Area inflows can be applied to the system using the Area Inflow type.
Runoff
Area
An area can be entered directly or calculated automatically from the polygon drawn on the Plan.
Use Land Uses / Soil Types layers
Use the loaded Land Uses and Soil Types to calculate SCS Curve Number, PIMP, and CV from subcatchments.
Preliminary Sizing
The Area, Volumetric Runoff Coefficient, Percent Impervious and Time of Concentration values shown in the preliminary Sizing tab will be used for initial sizing of pipes and stormwater controls using Rational Method style calculations.
If these values are not entered here, the default values or the values from the current dynamic sizing runoff method will be used.
When the Use Land Uses/Soil Types layers box is checked, the Preliminary Sizing Percentage Impervious and Volumetric Runoff Coefficient are calculated from weighted averages of Land Uses.
Volumetric Runoff Coefficients
Used to factor the runoff when the Time Area Diagram, Time of Concentration or Green Roof Runoff Methods are selected.
If a UK Rainfall pattern ( FSR Rainfall / FEH Rainfall) is selected in the Analysis Criteria, values can instead be specified seasonally. The CVs specified will be used for the Summer and Winter storm analysis, if that type of storm is enabled in the Select Rainfall section within the Analysis Criteria.
When the Use Land Uses/Soil Types layers box is unchecked, the Runoff Coefficient Calculator can be used to calculate for the Volumetric Runoff Coefficient from Land Use and Overland Slope.
When the Use Land Uses/Soil Types layers box is checked, the Volumetric Runoff Coefficient is calculated from weighted averages of Land Uses.
Runoff Method
The preferred runoff methods can be selected - select from the methods below for details and required input parameters.