A novel raster and vector coupled model for urban storm water routing simulation in the plain river network region: A case in Beijing Municipal Administrative Center

Abstract:

As an important urban rainstorm-runoff process simulation tool, the urban routing model can accurately identify the nodes and paths of routing network, trace the flood source, thus play an important role in urban storm-flood management. In urban area, especially cities in the plain river network region (PRNR), the traditional watershed routing model which based on D8 model is difficult to be applied due to the poor accuracies of free available DEM in horizontal and vertical directions. SWMM and its improved model have been widely used in urban storm-water simulation and management, however there still be limitations in the surface routing simulation. The main purpose of this study is to combine grids data, which can better reflect surface routing process, and vector data, which can effectively reflect road and river routing process, build urban routing model, and quantitatively evaluate the temporal and spatial variation of urban rainfall runoff process. The study area is located in the sub-center of Beijing, a region with dense road and river network, highly impervious rate and flat terrain. The report shows that the southeast of the area has been suffering from severe inundation. This study applies DEM, roads, rivers, vector data can be freely access from public platform, to divide the study area into blocks depressions and above control area, roads, rivers and above control area of them, the Equivalent Storm Drain Network (ESDN) was established to link depressions in blocks or depression and the nodes of the roads, rivers. The flow directions of roads and rivers network have been rectified according to DEM and graph theory. A simplified dynamic wave model is adopted in the routing model. The dynamics response was evaluated by analyzing flood peaks, flood volumes and flood durations, number of inundation points and other indexes under different design storm return periods. This study provides a reliable general method for accurately simulating the flood change process of road and river nodes in urban.