The User Defined Rainfall (Design Storm) option allows you to create one or more rainfall events using a Temporal Pattern based on a given duration and an total Depth (or Average Intensity).


The following fields are available in the Storms tab.


Add - Adds a new row to the table ready for data to be entered.

A new row will be added automatically as the data is entered.

Delete - Deletes the currently selected event from the table.

Clear All - Clears all of the events from the table.

Select All - Selects all items from the table.

Deselect All - Deselects all entries from the table.

Create From IDF - Allows you to generate a User Defined Rainfall from either a Single RP IDF, or a Table IDF.


Use - Checkbox to indicate is the event should be run as part of the analysis.

At least one event must be turned on for the analysis to be run.

Duration - Length of the event to be built.

Run Time - The length of the analysis that will be run. Typically this will be twice the duration, which will be specified by default. However this can be overruled by entering your own run time manually.

Rainfall Depth - The depth of rainfall that falls for the given storm duration.

Rainfall Intensity - The average intensity for the rainfall that fell for the given storm duration.

This will be automatically calculated from the Depth/Duration. However it can be entered and the Depth is updated.

Temporal Pattern - Select from the drop-down list the temporal pattern that will be used.

Temporal Patterns

The Temporal Pattern forms allows the profile of the rainfall to be entered. This is then used to build an event from the duration and depth specified. For more information about this form, refer to Temporal Pattern.

The type of Temporal Pattern entered will affect the ability to generate a storm of a given duration.

Increase Rainfall

This will scale all rainfall by the amount specified. This can be used to take climate change, or other factors, into account.