Model:TopoFlow-Channels-Diffusive Wave

Contact

Name	Scott Peckham
Type of contact	Model developer
Institute / Organization	CSDMS, INSTAAR, University of Colorado
Postal address 1	1560 30th street
Postal address 2
Town / City	Boulder
Postal code	80305
State	Colorado
Country	USA"USA" is not in the list (Afghanistan, Albania, Algeria, Andorra, Angola, Antigua and Barbuda, Argentina, Armenia, Australia, Austria, ...) of allowed values for the "Country" property.
Email address	Scott.Peckham@colorado.edu
Phone	303-492-6752
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TopoFlow-Channels-Diffusive Wave

Metadata

Summary Also known as Model type Single Model part of larger framework Note on status model Date note status model Technical specs Supported platforms Unix, Linux, Mac OS, Windows Other platform Programming language Python Other program language None (but uses NumPy package) Code optimized Single Processor Multiple processors implemented Nr of distributed processors Nr of shared processors Start year development 2001 Does model development still take place? Yes If above answer is no, provide end year model development Code development status When did you indicate the 'code development status'? Model availability As code, As teaching tool Source code availability (Or provide future intension) Through CSDMS repository Source web address Source csdms web address Program license type Apache public license Program license type other Memory requirements Standard Typical run time Minutes to hours In/Output Describe input parameters 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) ADD ADDITIONAL, OUTPUT OPTIONS HERE. Input format ASCII, Binary Other input format Describe output parameters 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. Output format ASCII, Binary Other output format Pre-processing software needed? Yes Describe pre-processing software 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. Post-processing software needed? Yes Describe post-processing software None, except visualization software. Grid sequences saved in netCDF files can be viewed as animations and saved as movies using VisIt. Visualization software needed? Yes If above answer is yes Other visualization software VisIt Process Describe processes represented by the model The diffusive wave method for flow routing in the channels of a D8-based river network. Describe key physical parameters and equations 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) Describe length scale and resolution constraints 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. Describe time scale and resolution constraints The basic stability condition is: dt < (dx / u_min), where dt is the timestp, 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. Describe any numerical limitations and issues This model/component needs more rigorous testing. Testing Describe available calibration data sets This model/component is typically not calibrated to fit data, but is run with a best guess or measured value for each input parameter. Upload calibration data sets if available: Describe available test data sets 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. Upload test data sets if available: Describe ideal data for testing Several test datasets are stored on the CSDMS cluster at: /data/progs/topoflow/3.0/data. Other Do you have current or future plans for collaborating with other researchers? Collaborators include: Larry Hinzman (UAF), Bob Bolton, Anna Liljedahl (UAF), Stefan Pohl, Tom Over and others Is there a manual available? Yes Upload manual if available: Model website if any This site. Model forum / discussion board Comments 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: http://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". Introduction History Papers Issues Help Input Files Output Files Download Source