Research On Waterlogging Simulation And Risk Assessment In Haizhu District Of Guangzhou

Under the background of global warming and rapid urbanization,waterlogging disaster has become a prominent problem restricting the development of cities in our country.Taking Haizhu District of Guangzhou City,where waterlogging disasters frequently occur,as the research area,a 1D-2D coupled model of waterlogging for Haizhu District was constructed based on Info Works ICM.Besides,to comprehensively assess the risk of waterlogging in Haizhu District,a risk assessment index system was constructed based on disaster system theory,and the disaster-causing factor data was obtained according to the simulation results of stagnant water under different designed rainfall scenarios.The research provides the scientific basis for the prevention and control of waterlogging disasters in Haizhu District,which can be used in subsequent engineering practices.The research results of this thesis are as follows:(1)A 1D-2D coupled model of waterlogging for Haizhu District was constructed and the parameters of the coupled model had been calibrated and verified.Having collected and processed the basic data of Haizhu Island,including the Drainage network,rivers,lakes,topography,etc,a 1D-2D coupled model of waterlogging was established based on Info Works ICM.Data of two actual measured rainfall and water depth was selected to calibrate and verify the rationality of model parameter selection.The simulation results show good accuracy coupled with the certain reliability of the model.(2)Based on the coupled model of urban flooding,the operation status of pipeline system and water accumulation on the ground were simulated under different rainfall scenarios to find out the drainage capacity of the current pipeline system.A variety of rainfall scenarios were set up to simulate and analyze the operation status of pipeline system.The results show that manholes with the overflow water volume exceeding 10m~3 account for about 28.8%,and surcharged pipelines take a percentage of 75.32%in Haizhu District under the 1a design rainfall scenario.Besides,node flooding and water accumulation would aggravate with the increase of return period.In general,the drainage capacity of pipeline system in Haizhu District was insufficient,pipelines with drainage capacity less than 2a accounted for about 80%.Further,the water accumulation on the ground under different scenarios was simulated and analyzed.The results show that the accumulation of water in Haizhu District under low return period was not significant.Under high return period,there was widespread accumulation of water on municipal roads and the outer edges of buildings.The situation of stagnant water gradually aggravated with the increase of the return period.(3)A comprehensive risk evaluation index system for urban flooding was constructed to evaluate the risk of waterlogging for Haizhu District,and the waterlogging disaster loss under each rainfall scenarios was calculated.Based on disaster system theory,a comprehensive risk evaluation index system was constructed with the consideration of the main influencing factors of hazard and vulnerability in Haizhu District,and the disaster-causing factor data was obtained according to the simulation results of stagnant water under different designed rainfall scenarios.The risk level of each return period was classified,and the urban flooding risk maps were drawn.The results show that the hazard risk level was closely related to the submerged depth and inundation time,and the vulnerability risk level was mainly affected by population density and the type of underlying surface.In addition,the comprehensive risk level tended to rise with the increase of return period(from 1a to 100a).What’s more,the area of medium,medium-high and high comprehensive risk levels increased by 0.38%,4.49%,and 2.75%respectively.Further,the loss of waterlogging disaster was assessed based on the vulnerability curve as well as the local economic situation.The results show that the disaster loss keeps increasing with the lengthened of return period.Under the scenario of 100a design frequency rainstorm,252.23ha of housing construction was affected by waterlogging disasters,causing heavy economic losses,which is worth attention in waterlogging disaster prevention and control.