Relative Performance of Intensity-Duration-Frequency Functions

Abstract

The forms of the intensity-duration-frequency (IDF) function that best fit rainfall data in the United States are investigated. Analyses using data from 9,264 rainfall stations in the National Oceanic and Atmospheric Administration Atlas 14 database show that, for any given return period, the three-parameter Sherman and Kimijima equations give the best performance, with average relative errors typically less than 4%, although at some locations, errors are significantly higher. Geographic regions of the United States and their associated best-fitting IDF functional forms are identified. The performance of IDF functions that include both duration and return period are also analyzed, and the results show that four-parameter IDF functions derived from the Sherman and Kimijima equations perform best, although the best-performing function has a regional dependence.