Research On Optimal Utilization Of Low-impact Development Technology Of Sponge City In Coastal Area

In the current construction of ecological civilization projects in my country,the construction of sponge cities can effectively solve the problem of urban water use in my country,and is a key link to further realize the coordinated development of new socialist urbanization and natural resources.Compared with the traditional urban development model,Sponge City emphasizes the coordination between people and urban planning and ecological environment to realize rainwater retention,purification and utilization,which is very different from the development concept of traditional measures.Coastal areas are characterized by heavy rainfall,high groundwater levels,and frequent changes in seawater tidal levels.Urban waterlogging and water pollution are becoming more and more serious.Traditional urban drainage models can no longer meet the needs of rapid urban development.Based on the problems of short rainfall duration,high intensity,and widespread tidal support on the drainage network of large and medium-sized coastal cities,combined with the construction of sponge cities in coastal areas in my country,low-impact development technology and multi-objective optimization methods are used to have low impact on coastal areas Develop the facility plan for optimization research.First,sort out a large number of relevant domestic and foreign literature and data,and study sponge cities,storm flood management models,multi-objective optimization and resource value transfer accounting related theories,clarify the current research status of these aspects at home and abroad,and give relevant theories The basis was analyzed.It is found that my country has little research on the construction of sponge cities in the coastal area,and the purpose of the research is more to achieve the goals of hydrology and water quality,basically ignoring the phenomenon of cost and many other benefits.In-depth analysis of the principles of the SWMM model and the process of multi-objective optimization and implementation methods.Based on the analysis of resource value transfer accounting theory,the sponge city water resources value flow theory is proposed,which lays a foundation for the model establishment,simulation analysis and optimization decision-making research in the following The theoretical basis.Secondly,establish a storm and flood management model in the study area.The basic situation of the study area is summarized,and the climate,hydrology and geology conditions of the reclamation area where the study area is located are analyzed.On this basis,the drainage network and nodes of the study area were generalized and sub-catchment areas were divided.The determinability parameters of sub-catchment areas,pipelines and nodes were determined based on the existing data;for the short duration and intensity of rainfall in Shenzhen High characteristics,combined with the Chicago rain pattern and Shenzhen storm flood management model,designed the rain sequence with return periods of 2a,5a,and 10 a respectively;in the process of calibrating the uncertainty parameters of the model,the sensitivity of each parameter was carried out.Analyze and verify the scientificity and rationality of the model through the measured data of two actual rainfall events.Third,the LID facility combination in the study area was designed,and the operation effect of the LID combination under the tidal action and rainfall in each return period was simulated and analyzed.A set of LID facilities comparison and selection methods are proposed.According to the control objectives,site conditions and characteristics of the LID facilities in the study area,several LID facilities suitable for the study area are selected,and the LID combination scheme design is carried out;for each LID combination The runoff control effect of the plan was simulated,mainly by simulating the peak runoff flow,peak present time and runoff reduction rate of each combination under different return periods of rainfall;the investigation and data combing of the seawater tide level near the study area were carried out.The load of the drainage network in the study area under the influence of tides(outlet discharge and inspection well water depth)and the operation effect of each LID combination under the action of tidal jacking were simulated and analyzed,and the best combination plan was selected.Finally,combining the multi-objective optimization method and resource value transfer accounting theory,optimize and make decisions on the layout of LID facilities.A multi-objective optimization model was established,with the layout area of the two types of permeable pavement and rainwater garden in each subcatchment as decision variables,and the NSGA-Ⅱ algorithm was used to optimize the scale of LID facilities;according to the relevant documents of Shenzhen Four optimization schemes were selected and compared with the original scheme.The optimization scheme reduced costs while also meeting the runoff control objectives.According to the resource value transfer accounting theory,the relevant data of the four optimization schemes under the tidal action and the rainfall condition with a return period of 10 years are obtained through simulation,and the resource flow-value flow calculation of the water resources in the four optimization schemes is carried out to construct a sponge The urban water resources value flow decision-making model evaluates the water benefits of the four options and realizes the decision-making of the options.