Simulation And Systems Optimization Of Urban Rainwater Pipeline Drainage Load

The model of urban rainwater pipe network system is constructed.The model operation parameters are determined by model verification and analysis.The simulation of drainage load of rainwater pipe network is carried out for the current drainage system of XX County in Baoji City.Based on the current urban rainwater system,The green ecological drainage scheme of the design area was planned,and the current situation of the rainwater system in the study artea and the optimized drainage load of the green ecological rainwater system were compared and analyzed.The specific conclusions are as follows:(1)Define the concept of urban green ecological rainwater s.ystem,that is,a system con,sisting of a series of rainwater engineering facilities integrating infiltration,stagnation,storage,net,use and platoon.(2)Based on the impermeability method,time-area model and Saint-Venant equation theory,the urban rainwater pipe network system model is constructed.Through the model verification,the impermeability of each underlying surface,the simulation time step is 60s,the initial loss is 0.0006m,the hydrological attenuation coefficient is 0.9,and the surface convergence velocity is 0.3m/s.The process line of the discharge flow in the simulation results is extracted,and the analysis results show that the simulation value of the discharge flow has a high degree of coincidence with the actual measurement data.(3)Based on the model of urban rainwater pipe network system,the current situation of rainwater system load in County of Baoji City under different rainfall conditions is studied.It is known from the statistical results that the drainage capacity of the current rainwater pipe network is seriously insufficient,and it can bear the return period of 1,2.5.The proportion of pipelines with rainfall load conditions at 3 and 5 years was 29.8%,18.4%,17,8%,and 15.6%,respectively.Under the condition of 2.5 years and 2 hours of rainfall during the recurrence period,the volume of each regional drainage zone is 32329m3,30837m3,32916m3 and 38507m3 respectively.(4)It is determined that the annual total runoff control rate of the study area is 85%,which is equivalent to the rainfall of 2.5 years and 2 hours in the region.By adding LID and other rainwater storage facilities,we plan to study the regional green ecological rainwater system plan and optimize the design.The optimized green scheme has a total design of LID 1137415m2 and other rainwater storage facilities of 18,250m3.The corresponding reductions in peak discharges of each outlet are 52.9%,45.7%,50.1%,and 26.5%,respectively.The cumulative ratio of regional surface runoff is about 67.6.%;the pipelines and inspection wells that meet the drainage requirements are 76.7%and 72.8%,respectively.The estimated water volume is zero for each drainage division,and the total remaining storage volume is 2091m3,meeting the requirements of the planning control target,and the regional drainage system capacity is significant,improve.