Impact Of Temporal And Spatial Scale On Urban Rainstorm Waterlogging Simulation

The continuous acceleration of global climate change and urbanization process leads to the frequent occurrence of urban rainstorm and waterlogging,which poses a great threat to the life and property safety of urban residents.Rainstorm waterlogging simulation is one of the key technologies to solve urban flood.It has been widely used in current situation assessment of drainage system,simulation of urban waterlogging and risk analysis of urban flood disaster.Rainfall temporal resolution and two-dimensional grid scale are the main control factors affecting urban runoff simulation and a series of other hydrological problems.Especially in small urban catchment areas,the runoff process is fast and the response time is short.The accuracy of urban flood simulation is more sensitive to the change of rainfall temporal resolution and two-dimensional spatial grid scale.At present,most of the rainfall data with hourly accuracy and grid data with kilometer accuracy are used for urban flood simulation at home and abroad.However,compared with the urban flood process,the rainfall temporal resolution and two-dimensional grid scale is still too large to simulate the urban flood process well.This study simulates urban flood and analyzes the impact of rainfall temporal resolution and two-dimensional grid scale by using 5min,10 min,15min,30 min,1h and 6h six kinds of rainfall temporal resolution and 50 m,100m,150 m,200m,250 m and 300 m six kinds of two-dimensional grid scale based on the IFMS model chaired by the China Institute of Water Resources and Hydropower Research at Dongguan.The effects of rainfall temporal resolution and two-dimensional grid scale on urban flood simulation results and their variation rules are analyzed,so as to improve the accuracy of urban flood simulation and provide reference Suggestions for flood control and disaster reduction in domestic urban areas.The main results are as follows.(1)The simulation results of IFMS show that the simulated inundation range and inundation depth of waterlogging point in the process of model validation are consistent with the actual monitoring results.At the same time,the typical flood waterlogging point of process simulation of Nash-efficiency are greater than 0.55,the flood peak error less than 20%,shows that IFMS model can simulate the flood submerged condition well in the study area.(2)With the increase of the rainfall temporal resolution,the maximum flood peak of the flood becomes smaller,the peak occurrence time is delayed,and the morphology of the submerged water depth process line of the waterlogging point changes greatly,and the correlation with the actual rainfall process decreases.At the same time,the influence of different rainfall temporal resolution on urban flood simulation is different.The influence of 1h and 6h is greater than that of 5min,10 min,15min and 30 min,and the influence of 5 min,10min and 15 min is very close.(3)With the increase of two-dimensional grid scale,the flood peak decreases,and the error of flood peak increases as a whole,but the simulation result of 100 m two-dimensional grid scale is better.(4)The simulation effect of fine spatial and temporal scale is not necessarily the best,and the combination 5min×100m 、 10min×100m 、 15min×100m 、 30min×100m 、5min×150m、10min×150m、15min×150m is better for the simulation of urban flood.In order to ensure the accuracy of urban flood simulation,in IFMS,it is recommended to select the above spatial and temporal scale combination according to the actual situation for urban flood simulation.