Study On Estimation Method Of Sediment Depth In Urban Drainage Pipeline And The Analysis Of The Effect Of Waterlogging

In this paper,an independent rainwater drainage system in Guangzhou was taken as the research object,and SWMM modeling principle was combined with ArcGIS spatial data processing and analysis technology to build the SWMM rainwater system model in the research area.C# was used to realize automatic extraction of model input and output data,and back propagation-artificial neural network was created to realize nonlinear fitting between node water depth value and model parameter value,thus realizing the automatic calibration of model parameters.On this basis,a method for estimating the sediment depth of drainage pipes is proposed and applied in the research area.And four rainfall data and measured sediment depth were used to complete the checking and validation studies.The results show that the absolute error between the prediction and the measurement of the deposition depth is within 4cm for the pipe with a diameter of 1.2m to 1.8m.Two rainfall between simulation results and the measured data of water depth of peak time deviation less than 5% of the measured data for peak value deviation is within 3%,and other times the depth of simulated values and measured values show a good consistency,show that the method has good reliability,to effectively predict the drainage pipeline silting situation.For the first time,it is proposed to take the pipe sediment coefficient(SC)as the independent variable,and the node overflow flow and the number of overflow nodes of the drainage system as the dependent variables,to conduct a simulation analysis of the drainage system in the research area.In addition,the relative overflow nodal ratio and the relative overflow flow ratio are used to analyze and evaluate the influence of sediment deposition on the waterlogging disaster.The simulation results under all pipe sediment scenarios show that the node overflow flow and the number of overflow nodes,the relative overflow nodal ratio and the relative overflow flow ratio increase with the increase of average sediment coefficient(ASC),and the risk of waterlogging increases gradually.When ASC < 0.3,the four values increase slowly,while when ASC > 0.3,the four values increase rapidly,and the risk of waterlogging increases sharply.When ASC > 0.6,the relative overflow flow ratio exceeds 5 or even more than 10,which will seriously affect the drainage capacity of the drainage system.It can be concluded that the control of ASC < 0.3 is a cost-effective way to reduce the risk of urban waterlogging when the drainage pipe inevitably has different degrees of silting,because of maintenance costs and other reasons,in the actual drainage system management.The simulation results under the single pipe sediment scenario show that the single pipe with mild sediment(SC=0.3)has little effect on the drainage performance of the drainage system.However,if the deposition of a single pipe sediment is serious(SC=0.6),the drainage performance will also be affected to varying degrees,especially in the "bottleneck" position,and even local waterlogging may be caused.The results of this study can provide a method with strong promotion and engineering practicability for drainage pipe cleaning and maintenance,and provide a new intelligent management technology and idea for alleviating urban waterlogging.