GLOF Risk Perception in Nepal Himalaya

Khumbu valley Mt. Everest region Nepal on GlacierHub
Overlooking a village and glacial river in the Khumbu valley, Mt. Everest region of Nepal (Source: Matt W/Flickr).

Glacial lake outburst floods (GLOFs) pose a significant, climate change-related risk to the Mt. Everest region of Nepal. Given the existence of this imminent threat to mountain communities, understanding how people perceive the risk of GLOFs, as well as what factors influence this perception, is crucial for development of local climate change adaptation policies. A recent study, published in Natural Hazards, finds that GLOF risk perception in Nepal is linked to a variety of socioeconomic and cultural factors.

Sonam Sherpa, lead author of the study and PhD candidate at Arizona State University, spoke to GlacierHub about the study’s primary objectives. She and the other researchers aimed to “capture the complex natural-social system interactions of cryospheric hazards in the Nepal Himalaya.” She further emphasized the importance of understanding how communities, “perceive the risk coming from glacial lake outburst flood, as perceptions can influence their actions, beliefs, and responses to natural hazards and associated risks.”

GLOFs occur when a lake’s natural barrier, usually a moraine, suddenly fails. The trigger can be a natural disruption, like a landslide, earthquake, or avalanche, or simply the buildup of excess water pressure from increased melt. GLOFs result in a rapid discharge of a lake’s water, inundating the downstream ecosystem with little to no warning. These events are destructive and endanger the lives and livelihoods of communities downstream.

Himalaya Nepal on GlacierHub
The Himalaya in Nepal (Source: cb@utblog/Flickr).

While scientists are clear about the threats posed by GLOFs, downstream communities often ignore or underestimate the potential impact floods could cause to life and livelihoods. So what are the factors contributing to how communities perceive this risk, and what factors influence their opinions?

The researchers conducted a survey of 138 households across nine villages within the Mt. Everest region. The survey elicited self-reported demographic information, such as age, gender, and sources of income. It also assessed risk perception regarding climate change, natural hazards, and hazards specific to regions with glaciers.

One survey question asked locals to rank various hazards “based on their likelihood and potential to damage.” Twenty seven percent of people ranked earthquakes first, while 23 percent put glacial floods first.

The researchers noted the 7.4 magnitude Gorkha earthquake in Nepal one year before, and attributed this result to cognitive availability, whereby recent or common events are more readily recalled than rare events. Sherpa, who is from the Khumbu area within the Mt. Everest region, even recalled her own fear that a glacial lake outburst flood would occur following the Gorkha earthquake.

In addition, the researchers found that rapid-onset events, namely earthquakes and GLOFs, were consistently ranked much higher than slow-onset impacts of climate change, such as changing weather patterns and water availability. GLOFs and earthquakes, though infrequent, occur rapidly and have catastrophic impacts, so people fear these events more.

Experience was a huge influence on risk perception. Both among individuals and communities that had previously experienced a GLOF event, the researchers observed a direct correlation between their experience and their perception of GLOFs as a critical threat.

When responses were analyzed by demographic, however, there was increased variation in the results. For example, young people perceived GLOFs as a greater risk than older people. The researchers surmised that media exposure coupled with more sources of information on climate change among the younger generation could explain this result.

Dingboche village in Nepal on GlacierHub
A view of the Dingboche village in Nepal (Source: smallufo/Flickr).

In search of more factors influencing risk perception, the researchers chose two of the nine villages to compare—Dingboche and Monjo. The two villages are located in different altitudinal zones, Monjo at 2,835 meters and Dingboche at 4,350 m, are considered high-risk areas for GLOFs. Residents of Monjo perceived the most risk from earthquake, then unseasonal rainfall, and finally  drought, while residents of Dingboche ranked earthquake, GLOF, then wind in order of risk.

“As a local Sherpa from Khumbu (the Mt. Everest region) myself, I had a little hint with regard to how one would perceive risk from glacial hazard based on spatial proximity,” said Sherpa. “It was surprising to see that in the data showed a similar result as well.”

The study identifies several reasons for the two villages’ variety in rankings. First is their geographical location. At its higher altitude, Dingboche is in closer proximity than Monjo to glacial lakes. The Dingboche village sits directly below Imja Lake, a heavily studied glacial lake which scientists categorize as a moderate to critical GLOF risk.  

