Survey research on characteristics of extreme rainstorm flood and disaster-causing mechanism in urban new district:Taking Zhengdong New District in Zhengzhou's"7.20"heavy rainstorm as an example
In recent years,the possibility and uncertainty of extreme rainstorms have increased in the world,in-creasing the risk of severe floods in cities.The characteristics of urban rainstorm flood are significantly different from river flood.It is extremely important to investigate and collect information of urban rainstorm for recognizing its characteristics.In this paper,taking"7.20"heavy rainstorm in Zhengzhou as an example,based on the geo-graphic and social environment characteristics of Zhengdong New District,the converging and submerging charac-teristics of urban rainstorm flood and the disaster-causing mechanisms were investigated by means of survey,oral interview,data analysis and numerical simulation.The characteristics of urban rainstorm flood marks,and the basic method and routine of rainstorm flood marks survey were investigated.Based on the 93 flood marks in the sur-vey area,the regional submergence map of the rainstorm flood was figured,and the distribution characteristics of the peak water level of urban rainstorm flood and the confluence characteristics in the survey area were analyzed.Then,the measuring method of the road confluence velocity of the rainstorm flood and the resistance parameter of the road for discharging flood were explored.The results show that the main discharging channel of urban rainstorm flood is the road of the block.Therefore,the confluence direction attributes to the geographic environment and the layout of road network.The distribution of submerging depth of rainstorm flood is related to the underlying surface condition and the confluence characteristics of urban rainstorm.The disaster-causing mechanism of the urban rain-storm flood shows that,the converging volume of the extremely rainstorm is far exceed the discharging ability of the underground pipeline network.The surface runoff chooses the road with low resistant as the discharging channel of the rainstorm flood,and the flow velocity of the flood is also increased comparing with the normal rainstorm flood,worsening the disaster.Besides,the backwater and resistance effect around the junctions of the channels would ag-gravate the waterlogging.That's the main incentive of the extremely rainstorm disaster-causing.Moreover,the lack of coordination in flood discharging abilities between river lake systems as well and the rare dredging work of the river in the new developing city district leads to the flood channel obstruction of the urban river.There would turn up extremely high water level,and the backwater in the intersection of mainstream and tributaries,decreasing the capacity of flood discharging of the pipelines highly.These are the determine reasons of the severe water logging disaster-causing of the extreme urban rainstorm flood.The findings of the research might supply valuable technical support for establishing standard survey method of urban rainstorm flood and designing of flood control and drainage system in new developing district.
heavy rainstormurban rainstorm floodflood marks of blockroad roughnessriver-lake connectivity
刘明潇、朱勇杰、胡昊、ZHANG Hao、孙东坡
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华北水利水电大学港口、航道与海洋发展研究中心,河南郑州 450046
黄河水利职业技术学院,河南开封 475004
Faculty of Advanced Science and Technology,Kumamoto University,日本熊本 8608555
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