WRRCSR No. 9:23:83 Rainfall Frequency Study for Oahu: Option 1--Preparation of Rainfall Frequency Maps

Abstract

Annual maximum rainfall series at 157 gages were used to evaluate extreme value rainfall. Daily fixed-interval data were adjusted by a factor of 1.143 to represent true maxima. Records of short-term stations were extrapolated by regional analysis. Gumbel extreme value, log-Pearson Type III, and log-normal distributions were tested for applicability and found to have approximately equal goodness-of-fit. The Gumbel distribution was used, fitted by the method of moments. A topographically based interstation interpolation model was developed as an aid in mapping maximum rainfall for durations of 1-, 6-, and 24-hr and return periods of 2-, 10-, 50-, and 100 years.