Establishment of Numerical Model for the Simulation of Storm Flooding in Flat River Network Area Considering Polders Distribution: a Case Study of Jiaxing City, China (PAP014355)
Jing Wang, Na Li
A numerical model for the simulation of storm flooding in flat river network area with numerous polders is established for the case study area Jiaxing city in China, based on the existing numerical model for urban area which is built on the basis of one and two-dimensional unsteady flow theory and the technique of unstructured and irregular grids. The factors of polders having impacts on spatial and temporal distribution of flooding and water-logging in flat river network area are considered including flood control standard of levees, drainage capacity, as well as operation rules of different polders. Meanwhile, a concept called small water storage surface is put forward to reflect the storage function of small rivers, ponds and lakes to rainfall process inside and outside polders, which is hard to generate in two-dimensional hydraulics models but can't be ignored. According to the real river distribution, the area ratio of small water storage surface for each mesh is abstracted using GIS tools. Using the numerical model, several typical historical rainstorm processes of Jiaxing City in recent years are calculated. The comparison between simulation results and observed or investigated flooding and water-logging distribution shows that the generalization for this area in the model is reasonable, the characteristics of flood movement and inundation distribution under the integrated action of floods in upper reaches, influence of tidal level in lower reaches and complicated operating rules of flood control and drainage projects can be reflected. The simulation results are reliable and can provide support for flood hazard mapping and flood management.