PERMFILE114378

• Permit No: C1994082
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: Dodson & Associates Hydraulic Programs ‎(Trap, Pipe)‎
• Section_Exhibit Name: TAB 13 ATTACHMENT 13-1 ADDENDUM 2
• Media Type: D
• Archive: No

TRAPEZOIDAL AND CIRCULAR CHANNEL ANALYSIS HYDROCALC HYDRAULICS MANUAL. PAGE 16
T =Top width of flow (feet) O
r =Radius of Channel (feet) ~
F =Depth of Flow (feet)
2.1.3 EXAMPLES OF NORMAL DEPTH PROCEDURE
2.1.3.1 Computing Normal Depth in a Trapezoidal Channel
E,~rample 6-4 of Chow's "Open Channel Hydraulics" (Chow 1959) relates to the computation of
Normal Depth in a trapezoidal channel. The channel fn the example has a bottom width of 20
feet, side slopes of 2:1, a Mannfng's roughness coefficient of 0.025, and a required flow capacity
oC 400 cfs.
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Fgure 2-3 Example of Norma! Depth in irapezoidd Channel ll
t
Chocks manual computations indicate that the Normal Depth of flow !n the channel under the
stated conditions is 3.36 feet. As indicated Ln Figure 2-3, theTrapezoida] Channe]AnalysLsprogrsm
provides exactly the same result. The computed flow velocity also agrees very well with the value
computed by Chow. Chow computed a flow velocity of 4.46 fps, whereas the program computes
a value of 4.45 fps.
2.1.3.2 Computing Normal Depth in a Circular Channel
As an e.~cample of the Norma] Depth procedure for a circular channel, assume that a clroular pipe
culvert 8 Ceet in diameter connects two stormwater detention basins. The culvert has a bottom I
slope of 0.01 feet per foot, and the Manning's roughness coefficient for the pipe is assumed to be .
0.015. The Normal Depth of (low in the culvert is to be determined for a flow rate of 400 cis.
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