NAME¶
r.sim.sediment - Sediment transport and erosion/deposition
simulation using path sampling method (SIMWE).
KEYWORDS¶
raster, sediment flow, erosion, deposition
SYNOPSIS¶
r.sim.sediment
r.sim.sediment help
r.sim.sediment elevin=
name wdepth=
name
dxin=
name dyin=
name detin=
name
tranin=
name tauin=
name [
manin=
name]
[
maninval=
float] [
tc=
name]
[
et=
name] [
conc=
name] [
flux=
name]
[
erdep=
name] [
nwalk=
integer]
[
niter=
integer] [
outiter=
integer]
[
diffc=
float] [--
overwrite] [--
verbose]
[--
quiet]
Flags:¶
- --overwrite
-
Allow output files to overwrite existing files
- --verbose
-
Verbose module output
- --quiet
-
Quiet module output
Parameters:¶
- elevin=name
-
Name of the elevation raster map [m]
- wdepth=name
-
Name of the water depth raster map [m]
- dxin=name
-
Name of the x-derivatives raster map [m/m]
- dyin=name
-
Name of the y-derivatives raster map [m/m]
- detin=name
-
Name of the detachment capacity coefficient raster map [s/m]
- tranin=name
-
Name of the transport capacity coefficient raster map [s]
- tauin=name
-
Name of the critical shear stress raster map [Pa]
- manin=name
-
Name of the Mannings n raster map
- maninval=float
-
Name of the Mannings n value
Default: 0.1
- tc=name
-
Output transport capacity raster map [kg/ms]
- et=name
-
Output transp.limited erosion-deposition raster map [kg/m2s]
- conc=name
-
Output sediment concentration raster map [particle/m3]
- flux=name
-
Output sediment flux raster map [kg/ms]
- erdep=name
-
Output erosion-deposition raster map [kg/m2s]
- nwalk=integer
-
Number of walkers
- niter=integer
-
Time used for iterations [minutes]
Default: 10
- outiter=integer
-
Time interval for creating output maps [minutes]
Default: 2
- diffc=float
-
Water diffusion constant
Default: 0.8
DESCRIPTION¶
r.sim.sediment is a landscape scale, simulation model of soil erosion,
sediment transport and deposition caused by flowing water designed for
spatially variable terrain, soil, cover and rainfall excess conditions. The
soil erosion model is based on the theory used in the USDA WEPP hillslope
erosion model, but it has been generalized to 2D flow. The solution is based
on the concept of duality between fields and particles and the underlying
equations are solved by Green's function Monte Carlo method, to provide
robustness necessary for spatially variable conditions and high resolutions
(Mitas and Mitasova 1998). Key inputs of the model include the following
raster maps: elevation (
elevin [m]), flow gradient given by the
first-order partial derivatives of elevation field (
dxin and
dyin), overland flow water depth (
wdepth [m]), detachment
capacity coefficient (
detin [s/m]), transport capacity coefficient
(
tranin [s]), critical shear stress (
tauin [Pa]) and surface
roughness coefficient called Manning's n (
manin raster map). Partial
derivatives can be computed by v.surf.rst or r.slope.aspect module. The data
are automatically converted from feet to metric system using
database/projection information, so the elevation always should be in meters.
The water depth file can be computed using r.sim.water module. Other
parameters must be determined using field measurements or reference literature
(see suggested values in Notes and References).
Output includes transport capacity raster map
tc in [kg/ms], transport
capacity limited erosion/deposition raster map
et [kg/m2s]i that are
output almost immediately and can be viewed while the simulation continues.
Sediment flow rate raster map
flux [kg/ms], and net erosion/deposition
raster map [kg/m2s] can take longer time depending on time step and simulation
time. Simulation time is controled by
niter [minutes] parameter. If
the resulting erosion/deposition map is noisy, higher number of walkers, given
by
nwalk should be used.
NOTES¶
SEE ALSO¶
v.surf.rst, r.slope.aspect, r.sim.water
AUTHORS¶
Helena Mitasova, Lubos Mitas
North Carolina State University
hmitaso@unity.ncsu.edu
Jaroslav Hofierka
GeoModel, s.r.o. Bratislava, Slovakia
hofierka@geomodel.sk
Chris Thaxton
North Carolina State University
csthaxto@unity.ncsu.edu
csthaxto@unity.ncsu.edu
REFERENCES¶
Mitasova, H., Thaxton, C., Hofierka, J., McLaughlin, R., Moore, A., Mitas L.,
2004, Path sampling method for modeling overland water flow, sediment
transport and short term terrain evolution in Open Source GIS. In: C.T.
Miller, M.W. Farthing, V.G. Gray, G.F. Pinder eds., Proceedings of the XVth
International Conference on Computational Methods in Water Resources (CMWR
XV), June 13-17 2004, Chapel Hill, NC, USA, Elsevier, pp. 1479-1490.
Mitasova H, Mitas, L., 2000, Modeling spatial processes in multiscale framework:
exploring duality between particles and fields, plenary talk at GIScience2000
conference, Savannah, GA.
Mitas, L., and Mitasova, H., 1998, Distributed soil erosion simulation for
effective erosion prevention. Water Resources Research, 34(3), 505-516.
Mitasova, H., Mitas, L., 2001, Multiscale soil erosion simulations for land use
management, In: Landscape erosion and landscape evolution modeling, Harmon R.
and Doe W. eds., Kluwer Academic/Plenum Publishers, pp. 321-347.
Neteler, M. and Mitasova, H., 2008, Open Source GIS: A GRASS GIS Approach. Third
Edition. The International Series in Engineering and Computer Science: Volume
773. Springer New York Inc, p. 406.
Last changed: $Date: 2008-02-23 06:58:58 +0100 (Sat, 23 Feb 2008) $
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