WMS:Assigning the Regression Equation

Once a flow path (time computation) arc has been created for each sub-basin, the LACDPW TC regression equation must be assigned to each arc. This can be done in two ways:

1. After creating the Tc arc, double-click on it with the Select Feature Arc tool. The Time Computation Arc Attributes dialog will appear.
2. Select a sub-basin and bring up the Edit MODRAT Parameters dialog. Then click on the Compute Regression Tc button. This will invoke the Travel Time Computation dialog; the flow path arc can be selected and assigned an equation by selecting the Edit Arcs button. This button will invoke the Time Computation Arc Attributes dialog.

Once in the Time Computation Arc Attributes dialog, choose the LACDPW TC equation. The necessary variables will be shown in the window at the bottom of the dialog. If you have computed the watershed data and assigned rainfall, soil type, and percent impervious, all the variables will be assigned the appropriate values. If not, you can select the variables and enter a value manually.

NOTE: Once you have selected the LACDPW TC equation for one Tc arc in your model, it becomes the default for all other arcs.

Related Topics

• Automated Tc Calculations
• Compute Regression Tc
• Flow Path Arcs
• Regression Tc Arc Computations