Study On The Risk Sharing Of The Sponge City Ppp Project Based On Improved TOPSIS Method And Utility Theory

In order to alleviate the problems of urban water ecology and promote the sustainable development of cities,sponge city construction has been booming in many cities in China.Although sponge cities have an obvious effect in dealing with urban water ecological problems,their construction capital needs are huge,and the fund gap has become the main bottleneck restricting their development.In order to effectively relieve the funding pressure of sponge city construction,the country vigorously promotes and applies the PPP model to carry out project construction.However,the complexity of sponge city PPP projects is far higher than that of general infrastructure projects.Moreover,the development of sponge city construction and the application of PPP mode in China is still immature,and there are many risks in project construction.The key to the success of PPP projects lies in the reasonable sharing of project risks.Consequently,it is important to accurately identify the risk factors of sponge city PPP projects and develop a set of standardized and effective risk sharing framework for ensuring the smooth progress of sponge city PPP projects and promoting the comprehensive benefits of the projects.This paper takes the sponge city PPP project as the research object.Based on the literature analysis,the connotation and characteristics of sponge city and PPP model are elaborated,and the applicability of the application of PPP model construction in sponge city is discussed.At the same time,a comprehensive risk identification of sponge city PPP projects is carried out by using literature statistical research and risk decomposition method,and a risk list of sponge city PPP projects is constructed.On this basis,according to the basic principle of risk sharing,the risk sharing evaluation index system is established,and the weight of the index is calculated by the combined weighting method of G1 method and COWA operator.Consider the nature of the risk-sharing problem,and the vector Angle cosine improved TOPSIS method is adopted to initially share the risk,to determine the public-private independently bear the risks and risk should be Shared by both parties.Based on the utility theory,the risk sharing ratio between public and private parties is determined,and the risk sharing model of sponge city PPP project is constructed.Taking Guyuan Sponge City PPP project as a case study,this paper verifies the effectiveness of the risk sharing model through empirical analysis.Firstly,18 key risks of Guyuan Sponge City PPP project were screened out through expert interviews,and a questionnaire survey was conducted based on the risk sharing evaluation system.Then,the improved TOPSIS method is applied to share the key risks of Guyuan sponge city PPP project.The results show that public sector shall bear 6 risks related to politics,law and policy independently.The private sector is required to independently assume the risk of the 8 risk which major involves in the project financing,design,construction,operation and maintenance phases.Risks arising from inflation,operating-service payments,construction(contract)changes and public opposition must be shared by both scetors.Finally,based on the utility theory,the proportion of public and private risk sharing is calculated.