Statistical analysis of rainfall ecords of some Iraqi eteorological stations

الملخص EN

Since rainfall is an integral component in the hydrologic cycle, engineers must be able to quantify rainfall in order to design structures dealing with the collection, conveyance, and storage of runoff.

In this paper data of annual rainfall depth (mm) from 1969 to 2009 years for four meteorological stations in Iraq, namely, Baghdad, Najaf, Kerbala, and Diwaniya are analyzed to determine the characteristics of the observed frequency distributions.

An attempt is made to fit four of the available theoretical distributions, i.

e., the Normal, Log Normal, Log Normal type III, and Gamma distributions.

The Chi-Square and Kolmogorov-Smirnov indices, and the graphical goodness of fit tests are applied to compare each of the theoretical distributions and those observed.

In the remainder of this paper Intensity-Duration-Frequency (IDF) curves for extreme rainfall values for the four meteorological stations in Iraq with durations of 15, 30, and 60 min.

are obtained.

Gumbel's extreme value distribution, the Normal and the Log Normal distributions are used to fit the annual extremes rainfall data with 5, 10, 15, and 50 years return periods.