Sunday 31 May 2015

Dangerous changes in Nepal's mountain landscape seen by Sherpas

Nepal quake: Everest Sherpas warn of mountain risks
Everest Sherpas say they have seen potentially dangerous changes in their landscape after Nepal's 7.8-magnitude earthquake and aftershocks.

Nepal has more than 2,300 glacial lakes
29 May, 2015

They say they are living in fear of flooding and tumbling rock and ice because they have witnessed cracks in the ground and in glaciers.

Some glacial lakes have sunk underground with their outlets appearing at new place.

With temperatures increasing and the monsoon on the way, anxiety is rising.

Map showing glacial lakes in Nepal

Map showing glacial lakes in Nepal

Glacial lakes at risk of flooding following the 25 April earthquake

Hundreds of people from Sherpa villages fled to higher ground for safety on Monday night after a small glacial lake burst its banks, sweeping away two small bridges and a cowshed. It caused rumours that a major glacial lake had flooded.

Sherpas are members of an ethnic community that descended from Tibet hundreds of years ago - they use Sherpa as their surnames

A large number tend to be employed in helping climbers in expeditions or guiding trekkers, while others run lodges and tea houses for trekkers and mountaineers

Nepal has more than 2,300 glacial lakes and the most feared is Imja.

Government officials say a helicopter survey showed Imja was intact, but they admit a ground study of the area is yet to be done.

Imja Lake
Imja Lake - the most feared - is intact, according to government officials

Locals say they are relieved about Imja but uncomfortable about other changes they have observed.

During a field visit this week a team from Sherpa villages found ice and debris in a place they should not have been.

"That was a place where we used to see certain flowers bloom," said Ang Chiri Sherpa, chairman of the Sagarmatha buffer zone users' group.

"But when we went to see what had happened, we saw an unusual, small glacier-like body of ice and soil and rock debris that could potentially fall on our village.

"We have no idea where this potentially dangerous thing came from."

Glacial run-off

Sherpas have said new outlets have emerged from glacial lakes

With the summer season sending temperatures up and monsoon rains approaching, locals say they are increasingly worried.

"Rising temperatures mean glacier meltdown will accelerate and rains will mean moraines [rock and sediment deposited by a glacier] could become loose," said Tshering Sherpa, an official whose non-governmental organisation manages Everest base camp and the climbing route to the highest peak.

"All these could multiply the risk of outbursts, more so because the earthquake and continued tremors may have made the moraines of glacial lakes already weak.

"And then we have the recent horrifying experience of a lake breaking on Monday, even if it was a small one."

Most locals in the villages in the Everest region are still sleeping outdoors for fear of aftershocks and they say the concern over possible destabilised glacial lakes and glaciers are making them feel worse.

Pasang Sherpa, a lodge owner in Namche said the cries of women and children on Monday night still ring in her ears.

A crack in the ground

Sherpas have found visible cracks following the earthquake and subsequent aftershocks

"We were all holding torches and running uphill crying and shouting in fear, it was miserable."

Scientists say they have not seen any evidence of risks so far but they also warn that things could change in these shaky times.

"Except for this little event of a lake which somehow released all its waters on Monday, there has been no evidence [of risk] as such," said Walter Immerzeel, assistant professor of physical geography at Ultrecht University in the Netherlands.

"But I think it's a fair concern on the part of Sherpas [because] you have those moraine dams which block those lakes and they can be destabilised by earthquakes and aftershocks."

Dr Immerzeel was in a team that recently produced research on Everest glaciers published this week in The Cryosphere journal of the European Geosciences Union (EGU).

"Avalanches and earthquakes can breach the dams, causing catastrophic floods that can result in river flows 100 times greater in the Kosi basin," the EGU said.

The Kosi basin stretches from the Everest region in the north to the Kosi river that joins the Ganges in India across the border in eastern Nepal.

Although the government and scientists say they have seen no immediate threat, members of the Sherpa community argue say their focus has been limited to the Imja glacial lake.

"So many other glacial lakes have formed in recent years and none of them have been studied, all they talk about is Imja," said Ang Chiri Sherpa.

Rishiram Sharma, head of the government agency responsible for monitoring and taking care of the glaciers and glacial lakes in the Nepalese Himalayas, said his office was trying to co-ordinate with other government agencies for an urgent field study.

"We understand the frustration of the Sherpa community and we will conduct a ground study at the earliest," he said.

The Sherpas from villages right below the glacial lakes and glaciers say they have formed a committee to monitor the threat themselves.

"Our committee will now make a dam to protect a village that was hit by Monday's flood from a glacial lake and then we will prepare a database of all the risky glacial lakes including those around the Khumbu glacier," said Ang Chiri Sherpa.

"We have heard enough of the government and foreign agencies' plans and projects to help us."

Previous material on this. The video below is of special interest

Risk of Nepal Glacial Lake Outburst

1 May, 2015

At least 10,000 people live directly in the path of the three very unstable glacial lakes, Imja Tsho, Thulagi and Tsho Rolpa.  These areas include the dozens of towns on the main trekking route to Mt Everest Base Camp.  These lakes are extremely vulnerable to Glacial Lake Outburst Floods (GLOF) from aftershocks following the 7.8 Ricther earthquake on Saturday, 25 April 2015.

