Rainfall Frequency Distribution and Temporal Pattern of Some Climatic Regions of Iran

The most important factors about rainfall are its frequency, intensity and amount. The main goal of this study was estimating the time distribution of rainfall in some climatic regions of Iran. There are different methods in estimating time distribution of rainfall. Two of these are the Huff and Pilgrim methods in which real rainfall data are used to estimate rainfall temporal patterns. As the first step statistical analysis was performed to estimate the PDF curves. Then the minimum range for storm selection in each station was investigated. The results showed that the optimum rainfall range in each of the selected stations (Bam, Tehran, Shiraz and Gorgan) were 7.0, 10.5, 12.0 and 10.0 mm, respectively. Then the rainfall temporal pattern of the four climatic regions of Iran including sever arid (Bam), arid (Shiraz), semi- arid (Tehran) and semi humid (Gorgan) was identified applying the Huff and Pilgrim methods. Dimensionless curve fitting of the temporal patterns of the rainfall of each statin was also investigated. Comparison of the patterns of the two selected methods with the collected data indicated that the Huff method was superior to the Pilgrim method results