UP News - University of Potsdam

Photo : Dr. Ugur Öztürk

View of Nainital at Lake Naini

Photo : Dr. Ugur Öztürk

Nainital has grown into the surrounding steep slopes.

Photo : Dr. Ugur Öztürk

An old minor landslide that destroyed a house but is now covered.

Photo : Prof. Dr. Ankit Agarwal

Dr. Ugur Öztürk

Somewhere in the Indian part of the Himalayas: Narrow roads wind their way along steep slopes, cutting almost playful lines into the rugged rock. It often took months of hard work to create these important networks connecting widely scattered towns and settlements. For hours, long convoys of cars struggle along these roads through the high mountains, often in breakneck danger: Buses, trucks, overcrowded cars – anything that wants or needs to get from town to town rolls along these dusty, mostly unpaved paths. These lifelines are extremely fragile and – like cities, hydroelectric power plants, and other infrastructure – are repeatedly damaged or even destroyed by rockfalls, landslides, or flash floods. As a result of climate change, the number of these extreme events is increasing, as is their destructive power. Nowhere is this more evident than in the Himalayas, whose slopes are steeper and the forces of nature greater than in most other mountain formations in the world. That's why, in October 2024, two minibuses carrying researchers from the University of Potsdam and the Indian Institute of Technology Roorkee (IITR) are among the many cars on one of the dusty roads. Their destination: Areas and places that have been particularly affected by such natural phenomena in recent months and years and where they can best be researched.

Dr. Ugur Öztürk from the Institute of Environmental Sciences and Geography, who is particularly interested in landslides, is among them. "I have already conducted research on many mountains, including in Japan and Central Asia," the scientist says. "But the Himalayas are higher, more rugged, steeper and extreme in many ways." This simple formula applies to landslides: The steeper the slope, the greater the forces that can set huge masses of earth and debris in motion. When precipitation penetrates the soil, previously bound layers of earth become detached from each other and the upper layers begin to slide. If large areas are affected, entire slopes or parts of mountains can detach – and bury houses, roads, or entire villages.

"The terrain in the Himalayas favors landslides, no question about it," Öztürk says. "At the same time, human intervention in this landscape makes such extreme events more likely." The roads cut deep into the mountains make the slopes unstable. And this danger is growing: With climate change, heavy rainfall is becoming more frequent. And people are digging deeper and deeper into the largest mountain massif on earth. This applies not only to roads, but also to many villages – often in valleys between peaks – growing dangerously close to or even on top of at-risk slopes. One such city is Nainital, a small town with around 40,000 inhabitants in the Indian state of Uttarakhand. It is located at an altitude of over 2000 meters, surrounded by several mountain peaks and on the shores of Nainital Lake. The popular vacation and pilgrimage destination continues to grow into the surrounding slopes. At the moment, some of them are slipping, albeit slowly. In fact, this more or less "wild growth" of the city is dangerous, as the researcher explains. "The city is more or less completely sealed. Even the few trees are set in concrete." As a result, precipitation only reaches the soil in a few places, where it quickly becomes "overloaded". For Ugur Öztürk, this is an exemplary "field laboratory" that can be used to show in detail how human influence contributes to natural extremes such as landslides. "We want to use the example of Nainital to develop a model that takes human intervention into account." This would make it possible, for example, to make predictions for regions that have not yet been developed.

"We traveled to Nainital with a small group of researchers to take a close look at the situation on the ground," the scientist explains. "And to investigate how people perceive the dangers and how they deal with them." Thanks to the close cooperation between the Potsdam environmental scientists and IITR researchers, such as Prof. Roopam Shukla, they can draw on local expertise and more easily enter into discussions with the locals. "We split into three mixed German-Indian groups and visited different areas of the city," Ugur Öztürk clarifies. Residents were interviewed using a structured questionnaire: Are you aware of the danger of landslides? Are you worried about that? How do you prepare yourself and your homes – for example with reinforced walls, drainage and wastewater systems – for such an event? "People actually feel safe there at the moment," Öztürk adds. As a result, hardly anyone is taking precautions. This needs to be changed, he believes, as the danger of major landslides in Nainital is real. The complex model that the researchers want to create on the basis of their data would make it possible to show this - and hopefully react to it before devastating disasters occur.

For Ugur Öztürk, it is important to gain knowledge that can be used for risk assessment in urban regions across the world. He has been awarded an ERC grant that will allow him to study places like Nainital on several continents in the coming years, for example in Burundi and the Congo, Colombia, and India. "So far, landslides have mostly been regarded as natural phenomena and studied as such," he explains. "I want to research it in urban spaces, because ultimately human intervention in nature also makes it a social phenomenon."

More on the Indo-German research project CoPREPARE: https://www.uni-potsdam.de/en/umwelt/research/hydrology-and-climatology/research-projects/vorlage-7

Travel diary of the German-Indian research group in the Himalayas: https://www.uni-potsdam.de/de/up-entdecken/upaktuell/up-unterwegs-reisetagebuecher/indien-2024

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