Bentley SewerCAD supports the following runoff methods which can be selected by the user in the Property Editor or FlexTable under the attribute Runoff Method. They include:

• None - no runoff
• Modified rational method
• Unit hydrograph
• EPA SWMM
• User defined hydrograph

The data required varies for each method. The data requirements are summarized in "Catchment—Runoff" . The data needs for each method are described in their individual sections.

The input parameters for each method are listed below. Each of these methods is described in standard hydrology and stormwater references such as Stormwater Modeling Conveyance and Design, published Haestad Press.

Input Parameters for Unit Hydrograph Runoff Methods

• Loss method
• Capillary suction
• Ks
• Moisture deficit
• fc
• fo
• Initial abstraction
• K
• Recovery constant
• Maximum volume
• Time of Concentration (For more information, see "Specifying a Time of Concentration (Tc) Method for a Catchment" .)
• Unit hydrograph method (For more information, see "Unit Hydrograph Methodology" .)
• Generic unit hydrograph (For more information, see "Generic Unit Hydrographs" .)
• RTK Method(For more information, see "Adding Hydrographs Based On the RTK Method" .)
• SCS (For more information, see "Using the SCS Unit Hydrograph Runoff Method" .)

For more information on unit hydrograph runoff methods, see "Unit Hydrograph Runoff Methods"-443.

Related Topics

• "Adding Generic Unit Hydrographs"
• "Adding Hydrographs Based On the RTK Method"
• "Adding Storm Data"
• "Adding Global Storm Data"
• "Catchment Characteristics"