Geographical location further influences the primary source of livelihoods. Villages dependent on tourism are more likely to have access to have information about GLOF risks. Dingboche is heavily dependent on tourism because its altitude is too high to support much agriculture. In contrast, Monjo relies equally on the tourism and agriculture industries.

Imja Tsho on GlacierHub
A shot of Imja Tsho, the lake which stretches across the middle of the photograph. Taken in 2012, four years before the remediation project took place (Source: Kiril Rusev/Flickr).

In 2016, Imja Lake underwent emergency remediation work to lower its water levels by 3.5 m. Following the project’s completion, perceived risk of GLOFs decreased in Monjo, but not in Dingboche. For Monjo, the remediation was a cognitive fix, but not for Dingboche. The project lowered the probability of a GLOF occurring, but as the closest village to Imja Lake, residents of Dingboche continued to perceive it as a critical threat to their community. Sherpa noted the remediation’s function as a cognitive fix as one of the study’s most interesting results, following the finding that proximity was a huge influencing factor on risk perception.

“I went through an emotional roller coaster thinking how rapid the changes are, in the glacial system and how it could impact my community, but at the same time how, very little is understood with regard to what’s happening in this biophysical system,” said Sherpa. Through this risk perception analysis, the researchers aimed to emphasize the necessity of including locals in the development of climate change adaptation policies.

Accurate scientific information is critical, but it is equally as important to communicate potential hazards properly so communities truly understand the risks they face. Only then will scientists, government, and local communities truly be able to work together to create a comprehensive plan to mitigate and adapt to the risks they face.

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Roundup: Crack, Flood, Fight

Petermann Crack Develops

From Grist: “Petermann is one of the largest and most important glaciers in the world, with a direct connection to the core of the Greenland ice sheet. That means that even though this week’s new iceberg at Petermann is just 1/500th the size of the massive one that broke off the Larsen C ice shelf in Antarctica earlier this month, it could eventually have a much bigger effect on global sea levels. Scientists believe that if Petermann collapses completely, it could raise the seas by about a foot.”

Read more about the potential collapse of the Petermann here.

A satellite image from April 2017 shows existing and new cracks in the Petermann Glacier (Source: NASA).

 

Glacial Outburst Flood Rages in Iceland

From The Watchers: “A glacial outburst flood started in Iceland’s Múlakvísl river around midnight UTC on July 29, 2017. Electrical conductivity is now measured around 580µS/cm and has increased rapidly the last hour, Icelandic Met Office (IMO) reported 10:14 UTC on July 29. Increasing water levels of this river are an important indicator of Katla’s upcoming volcanic eruptions.”

Read about safety concerns associated with the flood here.

The Múlakvísl River appeared serene the day before the July 29 outburst flood (Source: Icelandic Met Office).

 

Conflict in the Himalayas

From The New York Times: “The road stands on territory at the point where China, India and Bhutan meet…The standoff began last month when Bhutan, a close ally of India, discovered Chinese workers trying to extend the road. Now soldiers from the two powers are squaring off, separated by only a few hundred feet. The conflict shows no sign of abating, and it reflects the swelling ambition— and nationalism— of both countries. Each is governed by a muscular leader eager to bolster his domestic standing while asserting his country’s place on the world stage as the United States recedes from a leading role.”

Learn more about the geopolitics of this standoff here.

A border post in Nathula, a mountain pass in the Himalayas that connects Sikkim and Tibet (Source: Indrajit Das/Wikimedia Commons).

 

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Using Drones to Study Glaciers

Understanding the nature of glacial changes has become increasingly important as anthropogenic climate change alters their pace and extent. A new study published in The Cryosphere Discussions journal shows how Unmanned Aerial Vehicles (UAVs), commonly known as drones, can be used to do this in a relatively cheap, safe and accurate way. The study represents the first time a drone has been used to study a high-altitude tropical Andean glacier, offering insight into melt rates and glacial lake outburst flood (GLOF) hazards in Peru.

The researchers used a custom-built drone (Source: Oliver Wigmore).

The study was carried out by Oliver Wigmore and Bryan Mark, from the University of Colorado Boulder and Ohio State University respectively. It is part of a larger project aimed at understanding how climate change is affecting the hydrology of the region and how locals are adapting to these changes.

The researchers used a custom-built hexa-multirotor drone (a drone with propellers on six arms) that weighed about 2kg to study changes in Llaca Glacier in the central Cordillera Blanca of the Peruvian Andes.

