The Research Of Storm Intensity Formula In Chunhua Country,Shanxi Province

Frequent occurrence of extreme rainfall events in many parts of China has caused great troubles for people and poses a serious threat to people's life safety and property safety.The storm intensity formula is the basis for urban stormwater drainage and prevention of urban intrinsic system planning and design.Therefore,it is indispensable to formulate a storm intensity formula suitable for local development and construction.Chunhua County did not compile a local storm intensity formula,so it is necessary to formulate a storm intensity formula suitable for Chunhua County.This paper uses the rainfall data from 1998 to 2017 provided by the Chunhua County Meteorological Bureau and uses the annual maximum method to select rainfall samples.Then use the Gumbell distribution curve,Pearson type third distribution curve and exponential distribution curve to adjust the frequency curve respectively.The Pearson type third distribution curve uses the appropriate line method to obtain the corresponding parameters,i~t~P data table and frequency.The figure is combined,and the theoretical distribution line of the Gumbell and the exponential type is obtained by the least squares method to obtain the corresponding parameters,i~t~P data table and frequency fitting map.Using the obtained i~t~P data table,the parameter values are calculated using the least squares method,the Marquardt and the Guss-Newton method.The absolute mean square error and the relative mean square error obtained are analyzed and proofread,and the storm intensity formula of Chunhua County is selected.Finally,the accuracy of the formula is verified by analyzing the calculated value and theoretical value of the storm intensity formula.The general formula for the intensity of rainstorm in Chunhua County is:(?).When the rainfall intensity formula of Chunhua County is P=2~20a,the absolute mean square error and relative mean square error are 0.0287mm/min(less than 0.05mm/min)and 3.07%(less than5%)respectively;when P=2~ 100 a,the absolute mean square error and relative mean square error are 0.0402mm/min(less than 0.05mm/min)and 3.60%(less than 5%),respectively,which meet the specification requirements.When the design recurrence period of the actual project is the same as the recurrence period of the storm intensity sub-item estimated in this paper,since the accuracy of the storm intensity sub-form is higher than the total formula,it is recommended to use the sub-formula.