Implementation of an early warning for snowfall-triggered avalanche to road safety in the Tianshan Mountains

Avalanches are very active and are seriously threatening road safety in the Tianshan mountains. The snowfalltriggered avalanches have caused many serious casualties and paralyzed the transport system. A warning system of snowfall-triggered avalanches can improve the level of road management and reduce avalanche risk. However, an applicable warning model for snowfall-triggered avalanches has still not been developed for the Tianshan Mountains. This study developed a snowfall-triggered avalanche warning model (SFAW), which was tested on the 218 National Highway located in the central Tianshan Mountains - an area that was seriously affected by avalanches. Snowpack, terrain, and meteorology data were collected at the sites during the winter period from 2011 to 2019 and applied to parameterize the SFAW. The SFAW calculated the probability of regional avalanche release driven by snowfall and snow depth from automatic observation, and the simulated results were compared with the observed avalanche data. The results showed that SFAW had an overall accuracy of 80.5%, the probabilities of detection for the regional avalanche events (POD) of 75.0%, and the false alarm ratio of avalanche events (FAR) of 52.0%. SFAW can serve as an important reference for snowfall-triggered avalanche warning, help to protect local transportation, and reduce the damage caused by avalanches in the Tianshan Mountains.