DFrisk: Mitigating Debris-Flow Risks in a Warming Climate

Debris flows (DF) are fast-moving mixtures of water, fine sediments, and rocks that cause widespread destruction in mountain regions, with risks intensifying due to climate change. In the European Alps, warming is occurring 2 to 3 times the global average, accelerating glacier melt, snow cover shrinking and permafrost thaw, thereby destabilizing mountains, triggering more landslides, rockfall, debris flows and cascading hazards that threaten communities and infrastructure. At the same time, hotter summers and more intense storms are fueling sudden, high-impact events floods. The deadly summer of 2024, which resulted in fatalities and destroyed entire villages in France, Switzerland, and Italy, exemplifies this growing global threat. These hazards pose a serious risk to expanding infrastructure and development plans in mountain areas.

However, significant gaps in observations and understanding of debris-flow processes limit our ability to accurately forecast, assess risk, and implement effective adaptation measures. This urgent challenge highlights the need to advance understanding of DF dynamics. Prof. Markus Stoffel, AXA Chair in Mountain Disaster Risks at the University of Geneva, leads this pioneering research to develop a comprehensive approach for quantifying and evaluating future debris-flow and other mountain disaster risks. The program aims to reconstruct past and contemporary activity to identify the climatic drivers of these processes. It will assess how debris-flow supply and transport conditions have evolved over time by integrating historical records with geomorphic change detection, climate analysis, and numerical modelling. The insights gained will inform innovative risk‑mitigation strategies for the European Alps.

The program will provide a comprehensive approach to quantify and evaluate future mountain disaster risks and help define strategies, together with public and private actors, to limit loss and damage in the future, enabling Alpine countries to take a leading role in this emerging field.  The findings are expected to be adopted globally, with new geographies applying these insights to their own conditions. The project aims to advance knowledge on sediment supply under extreme storm regimes, integrate two-phase debris-flow models, and improve the realism of debris-flow spread simulations while enhancing mitigation efforts.

All of this will be crucial for policy makers, advance hazard management, inform public discourse on climate impacts, and support training the next generation of researchers and practitioners,  

Prof. Dr. Markus Stoffel is an internationally recognized interdisciplinary environmental scientist renowned for advancing understanding of climate-change impacts on high-altitude and high-latitude environments. His work focuses on mountain disasters and their societal implications across Europe, the Americas, and Asia. His research combines process reconstructions using tree rings and historical archives, field observations, remote sensing, climate analysis and process-based modelling to better understand and ultimately quantify where and when slopes fail, how far destructive flows can travel, and what this means for exposed communities and critical infrastructure . He has led extensive international collaborations across most mountain ranges, founded the Swiss Tree-Ring Lab, and established the Climate Change Impacts and Risks in the Anthropocene (C-CIA) program at the University of Geneva.