Comprehensive Rainstorm Intensity Formula Based on Particle Swarm Algorithm

[Objective] The research aimed to simplify the traditional method and gain the method which could directly construct the comprehensive rainstorm intensity formula.[Method] The particle swarm optimization was used to optimize the parameters of uniform comprehensive rainstorm intensity formula in every return period and directly construct the comprehensive rainstorm intensity formula.Moreover,took the comprehensive rainstorm intensity formula which was established by the hourly precipitation data in wuhu City as an example,the calculation result compared with the computed result of traditional method.[Result] The calculation result precision of particle swarm algorithm was higher than the traditional method,and the calculation process was simpler.[Conclusion] The particle swarm algorithm could directly construct the comprehensive rainstorm intensity formula.

Study on Revision and Compilation of Rainstorm Intensity Formula in Liuzhou City and County

Rainstorm intensity formula,main basis of solving urban waterlogging,is the basis of scientifically and rationally making urban drainage professional planning and drainage engineering design. In this paper,compilation of rainstorm intensity formula in Luzhai County was taken as the case,revision and compilation techniques and research methods of rainstorm intensity formulas in municipal district and administrated county of Liuzhou were introduced. According to the Design Specification for Outdoor Drainage（ GB 50014-2006,2016） and the Technical Guidelines for Establishment of Intensity-Duration-Frequency Curve Design Rainstorm Profile,historical rainfall data at Luzhai National Weather Station were sampled by using annual maximum method,and sampling time was from1980 to 2016. The period with the maximum rainfall was divided into 11 time intervals： 5,10,15,20,30,45,60,90,120,150 and 180 min. Fitting adjust of rainstorm sample data was conducted by using Pearson-III distribution curve,rainstorm intensity formula was fitted by the least square method,and calculation accuracy test corresponded with the requirement of Design Specification for Outdoor Drainage（ GB 50014-2006,2016）. Conclusions and suggestions were as below： firstly,rainstorm intensity formula was compiled and calculated according to the recommended methods of the Design Specification for Outdoor Drainage（ GB 50014-2006,2016） and the Technical Guidelines for Establishment of Intensity-Duration-Frequency Curve Design Rainstorm Profile,calculation process was normative,and calculation result error met the requirement of the specification. Secondly,sampling by annual maximum method was more suitable for the expression of periodic hydrometeorological law by taking year as reappearance period,and could cause better randomness and independence of statistical sample,and the method was scientific and reliable. Thirdly,rainstorm intensity formula compiled by taking rainfall data in national weather stations of Liuzhou and its administrated counties as the sample could be used in the scope of the local jurisdiction.

Derivation of Rainstorm Intensity Formula in Guilin City

A total of 58 years self-recording rainfall records at Guilin National Weather Station from January 1957 to December 1957 were used. Using the annual maximum sampling method,11 short-duration maximum rainfall records in every year were selected,and statistical samples of rainstorm intensity formula were obtained. Fitting of statistical samples was conducted by using three kinds of frequency distribution curves: Pearson-Ⅲdistribution,Gumbel distribution and exponential distribution. The formula of rainstorm intensity was derived by the least square method and Gauss Newton method,and then the accuracy of results was inspected. The results showed that the fitting effect based on the Pearson-Ⅲdistribution and Gumbel distribution was better than that of the exponential distribution;the accuracy of rainstorm intensity formula based on Pearson-Ⅲdistribution was better than that of Gumbel distribution and exponential distribution;the accuracy of rainstorm intensity formula derived by the least square method was better than that of Gauss Newton method;the accuracy of interval parameter formula of rainstorm intensity was better than that of rainstorm intensity formula.