Analysis Of Precipitation Characteristics In Coastal Areas And Simulation Of Urban Waterlogging Process

Global climate change may lead to an increase in extreme precipitation.The changes of precipitation characteristics may be an important reason for the frequent occurrences of waterlogging at present.The in-depth analysis and study of regional precipitation characteristics will advantageous to reveal the occurrence law of disasters.Meanwhile,many cities are constantly attacked by heavy rainfalls or continuous rainstorms across China,resulting in frequent urban waterlogging disasters.With the changes of land use in the process of urban modernization,the impervious areas increases;the drainage capacity of urban drainage network system is insufficient,which aggravates the severity degree of urban waterlogging.Therefore,flooding disasters have hindered the sustainable development of parts regions in China,it is necessary to study and analyze the waterlogging process so as to provide scientific basis and decision supports for flooding control and disaster resistance.On the basis of domestic and foreign research,this paper firstly selects Fujian Province as the research object of regional precipitation characteristics,analyzes the precipitation characteristics and the causes of flooding trend in Fujian Province.Then,it further focuses on the typical researches in Jiangbei District of Fuzhou City,and uses info on the basis of basic data collection works ICM constructs urban waterlogging model,simulates and analyzes the waterlogging situation under different scenarios in Jiangbei District of Fuzhou City;in particular,considering the influence of different rainfall patterns on the results of waterlogging model,the waterlogging situation is simulated by using the designed rainfall with different durations and peak coefficients in Chicago under different rainfall reappearing periods,and deeply discusses the waterlogging process changes under different precipitation scenarios and analyzes its influence on regional waterlogging.The main conclusions are as follows:1)It is found that the Precipitation Concentration Index(PCI)is seasonal,and there is more precipitations and higher concentration index in autumn,which makes the higher possibility of floods.The rising trend of SPI indicates that the possibility of floods is greater in Fujian Province.The total annual precipitation,the maximum daily precipitation,and the frequency of heavy rains all show an upward trend,and the rainfall and heavy rains have obvious seasonality,concentrated in summer and autumn in Fuzhou.2)The results of scenario simulations for different return periods by using infoworks ICM show that: with the increase of return period,the number of overload full pipes caused by insufficient downstream flow capacity and insufficient flow capacity of pipeline gradually increases,and the proportion of overload caused by insufficient downstream flow capacity of pipeline is higher than that caused by insufficient flow capacity of pipeline The results show that the maximum submergence depth and total inundation area increase with the increase of return period;when the design rainstorm intensity is low,the submerged area with the submergence depth of 1-5cm is the largest;when the corresponding high design rainstorm intensity,the submerged area with the submergence depth of 10-20 cm is the largest;As the forecast range increases,the full pipe and submerged area are increasing.3)Considering the influence of rainfall duration and rainfall peak coefficient on the results of waterlogging model,the analysis results show that: the interaction between rainfall duration and return period,the number of pipe sections under full pipe decreases with the increase of recurrence period,and the number of full pipe sections increases with the increase of recurrence period;under different rainfall duration,the submerged area increases with the increase of return period In the same return period,the inundation area of different rainfall duration is different,rainfall intensity and total rainfall will have an impact on the inundated area,and the impact of total rainfall on the submerged area is slightly greater than that of rainfall intensity.When the rain peak coefficient is the same,the number of pipe sections under full pipe decreases with the increase of return period,and the number of full pipe sections increases with the increase of return period,which indicates that the rain peak appears late,and the drainage capacity of pipe network is insufficient when reaching the rain peak coefficient,resulting in serious waterlogging;when the rain peak coefficient is the same,the submerged area increases with the increase of return period When the rainfall peak coefficient is high,the total inundation area and the inundation area of each submergence depth range are larger than that of small rain peak coefficient.