Refinement risk identification of loess geo-hazards based on DEM and remote sensing——Taking Mizhi County in the Loess Plateau of Northern Shaanxi as an example

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.

Methods 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 2 m×2 m is used to identify the slopes prone to induce collapses and landslides. The remote sensing data with resolution of 0.2 m 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 44716 landslide-prone slopes with inclination degree greater than 40° and height larger than 20 m and 4198 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.