Research Of High-precision Risk Simulation Of Urban Flooding And Resilience Optimization Strategy

In recent years,with the global climate change and rapid urbanization,the frequency and intensity of urban flooding are increasing day by day,which causes substantial harm to the economy,society and human safety and property.The city has become a sensitive response area to flooding disasters.How to improve the city's ability to cope with flooding disaster and ensure the safety and sustainable development of the city has become a hot issue in urban disaster research.In this paper,the core area of downtown Shanghai—Huangpu District,is selected as the study area to construct a high-precision urban rainstorm model.And then,we constructed future rainfall scenarios by analyzing the potential impacts of climate change on future precipitation.Based on the methods of scenario simulation and numerical simulation,we simulated the flooding risk for different rainfall return periods.Finally,according to the simulation results of flooding risk and guided by the theory of resilient city,we proposed the prevention and control measures for flooding disasters in Huangpu District.The main work and conclusions are as follows:(1)High-precision rainstorm model construction in the study area.Specifically,InfoWorks ICM model was selected to construct the rainstorm model in the study area.Then,by summarizing and sorting out the existing studies,we summarize the main factors that improve the accuracy of the model into three aspects.The first is to generalize the underground drainage system,the second is to rationally divide the sub-catchment,and the third is to use high-precision terrain data to establish a ground elevation model.Finally,based on the above method optimization and data preparation,combined with the characteristics of the study area,we constructed a high-precision urban rainstorm model,and selected the measured rainfall events to verify the reliability of the model.The results show that the model can realistically simulate the actual catchment of rainwater and the drainage process of the underground pipe network,which is in good agreement with the measured results.(2)Construct a typical rainfall scenarios in the study area.Combining the rainstorm intensity formula of Shanghai with the rainfall pattern of Chicago,the rainfall processes of three return periods of rainstorm in 10 years,50 years and 100 years were simulated respectively.Then,based on the analysis of the related literature and data of future rainfall prediction in the middle and lower reaches of the Yangtze river,we obtained potential changes of rainfall under the climate change scenarios by taking historical rainfall as the baseline and 2050 as the target year.And the future rainfall intensity is obtained using the Delta-Change method.Finally,9 future rainfall scenarios were constructed based on 3 rainfall return periods(10-years,50-years and100-years)and 3 rainfall intensities(increased by 10%,15% and 20%).(3)Hazard simulation and risk assessment of flooding in the study area.Based on the established high-precision urban rainstorm model,the numerical simulation of urban flooding in both historical and future rainfall scenarios was carried out with rainfall events of different intensities as water boundary conditions.Then,we combined the depth and duration of waterlogging to evaluate the level of flooding risk in the study area under different rainfall scenarios.The results show that the response of urban flooding to climate change is significant in the future.It was clear that both the outlet flow and the node overflow increase with the increase of rainfall intensity,which further reducing the drainage capacity of the drainage system.The waterlogging area and the waterlogging depth also showed a significant increase trend,and the rainfall events in the smaller return period were more sensitive to the change of rainfall intensity.With the increase of rainfall return period and rainfall intensity,the risk of flooding increased significantly,and the East Nanjing Road is the main high risk area for flooding.(4)Urban resilience assessment and improvement strategy research.By referring to the existing toughness evaluation methods and combining the characteristics of the study area,we construct the urban resilience evaluation systemunder the situation of urban flooding disaster.Then based on the evaluation results,we propose a resilience promotion strategy for the weak links of urban resilience,mainly including engineering measures and non-engineering measures.The results show that the comprehensive resilience of Huangpu District has been continuously improved in recent years,but the level of infrastructure resilience and social resilience is relatively backward.The engineering measures include gray engineering measures and green engineering measures,both of which have better runoff reduction efficiency.And the non-engineering measures include improving the level of urban flood warning,improving disaster emergency management and raising public awareness of disaster prevention.Finally,combining engineering and non-engineering measures is a key means to enhance urban resilience.