Simulation Of Urban Waterlogging In Typical County Based On MIKE FLOOD

With the rapid development of our country's economy and society,the process of urban-rural integration is speeding up,which leads to a sharp change in the underlying surface structure of the county-level urban area.In addition,compared with the city level urban area,the standard of the drainage pipe network in the county-level urban area is low and the infrastructure is weak,which makes "see views in the city" no longer a common problem in large and medium-sized cities,and has gradually involved in small and medium-sized cities,providing residents with normal life and property safety It became a huge impact.In this situation,how to evaluate the risk of urban waterlogging quickly,accurately and effectively,and reduce the loss of urban waterlogging disaster has become one of the important work of urban emergency management.In this study,Lincheng County,a typical county in North China,is selected as the research area.On the basis of summarizing the relevant research progress of urban flood disaster and urban rainfall and flood model at home and abroad,four typical rainfall processes are selected to calibrate and verify the model parameters on the platform of MIKE FLOOD,and the regional-2d hydrodynamic coupling model is successfully constructed.Based on this model,according to the local rainstorm intensity formula,combined with the actual situation of the region,the hydrological effect and waterlogging risk of the region under different design rainfall scenarios are analyzed and evaluated.The main contents and achievements are as follows:(1)The construction of a two-dimensional coupled hydrodynamic model.Based on the data of drainage pipe network,land use type and digital elevation data(DEM)in the central urban area of Lincheng County,MIKE URBAN urban drainage pipe network model and MIKE 21 two-dimensional surface flood model in the study area are constructed.Based on the data of four measured rainfall runoff and ponding,the model parameters were calibrated and verified by the method of maximum ponding depth survey at typical points,and the regional two-dimensional coupled hydrodynamic model was successfully constructed.(2)Analysis of regional hydrological effects under different scenarios.Under different return period design rainfall scenarios,the total amount and peak flow of surface runoff increase with the increase of return period,while the peak flow has no obvious relationship with rainfall duration;under the same rainfall conditions,the peak flow of sub catchment area with the same runoff coefficient increases with the increase of catchment area;the regional ponding is mainly concentrated on the road and its line,with the largest and the average ponding depth of 100-year return period is 1.53 times and 1.96 times 3-year return period respectively,and the range and depth of ponding increase with the return period.With the increase of rainfall duration and period,it mainly diffuses to the road and its surroundings,but the change is not obvious.(3)Pipeline load and waterlogging risk assessment under different scenarios.The rainfall runoff simulation of different scenario design shows that the depth of node overflow and the degree of pipeline load increase with the increase of recurrence period and rainfall duration,but the number of overflow nodes and overloaded operation pipelines does not change significantly.Based on the comprehensive comparison and analysis of hydrological effect,pipeline load and other conditions,and the assessment of regional waterlogging risk,the region is divided into four types of waterlogging prone areas,namely,rainwater discharge area,low-lying area,road and its line and overload operation pipeline area.The relevant results of this study can provide technical support for the early-warning deployment of regional flood prone points under extreme weather in Lincheng,and provide decision-making reference for the emergency work of urban waterlogging at county level and the refined management of urban rainwater and flood.