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NAME

r.sim.terrain - Dynamic landscape evolution model

KEYWORDS

raster, terrain, landscape, evolution

SYNOPSIS

r.sim.terrain
r.sim.terrain --help
r.sim.terrain [-f] elevation=name runs=string mode=string [rain_intensity=integer] [rain_duration=integer] [precipitation=name] [k_factor=name] [k_factor_value=float] [c_factor=name] [c_factor_value=float] [m=float] [n=float] [walkers=integer] [runoff=name] [runoff_value=float] [mannings=name] [mannings_value=float] [detachment=name] [detachment_value=float] [transport=name] [transport_value=float] [shearstress=name] [shearstress_value=float] [density=name] [density_value=float] [mass=name] [mass_value=float] [grav_diffusion=float] [erdepmin=float] [erdepmax=float] start=string rain_interval=integer temporaltype=name [threads=integer] elevation_timeseries=name [depth_timeseries=name] [erdep_timeseries=name] [flux_timeseries=name] [difference_timeseries=name] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags:

-f
Fill depressions
--overwrite
Allow output files to overwrite existing files
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog

Parameters:

elevation=name [required]
Name of input elevation raster map
runs=string [required]
Run for a single rainfall event or a series of events
Options: event, series
Default: event
event: single rainfall event
series: series of rainfall events
mode=string [required]
SIMWE erosion deposition, USPED transport limited, or RUSLE 3D detachment limited mode
Options: simwe_mode, usped_mode, rusle_mode
Default: simwe_mode
simwe_mode: SIMWE erosion deposition mode
usped_mode: USPED transport limited mode
rusle_mode: RUSLE 3D detachment limited mode
rain_intensity=integer
Rainfall intensity in mm/hr
Default: 50
rain_duration=integer
Total duration of storm event in minutes
Default: 60
precipitation=name
Precipitation file
Name of input precipitation file
k_factor=name
K factor
Soil erodibility factor
k_factor_value=float
K factor constant
Soil erodibility constant
Default: 0.25
c_factor=name
C factor
Land cover factor
c_factor_value=float
C factor constant
Land cover constant
Default: 0.1
m=float
Water flow exponent
Water flow exponent
Default: 1.5
n=float
Slope exponent
Slope exponent
Default: 1.2
walkers=integer
Number of walkers (max = 7000000)
Default: 1000000
runoff=name
Runoff coefficient
Runoff coefficient (0.6 for bare earth, 0.35 for grass or crops, 0.5 for shrubs and trees, 0.25 for forest, 0.95 for roads)
runoff_value=float
Runoff coefficient
Runoff coefficient (0.6 for bare earth, 0.35 for grass or crops, 0.5 for shrubs and trees, 0.25 for forest, 0.95 for roads)
Default: 0.35
mannings=name
Manning's roughness coefficient
Manning's roughness coefficient
mannings_value=float
Manning's roughness coefficient
Manning's roughness coefficient
Default: 0.04
detachment=name
Detachment coefficient
Detachment coefficient
detachment_value=float
Detachment coefficient
Detachment coefficient
Default: 0.01
transport=name
Transport coefficient
Transport coefficient
transport_value=float
Transport coefficient
Transport coefficient
Default: 0.01
shearstress=name
Shear stress coefficient
Shear stress coefficient
shearstress_value=float
Shear stress coefficient
Shear stress coefficient
Default: 0.0
density=name
Sediment mass density
Sediment mass density in g/cm^3
density_value=float
Sediment mass density
Sediment mass density in g/cm^3
Default: 1.4
mass=name
Mass of sediment per unit area
Mass of sediment per unit area in kg/m^2
mass_value=float
Mass of sediment per unit area
Mass of sediment per unit area in kg/m^2
Default: 116.
grav_diffusion=float
Gravitational diffusion coefficient
Gravitational diffusion coefficient in m^2/s
Default: 0.1
erdepmin=float
Minimum values for erosion-deposition
Minimum values for erosion-deposition in kg/m^2s
Default: -0.5
erdepmax=float
Maximum values for erosion-deposition
Maximum values for erosion-deposition in kg/m^2s
Default: 0.5
start=string [required]
Start time in year-month-day hour:minute:second format
Default: 2016-01-01 00:00:00
rain_interval=integer [required]
Time interval between evolution events in minutes
Default: 1
temporaltype=name [required]
The temporal type of the space time dataset
Options: absolute, relative
Default: absolute
threads=integer
Number of threads for multiprocessing
Default: 1
elevation_timeseries=name [required]
Name of the output space time raster dataset
Default: elevation_timeseries
depth_timeseries=name
Name of the output space time raster dataset
Default: depth_timeseries
erdep_timeseries=name
Name of the output space time raster dataset
Default: erdep_timeseries
flux_timeseries=name
Name of the output space time raster dataset
Default: flux_timeseries
difference_timeseries=name
Name of the output space time raster dataset
Default: difference_timeseries