Llaca, one of more than 700 glaciers in the Cordillera Blanca, was chosen for both logistical and scientific reasons. It covers an area of about 4.68 square kilometers in Huascaran National Park and spans an altitudinal range of about 6000 to 4500 meters above sea level. Like other glaciers within the Cordillera Blanca, it has been retreating rapidly because of anthropogenic climate change.

The researchers hiked to the glacier to conduct surveys (Source: Oliver Wigmore).

To obtain footage, the researchers had to drive three hours on a winding, bumpy road from the nearest town, located about 10km away from the valley. “This was followed by a halfhour hike to the glacier,” Wigmore stated.

To overcome some of the challenges of working in a remote, high-altitude region, the drone was custom-built using parts bought directly from manufacturers. In this case, a base was bought from a manufacturer. “I modified it by making the arms longer, lightening it with carbon fiber parts, and adding features like a GPS, sensor systems, infrared and thermal cameras, and other parts required for mapping,” Wigmore shared.

Building their own drone allowed the researchers to repair it or replace parts when necessary, as sending it off to be repaired while in the field was not possible. It also allowed them to customize the drone to their needs.

A drone selfie taken by Wigmore, with the shadow of the drone in the bottom right corner (Source: Oliver Wigmore).

“No commercial manufacturers could promise that our equipment would work above an altitude of about 3000m, which is well below the glacier,” Wigmore said.

Using drones to study glaciers has advantages over conventional methods in terms of access to glaciers and spatial and temporal resolutions of data. These advantages have been further enhanced by hardware and software developments, which have made drones a relatively cheap, safe and accurate remote sensing method for studying glaciers at a finer scale. For example, Wigmore can build a UAV for about $4000, compared to the high cost of airplanes and satellites also used in remote sensing.

Wigmore and his team carried out aerial surveys of the glacier tongue (a long, narrow sheet of ice extended out from the end of the glacier) and the proglacial lake system (immediately beyond the margin of the glacier) in July 2014 and 2015. The drone was flown about 100 meters above the ice while hundreds of overlapping pictures were taken to provide 3-D images and depth perception.

High resolution (<5cm) Digital Elevation Models (DEMs) and orthomosaics (mosaics photographs that have been geometrically corrected to obtain a uniform scale) were produced, revealing highly heterogeneous patterns of change across the glacier and the lake. The data also revealed that about 156,000 cubic meters of ice were lost within the study period.

High resolution images showed rapid ice loss around exposed cliffs and surface ponds (Source: Wigmore and Mark, 2017).

The images revealed, for example, that the location of exposed cliffs and surface melt water ponds serve as primary controls on melt rates in the glacier tongue. Exposed cliffs lack the insulation of thick debris that are common on the glacier tongue, while ponds are less reflective than ice and absorb more solar radiation, causing higher melt rates.

The thickness of debris layers on the glacier constitute a secondary control. Thicker layers (often over 1m deep) provide insulation from solar radiation, while thinner layers increase the absorptivity of the surface to solar radiation.

The study also found that the upper section of the proglacial lake contains sections of glacier ice which are still melting. This suggests that the extent and depth of the lower section of the lake will increase as the ice continues to melt. This could increase the risk of GLOF, as expansion of the lake will bring it closer to the steep headwalls of the valley, which are potential locations for avalanche and rockfall debris.

Wigmore’s research is part of a series of larger projects still under publication that involve using drones to study glaciers, wetlands and proglacial meadows in the region. The results contribute to our understanding of hydro-social changes in the Cordillera Blanca, and how they can be managed.

Find out more about drone research here, or learn about Wigmore’s other research here.

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Climate Change Increases Flood Risk in Peru

The rising danger of glacial lake flooding in a warmer climate has important implications for humans and animal populations in Peru’s Cordillera Blanca. A recent study in CATENA by Adam Emmer et al. examined a large swath of nearly 900 high altitude Peruvian lakes in the mountainous Cordillera Blanca region, studying their susceptibility to outburst floods in light of modern climate change.

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A variety of glacial lake sizes in the Cordillera Blanca (Source: Elizabeth Balgord).

An outburst flood occurs when the dam containing glacial meltwater, usually comprised of either glacial ice or a terminal moraine (glacial debris lying at the edge of the glacier), fails. Glaciologist Mauri Pelto commented in the American Geophysical newsletter that the moraine dams are “just comprised of gravel, sand and clay dumped by the glacier” and “high water levels caused by upstream floods, avalanches or landslides can cause failure,” leading to major damage of the landscape. The team’s research elucidated that the incidence of glacial lake outburst flooding (GLOF) is increasing and the general distribution of alpine lakes is shifting upward in the region as temperatures warm. 

