Rock avalanches on a small scale: Researchers are investigating mass movements using a 3D model of Blatten.
Improving the basis of computer models: Experiments show how mixtures of water, ice and rock move.
Better assessment of natural hazards: The models are intended to show where settlements and infrastructure are at risk.
We see the Lötschental valley around Blatten, with the Birchchinn channel rising above it all the way up to Kleines Nesthorn. Everything is a gleaming blue colour. Then a hatch opens, and a mixture of water, sand and clay rushes down into the valley from the direction of Kleines Nesthorn, settling and covering vast areas. It is almost like back in 2025, when a rock avalanche almost completely destroyed and buried the village of Blatten. This time, however, it is happening in miniature, at a scale of 1:577. On a smaller scale than a model railway landscape, and without the trains. "We want to use models like this to find out how mixtures of different materials move in the natural environment," explains Johan Gaume, Professor of Alpine Mass Movements at ETH Zurich and head of the research group of the same name at the WSL Institute for Snow and Avalanche Research SLF.
Alongside these physical models, the research group is also developing virtual ones on computers. They show scenarios describing what can happen during mass movements in the Alps, from debris flows to rock avalanches. In the future, this is intended to enable those responsible for natural hazards at cantonal and municipal levels to determine whether infrastructure or even settlements are at risk. "For these models to be reliable, they must be thoroughly tested in carefully controlled experiments," says Gaume. These are the exact experiments he is conducting on the 3D-model. Such experiments also give him key insights into how mixtures of water, ice and other materials move, what happens when they hit an obstacle, and much more.
The Blatten model is just the first of this size (see box). The researchers used specially programmed software to select the landform, break it down into small sections and print the terrain segments (each of which measures approximately 50 x 50 cm) piece by piece. They then assembled, coated and painted the model in a former military bunker near Davos that now belongs to the SLF. "This is a vital step to achieve the desired roughness and optical properties," clarifies Gaume.
Numerous cameras, lasers and sensors, as well as a 3D scanner, measure parameters such as depth of runoff, speed, runout distance, deposition and impact dynamics of the artificial mass movement. The researchers precisely calculate the composition and the required proportions of the individual components, then blend the mixture in a bucket. They tip the mixture into a box at the top of the model before opening a hatch, triggering the event.
Dimensions of the flow channel:
Inclined section: 4.5 x 2 m
Horizontal runout: up to 6 m long
Dimensions of the printed topographic model: 5.4 x 4.5 m (max.)
Surface area of the model: approx. 12 m²
Number of printed parts: 56
Printing time: approx. 100 days
Maximum input mass: 1 t
Current input volume: 48 l
Key measurement systems: cameras, lasers, 3D scanner, force plate, pore pressure sensors
In the future, researchers will also be able to mount other areas and landforms onto the substructure. "This is a long-term investment in research, not a short-term experiment," explains Gaume. Numerous projects are set to be conducted here to investigate various effects, from erosion and impact against obstacles to the distance the masses travel up counter slopes. Gaume is currently focused on one process in particular: "At the moment, we’re especially interested in the influence of terrain curvature on flow dynamics."
Computational simulation/modeling