Study On Risk Assessment Of Excessive Water Drainage In Urban Stormwater Pipeline Network Based On SWMM

As one of the important infrastructure of the city,the rainwater pipe network system often has many uncertainties in the course of operation.Especially,the extreme rainstorms which have occurred frequently in the urban areas in recent years have caused many areas to suffer from waterlogging.The paper makes a systematic study on the water delivery capacity of the urban drainage pipe network,and makes a scientific assessment of the risk level of the water supply line of the pipe network,draws the water distribution map of the drainage network,and then identifies the weak link of the drainage system.Pipe network upgrade,maintenance and management of the content and direction to provide technical reference.Based on the theory of drainage pipe network model and the SWMM model and risk analysis theory,this paper systematically studies the simulation,evaluation and prevention measures of waterlogging in 03 area of Xiushan county's drainage network,and obtains the following results:1)According to the theory of system engineering,the basic theory of drainage pipe network model and the basic calculation principle of SWMM model are expounded.Based on the runoff coefficient as model correction method,the Xiushan county's model parameters are optimized and the model parameters are used sensitivity analysis.According to the results of the analysis,the sensitivity of the parameters in the model is as follows:N-Imperv>N-perv>Min Rate>Max Rate>S-Perv>Decay>S-Imperv>Dry Time.2)According to the rainstorm intensity formula of Chongqing,the rainfall process line under different reproduction period is synthesized by using the software and formula of the rainstorm process in Chicago,and the operation of Xiushan County's rainwater pipe network under different reproduction period is simulated.The simulation results show that the number of nodes in the study area is 0,1 and 4 respectively when P= 1a,2a and 3a,respectively.When P=5a,the number of nodes that are overloaded increases to 26 And can be located to the corresponding pipe;when P?10a,the number of nodes that can be overloaded can reach 1/3 or more of the entire pipe network node,and the overload distribution map under different reproduction periods is drawn.According to the analysis of different rainfall scenarios,the results show that when P<5a,the disaster resistance of the area can be improved by modifying the inspectionwells and buried the new pipelines.When 5a?P?10a,the rain can be used to adjust the reservoir or LID measures;and when P>10a,it should be used LID measures combined with the rainwater storage pool,but with the increase in the reproduction period,LID measures and rainwater storage The pool will also fail.In the study,it is found that the LID facility has some effect on the flood peak and the delay effect is about 1min.With the increase of the rainfall recurrence period,the effect of the flood peak delay is weakening.The weakening of the peak increases with the increase of rainfall,but there is a certain upper limit,that is,the LID facility has a certain degree of saturation.3)According to the theory and method of risk analysis,combined with the actual situation of Xiushan County in Chongqing,the functional risk coefficient of the node is used as the evaluation index,and the degree of membership of fuzzy mathematics is used to quantify and evaluate the drainage capacity of P = 5a,The influence of node water depth on the operation of the drainage system is analyzed,and the risk level of the nodes in the system is judged.The evaluation analysis shows that the study area is a high risk area of rainwater flooding.In this study,the method of hydraulic simulation and risk analysis is used to identify the influence of multiple factors on the system risk in the operation of Xiushan county's pipe network,which can provide reference for the modeling and risk analysis of stormwater pipe network in the relevant cities or regions.It is of great theoretical and practical value to provide scientific basis and reference for the prevention and control of urban waterlogging and the design of LID facilities in sponge city.