GLOFs occur when earth structures damming large glacial lakes collapse.  Formed out of deposited rocks and mud these dams are inherently unstable and can be ruptured by a single landslide or avalanche into the lake.  Past floods have obliterated small hydro electric plants in their path.  In 1980 a GLOF in north eastern Nepal devastated villages over 70km downstream.

The UN and World Bank have a number of development projects in place to improve warning systems about GLOFs, but they have not been adequately successful.  Most towns have limited awareness of these risks and few (if any) have evacuation plans.  Due to lack of resources many of the monitoring systems that did exist have degraded.  The glacier lakes themselves serve as major tourist attractions, so locals’ incomes rely on remaining in endangered areas.  In fact, as visitor numbers to Mt Everest have increased significantly over the past ten years, the local population living the the path of the Imja glacier lake has swelled.

Local District Disaster Relief Committees generally have very little knowledge about climate change or GLOF risk management.  There is also insufficient coordination between different agencies for systematic information sharing on GLOF risk management and no efficient mechanism for communicating GLOF warnings effectively. UNDP Report September 2012

The natural moraine banks that form the dam for these lakes are unstable and are vulnerable to earthquakes.  This instability is exacerbated by the fact that the volume of the glacial lakes has been increasing due to climate change.

Government and disaster management authorities have limited understanding and experience of managing growing climate risks, including current variability and the projected impacts of climate change, that are increasing the range and magnitude of disasters that Nepal is having to cope with UNDP Report September 2012

As these lakes only began forming in the late 1950s, they were not a threat when Nepal last experienced major earthquakes in the 1930s.  Given the volume of water and steep terrain, World Bank flood models predict walls of water and debris up to 10 metres high, even 100km from the source.  There is also a chain reaction risk where a comparably small lake, situated above larger lake, causes a sudden surge of water that then bursts the larger lake’s moraine dam.

Nouveau Eco created this risk map (above) because we want people in this zone, both local and international first responders, to be made aware of the risks facing them so that they can take steps to prevent further disaster in this already devastated region.

This same problem was identified in this excellent documentary

Nepal - I Have Seen the Earth Change

Solukhumbu is one of the 75 districts in Nepal. It gathers most of the 3300 glaciers and 2300 artic lakes of the country. Inhabitants witness huge climatic changes in the Everest area. The most striking being the fast glacier recession, which have given birth to new lakes where there was only ice and snow. Those lakes are a danger for the population, natural bombs, ready to explode. If the water overflows, it will sweep away inhabitants, bridges, houses and villages.

Not only that, but this

Monsoon rains increase risks of landslides in Nepal
Nepal needs to act quickly to reduce the destruction of landslides in earthquake-affected areas before the monsoon rains arrive, warn scientists

8 May, 2015

Nepal needs to urgently assess the risks from existing and potential landslides in earthquake affected areas before the monsoon rains come, say scientists who have produced a detailed map of landslide risks using satellite data.

The report released by scientists at the British Geological Survey, Durham University and University of East Anglia this week says: “The need to plan measures to mitigate landslide deaths and disruption in the forthcoming monsoon season must remain a priority. Many more damaging landslides may occur in the 2015 monsoon, likely to start in late June, than would be expected if a major earthquake had not occurred.”

The scientists identified at least six major landslides blocking valleys in areas hit by the 7.8 magnitude earthquake on 25 April. But the team says more major landslides may be found as more satellite imagery becomes available (large areas of the region are still obscured by cloud and dust).

The risks of landslides will “escalate significantly” as the monsoon rains begin, the report added. The monsoon that reaches Nepal in second week of June and withdraws in September brings almost 80% of the country’s total annual rainfall.

Fresh landslides will threaten already-affected areas and wash sediment downstream onto valley floors and floodplains.

Major landslides are limited to a zone that runs east-west almost parallel to the transition between the lesser and High Himalaya near the China-Nepal border. 

This zone includes parts of the most affected districts –Gorkha, Dhading, Nuwakot, Rasuwa, Sindhupalchwok, Dolakha, Ramechhap and Kavre, where most of the fatalities due to the earthquake occurred.   Major roads to Tibet in the north and India in the south have also been blocked.

A team led by the University of Michigan geomorphologist Marin Clark has also identified tens of thousands of locations at risk of mudslides and landslides in the mountainous area along the Nepal-Tibet border, north of Kathmandu and west of Mount Everest.

Dam hazard (1)
Image credit: Dam Hazard ~ University of Michigan

According to satellite images, avalanches and landslides have blocked the upper reaches of Buri Gandhaki river in Gorkha district, the Trishuli river near Thansing and the Sunkoshi river near  Sarsunkharka.

No local warning systems

Satellite images provided by the International Centre for Integrated Mountain Development (ICIMOD) on their website are consistent with Clark’s assessment.

But this information is not reaching local people. “The district administration has not informed us about the river blockages. People are more concerned about procuring plastic sheets right now,” Kapil Koirala, a resident of Dhulikhel, which lies on the Arniko highway to Tibet, told People are scared about the floods and want to move to safer districts but they don’t know which places are safer, he said.

The cloud cover has made it difficult for us to get accurate satellite pictures and travelling to the areas where landslides have occurred is not possible right now,” said Narendra Raj Khanal of ICIMOD. “I have asked for water discharge data and once I have this I will be in a better position to say how serious the river blockages could be,” he said.

In 2014 flash floods in Sindhupalchowk district on the Nepal-China border killed 156 people, after a massive landslide blocked the Sunkoshi River

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