Modeling of Short Duration Rainfall Intensity Duration Frequency(SDR-IDF) Equation for Basrah City

  • Zainb Abd Alelah Department of Civil Engineering, College of Engineering, University of Basrah, Iraq.
Keywords: Chi-Square tests, Probability Distribution Function, Return Period, Short Duration rainfall


The Rainfall Intensity-Duration-Frequency (IDF) relationship is one of the
most commonly used tools in water resources engineering, either for planning,
designing and operating of water resource projects or for various engineering
projects against floods. The objective of this study is to develop an empirical
formula to estimate rainfall intensity for any duration and any return period with
minimum effort. Daily rainfall data for years 1980-2010 from Iraqi Metrological
Organization and Seismology was used in this study. Hershfeildʼs method was
used to estimate the short duration rainfall intensity from daily rainfall data.
Various distribution functions were used for analysis and Chi-Square goodness to
fit test were used to identify the best statistical distribution among them. Study
showed that Log Pearson type III is the best probability distribution and the best
(IDF)empirical formula was in the form [i=a/(b=td)].