Rockfall triggering and meteorological variables in the Dolomites (Italian Eastern Alps)

Alpine areas are undergoing the highest change in temperature and rainfall intensity that represent main rockfall triggering factors. Since few approaches were proposed to analyse it, a new approach using meteorological variable frequencies was developed to comprehend climatic scenarios from 1970 to 2019 with implication on triggering historical rockfall events in the Dolomites. The analysis considered key climate variables: mean air temperature, precipitation, thermal amplitude, freeze/thaw cycles and icing, under different aggregation scales. Results reveal that highest warming rates were observed during spring, while a notable reduction in icing and freeze-thaw cycles frequency was obtained during spring and autumn. An anticipation of both starting of summer and ending of winter was detected. Analyses with Rescaled Adjustment Partial Sums method provided valuable insights into precipitation long-term trends and fluctuations. The analysis showed an increasing trend over last decade (2000–2019) suggesting variation in precipitation frequencies over years. The Bayesian method was employed to study conditional probability of meteorological variables on rockfall events. Rockfalls and high intensity rainfall are correlated in autumn, while with mean temperature at different altitudes in summer and autumn. Higher values probability of temperature amplitude characterises spring, while autumn seasons are interested to high temperature variation values. Finally, it was observed strong dependency of the freeze-thaw cycles and icing periods by regional timeseries.