Characteristics Of Precipitation Variation In Xiangzhou Urban District Of Zhuhai And Evaluation Of Current Drainage Network

Under the background of global warming and accelerated urbanization,the area of urban built-up areas has expanded rapidly and the density of buildings has increased.The intensification of human activities has led to the increase of nodules in the air and the instability of the tropospheric air stratification,resulting in heat island effect and rain island effect.The increase in the proportion of impervious surface caused by the change of land use changed the infiltration capacity of the original natural environment,the runoff coefficient increased,and the confluence process accelerated.While the city expanded rapidly,it did not establish a high standard modern drainage facility system suitable for it.,Increasing the risk of flood disasters to varying degrees.Therefore,it is necessary to analyze and evaluate the characteristics of precipitation changes and the drainage capacity of the pipe network.In view of the typhoon surges often encountered in Xiangzhou City,Zhuhai City,the special geographical location and topographical conditions have caused frequent flooding disasters.The source of waterlogging summarizes the characteristics of the inter-annual and intra-annual changes of the total rainstorms in the past 39 years and the time-distribution characteristics of the heavy rains.In addition,based on the Chicago rain pattern and rain peak coefficient,the 2h short-duration rainfall process of the recurrence period of 1a,2a,3a and 5a was simulated.According to Mike Urban,the surface production and confluence model and drainage pipe network model of Xiangzhou urban area were constructed to analyze the different weights.The current overflow situation of the drainage pipe network under the current rainfall conditions.Finally,the road conditions at the peak period were obtained by superimposing the population,economic spatial distribution characteristics and Python web crawler.The impact of the pipe network overflow in different recurrence periods was analyzed.The results showed that:(1)In the past 39 years,the total precipitation in Xiangzhou City,Zhuhai City has shown a trend of decreasing fluctuations,with a decline rate of 65.70 mm / 10 a.The annual precipitation days and total precipitation change with a main cycle of about 25 years.The increase in surface roughness caused by the urbanization process has had an impeding effect on the mobile rain system,which has increased the duration of rainstorms in urban areas.(2)The surface runoff and pipe flow are roughly equivalent to the rainfall change process of the designed rain type.The cumulative total runoff in the rainfall recurrence period of 1a,2a,3a and 5a is 2.41 million m~3,3.33 million m~3,and 3.87 million m~3 And 4.56 million m~3,and the total inflow of pipe network is 1.90 million m~3,26.17 million m~3,3.07 million m~3 and 3.59 million m~3,the total drainage volume is 1.59 million m~3,2.10 million m~3,2.39 million m~3 and 3.59 million m~3 respectively.(3)The current pipeline network drainage capacity is less than 62.33% of the three-year precipitation,and the main reason for the overflow of the pipeline network is the small pipe diameter or the occurrence of flat slope or reverse slope phenomenon The pipeline has insufficient flow capacity.(4)The impact of pipe network overflow on population,economy and road conditions increases with the recurrence period.Under each recurrence period,the area with the greatest impact is Zhuhai City,Shishan Street,which has a large population and economic distribution density Along the government and education bureaus,in addition,the design standards of the drainage pipeline network in the old city are relatively low.The urban development model of expanding along the river channel to the surroundings makes the under-flowing pipelines jack up the upstream,which leads to the overflow of upstream nodes.The simulation results of the model and the method of obtaining real-time road conditions based on the Python web crawler can provide technical support and decision-making basis for urban drainage pipeline network transformation,flood prevention and disaster reduction,and path planning.