SHORT RAINFALL DURATION EVALUATION IN DESIGN STORMS DEVELOPMENT
ABSTRACT: A 5-minute
incremental rainfall data taken from 5
stations distributed in Johor southwest region was analyzed to study an inten-sity-duration-frequency
(IDF) related to design storm development. The study includes a regional
rainfall analysis, determination of probability distribution, estimation
parameter and quantiles of the distribution, development of IDF, and the comparison
study for IDF estimates based on daily rainfall. In the study, the duration
pattern is set to 15-, 30-minute, 1-, 2-, 4-, 8-, 16- hour, and 1-day. An X10-
test is used for regional analysis to define homogeneous region and probability
weighted moments (PWM) is used to do a frequency analysis. To see the presence
of trends, the Kendall’s method is applied. It is found that the region is
passed the tests to be the homogeneous region. Based on frequency analysis, the
data tends to follow the generalized extreme value (GEV) and generalized
logistic (GLOG) distribution. In regression analysis, the IDF-curve for return
period of 2-, 5-, 10-, 20-, 50-, 100-, 200-, and 500-year tends to follow a
power relationship. The IDF family curves calculated based on daily data gives
over estimates about 10% compared to
those of calculated based on the 5-minute incremental rainfall data.
Author: Masimin and Sobri
Harun
Journal Code: jptsipilgg110022
