Option

Description

Paved Area (%)

The percentage of the sub-catchment that consists of impervious material.

Paved Area Entry Time (min)

The paved entry time is the time it takes the runoff from the paved area to run along a gutter with a hydraulic radius of 60mm and a Manning factor of 0.02 to the inlet. The overland flow time for the runoff to reach the gutter is assumed to be two minutes, which is added to the gutter travel time.

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Paved Depression Storage (mm)

The average losses, in millimetres, due to surface irregularities in the paved area.

Supplementary Area (%)

The percentage of the sub-catchment that consists of impervious material, which discharges onto a permeable surface i.e. roofs that discharge onto a lawn.

Grassed Entry Time (min)

The time, in minutes, for a drop of water to travel from the furthest part of the grassed zone to a point on the contributing paved area or to the stormwater inlet, if the contributing paved area is zero.

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Grassed Depression Storage (mm)

The average losses in mm due to surface irregularities.

Soil Type

The soil classification that determines the rate of infiltration.