Abstract:
Zhaotong City of Yunnan Province is one of the regions most seriously affected by geological disasters in the upper reaches of the Yangtze River. In this study,
Z index, principal component analysis and effective precipitation analysis during the early stage of geological hazards were used to analyze the historical geological hazards, 12−hour and daily precipitation data of the regional and national stations in the duration of these hazard events. The results show that there are many potential geological hazards in Zhaotong, mainly landslides; and large and medium−sized geological disasters also occur. More than 95% of the geological disasters occur in the rainy season, with a summit in August, which corresponds to the change of the dry and wet seasons in Zhaotong. The precipitation−type geological hazards are closely related to the precipitation factors, such as the precipitation till 12−hours before the disaster's approaching, the precipitation intensity on that day of the disaster, cumulative precipitation and precipitation intensity of the 3−days and 12−days before the coming of the geological disaster. Therefore, a meteorological risk early-warning model for precipitation−type geological hazards is established, based on the short−term, medium and long-term cumulative precipitation effect, and the geological disaster zoning results of the the Ministry of Land and Resources. Then, the geological hazards in Zhaotong in 2018 were selected to test the model, and it was found out that this model has a good early warning indication for the geological disasters in the rainy season in Zhaotong.