Mass movements are hazardous events that may cause up to tens of thousands of fatalities. These types of mass movements are often triggered by high volume, high intensity rainfall events, intensive snow melt, and earthquakes. In debris flows, large rock fragments are transported at high speeds in a dense mixture of soil and water (as illustrated in the animation below), which produce large impact forces when impacting infrastructure. It is therefore difficult to protect infrastructure from such events.
The frequency and magnitude of mass movements are likely to increase in the near-future as a result of climate change, by an increase in extreme rainfall events, a prolonged snow-free season and disappearing permafrost that would otherwise stabilize soils and rock. We aim at understanding the processes and triggering factors of these mass wasting processes in order to mitigate damage and reduce fatalities, through a combination of fieldwork and scaled laboratory experiments.
An ongoing project in the Department of Physical Geography (NOW-Veni of Tjalling de Haas) focusses on unraveling debris-flow entrainment, through a combination of field measurements in the European Alps and physical modelling in the Earth Simulation Lab. The extent of a debris-flow hazard strongly depends on debris-flow volume, which depends on the amount of bed and bank material entrained by a debris flow. For hazard assessment and mitigation it is therefore of key importance to accurately estimate debris-flow volume. Unfortunately, accurate estimation of debris-flow volumes is currently hampered by a limited understanding of debris-flow entrainment. Our work on debris-flow entrainment will lead to more accurate debris-flow volume estimation, facilitating better hazard prediction and mitigation. The video below explains the field measurements related to this project in more detail.