Scale Optimization Of Green Rainwater Infrastructure Based On Coupled Coordination Model

With the rapid development of cities,the impervious ground area continues to increase,which leads to the urban stormwater runoff exceeding the original absorption level.The increase in urban surface runoff also increases the probability of urban flooding.Traditional cities rely on the existing gray drainage infrastructure,with the purpose of "fast discharge",that is,relying on engineering pipelines to discharge rainwater within the city.This type of treatment method often ignores the problem of urban water utilization.At this time,green rainwater infrastructure came into being,focusing on strengthening the principles of scientific utilization of rainwater,such as infiltration,storage,storage,retention,etc.after natural rain falls,and emphasizing the comprehensive utilization of rainwater resources to control urban rainwater runoff pollution and reduce Waterlogging occurs in the city,and the natural rainwater ecological resources are fully and scientifically and reasonably used to protect the city's ecological water environment and effectively promote the city's benign ecological water cycle.This study aims at small-scale existing sites.By analyzing the gray and green rainwater infrastructure structure and drainage capacity elements,based on the coupling and coordination method,a theoretical model of coupling and coordination between gray and green rainwater infrastructure is proposed.The influencing factors of the drainage capacity of the system,using the analytic hierarchy process to establish the weight of each factor,construct a complete evaluation index system of the gray and green rainwater infrastructure system,and obtain a perfect coupled coordination model for the gray and green rainwater infrastructure;Taking the control target,benefit target and construction cost target as the optimization objectives of the green rainwater infrastructure subsystem,combined with the coupling and coordination degree between the gray and green rainwater drainage infrastructure systems,constructing a multi-objective optimization equation set plan to obtain various types of green rainwater infrastructure area.Taking a university in Xi'an as an example to carry out site greening and reconstruction calculations,the scale of green rainwater infrastructure was obtained,and SWMM software was used to model the site of a university in Xi'an to simulate the site runoff situation and site pipe network node blockage under different rainfall recurrence periods Overflow situation.Then,according to the location of the site node blockage and the site water accumulation position,combining with the various types of green rainwater infrastructure scales,the reasonable facility location is arranged,and the SWMM is used to analyze the effect of the site reconstruction.The final result shows that after the reconstruction,the site has obvious improvement effects in rainwater runoff reduction and pipe network blockage.