Research On Investment Risk Evolution Of Sewage Treatment PPP Projects Based On System Dynamics

As one of the important fields in the battle of pollution prevention and control,water pollution prevention and control will release the market demand of water environment treatment rapidly with the implementation of supervision and assessment of relevant work in various places,and its systematic prevention and control has become the development trend of the market in the future.In this context,the implementation of sewage treatment project has gradually changed into PPP mode which is conducive to increasing the intensity of sewage treatment,encouraging the active participation of social capital,and reducing the financial pressure of the local government.The process of marketization will also promote the two-way growth of project processing rate and market space.However,considering the characteristics of public welfare,large amount of investment and long cycle of sewage treatment PPP project,while responding to the policy,we should also analyze a large number of hidden risks for the project investment,so as to provide theoretical support for the long-term development of the project.Combined with the theory of public goods,principal-agent and project differentiation,this paper explores the investment risk of sewage treatment PPP project,and with the help of ANP to determine the importance of relevant indicators,reasonably and effectively constructs the system dynamics(SD)model of investment risk of sewage treatment PPP project.From system point of view of,this paper comprehensively expounds the investment risk factors,clarifies the relationship between each factor,simulates the risk value of policy and law,economic market,construction,operation and maintenance transfer and other risk subsystems,and the overall risk value of project investment,so as to determine the main risks and propose control measures.Firstly,by analyzing the investment entities and investment patterns of the sewage treatment PPP project,combined with the related basic theories,the investment risk is defined,and the risk characteristics of its stage,diversity and policy-relevant are analyzed.Secondly,based on a large number of literature,according to the characteristics of investment risk,this paper sorts out the investment risk factors of PPP project of sewage treatment from the aspects of policy and law,economic market,construction,operation and maintenance and transfer,constructs the index system of project investment risk,and calculates the corresponding weight by ANP,so as to make the relevant risks hierarchical and structured.Thirdly,the applicability of system dynamics is expounded.Based on the causality feedback relationship,the causality loop diagram of the investment risk of PPP project and its subsystems is drawn,and the system dynamic flow diagram is determined.Then,the quantitative relationship among the parameters in the flow diagram is determined,and the dynamic model of project investment risk evolution is established.Finally,combined with the actual engineering case,the model is used for simulation analysis.The simulation results show that the investment risk value of sewage treatment PPP project presents an upward trend in the early stage,and the risk will gradually accumulate and reach a risk peak.After continuous safety investment,the implemented risk control measures gradually come into effect,the project investment risk value will decline before reaching the peak,and the downward trend is obvious,indicating that the control effect is good.Through the risk simulation of the four subsystems,the corresponding management countermeasures and suggestions are put forward according to the simulation results.