Hefei City Rainstorm Intensity Formula Derivation And Application Research

The accuracy of rainstorm intensity formula directly affects the design of city water supply and drainage pipeline network. Hefei’s original rainstorm intensity formula was determined in the 70’s of last century which has been unable to meet today’s requirements in the precision and standardization. For the urgent need to revise a new formula, a collection of short duration precipitation data in 1965-2012 of Hefei Dong Pu station was analyzed. All the data was taken through annual maximum sampling method. Pearson-III type of distribution, exponential distribution and Gumbel distribution were adopted In order to determine the four parameters of the formula,six optimization algorithm such as Levenberg-Marquart algorithm, Gauss-Newton method, quasi-Newton method, genetic algorithm, simulated annealing algorithm and particle swarm algorithm were used. Finally the best formula is ascertained through exponential distribution maching Marquart algorithm. The Accuracy is greatly improved relative to the original formula. The new formula can be used in many fields such as risk analysis of flood disasters and the design of city water supply and drainage pipeline network. This new formula has great significance to prevent waterlogging, drainage, drainage facilities planning and engineering design of Hefei city.The second part of this paper is about using the rainstorm intensity formula to ascertain the relationship between storm sewer standard and river draining standard-First using the rainstorm intensity formula to calculate the duration of rainfall based on the main rain water outlet statics of The fifteen Mile River.Then the reappearing period relationship between waterlogging and drainage can be obtained through the maximum of the statistical table of short duration of Hefei station.