1.Xi’an Center of China Geological Survey,Xi’an;2.Xi’an jiaotong university,Xi’an
This paper is the result of geo-hazards survey engineering. [Objective] The Loess Plateau is one of the regions with the most serious geo-hazards in China. The key to effectively and accurately prevent and control the loess geo-hazards is to precisely identify the hidden geo-hazards dangers and thoroughly understand the number of geo-hazards risks. [Method] This paper takes Mizhi County in the Loess Plateau region of northern Shaanxi as an example to perform the identification, investigation and evaluation of the hidden loess geo-hazards dangers step by step and establish the system of refined risk identification technology method for the loess geo-hazards at the county level. The DEM data with resolution of 2m × 2m is used to identify the slopes prone to induce collapses and landslides. The remote sensing data with resolution of 0.2m is applied to identify the dangerous slopes. The natural village is taken as the unit to investigate the dangerous slopes and evaluate their risks. [Results] The results show that: (1) a total of 44,716 landslide-prone slopes with inclination degree greater than 40° and height larger than 20m and 4,198 dangerous slopes with threatening objects were identified; (2) Through risk identification, field investigation and evaluation, the total number of geo-hazard risks in Mizhi County was thoroughly understand. There are 4406 geo-hazards risks, including 11 extremely high risks, 304 high risks, 1451 medium risks and 2640 low risks. (3) A number of 3880 risks accounting for 88.06% of the total risks were identified by the DEM and remote sensing with the identification accuracy of 92.42%. (4) From July to August 2022, 36 geo-hazards risks occurred, which are within the scope of this risk identification including 2 extremely high risks, 28 high risks, 5 medium risks and 1 low risk. The proportion of disasters located at extremely high risks is 18.18%, and the proportion of disasters occurred at high risks is 9.21%. The results of risk identification have been effectively verified. [Conclusions] The research results significantly reduced the losses caused by geo-hazards in Mizhi County, and provided scientific references for effectively and accurately preventing and controlling the loess geo-hazards.