Model help:TopoFlow-Channels-Diffusive Wave
TopoFlow-Channels-Diffusive Wave
The module is used to compute flow routing in a D8-based, spatial hydrologic model.
Model introduction
This process component is part of a spatially-distributed hydrologic model called TopoFlow, but it can now be used as a stand-alone model. It uses the "diffusive wave" method to compute flow velocities for all of the channels in a D8-based river network. This wave method is similar to the kinematic wave method for modeling flow in open channels, but instead of a simple balance between friction and gravity, this method includes the pressure gradient that is induced by a water-depth gradient in the downstream direction. This means that instead of using bed slope in Manning's equation or the law of the wall, the water-surface slope is used. One consequence of this is that water is able to move across flat areas that have a bed slope of zero. Local and convective accelerations in the momentum equations are still neglected, just as is done in the kinematic wave method. For more information.
Model parameters
Input parameters
| Parameter | Description | Unit |
|---|---|---|
| Flow_codes | D8 flow codes (Jenson convention)[NE,E,SE,S,SW,W,NW,N][1,2,4,8,16,32,64,128] | [-] |
| Bed_slope | slope of the channel bed or hillslope | [m/m] |
| Manning_n | Manning roughness parameter | [s/m1/3] |
| Bed_width | bed width for trapezoidal cross-section | [m] |
| Bank_angle | bank angle for trapezoid (from vertical) | [deg] |
| Sinuosity | channel sinuosity(along-channel / straight length) | [-] |
| Init_depth | initial water depth | [-] |
Uses ports
This will be something that the CSDMS facility will add
Provides ports
This will be something that the CSDMS facility will add
Main equations
- Equations Used by the Diffusive Wave Method
[math]\displaystyle{ \Delta V \left (i,t \right)=\Delta t \left (R \left (i,t \right) \Delta x \Delta y -Q \left (i,t \right) +\Sigma_{k} Q \left (k,t \right) \right) }[/math] change in water volume [m3]Mass Conservation
[math]\displaystyle{ d=\left (\left (w^2 + 4 \tan \left (\Theta\right) V / L\right)^{\frac{1}{2}} -w\right) / \left ( 2 \tan \left (\Theta\right)\right) }[/math] mean water depth in channel segment [m] (if θ > 0)
[math]\displaystyle{ d= V / \left (w L\right) }[/math] mean water depth in channel segment [m] (if θ = 0)
[math]\displaystyle{ Q=v A_{w} }[/math] discharge of water [m^3 / s]
[math]\displaystyle{ v=n^{-1}\lt /sup\gt R }[/math] section-averaged velocity [m / s], Manning's formula
Notes
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Numerical scheme
Examples
An example run with input parameters, BLD files, as well as a figure / movie of the output
Follow the next steps to include images / movies of simulations:
- Upload file: http://csdms.colorado.edu/wiki/Special:Upload
- Create link to the file on your page: [[Image:<file name>]].
See also: Help:Images or Help:Movies
Developer(s)
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References
Key papers
Links
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