Study On Risk Assessment Of Water Environment Pollution Of The Accident Type And Simulation Of The Water Pollution Diffusion In The Three Gorges Reservoir Area Based On GIS

The water environment security of the Three Gorges Reservoir has a great influence on social stability and national economic development, Research in risk assessment of sudden water pollution accidents and water pollution diffusion simulation has important practical significance and academic value of the Three Gorges Reservoir water environment security assessment and emergency management. In this paper, we study the Three Gorges Reservoir area of sudden water pollution accident risk assessment method and water pollution diffusion simulation method based on cellular automata.The main work is as follows:Based on risk source information of field research, with reference to relevant information, documents, extract number, critical mass, concentration, allowable limits, the probability of accidents and other relevant factors, build the hierarchical assessment model of risk sources, calculate the value-at-risk(R1) of risk sources, then grading the risk source of the study area by Rl.Referring to the risk source grading standards, the risk source is divided into three different levels:large risk sources, major sources of risk and general risk source, respectively, red, blue, green circles of different colors symbol is displayed on the map, in order to distinguish.Based on sensitive target information of field research, combined with the relevant literature, in addition to considering the range of upstream sources of risk, with exposure-related indicators such as diffusion time of selected contaminants in water, population and cross-impact factor, build the hierarchical assessment model of sensitive target, calculate the value-at-risk(R2) of sensitive target, then grading the sensitive target of the study area by R2. and then refer to the sensitive target grading standards, the sensitive target is divided into three different levels: King sensitive targets, objectives and general sensitive material sensitive targets, respectively, red, blue, green pentagram symbol different colors displayed on the map, in order to distinguish.According to the difference of risk sources of Rl and R2, adopted is based on the risk source and risk zoning based on risk source and the sensitive target coupling risk zoning. Based on the classification of risk source and sensitive target, according to the different and values, calculated various risk zoning result, then according to the partition standard will be different risk areas are divided into3types: high risk areas, medium risk zone and low risk zone, respectively, with red, blue, green colors displayed on the map in order to distinguish.Considering and analyzing the diffusion of pollutants in the study area, attached to the shore, meteorology, hydrology, reservoir operation and other factors, to establish pollution diffusion simulation model based on cellular automata, set the initial state of pollution, quantify and the assign the model factors, combined with cellular automata simulation technology and GIS spatial processing capabilities, intuitive visualization of real-time dynamic simulation of space-time diffusion process of water pollution in the Three Gorges Reservoir.