Comparison Of Flood Risk Assessment In Different Scale

Disaster risk assessment as the core content of disaster risk management,it is an important basic research of human society to prevent natural disasters, control and reduce the risk of natural disasters.Flood risk assessment is one of the important contents of disaster risk assessment,the range of study from regions, countries, river valley to city, village and community.Due to the impact of global warming, rising sea levels, increased human activity and expanding sphere of influence,the causes of flood became more complexity.Therefore, flood risk assessment has a very important significance to improve disaster mitigation decision-making capacity of all levels of government and lighten the unfavorable factors brought by the flood risk events.I started to participate in the973Plan in2011,1collected and collated datas of the study which is called extreme weather/climate events and Integrated Risk Management Approaches on the Tibetan Plateau,At the same time, referring to the research results of flood risk at home and abroad,then analysis the theory and method of flood risk assessment.Flood risk on the Tibetan Plateau were analyzed based on different scales,the conclusions obtained from this study are summarized as follows.(1)Flood risk assessment has gone from a single scale to multi-scale process and scale exist in various aspects.Driving force, processes, mechanisms and effects of floods have a significant multi-scale feature,Only the multi-scale assessment can reflect the essence of flood disaster risk,so flood risk assessment is the multi-scale assessment.(2) The regional flood system is composed of disaster causing factors, hazard-formative environment and disaster bearing bodies.Flood risk assessment is the probability of occurrence of different intensity and the possible loss caused by the flood.Flood risk analysis includes risk analysis and vulnerability analysis.The objects of risk analysis are disaster causing factors and hazard-formative environment,and vulnerability analysis includes the physical exposure analysis, sensitivity analysis and the disaster response capability analysis.(3) Based on large scale empirical analysis of flood risk on the Tibetan Plateau we found that the eastern section of the Kunlun Mountains in the eastern Tibetan PlateauQilian mountion Gannan PlateauWestern Sichuan Plateau the central mountains area of Tibetare and the western part of the northern karakorum mountains are on the top of risk ranks,Edge mountainous region of Qaidam Basin Western Tibet and Tanggula Mountain Area are on the second place.The focus prevention area is Hehuang valley, Three Rivers region in Tibet, Gannan plateau and the Northwest Sichuan Plateau Mountainous Area.(4) Based on small and medium scale empirical analysis of dam break flood risk we found that Under1/3dam break scenarios,high loss rate mainly distributed in the beach area,the loss rate is higher in some areas of Guide County, north of the city,the loss rate in other areas is lower.Under1/2dam break scenarios,high loss rate focused on both sides of the river and gradually expanded,higher loss rate areas are concentrated in the county, followed by the surrounding areas.Under the whole dam break scenarios,the loss rate is higher in most areas, followed by the surrounding areas,and is lower in the edge area of the study.(6) Compared with the different scale flood risk analysiswe found thatâ‘ different scale floods risk have different Driving force,process and results;â‘¡Large-scale study selected on the basic data is macroscopic and low precision,small and medium scale study selected data is accurate;â‘¢Aspects of indicator selection and characterization of the extent of the large-scale is rather vague,and the small and medium scale is relatively fine;â‘£Large scale flood risk assessment is to provide a scientific basis for the government and the regional disaster prevention; small and medium scale provide scientific basis for the production construction and disaster prevention project.