Monetary Evaluation Of Debris Flow Disaster Integrated Risk And Acceptable Risk Study

The core task of risk management is to clear “how safe is safe enough”.Acceptable risk study of natural disaster is so weak that the results of risk assessmentare out of risk management decision,because of that the absolute risk value is lack andacceptable risk as the bridge of risk analysis and risk management is ignored.Therefore, the study of monetary evaluation of debris flow disaster integrated risk andacceptable risk has scientific and practical significance.Risk assessment models of life risk, economic risk and eco-environmental riskwere established by the methods of comparative analysis and quantitative analysis.The influence factors of acceptable risk were analyzed, and acceptable levels wereproposed by F-N curve and risk matrix, at last the relationship of acceptable risk andrisk management was explored. Major results of this paper were outlined as follows:(1) Debris flow disaster risk assessment models were made perfect and theexpression of disaster risk absolute value was proposed. In this paper debris flowdisaster risk was expressed as the combination of the frequency of a disaster event, theexposure of hazard-affected bodies and its potential loss rate. This expression wasused in risk assessment on different types of disaster risk, the key to which was theexposure referred to people, property, ecosystem present in hazard zones, and itspotential loss rate in life risk, economic risk and eco-environmental risk. Theexposure of life risk was risk population, and its potential loss rate was determined bymagnitude, time of occurrence, the proportion of vulnerability population and warningtime. The exposure of economic risk was expressed as the value of housing property,primary industry, industry, the tertiary industry and public facilities, and the exposureof eco-environmental risk was calculated by forest, farmland, grassland ecosystemand human social system, the potential loss rate of life and eco-environmental riskwas relevant to the magnitude of the disaster and the types of hazard-affected bodies.(2) The monetary value of debris flow disaster integrated risk were investigated.Because the measurement unit of life risk, economic risk and eco-environmental riskwas different, life risk and eco-environmental risk were transferred to monetary value.For life risk, the outcome of life risk was converted to life monetary value by LQI.For eco-environmental risk, the monetary value was calculated based on ecosystem function theory and analysis of eco-environmental loss. Then the monetary value ofdisaster integrated risk as uniform measurement units was proposed combined witheconomic risk.(3) The influence factors of debris flow disaster acceptable risk were analyzed inthis paper. The questionnaire on professionals and the public showed that the topfactors were the same from their views, the sorts of which were consequence,probability, the public mental capacity, economic development and the recommendedstandards of experts. This paper analyzed the influence of risk characteristics, riskperceptions and individual characteristics on acceptable risk, the outcomes of whichshowed that acceptable risk levels was varied by risk characteristics and riskperceptions. Acceptable risk of the public was different because of different sex, ageand level of education. Male sex accepted higher risk than female sex, the public of0to25years old accepted highest risk while the public of over65years old acceptedlowest risk. And the acceptable risk level was more and more high with the higheducation level of the public.(4) Recommended acceptable risk levels of debris flow disaster was proposed.Under the direction of acceptable risk criteria, acceptable risk levels of life risk,economic risk, eco-environmental risk were proposed. For life risk, the limit ofindividual acceptable risk was210-6per year, the limit of tolerable risk was210-4per year, and tolerable risk was located between210-6and210-4per year; socialrisk was expressed by F-N curve, the slope valued-1, the intercept valued10-2peryear, the cuts-off of abscissa was100deaths, so more than100deaths wasunacceptable risk. For economic risk, individual risk was expressed as individualeconomic risk index, the limit of individual acceptable risk was0.1, the limit oftolerable risk was0.2, and tolerable risk was located between0.1and0.2; social riskwas expressed by F-D curve, the cuts-off of abscissa was￥100106per year, somore than￥100106per year was unacceptable risk. Acceptable risk level ofeco-environmental risk was determined by risk matrix.(5) Risk assessment in practice of9typical debris flow disasters were carried outin this paper. Shenjia Gully in Luding County, Bayi Gully in Dujiangyang City,Chayuan Gully in Wenchuan County, Qiongshan Gully in Danba County andSanyanyu in Zhouqu County were taken as examples to verify risk models of life riskand economic risk. The results showed that risk models had a certain reablity, especially in life risk model that the difference was very small. After that, integratedrisk was assessed of Longdong Gully in Maoxian County, Shuixi Gully in MaoxianCounty, Yangjuan Gully in Luding County and Luoyu Gully in Qinzhou County ofTianshui City, the monetary values of which were￥114582104,￥7799104,￥810104,￥35318104. On the basis of risk assessment results, the risk acceptacewas evaluated as follows: the risks of Shenjia Gully, Chayuan Gully and YangjuanGully were tolerable, the risks of Bayi Gully, Qiongshan Gully, Sanyanyu, LongdongGully, Shuixi Gully and Luoyu Gully were unacceptable.(6) The risk management theory based on acceptable risk was explored. Thispaper analyzed the relationship of acceptable risk and risk management, andacceptable risk played the role of a bridge between risk assessment and riskmanagement. For risk management on the operation, debris flow disaster prone areawas divided into prohibited development zone, restricted development zone, alloweddevelopment zone by the core means of land use planning. Accepting the risk,reducing the risk, risk aversion, risk transfer were proposed as the basic measurementsof risk treatment, the efficiency of which was analyzed by cost-benefit analysis andthe example of Zhouqu was10, which showed the risk management performance washigh.