Knowing a lake’s size, configuration and type allows local water management in the Cordillera Blanca to be improved, according to Emmer et al. By mapping lakes with the classification of either moraine-dammed or bedrock-dammed, the team’s analysis can help local hydrological experts improve water management techniques for the changing distribution of alpine water. It also contributes to the scientific community’s overall understanding of ongoing environmental change.

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A large, high elevation glacial lake lying before the high Andes (Source: Elizabeth Balgord).

By studying the Cordillera Blanca region’s alpine lakes through a combination of remote sensing (high resolution aerial imagery and measurements) and field observations, Emmer’s team categorized 882 lakes by their size and altitude, ultimately referencing their findings with historical data to observe water redistribution over the last 60 years. Emmer et al. established that glacial lakes had expanded in size and number at higher elevations and disappeared at lower elevations since the 1951 study by Juan Concha in the same region. This finding confirms that environmental change and glacier retreat are strongly correlated in the high alpine.

Results from the analyses showed that from 1948 to 2013, lakes that remained in already deglaciated areas tended to be resilient and generally maintained water levels throughout the 65-year examination. Moraine-dammed lakes in particular resisted disappearing despite glacial retreat, suggesting that bodies of water dammed by materials other than ice were more adaptable to recently warmer temperatures. 

The team also noticed that despite the recent resiliency of moraine dammed lakes, glacial lake outburst flooding was caused predominantly by these dams in the early portion of the Cordillera Blanca’s glacial retreat, in the 1940s and 1950s. Flooding in more recent years has occurred in bedrock-dammed lakes. Although glacial lakes were recorded to have shifted from 4250-4600m in the late 1940s to predominantly above 4600m today, no statistically significant trend was established relating outburst flooding to any particular elevation.

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A research team gathered at the waters edge (Source: Elizabeth Balgord).

In order to reduce the risk of flood damage in local communities, Emmer et al. suggested continuous monitoring of young, developing proglacial lakes, using extensive flood modeling and outburst susceptibility assessments to account for future changes in the glacier. Understanding that the melting of glaciers is accelerating in a warming world, the need for more intensive local efforts in response to the threat of flooding is apparent.  

The Peruvian government has responded to high lake levels in the mountains of the Cordillera Blanca by “building tunnels and concrete pipes through the [weakest] moraines to allow lake drainage to safe levels,” according to Pelto. The government then rebuilds the moraines over the drainage system to strengthen it. By incorporating the monitoring techniques suggested by Adam Emmer, the government has the opportunity to manage and stay ahead of the flood risk as temperatures continue to rise. 

Glacial lake outburst flooding is hardly unique to the Peruvian landscape. This December, the Kathmandu Post illuminated the growing danger of GLOFs as the Nepalese Dhaulagiri Glacier recedes, creating a hazardous environment in the Mt. Nilgiri region. Researchers at the Chinese Institute of Mountain Hazards and Environment also established a strong link in Tibet between rising temperatures and glacial melting, contributing to more frequent and larger glacial lakes than in the past 50 years. With the growing number of alpine lakes and increased temperatures, ice dams are highly fragile and prone to failure.

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A variety of landscapes exist at different elevations in the Peruvian Andes (Source: Elizabeth Balgord).

Emmer et al.’s study offers an interesting evolutionary perspective on the state of the Cordillera Blanca. The study’s publication illustrates that even the planet’s most dramatic, seemingly unchangeable environments are plastic under the force of global climate change. The redistribution of alpine glacial lakes across the world’s mountainous regions indicates that the risk of outburst flooding should not be taken lightly. The team’s suggestions for future monitoring, to either mitigate the flooding hazard in populated regions or coordinate adaptation efforts, further illustrates the gravity of the situation. Although the risk of outburst flooding has only been studied in specific locations, the changing state of glacial lakes is already quantifiable and may be an effective proxy for monitoring the future extent of global warming.

