Exploring Landslide Hazards in the Mystical Landscapes of Bhutan
"Swapping desk and laptop for hammer and lense is a highlight for many geologists. And when this fieldwork takes place in the beautiful and mystical country of Bhutan, it becomes even more exciting." by Muriel Zeller
In September and October 2024, two engineering geology students, Naomie Bürki and Muriel Zeller, had the opportunity to spend three weeks in Bhutan for their Master’s thesis. Accompanied by their supervisors, Dr. Larissa de Palézieux and Prof. em. Dr. Simon Löw, both of whom have been working in Bhutan for many years, the team contributed to a research project assessing landslide hazards along highway corridors in Bhutan and studying landscape evolution since the Quaternary in two valleys in the northwestern part of the country by dating major geomorphological events.
Naomie and Simon focused on mapping landslide process zones and roadcut failures in two pilot areas: the Paro Valley in the northwest and Gelephu in the south. They assessed landslide hazards and risks along specified road sections using standards defined by the Swiss Federal Office for the Environment.
Meanwhile, Larissa and Muriel investigated the geomorphological history of the Wong Chhu and the Puna Tsang Chhu valley in northwestern Bhutan. Despite their proximity, these valleys show strikingly different geomorphic characteristics. Muriel’s thesis focuses on dating significant Quaternary events and landslides to complement existing qualitative analyses with precise ages. During the field campaign, the team collected 35 kg of samples at geomorphological key locations which were documented in detail. This work will be supplemented by an analysis of terraces and river profiles based on remote sensing data.
The project is conducted in collaboration with the Bhutanese Department of Geology and Mines (DGM). Four DGM geologists joined the team for the entire fieldwork campaign, facilitating permits and logistics while sharing their local expertise. The exchange was mutually enriching: the ETH Zurich team shared knowledge on landslide processes and geomorphology, while the Bhutanese team provided insights into local geology, culture, and history.
Why Bhutan?
This question arises often. Bhutan’s unique geomorphology makes it an exceptional natural laboratory. Similar in size to Switzerland but with twice the elevation range, the study area lacks glacial overprint, leading to extensive slope weathering. Despite the high risk of natural hazards in this mountainous region, there is no established framework for assessing and mitigating these risks—particularly along critical transport corridors. This project aims to raise awareness of landslide hazards and support the development of a hazard and risk management strategy for Bhutan’s major roads. Additionally, it seeks to enhance understanding of the long-term geomorphological history of the study area, including regional-scale processes of landslide formation and landscape evolution over multiple glacial cycles.
While the lack of slope stabilization poses challenges—like long roadblocks after heavy rains—it also provides geologists with a significant advantage: the roadcuts offer ideal outcrops for study!
Cultural Discoveries
Beyond fieldwork, the team immersed themselves in Bhutan’s rich culture and traditions. Highlights included visiting majestic dzongs (administrative and religious centers), exploring the vibrant markets of Thimphu, and hiking to the iconic Tiger’s Nest Monastery perched on a cliff. The team working in the south also had the opportunity to enjoy an elephant safari in the Phibsoo Wildlife Sanctuary. And of course, the trip also offered a chance to enjoy Bhutan’s local cuisine, featuring spicy chilies, rice, and traditional cheese-based dishes—a delicious highlight of the experience.
Gallery
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The digging of our first pit for depth profile samples attracted a lot of interest and much needed support. (Larissa de Palézieux) -
Regaining strength with a home cooked lunch by our Bhutanese colleagues. (Kinley) -
With the rains continuing beyond the usual monsoon period, many road cut slope failures are still occurring at the time of our field campaign. (Simon Löw) -
Muriel taking a sample for exposure age dating. (Larissa de Palézieux) -
Driving through the boxcut lanslide is a humbling experience. (Simon Löw) -
Team ‘Gelephu’ after a safari through the Phibsoo Wildlife Sanctuary. (Larissa de Palézieux)