Explore the challenges of Illgraben, Blatten and the remote kingdom of Bhutan for Swiss mountain scientists. In October 2025 Leuk celebrated 20 years of its Bhutan bridge linking French to German (Swiss) Valais.
Since the 14th century, Illgraben -- the remains of a torn-off mountain that still dumps thousands of tonnes of rubble into the Rhone River every year -- has separated French- from German-speaking Switzerland in the canton of Valais near Leuk.
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But in 2005, a bridge over the canyon finally linked upper and lower Valais, joining its Swiss-French and -Swiss-German part, via a 134m pedestrian walk over the Illgraben canyon.
Even more unpredictably, the suspension walkway is a Bhutan bridge, built under the supervision of a Bhutanese engineer over "The Grand Canyon of Valais". The bridge project was launched in 2002, the UN's International Year of Mountains, which promoted solidarity between the world's mountain regions.
A Christian Cross and a Bhutanese stupa built by Lamas in France were installed nearby and prayer flags decorate the bridge along both sides of the rail. It receives 4.6 out of 5 stars on the Web for its spectacular experience.
The Bhutan Bridge is in the circle
In the two decades since, it has become a place of pilgrimage for tourists and others who do not fear having to descend 24m on the crossing.
Even today, though, some websites warn visitors that debris flows occur three to five times a year, bringing a wall of rocks and mud two metres high, rushing through at 25km an hour.
At these times, pedestrians cannot cross Illgraben on the bridge, and the excursion is only recommended by some websites between April and October, though it is accessible year-round.
A metal-mesh tread introduced in 2019 for the one-metre-wide walkway, replacing wooden steps, offers increased safety and durability, though the railing is comparatively low at 110cm. Its estimated maximum capacity is 536 people at a time.
But in view of the 20th anniversary of the Bhutan Bridge (Bhutanbrücke) Leuk decided to mount a 10-day celebration of Bhutan-Valais relations, free to all, and also the 40th anniversary of Switzerland's diplomatic recognition of the Himalayan mountain kingdom.
Forty events from 17-26 October included exhibitions of 126 works by 64 artists, workshops, meditation sessions, and 4 excursions from Leuk's 12th-century castle to the Bhutan Bridge and Illgraben.
The Swiss commemoration put the spotlight on Bhutan as a similarly landlocked country though one with a population of less than one million. Both countries were never directly colonized, and have significant hydropower reserves. Both countries are climatically challenged republics, and home to marmots, mountain agriculture as well as progressive environmentalism.
The event included a unique exhibition organized by the Royal Textile Academy of Bhutan and the Thimphu Artists' Initiative VAST, featuring traditional clothing, weaving and tapestries, photos of Bhutanese life by Karma Jigme and Christine Jäggi, and workshops in calligraphy, textile production and dance.
Saturday 18 October offered a Bhutan night with music, dance, films and a buffet of Bhutanese food open to all. Some 30 cultural representatives, scientists and monks from Bhutan came to Leuk for the festivities.
The link between Leuk and Bhutan came through the Swiss development association Helvetas, long committed to helping low-income communities out of poverty, and particularly concerned with water issues and education.
Helvetas has been active in Bhutan since 1975 (LINK): "We have successfully completed projects in dairy farming, agriculture and forestry and in building suspension footbridges, as well as a teacher training project that has significantly increased school enrollment among Bhutan's children" (LINK).
Photo by Karma Jigme
A Switzerland-Bhutan friendship society was created in 2000, involving many Swiss who had worked for Helvetas, with the slogan "Far Apart and Close Together".
Modern and traditional Bhutan work together
The 2025 celebration received significant support from the billionaire Swedish pharmaceutical magnate and explorer Sir Frederik Paulsen, emeritus chairman of Ferring chemical company, now based in St-Prex near Morges. 12 years ago he became the first person to all explore all the Earth's poles (geographic, geomagnetic, magnetic, and ice).
Dr Paulsen took part in the official celebrations of 40 years of Switzerland-Leuk diplomatic relations at Leuk Castle, along with representatives of the permanent mission of the Bhutan mission to the UN in Geneva.
Pointing to the private initiatives that have been a feature of Swiss aid to Bhutan, he said the "community forestry" groups had proven "one of the most successful international collaborations in Bhutan", particularly because of Swiss involvement, and he hoped the meetings in Leuk would lead to new projects.
