2.0

Table Of Contents
Chapter 5 Working with Hydrology Commands
548
2 Click Select to display the County Selection dialog box.
3 From the County Selection dialog box, select the county, and then click OK.
As you return to the Define Rainfall-Frequency dialog box, the county you
selected displays in the County box.
4 From the Rainfall Frequency list, select a rainfall frequency. For example, for a
10-year storm event, select 10 years.
When you select the rainfall frequency, the Rainfall label shows the amount of
rainfall for a 24-hour event of the frequency type you selected. For example, if
you selected 10 years in the Rainfall Frequency list, then the Rainfall labels
displays the amount of rain you could expect for that location in 24 hours in a
10-year storm event.
If you arrived at this dialog box by clicking Rainfall on the TR-55 Tabular
Hydrograph Method dialog box, then an Apply Rainfall list is available. You can
use this list to apply the rainfall amount that is shown in the Rainfall label to
the watershed(s) in the TR-55 Tabular Hydrograph Method dialog box.
5 From the Apply Rainfall list, select All to apply the rainfall amount to all
watershed subareas, or select Single to apply the rainfall amount to the single
subarea.
NOTE
When you click OK, the rainfall value is added to the 24-hrs Rainfall In.
column in the TR-55 Tabular Hydrograph Method dialog box. If you specify
Single, then the value is added to the column of the row in which your
cursor was located when you selected the Rainfall button. If you specify All,
then the value is added to all of the columns of data.
NOTE
To access the Rainfall-Frequency Editor dialog box to edit and define new
values, click the Edit button.
6 Click OK.