Technical data

Chapter 3 Performing Hydrologic Studies
46
To calculate the peak discharge using the TR- 55 Graphical Peak
Discharge Method
Steps
Use
to look up
1 Determine the specific watershed characteristics
and design criteria, including soil and vegetation
types, rainfall frequency and distribution, and
sheet, shallow, and channel flow parameters.
To do this, use hydrologic data from soil maps,
rainfall frequency distribution charts and other
relevant publications acquired for your county or
region from your local SCS office or county Soil
& Water Conservation District office.
2 From the Hydrology menu, choose Settings to
access the Hydrology Tools Settings dialog box.
Click Units to specify the Graphical Peak
Discharge Method measurement units. Click
Precision to specify the required precision
settings for your units.
Change the Hydrology
Unit Settings
3 From the Hydrology menu, choose
Runoff ➤ TR-55 Graphical Method to display the
TR-55 Graphical Peak Discharge Method dialog
box.
Calculate the Peak Runoff
Flow by Using the TR-55
Graphical Method
4 Select the applicable rainfall distribution type
from the Rainfall Distribution list.