Also known as
Model type Modular
Model part of larger framework
Note on status model
Date note status model
Spatial dimensions 2D
Spatial extent Landscape-Scale
Model domain Coastal, Hydrology, Terrestrial
One-line model description Landscape evolution resulting from feedback between flow, vegetation, and sediment
Extended model description Simulates the evolution of landscapes consisting of patches of high-flow-resistance vegetation and low-flow-resistance vegetation as a result of surface-water flow, peat accretion, gravitationally driven erosion, and sediment transport by flow. Was developed for the freshwater Everglades but could also apply to coastal marshes or floodplains. Described in Larsen and Harvey, Geomorphology, 2010 and Larsen and Harvey, American Naturalist, 2010 in press.

landscape evolution, everglades,

Name Laurel Larsen
Type of contact Model developer
Institute / Organization USGS
Postal address 1 12201 Sunrise Valley Drive
Postal address 2 Mailstop 430
Town / City Reston
Postal code 20192
State Virginia
Country United States
Email address
Phone 703-648-5891
Fax 703-648-5484

Supported platforms
Linux, Windows
Other platform
Programming language


Other program language
Code optimized Single Processor
Multiple processors implemented
Nr of distributed processors
Nr of shared processors
Start year development 2008
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
Source code availability
(Or provide future intension)
Source web address
Source csdms web address
Program license type GPL v2
Program license type other
Memory requirements 1G
Typical run time 1-7 days

Describe input parameters
  • Input topography OR initial relative coverage of high-resistance vegetation community
  • Annual duration of high-flow events
  • Initial surface-water level
  • Water surface slope during high-flow events
  • Bed sediment diffusion coefficient (for erosion by gravity)
  • Critical shear stress for entrainment of bed sediment (model uses a flocculent sediment transport relation) and corresponding entrainment function
  • Scaling factor affecting maximum peat accretion rate of high-flow-resistance community
  • Scaling factor affecting equilibrium elevation of high-flow-resistance community
  • Scaling factor for vegetative propagation/below-ground biomass expansion rates
  • Scaling factor for lateral velocities
  • Effected suspended sediment settling velocity
  • Soil bulk density
  • Optional: Mean annual evapotranspiration in each vegetation community
  • Optional: Vertical profiles of vegetation stem architecture and diameter and drag coefficient relationships for vegetation communities (otherwise model will use default high-flow-resistance and low-flow-resistance communities = ridge and slough vegetation communities in the Everglades)
Input format ASCII
Other input format
Describe output parameters 2-dimensional distributions of the following:
  • Vegetation community (high- or low-flow-resistance)
  • Depth-averaged flow speed and directional components
  • Bed shear stress
  • Soil elevation
  • Suspended sediment concentration
Output format ASCII, Binary
Other output format
Pre-processing software needed? Yes
Describe pre-processing software Pre-processing software is optional and should be used if the code is to be developed for specific vegetation communities. The software creates two-dimensional lookup tables for fluid mechanical parameters such as bed shear stress, depth-averaged drag force, and dispersion coefficients as a function of water depth and mean flow velocity. Lookup tables encapsulate the results of detailed simulations of velocity profiles under different combinations of water-surface slope and surface-water depth. See description in Larsen et al., Ecological Engineering, 2009.
Post-processing software needed? No
Describe post-processing software
Visualization software needed? Yes
If above answer is yes Matlab
Other visualization software

Describe processes represented by the model The main source code calls sub-modules that simulate the following processes:

- Vegetation community colonization as a function of local water depth. Colonization is deterministic over some ranges and stochastic in others. - Solution of flow field in two dimensions using a cellular automata algorithm (see Larsen and Harvey, 2010, Geomorphology, and Larsen and Harvey, 2010 in press, American Naturalist). The flow field is only simulated during high-flow events that entrain sediment. - Sediment transport by flow according to an advection-dispersion equation. Within each high-flow pulse, steady conditions are assumed. - Evolution of the topography through sediment transport, peat accretion (which is based on Larsen et al., Ecological Monographs, 2007), diffusive erosion of topographic gradients, vegetative propagation, and below-ground biomass expansion. - Adjustment of water levels and high-flow discharge to satisfy a water balance and compensate for the growth of vegetation patches.

Describe key physical parameters and equations See Larsen and Harvey, 2010, Geomorphology and Larsen and Harvey, 2010, American Naturalist (currently in press)
Describe length scale and resolution constraints Code has been most commonly run for 10x5 m cells (with the long axis parallel to flow) and domain size of 1.27 x 1.86 km. Other scales are possible, but adding additional cells will slow down processing. This model is only designed to simulate mean flows; resolution of fine turbulence structure is not possible with the code.
Describe time scale and resolution constraints Code has been most commonly run at 1 year time steps for up to 6000 years. Time steps are constrained by rates of evolution of topography due to episodic sediment transport events and peat accretion and how quickly those processes affect the flow field. In the situation for which the model was developed, sediment accumulates at a mean rate of 1 mm/yr.
Describe any numerical limitations and issues The model was designed for laminar to transitional flows, up to 10 cm/s. Under these conditions, the flow velocity solution is approximate but is realistic and stable.

Describe available calibration data sets
Upload calibration data sets if available:
Describe available test data sets Flow velocities measured under current conditions in the Everglades in ridge (high-flow-resistance) and slough (low-flow-resistance) vegetation communities. This is very limited validation, as it only tests simulated velocities at the low end of the range of velocities the model is capable of simulating. Results are shown in Larsen and Harvey, Geomorphology, 2010, Fig. 4.
Upload test data sets if available:
Describe ideal data for testing More aspects of the model will be tested in the Everglades as part of the upcoming Decompartmentalization Physical Model, a series of experimental flow releases that will elevate water-surface slope and flow velocities and likely entrain sediment. Coinciding measurements of flow velocities and sediment transport characteristics will be made within different vegetation communities as part of the experiment.

Do you have current or future plans for collaborating with other researchers? Yes.
Is there a manual available? No
Upload manual if available:
Model website if any
Model forum / discussion board

This part will be filled out by CSDMS staff

OpenMI compliant No but possible
BMI compliant No but possible
WMT component No but possible
PyMT component
Is this a data component
Can be coupled with:
Model info
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Input Files

Output Files