Research On Deriving Jiaxian Country Storm Intensity Formula Based On MATLAB

With the background of global warming and the accelerating process of urbanization in our country, the pattern of urban rainfall has made a great change. The waterlogging caused by rainstorm is becoming more and more serious, and has made great loss of life and property for the people. Therefore, determining the design flow of city rainwater drainage system, so as to reasonably determine the caliber design of rainwater pipe network is particularly important. However, the rainstorm intensity formulas used in large and medium-sized cities are often developed in the last century seventy or eighty’s, and can not adapt to the current rainfall variation. Those small cities with no suitable rainstorm intensity formulas can still not apply the formulas used in adjacent big cities.This paper discussed the rainstorm intensity formula research status at home and abroad, and designed useful rainstorm intensity formula technical route for Jiaxian. Based on 21 years rainstorm data of Jiaxian, this paper applied annual maximum value method and made use of MATLAB to analyze data. Then the sample data were fitted by three kinds of theoretical frequency distribution curves (Pearson-Ⅲ distribution, exponential distribution and Gumbell distribution), and the model with least error was used to generate T-t-i table. This paper further compared the results of Marquardt and GA for calculating rainstorm intensity formulas, and chose the more effective algorithm, Marqualdt, to evaluate the parameters of rainstorm intensity formulas. In the calculating process, the extraordinary values of raw data were dealt with correctly and that resulted in a more accurate rainstorm intensity formula.Based on MATLAB GUIDE platform, this paper developed a Jiaxian rainstorm intensity formula calculating system. What’s more, Jiaxian rainstorm intensity general formula and single reappearing period formula were dertermined. Finally, the rainstorm intensity general formula of 2-20 years reappearing period is whose absolute mean square deviation is 0.0207 and relative mean square deviation is 2.6478%; The rainstorm intensity general formula of 2-100 years reappearing period is whose absolute mean square deviation is 0.0270 and relative mean square deviation is 2.9029%. The formulas achieve high accuracy and provide reasonable and reliable foundation for designing Jiaxian rainwater drainage system.