The Research Of Storm Intensity Formula And Simulation Research On Present Situation Of Rainfall And Drainage In Zhengding Country

In recent years,heavy rainfall has occurred in many cities in China,which has caused serious waterlogging problems.When the precipitation exceeds a certain range within a certain period of time,rainwater will collect in low-lying places in the city.Due to the fact that the rainstorm intensity formulas in many areas have been estimated for an earlier period,they cannot reflect the true precipitation.Zhengding County currently uses the formula of Shijiazhuang City,which lacks targeted accuracy and has relatively large errors.By deducing a more accurate formula and studying the urban drainage pipe network system,it can alleviate the urban waterlogging problem to a certain extent.In this paper,the annual maximum method is used to establish statistical samples.According to the data of Zhengding County from 1999 to 2018,the curve distribution is fitted based on Pearson-Ⅲ,Gumbel,and exponential distribution models.Newton’s method and Macquart’s method infer parameters.For the comparison of the absolute error and relative error of each group,select the two groups for comparison with the currently used formula to determine the final formula.The Gumbel curve fitting result is the best formula using Mcquart’s method to solve the parameters.The SWMM model is a model for fitting analysis of urban rain and flood and environmental governance.According to the model results,the runoff situation of the sub-catchment in different recurrence periods,the operation and discharge of the pipe network,and the water accumulation of some nodes are analyzed.According to the measured pipeline network,road and other information,the SWMM model is established.The deduced rainstorm intensity formula fits the Chicago rainfall process line to calculate the time series table of different recurrence periods.Determine the impervious rate and subsequent parameters of the sub-catchment area according to the land situation.When the recurrence period is two years,water accumulation occurs at four nodes,of which the maximum water accumulation is 1608.23m3.When the recurrence period is three years,water accumulation occurs at seven nodes,and the maximum water accumulation is 5939.74m3.When the recurrence period is five years,water accumulation occurs at eleven nodes,and the maximum water accumulation is 10723.54m3.When it encounters a heavy rain once in thirty years,the maximum water accumulation is 26000m3,and most road sections are accumulated.Three suggestions are proposed according to the current situation: First,the permeable pavement is laid on the pavement,the construction is simple and the peak value of runoff can be effectively reduced.Second,the construction of a new rainwater pipe network,this method can effectively solve the existing waterlogging problems.Third,the initial runoff rainwater is discharged after being treated by the Fenton method.This method has a fast reaction speed and does not produce pollutants.