Table of contents

DESCRIPTION

r.sim.terrain is a short-term landscape evolution model that simulates topographic change for both steady state and dynamic flow regimes across a range of spatial scales. It uses empirical models (RUSLE3D & USPED) for soil erosion at watershed to regional scales and a physics-based model (SIMWE) for shallow overland water flow and soil erosion at subwatershed scales to compute short-term topographic change. This either steady state or dynamic model simulates how overland sediment mass flows reshape topography for a range of hydrologic soil erosion regimes based on topographic, land cover, soil, and rainfall parameters.

EXAMPLES

Basic instructions

A basic example for the North Carolina sample dataset. Install the add-on module r.sim.terrain. Copy the raster elevation map elev_lid792_1m from the PERMANENT mapset to the current mapset. Set the region to this elevation map at 1 meter resolution. Run r.sim.terrain with the RUSLE model for a 120 min event with a rainfall intensity of 50 mm/hr at a 3 minute interval. Set the empirical coefficients m and n to 0.4 and 1.3 respectively. Use the `-f` flag to fill depressions in order to reduce the effect of positive feedback loops.
g.extension  extension=r.sim.terrain
g.copy raster=elev_lid792_1m@PERMANENT,elevation
g.region raster=elev_lid792_1m res=1
r.sim.terrain -f elevation=elevation runs=event mode=rusle_mode rain_intensity=50.0 rain_duration=120 rain_interval=3 m=0.4 n=1.3
r.sim.terrain basic example
Figure: Net difference (m) for a dynamic RUSLE simulation of a 120 min event with a rainfall intensity of 50 mm/hr with a 3 minute interval.

Spatially variable soil and landcover

Clone or download the landscape evolution sample dataset with a time series of lidar-based digital elevation models and orthoimagery for a highly eroded subwatershed of Patterson Branch Creek, Fort Bragg, NC, USA.

Run r.sim.terrain with the simwe model for a 120 min event with a rainfall intensity of 50 mm/hr. Use a transport value lower than the detachment value to trigger a transport limited erosion regime. Use the -f flag to fill depressions in order to reduce the effect of positive feedback loops.

g.mapset -c mapset=transport location=nc_spm_evolution
g.region region=region res=1
r.mask vector=watershed
g.copy raster=elevation_2016@PERMANENT,elevation_2016
r.sim.terrain -f elevation=elevation_2016 runs=event mode=simwe_mode \
rain_intensity=50.0 rain_interval=120 rain_duration=10 walkers=1000000 \
detachment_value=0.01 transport_value=0.0001 manning=mannings runoff=runoff
r.sim.terrain advanced example
Figure: Net difference (m) for a steady state, transport limited SIMWE simulation of a 120 min event with a rainfall intensity of 50 mm/hr.
For more detailed instructions and examples see this in-depth tutorial.

ERROR MESSAGES

If the module fails with
ERROR: nwalk (7000001) > maxw (7000000)!
then a lower nwalkers parameter value has to be selected.

REFERENCES

SEE ALSO

r.sim.water, r.sim.sediment

AUTHORS

Brendan A. Harmon
Louisiana State University
brendan.harmon@gmail.com

Last changed: $Date$

SOURCE CODE

Available at: r.sim.terrain source code (history)


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