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Mapping Landslides in the Himalayas

Uttarakhand Himalaya in northwest India is a rural, mountain region that shares borders with Nepal and Tibet. Often referred to as “The Land of Gods” for its physical grandeur, Uttarakhand is surrounded by some of the world’s highest peaks and glaciers. However, such beauty comes at a price. The Uttarakhand area is prone to natural and glacier-related disasters, often exacerbated by the region’s topography and climate patterns. Landslides, triggered by heavy rainfall and events called glacial lake outburst floods (GLOFs), expose the high mountain communities to infrastructure, life and community losses. A recent article by Naresh Rana Poonam et al. in Geomorphology measured and mapped susceptibility in Uttarakhand to help create a template that can be applied to locations facing similar climate-related landslides.

Village of Jhakani, Pauri, Uttarakhand (Source: A Frequent Traveller/Creative Commons).
Village of Jhakani, Pauri, Uttarakhand (Source: A Frequent Traveller/Creative Commons).

To conduct their research, Poonam et al. relied on Landslide Susceptibility Zonation (LSZ) mapping in order to deepen understanding and response in Uttarakhand to local hazards in a manner that can also be replicated elsewhere. Landslide Susceptibility Zonation (LSZ) is a type of mapping system that organizes different variables like geological, geomorphic, meteorological and man-made factors as high-risk based on the chances of slope failure. A slope failure occurs whenever a mountain slope collapses due to gravitational stresses, often triggering a destructive local landslide. Mapping these vulnerabilities is critical to understanding the dynamics and potential force of future landslides in the Himalayas and elsewhere.

Many of Uttarakhand’s peaks have year-round snowpack with glaciers and glacial lakes that can be disturbed by shifting rainfall patterns and changes in the onset of monsoon season. These disruptions can cause a destabilization deep within the ground, causing the initial movement needed to produce a landslide. Additionally, Uttarakhand’s proximity to the Indian Plate, a large tectonic plate where movement occurs along the boundaries, makes it especially vulnerable to frequent earthquakes. According to the United States Geological Survey, the last earthquake in Uttarakhand occurred on December 1, 2016, with a 5.2 magnitude. The energy released during an earthquake of that magnitude has the potential to trigger multiple, large-scale landslides.

Floodwaters of the River Alaknanda in the Chamoli district in Uttarakhand on June 18, 2013 (Source: Indian Army/Creative Commons).
Floodwaters of the River Alaknanda in the Chamoli district in Uttarakhand on June 18, 2013 (Source: Indian Army/Creative Commons).

Given the high-altitude location of Uttarakhand, earthquakes can also cause glacial lake outburst floods (GLOFs), a type of flood that occurs when the terminal moraine dam located at the maximum edge of a glacier collapses, releasing a large volume of water. These events can be especially destructive to rural mountain communities that are hard to access, making recovery efforts challenging and untimely. Additionally, these villages are often settled in areas where landslides naturally funnel. Preparing mountain communities to understand the risks they face is critical to minimizing damage associated with natural disasters. As a recent article in GlacierHub points out, “Educating and adapting ensures resilience to risks associated not only with glacial outburst flood risks, but also other risks associated with changing climates.” In an attempt to lower the risk of a landslide disaster triggered by a glacial lake outburst flood or rainfall event, Poonam et al. looked at ways to increase accuracy of floodplain mapping. The hope is to help increase the resiliency of communities by encouraging smart expansion with higher predictability of slide prone areas.

Flash floods in Uttarakhand
Damage caused by flash floods in Uttarakhand (Source: European Commission DG ECHO).

LSZ mapping is created using the Weights of Evidence method, a statistical procedure for calculating risk assessment using training data, like an established inventory of previous landslides. This statistical approach allows for information retrieved from a geographic information system (GIS) and remotely sensed data to be integrated regionally. LSV maps can also be derived from a knowledge-driven method that involves more human interpretation; however, this method is based on expert evaluations of a location. According to the article, the statistical approach is used more frequently because it lacks the subjective nature of the knowledge-driven method. When a location is evaluated by an expert, risks and interpretation of potential risks will differ based on the expert, leaving the risk of human error. The statistical approach provides consistency and confidence of regional LSZ maps because they can be interpreted using a common baseline.

The researchers hope that more precise mapping will help communities prepare for disasters such as the one that occurred in Uttarakhand in 2013. In a normal year, the monsoon rains soak Uttarakhand during the second week of July; however, in 2013, those rains arrived in June, a month earlier than expected, catching Uttarakhand off guard. During the spring months, water levels are high with snowmelt from rivers and glacial lakes. Combining monsoon rains with snowmelt during the spring can lead to devastating floods and landslides. As a result, 7,000 people and hundreds of animals lost their lives in a rainfall event on June 15th that took place in the Mandakini Valley, east of Nanda Devi National Park, according to BBC News. Adding to the devastating losses, the Manadkini Valley is also home to the Kedarnath Temple, where Hindu pilgrims travel between the months of May to October. The high volumes of people paired with the early-activated monsoon resulted in increased losses.

