Rainfall data for Rational Method property sheet
This window is used to enter ten values that define the key average recurrence intervals (ARIs) and rainfall intensities required to define the intensity-frequency-duration relationships to be used in rational method calculations.
The ARIs entered define the values that are to be used for design and analysis. In rational method calculations pipes will be sized to carry flowrates of the first, minor ARI, and the operation of the system in the second, major ARI will be modelled, as a check.
The remaining eight rainfall intensities can be entered from:
charts and tables supplied by the Australian Bureau of Meteorology, which are commonly available from the engineering departments of local councils,
the ARR Wizard operated by clicking on the ARR Wizard button to the right of the dialog box.
The Wizard calculates intensities using the procedure from Australian Rainfall and Runoff (1987) Volume 2. It opens the IFD Data property sheet.
Once you enter the required nine numbers taken from charts in Australian Rainfall and Runoff
and close this sheet, the required intensities are calculated and appear in the boxes as shown above.
DRAINS interpolates between the intensities shown to define intensities of the given ARIs for all durations between 5 minutes and 72 hours.
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