Critical environmental factors affecting mountain geohazards in a warming climate in Southwest China

Abstract

Environmental factors are essential input variables for susceptibility assessment models of mountain geohazards. However, the existing literature provides a limited understanding of the relative contribution of these factors to the occurrence of geohazards with a warming climate, posing tremendous challenges for risk management in mountainous areas. Ya'an city is susceptible to hazards because of its steep terrain, abundant precipitation and active seismic activity. In this regard, we utilise the GeoDetector model to extract critical environmental factors affecting the spatial patterns of mountain geohazards (i.e., landslide, debris flow and rockfall) in Southwest China. The analysis indicates that the factors with the highest explanatory power for the spatial distribution of landslides, debris flows, and rockfalls are soil property, extreme precipitation and extreme temperature, respectively. Notably, we revealed the synergistic effects among factors given their larger q-value than individual ones. We further explored the responses of mountain geohazards to climate change, including the rising temperature and precipitation, because the frequent occurrence of mountain geohazards is closely related to a warming climate. The variation in snow water equivalent caused by antecedent snowfall and snowdrifts acts as a crucial indicator for geohazards, highlighting the significance of snow and wind observations in meteorological nowcasting and disaster prewarning. We disclose the phenomenon of the geohazard hysteresis to the precipitation peak resulting from the top–down (i.e., precipitation-runoff and surface-deep soil moisture) peak shifts. Our work is expected to enhance the precision of susceptibility assessment models and the reliability of short-term forecasts for mountain geohazards.