Changes of hydro-meteorological trigger conditions for debris flows in a future alpine climate

Debris-flow activity is strongly controlled by hydro-meteorological trigger conditions, which are expected to change in a future climate. In this study we connect a regional hydro-meteorological susceptibility model for debris flows with climate projections until 2100 to assess changes of the frequency of critical trigger conditions for different trigger types (long-lasting rainfall, short-duration storm, snow-melt, rain-on-snow) in six regions in the Austrian Alps. We find limited annual changes of the number of days critical for debris-flow initiation when averaged over all regions, but distinct changes when separating between hydro-meteorological trigger types and study region. Changes become more evident at the monthly/seasonal scale, with a general trend of critical debris-flow trigger conditions earlier in the year. The outcomes of this study serve as a basis for the development of adaption strategies for future risk management.

Automated summary

By connecting a regional hydro-meteorological susceptibility model with climate projections, this study assesses changes in the frequency of critical trigger conditions for debris flows in different regions in the Austrian Alps. It finds limited annual changes in the number of critical days for debris-flow initiation when averaged over all regions, but distinct changes when separating between trigger types and study region. Monthly and seasonal scales show a trend of earlier critical trigger conditions. The outcomes of this study provide a basis for future risk management and adaptation strategies.