Provided by: grass-doc_6.4.3-3_all 
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: 2008-02-22 21:58:58 -0800 (Fri, 22 Feb 2008) $
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GRASS 6.4.3 r.sim.sediment(1grass)