2.0

Chapter 5 Working with Hydrology Commands
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10 In the Entrance Coef box, type an entrance coefficient. You can also click Select
and choose a coefficient from the Pipe Entrance Coefficients dialog box. For
more information, see Specifying Pipe Entrance Coefficients in this chapter.
11 In the Bend Angle box, type a pipe bend angle. This is the angle where the
vertical section of the riser and the horizontal (pipe) section of the riser meet.
The computed values for the riser display at the right of the dialog box. The box
at the top right area of the dialog box displays a graphic of the currently defined
riser. This information is for display only and cannot be edited.
NOTE
If the data you entered has an error, the riser graphic image does not
display. Check for an error message at the bottom of the dialog box.
12 Click Save to save the riser calculations.For more information, see Saving Riser
Data from the Riser Calculator in this chapter.
13 Do the following to output the riser data:
If you want to}
Then click
output the riser data to a text editor Output.
output and save a rating curve of the riser data Rating.
14 Click OK to exit the dialog box.
Riser Head Flow Formula
The Riser Calculator uses the following formula for calculating head flow:
Qa
gH
KKKL
eb p

2
1
where:
Q = Design flow rate
a = Pipe cross-sectional area
g = Acceleration due to gravity (32.174 ft/s
2
or 9.807 m/s
2
)
H = Elevation head differential
K
e
= Entrance loss coefficient
K
b
= Pipe bend loss coefficient
K
p
= Pipe friction coefficient
L = Pipe length