Research On The Revision Of The Rainstorm Intensity Formula And The Design Of Rainstorm Patterns In Taizhou City

In recent years,the global climate has gradually warmed up,the El Nino phenomenon has occurred frequently,the urban heat island and the effect of increasing rainfall have been obvious,and the proportion of impervious areas in the catchment area has increased,which has put a lot of pressure on the urban drainage system.As early as 2011,the People's Government of Jiangsu Province issued the "Notice on Strengthening the Management Opinions on the Construction of Drainage Facilities in the Province":"Every city must promptly organize and carry out the revision of the urban rainstorm formula,scientifically determine Urban Drainage Facilities Construction Standards".In view of this,in 2013,Taizhou compiled the rainstorm intensity formula of Taizhou according to the "Outdoor Drainage Design Code"(GB50014-2006,2011 edition).According to "Outdoor Drainage Design Code"(GB50014-2006,2014 edition)and"Technical Guidelines for the Establishment and Design of Storm Rainfall Intensity Formulas for Urban Storms"(2014),this paper first revised the storm intensity formula before the rainstorm pattern is determined,to make the Taizhou rainstorm intensity formula meet the latest Specifications.Thus ensuring the consistency of the rainstorm intensity formula and the rainstorm pattern.Firstly,the paper summarizes the research status of rainstorm intensity formula at home and abroad.Through the analysis of 34 years of rainfall data from three hydrological stations in Taizhou from 1982 to 2015,the sample is selected by the annual maximum method.Then find out the relationship between rainfall intensity and frequency of the three hydrological stations in Taizhou,Madian and Qintong by Exponential distribution,Gumbel distribution and Pearson-?type.It is more scientific to find the Pearson-? type fitting curve to determine the storm intensity formula.Using the modified Gauss-Newton method(McQuartert method)to calculate the rainstorm intensity formula parameters.Considering the inconvenience of using three formulas in a city,by comparing the rainstorm intensity formulas of three hydrological stations,it is recommended to use the Taizhou hydrological station rainstorm intensity formula as the urban rainstorm intensity formula of Taizhou City.According to the rainstorm samples,the characteristic parameters of rainfall in Taizhou City were extracted,and the design rainstorm time-history distribution rain pattern was established in Taizhou City for 5 minutes.The actual rainfall process was analyzed.It was found that the short-duration rainstorm was dominated by unimodal distribution,and most of the rain peaks were located.In the first half of the whole rainfall process,the Chicago method was used to design the short-duration rainstorm type of Taizhou City,and the rainfall type formula and storm intensity formula were compared to obtain the rationality of the rain type calculation formula.