IDF Storm Group, Return Periods and Durations

On the first page of the wizard, select the IDF Storm Group to use to convert intensities into depths. An IDF Storm Group is defined as a storm event group that creates IDF curves.

If there are no IDF Storm Groups listed, using the […] button to the right of the drop-down to open the storm data dialog. In this dialog you can add new IDF Storm Groups.

The following are the available IDF Storm Group types available in the storm data dialog:

• User Defined IDF Table
• Hydro-35
• IDF Table Equation
• IDF Curve Equation
• IDF Polynomial Log Equation
• Flood Studies Report (United Kingdom)
• Australia Rainfall and Runoff (2016)
• Flood Estimation Handbook (United Kingdom)

When an IDF Storm Group is selected, the return periods and durations are populated in the return period and duration lists. At least one return period and duration selection is required to click Next and move to Step 2.

The climate change factors are an option that adds a percentage to the base depth of the storm event. This allows you to design your system with climate change in mind. The entered climate change factors must be greater than 0.