Flash floods in Uttarakhand (Source: European Commission DG ECHO)
Damage caused by flash floods in Uttarakhand (Source: European Commission DG ECHO).

After experiencing the devastation of the landslides resulting from the June 2013 monsoon, many people thought the risk of staying in Uttarakhand was too high, so they relocated to the plains. The outmigration left 3,600 villages mostly deserted, as reported by Poonam et al. Outmigration due to climate-related disasters places mountain communities at additional risk for economic stagnation that may lead to increased forced migration to other areas.

Educating communities in both a scientific and social capacity on the risks associated with the natural interaction of weather and a geography allows for increased awareness among local populations which can help lead to better preparedness for future events. According to a recent GlacierHub article, the state of Jammu and Kashmir, located nearby, held a workshop to communicate risk to small mountain communities to help them understand and raise awareness into the unique risks associated with their location. Like with Uttarakhand, it’s not a question of if these events will happen, but when. Providing communities with detailed maps highlighting certain areas that are more prone to landslides and GLOFs will not eliminate the risk, but it may lower it. Combining LSV mapping with education programs on how to use the mapping information will provide small mountain villages with the future tools to build more sustainable and resilient communities. Since LSV mapping efforts are still being integrated, success may not be immediate. However, LSV mapping shows tremendous potential to enable people to continue residing in the world’s richly historic and picturesque locations.

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New Study Offers Window into Glacial Lake Outburst Floods

A recent geological study has shed some light on the cause of a major, yet elusive destructive natural hazard triggered by failed natural dams holding back glacial lakes. The findings show how previously unrecognized factors like thinning glacier ice and moisture levels in the ground surrounding a lake can determine the size and frequency of Glacier Lake Outburst Floods, or GLOFs.

Palcacocha Lake in 2008, showing its enclosing moraine; the 1941 breach is visible in the lower right (Source: Colette Simonds/The Glacial Lake Handbook).

The risks of these glacial floods are generally considered increasingly acute across the world, as warming atmospheric temperatures prompt ice and snow on mountain ranges to retreat and to swell glacial lakes.

Landslides in moraines as triggers of glacial lake outburst floods: example from Palcacocha Lake (Cordillera Blanca, Peru), published in  Landslides in July 2016, centers its study on Lake Palcacocha in the Cordillera Blanca mountain region of central Peru.  Since Palcacocha is one of almost 600 lakes in the Cordillera Blanca mountain range dammed by glacial moraines, the population of the region lives under serious threat of GLOFs.

The Landslides article is a step in understanding a previously understudied geological phenomenon.  As little as five years ago scientists acknowledged the lack of research on the subject.

“We don’t really have the scientific evidence of these slopes breaking off and moraine stability… but personal observations are suggesting there are a lot of those…” said Ph.D. environmental historian Mark Carey in a 2011 video where he describes GOLFs.

 

Glacial Lake Outburst Flood risks do not always emanate from mountain glacier meltwater that flows downstream. As this study shows,  in some instances, trillions of gallons of water can be trapped by a moraine, a formation of mixed rock, which forms a natural dam.  A weakening over time, or a sudden event, such as a landslide, could then result in the moraine dam’s collapse.

The massive amount of water is suddenly then released, and a wall of debris-filled liquid speeds down the mountainside with a destructive force capable of leveling entire city blocks.

GLOFs have presented an ongoing risk to people and their homes dating back to 1703, especially in the Cordillera Blanca region, according to United States Geological Survey records.  In December of 1941, a breach in the glacial moraine restraining Palcacocha Lake led to the destruction of a significant portion of the city of Huaraz and killed approximately 5,000 people.

Looking north over Huaraz towards the highest region of the Cordillera Blanca (Source: Uwebart/CC).

Scientists and government agencies, like the Control Commission of Cordillera Blanca Lakes created by the Peruvian government following the 1941 GLOF, have recognized the need to better understand and control GLOFs.  The study found that as global temperatures rise and glaciers retreat, greater amounts of glacier melt water will continue to fill up mountain lakes, chucks of ice will fall off glaciers, and  wetter moraines will become  more prone to landslides.

