Option

Description

Return Period

The return period or statistical frequency of the storm event.

Duration (hours)

The time elapsed from the start to finish of the storm event in hours.

Average Annual Rainfall

The standard average annual rainfall in mm, as read from the Average Annual Rainfall (1941-1970) map.

Proportional Flow Depth (%)

Specify the proportional flow depth to be used to calculate culvert capacity and select a culvert size.

Time Step

The time increment in minutes used in the analysis of the storm and runoff model.

Routing Method

Specify which routing method to use:

• Continuity Equation

• Time Shift

Rainfall Depths M5-60min

Read from the maps the rainfall depths of the five year return period and 60 minute duration.

Ratio of M5-60min to M5-two day (r x 100)

Read the ratio of 60 minute to two day rainfall of five year return period from the maps.

Geographic Location

Specify one of the following locations:

• England and Wales

• Scotland and Northern Ireland

Next Button

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Cancel Button

Click to cancel the function.