Construction And Application Of Sponge City Evaluation System Based On Analysis Of Urban Ecological Features

In recent years,most cities have encountered environmental problems such as frequent waterlogging,runoff pollution,waste of rainwater resources,and destruction of the ecological environment in the process of urbanization.In order to solve the above problems,the country has proposed a method of building a sponge city.At present,with the advancement of our country's sponge city pilot work,there is an urgent need to establish a scientific and effective sponge city construction evaluation system and a scientific evaluation model to provide scientific analysis and decision-making tools for the subsequent comprehensive development of sponge city construction.First of all,for the single evaluation system of the existing sponge city construction,and mainly for the performance evaluation after completion,the lack of pre-construction evaluation system,this study is based on the scientific connotation of ecological red line,ecological carrying capacity,and sustainable development.On the basis of systematic reading,combined with data frequency mining technology,an evaluation index system was initially established.At the same time,the index system in the 30 pilot sponge city acceptance reports was selected to screen the initially established index system.The evaluation index system after screening includes: annual runoff total control rate,greening coverage rate,permeable pavement rate,ecological shoreline restoration ratio,water area area rate,urban heat island value,urban water function zone water quality compliance rate,annual SS total Reduction rate,removal rate of black and odorous water bodies,removal rate of historical water accumulation points,annual reduction rate of combined overflow frequency,average annual overflow volume reduction rate of combined system,sewage regeneration utilization rate,uti lization rate of rainwater resources,sewage treatment rate,Water supply network leakage control rate,drainage network standard,flood control standard,flood dike compliance rate,urban waterlogging prevention and control standard,continuous demonstrat ion effect,park green space per capita,water supply penetration rate,23 quantitative secondary indicators,as well as planning and construction There are 7 qualitative indicators,including the degree of control,the delineation and protection of the bl ue and green lines,the construction of technical specifications and standards,the construction of investment and financing mechanisms,the performance evaluation and reward mechanism,industrialization,and preferential policies for the development of related enterprises.Secondly,in view of the uniformity of the weights of the existing sponge city construction evaluation system,or the simple determination of the weight of the index system using the Delphi method,expert method,brainstorming method and other subjective factors,this study uses principal component analysis and factors The analysis method,from a relatively objective perspective of mathematical statistics,conducts a structural exploration of the 23 quantitative indicators in the indicator system,and performs an index correlation analysis based on the obtained correlation coefficient,and at the same time classifies the indicators according to the size of the correlation coefficient Complete factor extraction,factor naming,and determination of index weights at all levels.Analysis results: A total of eight public factors including overflow control factor,water safety factor,runoff control factor,visibility factor,aquatic ecological factor,water environment factor,ecological greening factor,and water resource factor were obtained and used as the index system The second-level indicators determined in the previous step are downgraded to the third-level indicators;the weights corresponding to the second-level indicators are 0.230,0.177,0.147,0.117,0.106,0.091,0.069,0.064;23 third-level indicators correspond to The weights are 0.082,0.080,0.068,0.027,0.074,0.076,0.074,0.074,0.038,0.034,0.046,0.053,0.053,0.034,0.028,0.029,0.069,0.027,0.027,0.010.Finally,for the unified evaluation of all sponge city construction schemes using a set of constant weights,it is often impossible to achieve a balanced overall state and better evaluate the construction scheme.This study is based on the determined constant weight evaluation weights,using Matlab software to randomly Generate three construction schemes,establish a set of sponge city construction variable weight evaluation system by introducing variable weight theory,punitive variable weight formula,and local variable weight formula,and calculate the evaluation results of various indicators at all levels under constant weight and variable weight And compare and analyze the difference and connection of the three construction scheme scoring results under the two evaluation systems of constant power evaluation and variable power evaluation.The analysis results show that the variable weight evaluation realizes the idea of "punishing disadvantage indicators and incentivizing advantage indicators" by changing the weight of the evaluation indicators at various levels to the indicators at the negative level and excellent level,to a certain extent,amplifying the relative advantages of some indicators.In order to achieve incentives and enlarge the relative disadvantages of some indicators to achieve punishment,which affects the evaluation results of various programs.