Preliminary study on the“point-surface dual control” model of geological hazard risk in typical mountainous towns in Gansu Province

This paper is the result of mineral exploration engineering. [Objective] Gansu Province is one of the areas with high incidence of geological disasters in China. The scientific construction of a "point-surface dual control" model of geological disaster risks is the key to disaster prevention and mitigation.[Method] Taking Longlin Town as an example, on the basis of on-site refined survey and mapping, multi-phase remote sensing data modelling, indoor test and numerical simulation analysis, the paper expounds the typical urban geological disaster risk management and control technical process with six steps, including geological disaster risk identification, disaster mode research, risk analysis, vulnerability assessment, risk assessment and risk prevention and control countermeasures, and introduces the semi-quantitative risk assessment process of urban risk slope, the quantitative risk assessment method of single geological hazard based on dynamic process and the "point-surface dual control" mode of geological hazard risk have been formed. [Results] (1) The main types of geological hazards in the study area are landslide and debris flow, with a total of 71 hidden danger points of geological hazards developed, 15 of which directly threaten the safety of people's lives and property. The three types of landslide hazard models are summarized and the geological early identification signs are established; (2) Based on the geological hazard risk zoning of different precipitation frequencies (5%, 2%, 1%), 75.23% of the regions always maintain low risk under different precipitation frequencies, 24.38% of the regional risk level increases with the reduction of precipitation frequency, and 0.39% of the regions always maintain high risk; (3) Based on the results of risk assessment, a comprehensive risk dual control proposal for disaster reduction in towns and specific disaster sites is proposed. [Conclusions] Relevant research can provide technical support for disaster prevention and mitigation, land space planning and control and use control of complex mountain towns.