Study On Risk Simulation And Early Warning Of Urban Rainstorms

Cities play an important role in national political,economic and cultural activities.The healthy,stable and sustainable development of cities is an important condition for a country to maintain prosperity and prosperity.China is in the period of rapid urbanization,urbanization construction will inevitably promote the expansion of urban scale,but in recent years,the grade and frequency of urban rainstorms have increased,and the corresponding frequency and damage caused by urban rainstorms have increased year by year.Because of the wide impact of waterlogging disasters on the city and the increase of its occurrence frequency,waterlogging disasters have become a serious problem.To hinder the rapid and healthy development of the city is one of the important reasons.Therefore,it is necessary to study the formation process and mechanism of urban rainstorm waterlogging,further analyze the causes of urban rainstorm waterlogging,assess the risk of urban waterlogging,and on this basis,establish an early warning system of urban rainstorm waterlogging risk based on Meteorological information,so as to control urban waterlogging,build water ecological civilization and sponge city,and establish an early warning mechanism of urban waterlogging.Provide scientific theoretical basis.Through ArcGIS rapid modeling method for SWMM model,the Jinshuihe drainage system coverage area north of the South-to-North Water Transfer Project in Zhengzhou City was constructed as the study area waterlogging simulation model.The parameters of the model were calibrated and validated using the measured precipitation data of 20170522 and 20180515,and a good precision and reliability urban waterlogging simulation model was obtained.In this paper,Zhengzhou Rainstorm Intensity Formula is used to simulate the 10 typical design rainstorms with short duration of 1 hour and long duration of 6 hours at five different frequencies designed by Chicago Rainstorm Patterns.The results show that the proportion of the waterlogging risk areas caused by the design rainstorms in 5,10,30,50 and 100 h of the recurrence period is 0.9%,1.24%,2.96%,4.61%,6.42% respectively.The proportion of waterlogging risk area caused by rain in the study area was 3.32%,4.83%,9.90%,13.68% and 24.33% respectively.The full loading rates of the drainage pipes of the rainstorm water system designed for 5,10,30,50 and 100 h in the recurrence period are 64%,82%,85%,86% and 87% respectively;the full loading rates of the rainstorm water system drainage pipes designed for 6 h are 69%,83%,86%,88% and 90% respectively;and the proportion of the water accumulation area with the depth of 0.05 m in the design rainstorm water system designed for 1 h to the total area of the study area is 36.19%,55.49%,71.49%,76.45% and 82.00%,respectively.The proportion of the accumulated water area with the depth of 0.05 m under the 6h design rainstorm to the total area of the study area was 46.65%,61.23%,74.17%,79.49% and 83.54%,respectively.It can be seen that the higher the grade of design rainstorm recurrence period,the wider the waterlogging risk area;the longer the rainfall duration in the same recurrence period,the greater the waterlogging risk range and risk level.The results show that the waterlogging range is the widest and the impact of waterlogging disaster is the deepest under the design rainstorm of 6 hours once every 100 years in the recurrence period.The total area of waterlogging risk area is 1083.36 hm2.The total areas of low-risk area,medium-risk area and high-risk area are 986.98 hm2,72.27 hm2 and 24.12 hm2,accounting for 22.06%,1.62% and 0.54% of the total area of the study area,accounting for 91.10%,6.67% and 2.23% of the total area of waterlogging risk area,respectively.In view of the frequent occurrence of urban waterlogging,this paper puts forward some engineering measures,such as improving the design standard of urban drainage,reducing the proportion of impervious surface water and increasing storage facilities,strengthening the management of drainage facilities,improving the emergency plan system for urban waterlogging prevention and promoting the construction of early warning system for urban waterlogging risk,which can effectively prevent the occurrence of waterlogging disasters in the study area.In view of the waterlogging risk situation in the study area,a relatively simple early warning method of urban rainstorm waterlogging risk is proposed.Based on the risk assessment of ten typical design rainstorms in the study area,the early warning study of the waterlogging risk area in the study area can effectively enhance the ability of urban waterlogging risk prevention and control.