]> 2026-04-30T08:00:32-06:00 Model:TopoFlow-Channels-Diffusive Wave 3002 en About this component: *This component was developed as part of the TopoFlow hydrologic model, which was originally written in IDL and had a point-and-click GUI. For more information on TopoFlow, please goto: https://csdms.colorado.edu/wiki/Model:TopoFlow. *When used from within the CSDMS Modeling Tool (CMT), this component has "config" button which launches a graphical user interface (GUI) for changing input parameters. The GUI is a tabbed dialog with a Help button at the bottom that displays HTML help in a browser window. *This component also has a configuration (CFG) file, with a name of the form: <case_prefix>_channels_diff_wave.cfg. This file can be edited with a text editor. *The Numerical Python module (numpy) is used for fast, array-based processing. *This model has an OpenMI-style interface, similar to OpenMI 2.0. Part of this interface is inherited from "CSDMS_base.py". Yes 12 Boulder 1 Yes No but planned Single Processor United States Collaborators include: Larry Hinzman (UAF), Bob Bolton, Anna Liljedahl (UAF), Stefan Pohl, Tom Over and others This model/component is typically not calibrated to fit data, but is run with a best guess or measured value for each input parameter. Available test data sets: *Treynor watershed, in the Nishnabotna River basin, Iowa, USA. * (Two large rainfall events.) *Small basin in Kentucky. *Inclined plane for testing. *Arctic watershed data from Larry Hinzman (UAF). *See /data/progs/topoflow/3.0/data on CSDMS cluster. Several test datasets are stored on the CSDMS cluster at: /data/progs/topoflow/3.0/data. These inputs must be provided as grids: *flow_codes = D8 flow codes (Jenson 1984 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 / m^(1/3)) *bed_width = bed width for trapezoidal cross-section (m) *bank_angle = bank angle for trapezoid (deg) (from vertical) These inputs can be provided as scalars or grids: *sinuosity = channel sinuosity (m/m) (along-channel / straight length) *init_depth = initial water depth (m) (See HTML help) Grids must be saved in binary files with no header. All variables should be stored as 4-byte, floating-point numbers (IEEE standard) except flow codes, which are unsigned, 1-byte integers. The behavior of this component is controlled with a configuration (CFG) file, which may point to other files that contain input data. Here is a sample configuration (CFG) file for this component: Method code: 2 Method name: Diffusive_Wave Manning flag: 1 Law of Wall flag: 0 Time step: Scalar 6.00000000 (sec) D8 flow code: Grid Treynor_flow.rtg (none) D8 slope: Grid Treynor_slope.rtg (m/m) Manning N: Grid Treynor_chan-n.rtg (s/m^(1/3)) Bed width: Grid Treynor_chan-w.rtg (m) Bank angle: Grid Treynor_chan-a.rtg (deg) Init. depth: Scalar 0.00000000 (m) Sinuosity: Scalar 1.00000000 (m/m) Save grid timestep: Scalar 60.00000000 (sec) Save Q grids: 1 Case5_2D-Q.rts (m^3/s) Save u grids: 0 Case5_2D-u.rts (m/s) Save d grids: 0 Case5_2D-d.rts (m) Save f grids: 0 Case5_2D-f.rts (none) Save pixels timestep: Scalar 60.00000000 (sec) Save Q pixels: 1 Case5_0D-Q.txt (m^3/s) Save u pixels: 0 Case5_0D-u.txt (m/s) Save d pixels: 0 Case5_0D-d.txt (m) Save f pixels: 0 Case5_0D-f.txt (none) Main equations used by this component: ΔV(i,t)= Δt * ( R(i,t) Δx Δy - Q(i,t) + Σk Q(k,t) ) = change in water volume (m^3), mass conservation d = {( w^2 + 4 tan(θ) V / L)^1/2 - w } / (2 tan(θ)) = mean water depth in channel segment (m) (if θ > 0) d = V / (w * L) = mean water depth in channel segment (m) (if θ = 0) Q = v * Aw = discharge of water (m^3 / s) v = n^(-1) * Rh^(2/3) * S^(1/2) = section-averaged velocity (m / s), Manning's formula v = ( g * Rh * S)^(1/2) * LN( a * d / z0) / κ = section-averaged velocity (m / s), Law of the Wall Rh = Aw / Pw = hydraulic radius (m) Aw = d * (w + (d * tan(θ))) = wetted cross-sectional area of a trapezoid (m^2) Pw = w + (2 * d / cos(θ)) = wetted perimeter of a trapezoid (m) Vw = d^2 * ( L * tan(θ) ) + d * (L * w) = wetted volume of a trapezoidal channel (m) (Source: TopoFlow HTML Help System) Recommended grid cell size is around 100 meters, but can be parameterized to run with a wide range of grid cell sizes. DEM grid dimensions are typically less than 1000 columns by 1000 rows. This model/component needs more rigorous testing. This component computes the following variables, as grids: Q = discharge (m^3/s) u = flow velocity (m/s) d = flow depth (m) f = friction factor (none) Rh = hydraulic radius (m) S_free = free-surface slope (m/m) The user can choose which, if any, of these to save. Each may be saved as a grid sequence, indexed by time, in a netCDF file, at a specified sampling rate. Each may also be saved for a set of "monitored" grid cells, each specified as a (row,column) pair in a file with the name: <case_prefix>_outlets.txt. With this option, computed values are saved in a multi-column text file at a specified sampling rate. Each column in this file corresponds to a time series of values for a particular grid cell. For both options the sampling rate must no smaller than the process timestep. None, except visualization software. Grid sequences saved in netCDF files can be viewed as animations and saved as movies using VisIt. Another program must be used to create the input grids. This includes a D8 flow grid derived from a DEM for the region to be modeled. The earlier, IDL version of TopoFlow can be used to create some of these. The diffusive wave method for flow routing in the channels of a D8-based river network. The basic stability condition is: dt < (dx / u_min), where dt is the timestep, dx is the grid cell size and u_min is the smallest velocity in the grid. This ensures that flow cannot cross a grid cell in less than one time step. Typical timesteps are on the order of seconds to minutes. Model can be run for a full year or longer, if necessary. Active 2020 Yes 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 method includes a pressure gradient term 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. Scott 1 ASCII Binary CSDMS, INSTAAR, University of Colorado Peckham 0.06 Yes Standard Hydrology As code As teaching tool basins Single This site. wave diffusive spatial model model called topoflow spatially-distributed hydrologic model hydrologic model called called topoflow hydrologic model model called stand-alone model process component component is part spatially-distributed hydrologic compute flow velocities diffusive wave river network topoflow basins topoflow-channels-diffusive wave 1 Diffusive Wave process component for flow routing in a D8-based, spatial hydrologic model ASCII Binary 303-492-6752 true 1560 30th street 80305 true None (but uses NumPy package) Apache public license Python Minutes to hours Through web repository https://github.com/peckhams/topoflow 2D Landscape-Scale Watershed-Scale 2001 Colorado Unix Linux Mac OS Windows Model developer true VisIt 2010-02-16T01:44:56Z 2455243.5728704 2025-06-06T16:35:28Z 2460833.1912963 TopoFlow-Channels-Diffusive Wave 3002 0 plainlist 1 [[:Model:TopoFlow-Channels-Diffusive Wave]] TopoFlow-Channels-Diffusive Wave# QUERY203a3f777b4ff84a58cc8e6abc23c816 3002 1 plainlist 5 [[User:+]] [[First name member::Scott]] [[Last name member::Peckham]] TopoFlow-Channels-Diffusive Wave# QUERYf827ab8b81c27b3081932110253db0a7 3002 1 ul 5 [[Model:+]] [[First name::Scott]] [[Last name::Peckham]] TopoFlow-Channels-Diffusive Wave# QUERYdfb8ba22f24d8b31468ce7a2925ca174