chapter 3 hydraulics of open channel flow

3.36 Chapter Three
HYDRAULICS OF OPEN CHANNEL FLOW
Type of Channel Minimum Normal Maximum
d. Rock cuts
1. Smooth and uniform 0.025 0.035 0.040
2. Jagged and irregular 0.035 0.040 0.050
e. Channels not maintained, weeds
and brush uncut
1. Dense weeds, high as
flow depth 0.050 0.080 0.120
2. Clean bottom, brush on sides 0.040 0.050 0.080
3. Same, highest stage of flow 0.045 0.070 0.110
4. Dense brush, high stage 0.080 0.100 0.14
C.2 Channels with maintained vegetation
and velocities of 2 and 6 ft/s
a. Depth of flow up to 0.7 ft
1. Bermuda grass, Kentucky bluegrass,
buffalo grass
Mowed to 2 in 0.07 0.045
Length 4 to 6 in 0.09 0.05
2. Good stand, any grass
Length approx. 12 in 0.18 0.09
Length approx. 24 in 0.30 0.15
3. Fair stand, any grass
Length approx. 12 in 0.014 0.08
Length approx. 24 in 0.25 0.13
b. Depth of flow up to 0.7–1.5 ft
1. Bermuda grass, Kentucky bluegrass,
buffalo grass
Mowed to 2 in 0.05 0.035
Length 4–6 in 0.06 0.04
2. Good stand, any grass
Length approx. 12 in 0.12 0.07
3. Length approx. 24 in 0.20 0.10
Fair stand, any grass
Length approx. 12 in 0.10 0.16
Length approx. 24 in 0.17 0.09
D Natural streams
D–1 Minor streams (top width at
flood stage < 100 ft)
a. Streams on plain
1. Clean, straight, full stage
no rifts or deep pools 0.025 0.030 0.033
2. Same as above, but with more
stones and weeds 0.030 0.035 0.040
3. Clean, winding, some pools and
shoals 0.033 0.040 0.045
4. Same as above, but with some
weeds and stones 0.035 0.045 0.050
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