Design And Optimization Of Site Green Rainwater System Based On Comprehensive Benefits

With the frequent occurrence of extreme weather caused by urbanization process and climate change,internal disasters and water pollution caused by storm runoff often result in huge losses.At the same time,the lack of effective use of rainwater resources aggravates urban water scarcity and drought conditions.The problem of flood management has become increasingly prominent.In order to solve the problem of urban stormwater and change the rainwater into damage,it is necessary to change the traditional stormwater management concept and gray rainwater system that is based on platoons,and build a low-influenced development(LID)concept to fit in with a small decentralized green infrastructure.The composition of the green rain system.In the actual construction of site rainwater systems,comprehensive consideration should be given to various factors such as runoff control objectives,project budgets and benefits,and social impacts in order to maximize the project’s overall environmental,economic,and social benefits.At present,there is no quantitative research and effective evaluation model for the comprehensive benefits of green rainwater systems.Therefore,it is of great theoretical significance and application value to study the design optimization of green rainwater system based on comprehensive benefits.Firstly,the paper selects and quantifies the evaluation indicators of environmental benefits,economic benefits,and social benefits of LID measures by summarizing literature data,simulation data of stormwater management models,and economic analysis based on cost-effectiveness of the entire life cycle.Methods were studied.Among them,the use of stormwater management model(SWMM)simulation method to quantitatively identify the peaks of the rainwater system to reduce emissions,interception of pollutants in the water environment efficiency;using the full life cycle cost-benefit analysis method,combined with engineering practices on the construction cost of green rainwater systems,The economic benefits such as operation and maintenance costs and operating income are discussed.Based on the relevant literature and calculation methods,the social benefits such as flood prevention and reduction,energy conservation and emission reduction,and beautification of the environment are quantitatively analyzed.Then,a comprehensive benefit evaluation index system for the site green rainwater system was constructed.The weights of indicator combinations are determined using the Analytic Hierarchy Process(AHP)in the Subjective Empowerment Method and the Entropy Weighting Method in the Objective Weighting Method to reflect both subjective and objective information.The weighted summation method was used to quantitatively evaluate the various benefits and comprehensive benefits of the site’s green rainwater system.Finally,a case study was conducted on a plot of land in a new district in Nanchang City.Six kinds of LID measures including rainwater garden,sunken green land,vegetation shallow ditch,permeation pavement,green roof,and rainwater bucket were combined to form nine green venues.Rainwater system design plan,using the evaluation index system for benefit evaluation.The results of the study will help to compare the differences in environmental,economic,and social benefits of different measures,clarify the advantages of each measure in terms of benefits,and mutually corroborate it with theoretical analysis.At the same time,the optimal plan for maximizing the comprehensive benefits is selected as the combined design of concave green land + vegetation shallow ditch + infiltration paving + rainwater bucket.The research results provide reference and help to solve the design optimization problem of green rainwater system for the purpose of maximizing the environmental,economic and social benefits of the green rainwater system project.