Risk Assessment Of Sponge City Reconstruction Projects Under BOT Construction Mode

Rapid urbanization,the building volume keeps expanding,which leads to the increase of surface runoff in China’s cities,brings problems such as flood and pollution to the natural ecological water body,and also aggravates the pressure of urban rainwater pipe network.In order to alleviate this pressure,China launched the Sponge City plan in 2013.By using a series of facilities like "sponge" to collect,store and reuse rainwater,it can control surface runoff and achieve the goals of retention,slow infiltration and purification.Considering the implementation effect and later maintenance factors,BOT(build-operation-transfer)has become one of the relatively appropriate sponge city construction modes at present.Under BOT operation mode,sponge project conflicts with existing urban ecology,environment,construction planning,pipe network system,etc.,and there are many problems such as too many factors can not be known or controlled.The project risks are in a complicated and trivial state.Therefore,this paper uses the method of integrating ISM and ANP to identify and evaluate the risk factors of sponge city reconstruction projects under the BOT construction mode from the perspective of social capital and through the analysis of the impact of risk factors.In this study,44 risk factors were separated out through literature analysis,and27 risk factors were selected through 5 rounds of Delphi method to form a risk factor matrix.A questionnaire was designed to invite experts in the industry to give opinions on the relationship between risk factors,and the importance of each factor was scored.The membership function of each factor is given by the processing of fuzzy matrix,and the static risk assessment system is established by integrating ISM and ANP,the mutual influence relationship between different factors is obtained,and their importance is sorted.The evaluation results identify key factors,so as to evaluate the overall risk of the project.In addition,the critical risk path can be given according to the intermediate centrality data of the matrix.In the case,combined with the data of the actual project,the solution is given to the key factors and paths of the risk.The research results can provide certain help for the risk awareness of sponge city reconstruction projects under the BOT construction mode,provide certain reference materials for project managers,and contribute to the development of sponge city projects in my country.