| With the rapid development of social economy and the continuous improvement of urbanization rate,cities face the ecological environment problems which are becoming increasingly prominent.Especially the water problems,such as the degradation of water ecological functions,water environment damage,water quality deterioration,waterlogging and so on,which have posed a great threat to human survival.And it severely restricts the sustainable development of the social,economic and ecological environment.Faced with the water problem caused by urbanization,in 2012,on the basis of reviewing and drawing lessons from foreign advanced experience,the relevant government departments put forward new measures to build "sponge city" by applying the concept of low-impact development.It has successively issued the Technical Guidelines for the Construction of Sponge City-Construction of Low Impact Development Rainwater System(Trial)and The Performance Evaluation and Evaluation of Sponge City Construction and other documents.And in two batches,30 cities were selected to conduct pilot projects on sponge city construction.The results show that the indicators have basically achieved the desired results,but due to the shortage of time,lack of practical experience and inadequate consideration of the national conditions,there are some shortcomings in the evaluation index system,affecting the objective and impartial evaluation of the construction of sponge cities.Based on the present situation of water problems in the process of urbanization in China,this paper introduces the set pair analysis-variable fuzzy set(SPA-VFS)coupling theory to optimize the evaluation index system,aiming at the coexistence of many uncertainties in the evaluation system of sponge city construction.Firstly,it expounds the water problem caused by the process of urbanization,and deeply analyzes the connotation,goal and significance of the construction of sponge city.Taking the effect of sponge city construction as the objective function and the relevant laws and regulations,norms,technical regulations and standards as the constraints,and taking the total amount of runoff,the peak value of runoff,runoff pollution,water resources utilization and social economy as main factors,the evaluation model of sponge city construction was constructed.Secondly,the theory of set pair analysis and its application in rainwater engineering are elaborated.The model of evaluation index system for sponge city construction is optimized by coupling set pair analysis with variable fuzzy set theory.The weights of evaluation index factors are determined by combining AHP and entropy weight method.The results show that the weights of evaluation factors in quasi-lateral layer are as follows: total runoff control > peak runoff control > runoff pollution control > water resources control and utilization > social economy.In the index layer,annual rainfall,urban drainage network density,urban wetland area,water resources development and utilization,ecological construction and protection investment ratio and other indicators have a greater weight,which has a certain degree of impact on the construction of sponge cities.Finally,taking Chizhou as an example,it's a pilot city of sponge construction in Anhui Province,the paper uses SPA-VFS model to evaluate and analyze its impact,and puts forward some measures to optimize the construction of sponge city.The results show that the impact of various indicator factors on the construction of sponge cities has dropped from III(very important)to II(important),and with the implementation of various sponge measures,the overall ecological environment has improved.Through the analysis,the results are basically consistent with the actual situation of the study area,indicating that the set pair analysis-variable fuzzy set coupling(SPA-VFS)theory applied to the evaluation of sponge city construction is feasible,the results are reasonable,reliable,and the method is simple,which can provide a reference for the government departments concerned. |
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