| In the past 20 years,China is in a period of rapid urbanization,with remarkable achievements in urban construction,but at the same time there are problems such as excessive hardening of the surface and frequent occurrence of urban floods.Using hydrological model to simulate and calculate the urban hydrological process is an effective means to prevent and predict urban flood disasters.In this paper,through a comprehensive analysis of the occurrence and development process of urban storm flood and its influencing factors,a concise and efficient surface runoff generation and concentration model is constructed with typical communities in the city as the simulation scale and grid cells as the minimum calculation unit.The underground drainage pipe network model is established based on vector pipe network data.Through the spatial matching of vector point coordinates and grid unit row and column numbers,the vector model of underground pipe network transportation and the grid model of surface runoff generation and collection calculation are coupled,so that the pipe network vector model can be incorporated into the surface runoff generation and collection grid model.Finally,the urban rainfall and flood prediction model integrating the three hydrological processes of runoff generation,runoff collection and pipe network confluence is obtained,and a common typical community in the city,campus,is selected for application analysis of the model.The research contents and conclusions of this paper are as follows:(1)In this paper,the characteristics of urban surface runoff generation and concentration process are extracted by comparing and analyzing the urban surface runoff generation and concentration process with that of natural watersheds.SCS method is selected to simulate the surface runoff generation and concentration process according to the data preparation and its characteristics,and isochron method is used to simulate the surface runoff generation and concentration process,thus completing the simulation calculation of urban surface runoff generation and concentration.Considering the limitations of the runoff generation and concentration method,the applicability of the runoff generation and concentration method in community-scale flood simulation is discussed.(2)Considering that the underground pipe network system is usually expressed in the shape of points and lines in spatial modeling,this paper will establish an underground pipe network model based on vector data,which is limited by the data preparation and the calculation difficulty of the pipe network convergence method.This paper will explore the use of Muskingum method in the pipe network convergence simulation,and consider the limitations of Muskingum method,and discuss its applicability in the community-scale rain flood simulation.In order to merge the underground vector model with the surface grid model,it is necessary to study the coupling method of the two.In this paper,the vector point is infinitely small on the plane and its coordinates are matched with the grid row and column numbers.The vector point and its grid unit are connected to the underground and surface space to complete the coupling of the two models.Finally,an integrated urban rain flood prediction model is obtained.(3)In this paper,the North District of Xianlin Campus of NJNU is selected as the research area,and the rainfall event from 17:50 to 20:00 on June 16,2015 is taken as an example to simulate the rainfall process.The results show that grid cells can well describe the process of surface runoff and accumulation,and the process of water accumulation and elimination at any position in the area can also be quickly obtained by matrix operation for a small area within the city with fine DEM data.Therefore,when simulating the storm flood process at the community scale in the city,the results obtained by using the grid cell-based modeling method are more precise and can better meet the requirements of urban flood control and drainage. |
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