The team of mostly Czech geologists and hydrologists (J. Klimeš; J. Novotný; I. Novotná; V. Vilímek; A. Emmer; M. Kusák; F. Hartvich) along with Spanish, Peruvian and Swiss scientists (B. Jordán de Urries; A. Cochachin Rapre; H. Frey and T. Strozzi) investigated the ability of a glacial moraine’s slope to stay intact, called shear strength, and modeled the potential of landslides and falling ice to cause GLOFs.

After extensive field investigations, calculations and research into historical events, the study found several causal factors that can determine the severity of a GLOF.  These include size and angle of entry of a landslide,  shape and depth of the glacial lake, glacier thickness and human preventative engineering such as canals and supporting dams.  Frequency and size of a landslide is determined by the stability of surface material, a characteristic called shear strength, which can be influenced by something as subtle as the crystalline shape of the predominant mineral in the rock.

The terminal and lateral moraines that contain Palcacocha Lake, showing the 1941 breach that released a GLOF that devastated the city of Huaraz (Source: John Harlin/The Glacial Lake Handbook).

The scientists determined that waves caused by moraine landslides and falling ice would most likely lead to over-toppings of the natural dam.  An example would be the 2003 Palcacocha Lake GLOF, which was caused by falling ice.  No one died in this flood, but sediment from the floodwaters blocked the Huaraz’s main water treatment facility, leaving 60 percent of the population without drinking water for six days.  Additionally, small events like the one in 2003 weaken the natural and manmade dams, which without monitoring could eventually give out and result in a more catastrophic occurrence.

Most recent measurements estimate Palcacocha Lake holds 4.5 trillion gallons of glacier meltwater, which is enough to fill approximately 6,800 olympic size pools.  The potential of a catastrophic flood following the collapse of the moraine dam is a serious threat to the growing city that lies beneath it.
“Climate-driven environmental changes may critically affect stabilities of slopes above glacial lakes, possibly triggering large moraine landslides,” write the authors in the article.  They call for continued monitoring of glacial lakes.

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New Glacial Lakes to Transform Swiss Landscape

Ongoing climate change is causing glaciers in the Swiss Alps to shrink dramatically, and some predict they will disappear entirely by the end of the century. As they melt over the coming decades, Swiss scientists estimate that 500 to 600 new lakes covering close to 50 square kilometers of land will form in Switzerland. That’s about the equivalent of two Lake Eries, the eleventh largest lake in the world.

“The rapid melting of glaciers is radically changing the Alpine landscape,” world renowned Swiss glacier expert and University of Zurich professor Wilfried Haeberli reported at the annual meeting of the European Geosciences Union (EGU) in Vienna, according to Spiegel.

Haeberli and a team of scientists recently completed a project that attempts to predict where and when these new lakes will form using glacier bed models and time-based ablation scenarios for all Swiss glaciers. Using case studies, they also looked at the potential natural hazards that could be created by these new lakes, the development potential they might offer in terms of hydroelectric energy and tourism and legal issues they might present in terms of ownership, liability, exploitation and conservation.

One lake in particular they studied was Lake Trift in the Valley of Gadmen, which appeared in the 1990s due to melting of the Altesch Glacier. Local authorities built a breathtaking suspension bridge over the lake that has since become a tourist attraction. Energy companies are also considering putting it to use for the generation of hydroelectric power. The creation of a dam, which would be necessary for such a project, would likely diminish the attractiveness of the site for tourists, but it could protect the area against the risk of flooding.

“Whether the lake remains natural or becomes artificial, there is a significant risk of rock or ice avalanches due to the longterm destabilisation of slopes previously supported by the Trift glacier and the potential collapse of the current glacier tongue,” the scientists write. “Such avalanches can trigger a surge wave in the lake with disastrous consequences. The construction of a dam of adequate size could protect the area from floods and allow for the generation of power but it would reduce the appeal for tourists.”

Haeberli and his colleagues urge that debates over some of these complex issues begin now, before the Swiss landscape transforms from one of glaciers to one of glacial lakes.

