Channel
Type |
Minimum |
Normal |
Maximum |
|
Main Channels |
|
|
|
|
a. clean, straight, full stage, no rifts or deep
pools |
0.025 |
0.030 |
0.033 |
|
b. same as above, but more stones and weeds |
0.030 |
0.035 |
0.040 |
|
c. clean, winding, some pools and shoals |
0.033 |
0.040 |
0.045 |
|
d. same as above, but some weeds and stones |
0.035 |
0.045 |
0.050 |
|
e. same as above, lower stages, more ineffective |
0.040 |
0.048 |
0.055 |
|
slopes and sections |
|
f. same as "d" with more stones |
0.045 |
0.050 |
0.060 |
|
g. sluggish reaches, weedy, deep pools |
0.050 |
0.070 |
0.080 |
|
h. very weedy reaches, deep pools, or floodways |
0.075 |
0.100 |
0.150 |
|
with heavy stand of timber and underbrush |
|
Mountain streams, no vegetation
in channel, banks usually steep, trees and brush along banks submerged at
high stages |
|
a. bottom: gravels, cobbles, and few boulders |
0.030 |
0.040 |
0.050 |
|
b. bottom: cobbles with large boulders |
0.040 |
0.050 |
0.070 |
|
Floodplains |
|
|
|
|
a. Pasture, no brush |
|
|
|
|
1.short grass |
0.025 |
0.030 |
0.035 |
|
2. high grass |
0.030 |
0.035 |
0.050 |
|
b. Cultivated areas |
|
|
|
|
1. no crop |
0.020 |
0.030 |
0.040 |
|
2. mature row crops |
0.025 |
0.035 |
0.045 |
|
3. mature field crops |
0.030 |
0.040 |
0.050 |
|
c. Brush |
|
|
|
|
1. scattered brush, heavy weeds |
0.035 |
0.050 |
0.070 |
|
2. light brush and trees, in winter |
0.035 |
0.050 |
0.060 |
|
3. light brush and trees, in summer |
0.040 |
0.060 |
0.080 |
|
4. medium to dense brush, in winter |
0.045 |
0.070 |
0.110 |
|
5. medium to dense brush, in summer |
0.070 |
0.100 |
0.160 |
|
d. Trees |
|
|
|
|
1. dense willows, summer, straight |
0.110 |
0.150 |
0.200 |
|
2. cleared land with tree stumps, no sprouts |
0.030 |
0.040 |
0.050 |
|
3. same as above, but with heavy growth of sprouts |
0.050 |
0.060 |
0.080 |
|
4. heavy stand of timber, a few down trees, little |
0.080 |
0.100 |
0.120 |
|
undergrowth, flood stage below branches |
|
5. same as 4. with flood stage reaching
branches |
0.100 |
0.120 |
0.160 |
|
Excavated or Dredged |
|
|
|
|
a. Earth, straight, and uniform |
|
|
|
|
1. clean, recently completed |
0.016 |
0.018 |
0.020 |
|
2. clean, after weathering |
0.018 |
0.022 |
0.025 |
|
3. gravel, uniform section, clean |
0.022 |
0.025 |
0.030 |
|
4. with short grass, few weeds |
0.022 |
0.027 |
0.033 |
|
b. Earth winding and sluggish |
|
|
|
|
1. no vegetation |
0.023 |
0.025 |
0.030 |
|
2. grass, some weeds |
0.025 |
0.030 |
0.033 |
|
3. dense weeds or aquatic plants in deep channels |
0.030 |
0.035 |
0.040 |
|
4. earth bottom and rubble sides |
0.028 |
0.030 |
0.035 |
|
5. stony bottom and weedy banks |
0.025 |
0.035 |
0.040 |
|
6. cobble bottom and clean sides |
0.030 |
0.040 |
0.050 |
|
c. Dragline-excavated or dredged |
|
|
|
|
1. no vegetation |
0.025 |
0.028 |
0.033 |
|
2. light brush on banks |
0.035 |
0.050 |
0.060 |
|
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 as above, highest stage of flow |
0.045 |
0.070 |
0.110 |
|
4. dense brush, high stage |
0.080 |
0.100 |
0.140 |
|
Lined or Constructed |
|
|
|
|
a. Cement |
|
|
|
|
1. neat surface |
0.010 |
0.011 |
0.013 |
|
2. mortar |
0.011 |
0.013 |
0.015 |
|
b. Wood |
|
|
|
|
1. planed, untreated |
0.010 |
0.012 |
0.014 |
|
2. planed, creosoted |
0.011 |
0.012 |
0.015 |
|
3. unplaned |
0.011 |
0.013 |
0.015 |
|
4. plank with battens |
0.012 |
0.015 |
0.018 |
|
5. lined with roofing paper |
0.010 |
0.014 |
0.017 |
|
c. Concrete |
|
|
|
|
1. trowel finish |
0.011 |
0.013 |
0.015 |
|
2. float finish |
0.013 |
0.015 |
0.016 |
|
3. finished, with gravel on bottom |
0.015 |
0.017 |
0.020 |
|
4. unfinished |
0.014 |
0.017 |
0.020 |
|
5. gunite, good section |
0.016 |
0.019 |
0.023 |
|
6. gunite, wavy section |
0.018 |
0.022 |
0.025 |
|
7. on good excavated rock |
0.017 |
0.020 |
|
|
8. on irregular excavated rock |
0.022 |
0.027 |
|
|
d. Concrete bottom float finish with sides of: |
|
|
|
|
1. dressed stone in mortar |
0.015 |
0.017 |
0.020 |
|
2. random stone in mortar |
0.017 |
0.020 |
0.024 |
|
3. cement rubble masonry, plastered |
0.016 |
0.020 |
0.024 |
|
4. cement rubble masonry |
0.020 |
0.025 |
0.030 |
|
5. dry rubble or riprap |
0.020 |
0.030 |
0.035 |
|
e. Gravel bottom with sides of: |
|
|
|
|
1. formed concrete |
0.017 |
0.020 |
0.025 |
|
2. random stone mortar |
0.020 |
0.023 |
0.026 |
|
3. dry rubble or riprap |
0.023 |
0.033 |
0.036 |
|
f. Brick |
|
|
|
|
1. glazed |
0.011 |
0.013 |
0.015 |
|
2. in cement mortar |
0.012 |
0.015 |
0.018 |
|
g. Masonry |
|
|
|
|
1. cemented rubble |
0.017 |
0.025 |
0.030 |
|
2. dry rubble |
0.023 |
0.032 |
0.035 |
|
h. Dressed ashlar/stone paving |
0.013 |
0.015 |
0.017 |
|
i. Asphalt |
|
|
|
|
1. smooth |
0.013 |
0.013 |
|
|
2. rough |
0.016 |
0.016 |
|
|
j. Vegetal lining |
0.03 |
|
0.5 |
|
|
|
|
Chow, V.T. (1959). Open-Channel Hydraulics. McGraw-Hill. |
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