Hazard Analysis Of Mountain-hazards In The Areas Of The Silk Road Economic Belt

Mountain-hazards are important factors restricting the development of the Silk Road Economic Belt.Although many scholars at home and abroad have carried out a series of studies on the hazard research of mountain-hazards in different regions of the Silk Road Economic Belt,there are widespread problems of "fragmentation" of research regions and "simplification" of mountain-hazards types,which seriously restrict the overall understanding of the spatial distribution characteristics of mountain-hazards hazard in the Silk Road Economic Belt areas.The hazard assessment researches(including single-hazard hazard and multi-hazards comprehensive hazard)of mountain-hazards in the Silk Road Economic Belt areas are helpful for understanding the spatial characteristics of the mountain-hazards hazard from the macro-view,so as for contributing to the hazards prevention and mitigation,and the safety of infrastructures and major projects in this region.Corresponding to the major development needs of the country,this paper takes the Eurasian continent,the geographical carrier of the Silk Road Economic Belt,as the research area,and selects the most common rainfall-induced landslides(including collapses),mountain torrents and debris flows as the research objects to carry out the related mountain-hazards hazard analysis in the areas of the Silk Road Economic Belt.Firstly,the mountain-hazards activity characteristics and hazard-pregnant environments were analyzed,and the hazard assessment indicator system of mountain-hazards for large-scale regional research was constructed.After that,the single-hazard hazard index models for each hazard and the multi-hazards comprehensive hazard index models for different combination types of mountain-hazards were constructed corresponding to different mountain-hazards pregnant environment backgrounds.Finally,according to the classification and integration of the hazard index calculating results of the above models,the single-hazard hazard assessments and the multi-hazards comprehensive hazard assessments of mountain-hazards in the Silk Road Economic Belt region were realized.Some suggestions were also put forward in order to apply the hazard assessment results to hazards prevention and mitigation,which could be regarded as a reference for regional mountain-hazards prevention and mitigation.The paper has achieved the following main research results:1.Based on the analysis of the spatial and temporal characteristics of the large-area and long-time-scale mountain-hazards data in the Silk Road Economic Belt areas,activity characteristics of the mountain-hazards were preliminarily understood.Some high-frequency areas of mountain-hazards were identified,and the obvious high-frequency spatial-overlap areas of different mountain-hazards was found;June,July and August were determined as the high-frequency times of mountain-hazards,reflecting the strong dependence on precipitation;strong aggregation and directionality(northwest-southeast)of the mountain-hazards,and the "west-moving" of overall distribution over time in this region were explored.2.Using peak ground acceleration(PGA),annual average precipitation and topographic relief as root factors of hazard-pregnant environment(known as PPR factors)to represent the characteristics of geological structures,climatic impacts and geomorphology,the zoning of mountain-hazards pregnant environments of the Silk Road Economic Belt was done,fifteen subzones were gotten.A preliminary judgment of the mountain-hazards susceptibility for each zone according to the characteristics of PPR factors was made,and nine subzones were initially identified as high susceptibility areas of mountain-hazards.3.The concepts of the "forward" and "inversion" processes for the selection of mountain-hazards hazard assessment indicators were put forward.Because of the problem,paying more attention to the method than the indicator selecting,caused by "inversion" process,by using the "positive" processes,based on the analysis of the mountain-hazards pregnant environment,inducing element,hazard formation mechanism and hazard formation process,the roles and relationships of various elements in the development of mountain-hazards were clarified.The key causing elements of mountain-hazards were considered,and corresponding indicators were chosen to represent them according to six selection rules set by this paper.On the basis of these,the indicator system of mountain-hazards hazard assessment for large-scale areas,including two common indicators and eight characteristic indexes,was established.4.Based on the analysis of the characteristics of PPR factors and the mountain-hazards susceptibility characteristics in different mountain-hazards pregnant environment zones,the high susceptibility zones of mountain-hazards could be divided into three types: arid and active geologic zones,humid and active geologic zones,and humid and inactive geologic zones.By selecting typical sample zones,the random forest algorithm was used to establish the correlation between the hazard occurrences(yes,no)and the hazard assessment factors in the above three types of mountain-hazards high susceptibility zones,and the importance of each factor to the mountain-hazards occurrence could be obtained.Using the importances as the weights of different factors,hazard index models of landslides,mountain torrents and debris flows for different mountain-hazards pregnant environments were constructed,and the hazard assessments of various mountain-hazards were realized.Through the integration of the above assessment results,the single-hazard hazard assessment result of mountain hazards in the Silk Road Economic Belt region was realized.About 35.15% of the mountainous areas were identified as relatively-high and high hazard areas of the single-hazard hazard assessment.5.In order to solve the problem of over superposition effect coming from common factors when using the comprehensive hazard assessment method based on superposition of single-hazard hazard assessment results,a calculation method of mountain-hazards comprehensive hazard index based on the factor level was proposed in order to realize the comprehensive hazard assessment for different combination types of mountain-hazards.On the basis of integrating the comprehensive hazard assessment results above,the multi-hazards comprehensive hazard assessment of mountain-hazards in the Silk Road Economic Belt region was realized.About 36.09% of the mountainous areas were identified as relatively-high and high hazard areas of the comprehensive hazard assessment.