WMS:FHWA Channel Flow: Difference between revisions
From XMS Wiki
Jump to navigationJump to search
No edit summary |
No edit summary |
||
| (9 intermediate revisions by the same user not shown) | |||
| Line 5: | Line 5: | ||
where: | where: | ||
: < | : ''T<sub>t</sub>'' = travel time for open channel flow segments. | ||
: | : ''L'' = open channel flow length. | ||
: | : ''n'' = Manning’s roughness coefficient for channel flow. Suggested values are given in Table 3-4 of the FHWA HEC 22 manual and are repeated in the table below. | ||
: | : ''K'' = empirical coefficient equal to 1.49 for English units and 1.0 for Metric. | ||
: | : ''R'' = hydraulic radius (length, ft or m). | ||
: | : ''S'' = channel slope (length/length). | ||
{| class="thin" | {| class="thin" style="border-spacing: 2px; border: 1px solid darkgray;" | ||
|+ '''Values of Manning's coefficient for channels and pipes''' | |+ '''Values of Manning's coefficient for channels and pipes''' | ||
|- | |- | ||
! width=250px | Conduit Material !! align=center width=100px | | ! width=250px | Conduit Material !! align=center width=100px | ''n'' | ||
|- | |- | ||
| ''Closed conduits'' | | ''Closed conduits'' | ||
| Line 80: | Line 79: | ||
|} | |} | ||
The hydraulic radius may be computed using the [[WMS:Channel Calculator|''Channel Calculator'']]. In this case, assume an approximate depth of flow or flow rate in order for the channel calculator to be able to compute the appropriate hydraulic radius. | |||
The hydraulic radius may be computed using the [[WMS:Channel Calculator| | |||
==Related Topics== | ==Related Topics== | ||
| Line 88: | Line 86: | ||
{{WMSMain}} | {{WMSMain}} | ||
[[Category:Equations|FHWA]] | |||
[[Category:TR-55|FHWA]] | |||
Latest revision as of 14:27, 19 October 2017
Travel time for open channel flow segments is computed using the following form of Manning’s equation for open channel flow:
where:
- Tt = travel time for open channel flow segments.
- L = open channel flow length.
- n = Manning’s roughness coefficient for channel flow. Suggested values are given in Table 3-4 of the FHWA HEC 22 manual and are repeated in the table below.
- K = empirical coefficient equal to 1.49 for English units and 1.0 for Metric.
- R = hydraulic radius (length, ft or m).
- S = channel slope (length/length).
| Conduit Material | n |
|---|---|
| Closed conduits | |
| Asbestos-cement pipe | 0.011-0.015 |
| Brick | 0.013-0.017 |
| Cast iron pipe | |
| Cement lined & seal coated | 0.011-0.015 |
| Concrete (monolithic) | 0.012-0.014 |
| Concrete pipe | 0.011-0.015 |
| Corrugated-metal pipe (0.5-2.5 inch corrugations) | |
| Plain | 0.022-0.026 |
| Paved invert | 0.018-0.022 |
| Spun asphalt lined | 0.011-0.015 |
| Plastic pipe (smooth) | 0.011-0.015 |
| Vitrified clay | |
| Pipes | 0.011-0.015 |
| Liner plates | 0.013-0.017 |
| Open channels | |
| Lined channels | |
| Asphalt | 0.013-0.017 |
| Brick | 0.012-0.018 |
| Concrete | 0.011-0.020 |
| Rubble or riprap | 0.020-0.035 |
| Vegetal | 0.030-0.040 |
| Excavated or dredged | |
| Earth, straight and uniform | 0.020-0.030 |
| Earth, winding, fairly uniform | 0.025-0.040 |
| Rock | 0.030-0.045 |
| Unmaintained | 0.050-0.14 |
| Natural channels (minor streams, top width at flood stage < 100 feet) | |
| Fairly regular section | 0.03-0.07 |
| Irregular section with pools | 0.04-0.10 |
The hydraulic radius may be computed using the Channel Calculator. In this case, assume an approximate depth of flow or flow rate in order for the channel calculator to be able to compute the appropriate hydraulic radius.
Related Topics
WMS – Watershed Modeling System | ||
|---|---|---|
| Modules: | Terrain Data • Drainage • Map • Hydrologic Modeling • River • GIS • 2D Grid • 2D Scatter |  |
| Models: | CE-QUAL-W2 • GSSHA • HEC-1 • HEC-HMS • HEC-RAS • HSPF • MODRAT • NSS • OC Hydrograph • OC Rational • Rational • River Tools • Storm Drain • SMPDBK • SWMM • TR-20 • TR-55 | |
| Toolbars: | Modules • Macros • Units • Digitize • Static Tools • Dynamic Tools • Drawing • Get Data Tools | |
| Aquaveo | ||
