Option

Description

Inflow Calculation Method

The Storm module supports four inflow calculation methods - Rational, Illudas, Wallingford Rational and EPA SWMM. Select the required inflow method.

Mean Annual Precipitation

The average annual precipitation in mm for the Rational method.

Friction Loss Formula

The Storm module supports two friction loss formulae - Manning and Colebrook-White. Select the required friction loss formula.

Geometric Controls:

Minimum Drop Distance

Specify the minimum distance between the manhole invert level and the outlet level of an incoming culvert to apply a drop inlet in that manhole.

Flow Controls:

Minimum Velocity

Culverts will be placed at a slope which will maintain the minimum flow velocity specified here, or the maximum slope specified in the Link Tables, whichever is the least. In practice this results in the first upstream culverts being placed at the maximum link slope, typically 1 to 1.5%. As the link flows become significant down the line, the link slopes start flattening to the minimum slope specified in the Link Table.

Maximum Velocity

This setting results in all links where the velocity exceeds the specified value being flagged in the results with the ** symbol.