Rainfall temporal pattern has a marked influence on design of dams, urban water harvesting, culverts,

drainage design, flood potential and soil erosion. In this research we used data of 146 autographic rainfall

stations of Iran to implement the rainfall temporal pattern. Rainfall depth were calculated for each time

interval from rainfall charts and were categorized to four quarters. The ranking method was used to arrive

at rainfall temporal patterns corresponding to time intervals of 1,3,9 and 12 hours. After normalizing the

rainfall mass curves, every quarter of rainfall was ranked, number 1 for the highest. The final pattern was

derived by averaging the quarter ranks and percentage of rainfalls corresponding to each duration.

Adopting Ward method, 5, 9, 9, and 8 homogeneous regions were detected for short (<3 hr), medium (3-6

hr), and long (6-12, and >12 hr) rainfall time period, respectively. Design rainfall temporal pattern was

derived for every homogenous zone. There is a danger for mis-used temporal pattern by type patterns.