Study On Simulation Of Stormwater Accommodation Multiple Mesaures In Complex Underlying Surface Urban District

Under the background of global climate dramatic change and the rapid development of urbanization in China,the conditions of natural underlying surface is changing drastically,and water intake for human is becoming more and more frequent,which lead to the shortage of urban water resources and frequent urban flood disasters.In order to deal with this problem,flood control from the source and multi-measure combination are promoted and encouraged in national policies;scientific control and related technologies of urban hydrology and water resources are put forward new requirements and orientation.Especially urban runoff fine simulation and stormwater accommodation measures effectiveness analysis are the key technologies and research object,which is promoted for some popular issues such as watch the sea in city in recent years.However,with the urban-rural integration and the construction of urban agglomeration,the urban area like Beijing,Shanghai and other first-tier cities in China is larger and larger,the underlying surface become more and more complex,but the data of real-time monitoring has not yet realized for urban pipeline flow.Therefore digitalization of pipeline network and model calibration become the technical problem of urban hydrology in this type of urban.The core district of Beijing Yizhuang Economic Development Zone was selected as the research area in this paper.The research status of urban runoff simulation and stormwater accommodation measures are summarized,and Water Management Model Storm(SWMM)is established based on the data of the core district,including the information of the natural geographical conditions,the local waterlogging characteristics and DEM,drainage pipeline networks and land use types.And the response features of runoff and flow concentration are simulated in different underlying surface and different design torms.The main contents include:(1)A method for the classification of sub-catchments,the generalization of drainage network and rainwater wells are presented in this paper.Beijing Yizhuang core district is divided into 1072 sub-catchments with a total area of 17.84 km2,3274 drainage pipes with a total length of 107.1 km,and 3621 rain wells finally.(2)In view of the lack of city observed pipeline flow data,a simulation verification method that combines empirical calibration with site survey from the micro scale,and the maximum inundation depth is selected for the validation factor in storm flow process.The input was based on the fine digital district drainage and catchment data,6 validation points was selected according to the district land use types and drainage catchment situation.The runoff process of two typical heavy rainstorms of July 23,2011 and July 21,2012 was measured and the parameters were calibrated.The model was validated by the two typical rainfall processes of July 20,2016 and 9.07,calibration results are good.(3)Based on the constructed regional model,the characteristics of runoff generation and response of different sub-catchments of different land use types were analyzed with the design storms of different return periods(5,10,20 and 50 years).The results show that the response rate of traffic facilities to rainstorm was higher than that of green land and square land with the increase of rainstorm intensity and rainfall,and the difference between the two underlying surface conditions were indirectly reflected.The response rate of the other typical sub-catchments to the design rainstorm and the increase of the rainfall intensity is also more obvious.(4)The design storms of different return periods(5,10,20 and 50 years)were taken as the setting scenarios in the constructed regional model,and the surface runoff,max-depth and duration of waterlogging in measured districts are compared with no-measured districts.The response features of runoff and flow concentration are analyzed and evaluated in different dsign scenarios.The results show that the total amount of runoff and the max-depth were reduced,and the duration of waterlogging was also cut down.The obvious effect of reduction is residential land and industrial land in Yizhuang core district,it’s more obvious in 5-year design rainstorm than others.In general,Yizhuang core district is selected as the typical complex underlying surface area with the high-precision digital processing technology in the paper,as well as in the non-pipeline flow data urban model parameters calibration method for SWMM in urban rainwater runoff simulation.The design of different rainstorms scenarios and different land use types of different land types are compared,the effect of stormwater accommodation multiple measures are analyzed.The research results can improve the application of urban flood and runoff simulation to a certain extent,and provide a technical support for urban hydrology and hydraulics model,and provide reference for future urban planning and sponge city construction in China.