Study On The Measurement And Calculation Method Of The Volume Capture Ratio Of Annual Rainfall In Sponge City

At present,the construction of sponges in various parts of China is being carried out in an orderly manner.The Ministry of Housing and Urban-Rural Development of China has promoted the construction and assessment of sponge cities,and proposed the “Technical Guide for Sponge City Construction – Construction of Low Impact Development Rainwater System for the Status Quo of Cities in China(Trial Implementation))and "Sponsor City Performance Evaluation and Assessment Method(Trial)".It points out that the volume capture ratio of annual rainfall is a key indicator,which can effectively reflect the ability of low-impact development facilities to control runoff volume and assess the effect of sponge city construction.This paper selects the volume capture ratio of annual rainfall as the research object,selects and establishes 10 sponge city smart monitoring stations in Laoshan District,Chongqing,and collects the rainwater outlet runoff flow rate,liquid level and flow rate of 9 typical blocks in Laoshan District monitored by the monitoring station.As well as real-time rainfall and other data,and the subsequent processing and calculation of the data,a set of methods to accurately calculate the total annual runoff rate of the sponge city in Laoshan District,and calculate the total annual runoff control rate in the Laoshan District,for the Laoshan District sponge Urban construction puts forward relevant suggestions.In this study,nine BP neural network models were established to remove the dry season flow in the rainwater pipeline.The R2 value of the dry season liquid level model is greater than 0.83,and the dry season flow model R2 is greater than 0.75,which can effectively separate and identify the dry season water flow and liquid level of the rainwater pipeline.To ensure the accuracy of the rainy season runoff data.Because the monitoring of the flow rate during the rainwater pipe flow monitoring process is affected by many factors such as pipe diameter and pipe bottom siltation,it has great uncertainty.Therefore,through the measured multi-field rainfall data and the corresponding rainseason runoff level after removing the dry season flow,the parameters of the SWMM model of nine typical plots in Laoshan District are determined and verified.The simulation results of the current SWMM model of 9 typical plots are The measured Nvalue(Nash coefficient)of the liquid level process data is greater than 0.7;the peak deviation of the simulated result and the measured data is within 20% of the rainfall event duration;the numerical deviation of the simulated peak and the measured peak is within 25%.Through the SWMM model,the annual total runoff control rate of Laoshan District is calculated.The average annual runoff control rate of the eight non-sponge measures is 21%-57%,which does not reach the total annual runoff control of the sponge city planning.Rate requirements.The total annual runoff control rate of the completed sponge residential area(Jinke Community)is 91%.