glaciers above the capitol Bishkek are closely monitored in case of flooding. (Jessica Gardner/Flickr)
Glaciers above the capitol Bishkek are closely monitored in case of flooding. A potential flood could endanger a million people. (Jessica Gardner/Flickr)

The government has not allocated resources equally for all hazardous glacial lakes in the country. Officials blame the unequal monitoring on the lack of government funds. In particular, there is no monitoring in the southern province of Osh, which has a population of one million. The province has been scarred with ethnic tension between the Kyrgyz and Uzbeks. Kyrgyz make up 68 percent of the population and Uzbeks account for 30 percent. Over the years, the conflict cost thousands of lives on both sides. After the 2010 Osh riots, Uzbeks have been strategically disenfranchised and internally displaced by the dominant Kyrgyz who dominate the government. Disputes over natural resources, land and water could easily escalate ethnic violence. The lack of preparation for glacial lake outburst floods creates a risk of a disaster that could worsen the existing ethnic tensions.

Glaciologists predict glacial lakes will continue to around the world. Developing monitoring systems for glacial lakes near glacier communities is necessary to prevent massive loss. These initiatives should extent to all communities regardless of their economic, political or ethnic status.