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Glacier Hazards Linked to Prolonged PTSD in Kids

In June 2013, several days of torrential rains bombarded India’s northern state of Uttarakhand causing devastating glacier lake outburst floods (GLOFs), river flooding, and landslides. This event is considered to be the country’s worst natural disaster since the 2004 tsunami. Packed with Hindu pilgrimage sites, temples, and tourists, Uttarakhand saw entire settlements washed away. Roads were heavily damaged, stranding over 70,000 people and causing food shortages. Local rivers were flooded with dead bodies for more than a week, contaminating water supplies for the survivors.

Based on post-disaster studies, researchers from St. John’s Medical College in Bengaluru, India recently published findings indicating that the Uttarakhand flooding may have provoked sustained levels of post-traumatic stress disorder (PTSD) in adolescents in the region. The study, which was conducted three months after the disaster, found a 32 percent prevalence of PTSD and a wide-range of stress levels amongst the youth of one the hardest hit districts, Uttarkashi.

Torrential rain caused unimaginable flooding in Uttarakhand. Many traditional sites and statues were ruined. (Photo: Flickr)
Torrential rain caused unimaginable flooding in Uttarakhand. Many traditional sites and statues were ruined. (Photo: Flickr)

In order to secure these findings, the research team obtained consent from 268 adolescents at a high school in Uttarkashi. They assessed the mental health of the students by administering the Trauma Screening Questionnaire, an PTSD assessment recognized in the U.S., the U.K., and elsewhere. Another structured questionnaire was used to gather demographic information. The average age of children who participated in the study was 14.8, with slightly more male respondents than female.

Because of a lack of mental health care infrastructure in Uttarkashi, researchers were not able to prove the glacier-related event directly caused the high rates of PTSD amongst the students in this region. However, a similar study of 411 high school students, conducted prior to 2012 in Pune, India found a lower rate of PTSD (8.9 percent for girls, 10.5 for boys). These students had not suffered from a recent natural disaster related event. A meta-study of 72 peer-reviewed articles of US children and adolescents exposed to trauma found an overall rate of PTSD of nearly 16 percent..

A study of 533 tsunami victims in South India found a much higher rate of PTSD, roughly 70.7 percent for acute PTSD and almost 11 percent for delayed onset PTSD. Although there are many factors that may be able to explain the difference in rates, the increased prevalence of PTSD in the Uttarakashi youth certainly signals a link between glacial hazards and PTSD in children.

The loss of a stable lifestyle is a well-known risk factor for PTSD because of an increased feeling of vulnerability to harm. In Uttarakhand, many adolescents experienced this first-hand when their houses were washed away in the floods. (Photo: EU Humanitarian Aid and Civil Protection/Flickr)
The loss of a stable lifestyle is a well-known risk factor for PTSD because of an increased feeling of vulnerability to harm. In Uttarakhand, many adolescents experienced this first-hand when their houses were washed away in the floods. (Photo: EU Humanitarian Aid and Civil Protection/Flickr)

The researchers from St. John’s Medical College note that past research has been able to establish the relationship in adult subjects between natural disasters and PTSD, “the most prevalent psychological disorder after disaster.” Thus, they claim there is a need for greater recognition of post-disaster stress disorder assessment and for interventions among adolescent victims in developing countries.

“The majority of disaster studies have focused on adults, although adolescents seem to be more vulnerable to psychological impairment after disaster which manifests in a variety of complex psychological and behavioral manifestations,” wrote the authors of the study.

The exact cause of the 2013 Uttarakashi district flooding is contested; however, the unyielding rains contributed to heavy melting of the Chorabari Glacier, 3,800 meters above sea level, and this was a significant catalyst in the event. During the week of June 20, melting at Chorabari, due to above average rainfall, led to the formation of a temporary glacial lake. Further torrential rains caused this lake to swell and overflow, inducing flash flooding and disastrous landslides and mudslides. “Eyewitnesses describe how a sudden gush of water engulfed the centuries-old Kardarnath temple, and washed away everything in its vicinity in a matter of minutes,” according to Down To Earth Magazine.

Glacier-related PTSD risk is not unique to the Gangotri glacier region. There is also evidence and historical precedence to connect these environmental and psychological factors in the Hindu Kush region, the Cordillera Blanca area of Peru, and other high mountain ranges with large glacier dimensions because of their increased risk of glacial hazards. Further, as researchers begin to examine the link between climate change related disasters and the well being of communities, they are finding the increase in disasters will likely instigate greater rates of stress, anxiety, depression, and physical illness along with PTSD in exposed populations. The recognition of the impacts of disasters on mental health is an important complement to earlier work, which has focused almost exclusively on property damage and mortality.

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