Study On Fine Flood Simulation Of Urban Rainstorm And Flood Based On SWMM

The increasing frequency and scale of urban waterlogging seriously endangers the socio-economic and people's lives and property safety.Constructing a refined simulation model of urban rainstorm and flood and integrating multiple sources of rainfall data can predict and warn urban waterlogging,reducing the urban rainstorm Loss.According to the overview of Zhengzhou City,the drainage system of the study area,and the causes of accumulated water were briefly introduced,and the method of multi-source rainfall data fusion was predicted to improve the forecast period of the urban storm rainfall simulation model.Based on the SWMM model combined with the characteristics of the study area,a refined urban storm and flood simulation model is constructed.Study the classification method and principles of hydrological response units,classify them by combining their natural and social attributes,and calculate the values of model uncertainty parameters in different categories through statistical analysis methods.The main research contents and results are as follows:(1)To explore the application of rainfall forecast in urban flood simulation,and improve the model's forecast period.The application of 24 hrs rainfall forecast in Zhengzhou City was tested and analyzed,the accuracy and frequency of forecast results were obtained,and the guiding effect of different forecast magnitudes on urban flood simulation and early warning forecast was summarized;Radar rainfall measurement data was corrected based on ground observation data.Radar extrapolated prediction and precipitation forecast were merged with dynamic sine weight method,which can be used for short-term approaching 0-3hrs forecast.In the case of limited radar observation data,according to the correlation between the 24 h weather forecast rainfall and the 3h design rainfall and its recurrence period,the 3h forecast rainfall process line is obtained,using the spatial distribution of radar data as the basic unit,after the calibration of the ground station,the spatial and temporal distribution data of the forecasted rainfall in 3 hours are fused.(2)A detailed assessment of the characteristics of the study area,combined with land use classification extracted form high-resolution remote sensing images and urban land use planning map,combined the natural and social attributes of the underlying area of the study area,and classified them into industrial and commercial areas,residential areas and public areas.Statistical analysis of a large number of research parameter values,and clustering of these parameter values using the K-means clustering method.The value of the underlying surface in the three types of cities has acquired.The results show that in industrial and commercial areas,residential areas and public areas,the impermeable area depression storage values are 0.27 mm,1.98 mm and 3.36 mm,Manning coefficient in impermeable area values are 0.013,0.023 and 0.050,permeable area depression storage values are 2.50 mm,6.50 mm and 12.50 mm,and the Manning coefficients in permeable area are 0.044,0.205 and 0.477.(3)Based on SWMM,a detailed urban flood simulation model for the Jinshui District of Zhengzhou City was constructed.So,the details such as the information required for model construction,the sub catchment division method,and model parameter selection were introduced.Using the integrated runoff coefficient and actual water logging points in Zhengzhou City to check the simulation results of the developed model.The results show that the simulation of the model generally agrees with the actual water accumulation point.Especially,when the spatial distribution of rainfall is basically uniform and the model parameters will affect the distribution of water accumulation points.Differentiating the values of the model parameters in different underlying surfaces can reflect the characteristics of different underlying surfaces.Using the 3hrs forecast rainfall spatial and temporal distribution data fused with multisource rainfall data to predict water accumulation points,comparing the simulation results of the fused prediction rainfall data with the measured rainfall simulation results,it is found that the comprehensive runoff coefficient is basically the same;the number of water accumulation points is somewhat different;the water distribution is roughly similar.