A former local councillor at the ceremony reminded the gathering that in reality the bridge project had its origins in France, in Chambéry, when the Savoie department invited representatives of mountain populations in 2000 to prepare for the 2002 UN Year of Mountains. This led to adoption of a project by Valais Solidaire, a Martigny-based grouping of NGOs in the canton promoting North-South solidarity, particularly through the Agenda 2030 sustainability goals.
When the monks in France created the stupa, they ran up against Swiss frontier bureaucracy that wouldn't let it cross the border, she reported, until her husband explained that it would be put in their garden. She was loudly applauded when she expressed the hope that the Swiss would remain welcoming to people from other mountain cultures such as Afghanistan, Iran or Turkey.
Garden ornament?
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For scientists, a highlight of the Leuk-Bhutan events was a reporting session on 19 October bringing together Swiss-based mountain speciaists to talk about on the challenges facing nearby Blatten (30km away in the Lötschental and 90% buried under a landslide on 28 May 2025), the follow-up to a workshop in Bhutan on geohazards in the Himalayas before the session, and the future of high mountain regions.
Moderator Tom Battin came from the Alpine Polar Environmental Centre (ALPOLE) at EPFL’s Valais Wallis campus in Sion, which opened in December 2022 as a multidisciplinary research unit. He underlined the dangers from glacier lakes forming when ice melts and bursts through the end-moraine (debris dam) to flood land below. The threat became apparent for lower Lötschental's villages after 28 May, and happened in Bhutan during the workshop.
Of Illgraben's regular flow of debris below Leuk, Angel Fritz noted in the Washington Post this June: "It's predictable only in the sense that it's annual — other than that, there's nothing to signal when this flood of dirt and debris will occur." These were two reasons why Illgraben instigated the first and most long-lasting Swiss research activities to manage landslides.
For authorities dealing with Blatten's catastrophe and evacuation of its 365 people, Prof. Battin had nothing but praise. "The decision-takers were doing what scientists told them."
Nadine Salzmann, Head of Department at the WSL Institute for Snow and Avalanche Research SLF, reported Bhutan suffers particularly from glacier lake flooding. The kingdom has almost 600 glacier lakes that pose a risk, Bhutan researchers have found in recent research. Even the major airport and hydroprojects are endangered. Some early warning systems are now in place and hazard maps indicate danger zones.
On 5 October heavy rains fell across large parts of Bhutan and Nepal. YouTube has a video of the Tala Dam overflowing and forcing mass evacuations. The bad weather was expected, particularly with the end of the monsoon system, but not at the intensity experienced, and Bhutan has very few monitoring facilities, such as radar systems.
For the future, scientists recognize the risks from melting permafrost in the region but no permafrost monitoring stations exist at the moment, and the Swiss National Fund is financing the first scientific project with this aim, involving several Swiss university institutes and Bhutanese researchers. It focuses on the Tala glacier.
Daniel Farinotti, Professor for Glaciology at the ETH Zürich and the WSL research institute, showed some previously unbroadcast videos of the Blatten damage. He was pessimistic about the chances of resuming habitation in the original village site in view of the difficulty of knowing when the debris has completely settled.
In the post-presentations debate, recalling the discussions in Bhutan, Dr Salzmann stressed the importance of early warning systems, and information on when to notify people at risk, as Blatten had shown with its network of local observers.
In the Himalayas including Bhutan, as distinct from Blatten, glacial disturbances leading to overflows take place 30-60km from villages. Continuous local observers are not on the spot, and no person may have ever explored the glaciers there.
"A key technology here is [...] satellite interpretations," she commented. "The good news here is that we have very new satellites and sensors coming up which will allow us -- in a year or a few years from now -- to have [...] automatic monitoring of where we have slope movements."
Prof. Farinotti added: "The key question is where to look first. The region is so vast."
Dr Salzmann told the Bhutanese and Swiss who crowded into the old hose storehouse (Spritzuhüus) next to the castle for the one-hour session: "The second very important point is the social component.
"We need to ensure that people living downstream are aware of the situation and that they also need to know what to do in an emergency." These were the two factors on which today's communities and authorities must focus in coming years.
The official ceremony for 20 years of the Bhutan bridge took place on 25 October at 15:00, with the closing ceremony at Leuk Castle the next day at 17:00.
Our report on Blatten and its aftermath (LINK)
Discover Val d'Anniviers: Swiss Traditions & Stargazing (LINK)