CIVIL ENGINEERING FORMULAS

326 CHAPTER TWELVE

and the critical depth is

(12.99)

Then the discharge per foot (meter) of width is given by

(12.100)

Withg32.16, Eq. (12.100) becomes

(12.101)

Triangular Channels

In a triangular channel (Fig. 12.20), the maximum depth Dcand the mean depth
Dmequal Dc. Then,

(12.102)

and (12.103)

As shown in Fig. 12.20, zis the slope of the channel sides, expressed as a
ratio of horizontal to vertical; for symmetrical sections, ze/Dc. The area, a

. Then,

(12.104)

Withg32.16,

(12.105)

and Dc (12.106)
B

(^52) Q 2
gz^2
Q4.01zDc5/2

Q

B

g

2

zDc5/2

zD^2 c

Dc

2 V^2 c

g

Vc

B

gDc

2

(^1)  2
q3.087H3/2m
qg (^2  3 )3/2H3/2m
Dc^2  3 Hm
Dc
z = e
Dc

T

e e

FIGURE 12.20 Triangular open channel.