When the SCS Unit Hydrograph Runoff Method is assigned to a catchment, Drainage and Utilities allows you to choose between the following three dimensionless methods to further customize the hydrograph:

• Default Curvilinear—This method uses the standard dimensionless curvilinear unit hydrograph ordinates, as defined in "Chapter 4" of the National Engineering Handbook, Section 4.
• Triangular Unit Hydrograph—This method uses a triangular unit hydrograph shape to define the coordinates for the unit hydrograph. The default shape factor is 484 (37.5% of the volume on the rising limb of the unit hydrograph).
• Dimensionless Unit Hydrograph—This method allows you to customize the Q/Qp-T/Tp unit hydrograph that is used with the SCS Unit Hydrograph method. See "Adjusting the Q/Qp-T/Tp Unit Hydrograph" for more information.