Research On Uncertainty Of Water Environment Carrying Capacity In Fushun City Based On Monte Carlo Method-system Dynamics Model

Water Environment Carrying Capacity,as the core content of sustainable development research,is an effective way to solve the contradiction between social economic development and water environment pollution.As an old industrial base and an important water source protection area in Northeast China,Fushun has a long-term development method of high resource consumption and high pollution discharge,which has caused the ecological function of the local water environment to continue to decline.Finding a path suitable for Fushun’s development and balancing the contradictions that have already appeared are issues that Fushun needs to solve urgently.Based on this,this paper is based on sustainable development theory,system theory,uncertainty theory,etc.Firstly,the evaluation index system of water environmental carrying capacity of Fushun City was constructed,and the index weight was determined by Fuzzy Analytic Hierarchy Process(SD).Secondly,the System Dynamics(SD)method and Vensim software were used to establish the system dynamics model of the water environment carrying capacity of Fushun City,and the simulated values of all indicators in the index system from 2016 to 2025 were obtained.Thirdly,the scenario analysis method is used to design four planning schemes for comparative research.Combined with index weight and index simulation value,the water environment carrying capacity evaluation model is used to calculate the water environment carrying capacity index of the four schemes.The calculation results show that the development model of the benchmark scheme can make the water environment carrying capacity of Fushun City improve slowly in the future,and the water environment carrying capacity index can reach 0.57 in 2025,which is in the "general" carrying state.In 2025,the water environment carrying capacity index of Scheme 1 will drop to 0.32,while that of Scheme 2 will only rise to 0.60,both of which cannot effectively improve the local water environment.Scheme 3,which adopts the coordinated development strategy,can significantly improve the water environment carrying capacity index,reaching 0.72 in 2025,and entering the "good" carrying state.Taking into account the uncertainty of the water environment system,this paper introduces the Monte Carlo method.From the two aspects of economy and water environment,the probability distribution(the probability distribution in this paper is expressed in interval form,[a,b] where a is the minimum and b is the maximum)of precipitation and GDP growth rate in the past 20 years is used as an objective benchmark for the probability distribution of other indicators.The growth rate of the three industries and other parameters are further analyzed.Based on the probability distribution characteristics of the growth rates of the three industries,Scheme 1,Scheme 2 and Scheme 3 are revised to obtain the probability distribution of the water environment carrying capacity index in the different schemes from 2016 to 2025.The calculation results of the revised scheme show that the water environment carrying capacity index of Scheme 1 that only focuses on economic development is [0.22,0.45]in 2025,which cannot improve the water environment carrying capacity of Fushun City,which is in the "poor" to "general" carrying state.Scheme 2 will restrain economic development in order to reduce the discharge of pollutants.By 2025,the water environment carrying capacity index will be [0.48,0.67].Although the water environment carrying capacity has been improved,the effect is not obvious,which is in the "general " to "good" carrying state.Scheme 3,which combines economic development and environmental protection,controls various indicators within a reasonable range,and has achieved remarkable results.By 2025,the water environment carrying capacity index can reach [0.59,0.79],basically entering the "good" carrying state.In addition,this scheme has the highest probability of occurring,reaching 53.16%.Integrating the results of the two scheme designs,whether in terms of the probability of realization of the scheme or the size of the water environment carrying capacity index in 2025,Scheme 3 is the most preferred in Fushun.Only by constantly balancing or even resolving the contradiction between economic development and water environment,can Fushun truly embark on the road of sustainable development.