2.0

Chapter 5 Working with Hydrology Commands
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NOTE
When editing the dimensionless hydrograph, enter the time increment
values in the t/tp (time to peak) column. Enter the flow discharge values in
the q/qp (peak discharge) column.
4 Click Save to save your changes.
5 Click OK to return to the SCS TR-20 Unit Hydrograph Method dialog box.
Adding a Range of Time Increments to a
Dimensionless Hydrograph File
To quickly add new rainfall distribution information to a new or existing
dimensionless hydrograph file, you can add ranges. Ranges define the time
increments you want to add information for. You can manually type each
increment value in the Dimensionless Hydrograph Editor, but the Range option
automates this process for you.
To add a range of increments to a dimensionless hydrograph file
1 From the Hydrology menu, choose Runoff ä TR-20 Method to display the SCS
TR-20 Unit Hydrograph Method dialog box.
2 Click Edit next to the Dimensionless Hydrograph list to display the
Dimensionless Hydrograph Editor dialog box.
3 Click Range to display the Range Settings dialog box.
4 Enter the time range values according to the following guidelines:
n
In the From box, enter the start of the range you want to add increments for.
For example, if you want to create increments between 0 and 120 minutes,
type 0 in the From box.
n
In the To box, enter the end of the range. For example, if you want to create
increments between 0 and 120 minutes, type 120 in the From box. The To
value must be greater than the From value.
n
In the Increment box, enter the increment. For example, if you want to add
rainfall amounts to the dimensionless hydrograph file for every 30 minutes,
type 30 in the Increment box.
5 Click OK to return to the Dimensionless Hydrograph Editor dialog box.
If you are editing an existing dimensionless hydrograph file, then a dialog box
is displayed, asking if you want to delete the existing column data.