The Risk Assessment Of Landslide Disaster

China is a geological disaster-prone country about the landslide and debris flow.The statistics data of National Geological Disaster Bureau shows that landslides occupymost of the geological disaster that occur in China each year. Therefore, to strengthenlandslide risk assessment is of great significance to China’s economic development,social stability and the protection of people’s lives and property safety. Based on suchunderstanding and the summary theories of previous landslides risk assessment, thethesis has discussed and analyzed the risk assessment of landslide disaster and has triedto establish a theoretical system of landslide risk assessment, including the theoreticalfoundation, the basic assumptions and principles, index system, evaluation methods aswell as risk management. And the thesis has made a practical test to landslide riskassessment in the last which takes the landslides assessment of eighth car team of WenChuan country district as an example. The main contents of the text are as follows:(1) The theoretical basis of the landslide risk assessment. The basic theories oflandslide risk assessment mainly include contributing theory, statistical theory andinformational theory. The contributing theory is to explore the assessment methodabout landside disaster by its formation mechanism and dynamics process. It mainlyfits for landslide risk assessment and drawing of large-scale sections and engineeringsites. On the basis of statistics and applied mathematics, the statistical theory analyzesvarious marks, phenomena and variable quantities of landslides disaster and prepares toestablish the related risk prediction assessment equation on account of the statisticstheory, which is appropriate for small and medium-scale area of landslide riskassessment. Relying on information science and geographic information science andaccording to the related data and quantity of information, the informational theory predicts and judges the trends of geological disasters. It also makes risk assessment andmanagement including the specialized geological disaster analysis and handling andprediction and warning module, which utilize the theory and technique of geologicalinformation system. The widely application of it has become widespread technologyaround the world. Landslide risk assessment is established on the three assumptions:the past has the function of instruction to the future, the basic elements that result inlandslide disaster can be identified the hazards of prone, dangerous and risk characterscan be selected and quantified. The basic principle of landslide risk assessment are asfollows: the principle of hierarchy, the principle of qualitative and quantitative methodsthat to be selected, the principle of cartographic scale corresponding to precision andthe principle of economic and technical feasibility and priority of benefits.(2) The main contents of landslide risk assessment should include four aspects:data catalog, prone evaluation, dangerous assessment and risk estimation. Each contentof landslides risk assessment corresponds to its own evaluation index system andconstitutes a hierarchical structure. The most crucial and fundamental indexes aregeological environment index, landslide catalog index, induced conditions index andload bearing index. On such basis the target layer index can be set up, which includesprone index, vulnerability index, dangerous index and risk assessment index. Based onthe main contents and index system, the processing of landslides risk assessmentincludes target definition, data collection, survey prospect, data management, riskassessment and risk management.(3) Landslide risk assessment includes three aspects: landslide vulnerabilityassessment, landslide risk assessment and risk management of landslide hazard. Ofevaluation method, there are a lot about landslide vulnerability assessment. Generally,there are knowledge-driven, data-driven and physical modeling, of which, physicalmodeling being associated with probabilistic methods, it can be done to conduct alandslide risk analysis, constitute a landslide-prone evaluation model system. Inpractical application, it should be combined with the characteristics and type oflandslide of the study area, the scale and quantitative degree of evaluation, the type ofthematic data, quality and resolution. There also exist other factors to becomprehensively considered, in which there are the applicability and operability ofvarious methods, the accessibility of data, the reliability of the results and so on. Afterthat, it is important to choose model approach reasonably, focus on basic assumptionsand evaluation unit selecting, technical methods and software tools of analysis, ofwhich the selecting of evaluation unit is the most important. The method of landslide hazard assessment is on the basis of landslide-prone evaluation. In landslide hazardassessment, the evaluation from susceptibility to hazard zoning evaluation is donethrough frequency analysis of landslide, Runout analysis, the probability of significantinduced events analysis as well as statistical analysis of landslide intensity andprobability. As to how to choose a reasonable hazard assessment method, it should becombined with the genetic mechanism of the landslide hazard, the differences of riskpredisposing factors and the availability of data. Then it is a necessity to determine themain indicator parameters of the risk classification and qualitative and quantitativedegree of risk assessment. Based on the conclusions of the risk assessment and throughestablishing continuous monitoring and early-warning systems, landslide riskmanagement development develops methods of evacuation plans or transferring risk(insurance), considers how to mitigate risk, including acceptable risk, reducing the riskthat is likely to occur and the harm of risk and also carries out a set of disaster reductionprograms and the adjustment control measures that can be implemented.(4) Based on the risk assessment of landslides, this thesis has been applying therisk assessment of landslides, taking the landslide assessment of the eighth car team inWenchuan country district as an example. By analysis the development characteristicsof geological distribution of the car teams, the thesis does some calculation andevaluation of the stability of landslide, analyzes cause mechanisms and developingtrends of landslide and concludes with landslide prevention and treatmentrecommendations, based on which, it also conducts economic, social andenvironmental benefits assessment.