Regional intensity‐duration‐frequency curves for Jeddah region, Saudi Arabia, using ordinary and L‐moments approaches

Abstract

AbstractThe frequency analysis of rainfall in the Jeddah region, Saudi Arabia, has been disputed both on grounds of the methodology, statistical model and the resulting rainfall estimates. Frequency analysis of available rainfall records for Jeddah region, Saudi Arabia, is performed to develop regional intensity‐duration‐frequency (IDF) curves. The data cover nearly 40 years of records for 10 stations. Only three stations comprise short duration records of 10 min accuracy. The homogeneity of the region is first assessed using tests relying on the coefficients of variation of ordinary moments and also the discordancy and the heterogeneity measures based on L‐moments. The best fitting distribution to all region stations is selected comparing several approaches: namely the ordinary and L‐moment ratio diagrams, the goodness‐of‐fit measures based on L‐moments, the log‐log and the mean excess function plots, and finally the Akaike and Bayesian Information Criteria. The gamma distribution can be used for fitting the whole region. Jeddah region is thus divided into two homogeneous rainfall regions and two sets of rainfall IDF curves are developed for 2‐, 5‐, 10‐, 25‐, 50‐ and 100‐year return periods. The approach proposed by this study helps develop IDF curves derived using a regional approach in which several methods are investigated yielding converging results.