Rainfall Depth-Duration-Frequency Analysis for Major Cities in Taiwan

Wu, Baolin; Hsu, Ming-hsi; Yih, Victor; King, Shaohsing; Wu, Chian-min; ,

Rainfall Depth-Duration-Frequency Analysis for Major Cities in Taiwan

by Baolin Wu, Contra Costa County Flood Control, District, Martinez, United States,
Ming-hsi Hsu, Contra Costa County Flood Control, District, Martinez, United States,
Victor Yih, Contra Costa County Flood Control, District, Martinez, United States,
Shaohsing King, Contra Costa County Flood Control, District, Martinez, United States,
Chian-min Wu, Contra Costa County Flood Control, District, Martinez, United States,

Document Type: Proceeding Paper

Part of: Hydraulic Engineering

Abstract:

The annual series of extreme rainfall amounts for various durations are compiled. The statistics such as mean, standard deviation, coefficient of variation, coefficient of skewness, and coefficient of kurtosis are calculated. The durations selected in this study range from 5 minutes to 72 hours. The average record length in 49.0 years. The computed coefficients of skewness and coefficient of kurtosis of each series are plotted in the skewness-kurtosis diagram to determine the best fit distribution. The probability distributions investigated in this study are the log-normal, Pearson Type III, Gumbel, Weibull, and Burr Type III distributions. The results reveal that the overall best fit distribution is the Pearson Type III Distribution. The rainfall amounts for each duration and each return period are calculated by the frequency factor method. The return periods used in this study range from 2 to 1000 years. Finally, the rainfall depth-duration-frequency curves are constructed for each city and the rainfall intensity duration-frequency curves can be converted from the corresponding depth curves. The resulting rainfall depth-duration-frequency and rainfall intensity-duration-frequency curves can be used for various hydrologic designs, analyses, and studies in Taiwan.

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