Option

Description

Percentage Impervious Catchment (PIMP)

The percentage of the catchment area covered by impervious surfaces intended to drain to the storm sewer.

Time of Entry A (min)

The time it takes for a drop of water to travel from the most distant part of the catchment to the catchpit. Click ... to display the Time of Entry calculator.

Previous Pipe Length (m)

The length of pipe between the upstream sub-catchment and this sub-catchment.

Previous Pipe Velocity (m/s)

The calculated flow velocity in the pipe between the upstream sub-catchment and this sub-catchment.

Soil Type

The soil index SOIL is based on the Flood Studies Report, and may be obtained from the revised soil map covering the whole of the United Kingdom. The index takes one of the values 0.15, 0.3, 0.4, 0.45, 0.5 according to the five soil types 1 to 5, respectively.