.TH r.sim.sediment 1grass "" "GRASS 7.8.5" "GRASS GIS User's Manual"
.SH NAME
\fI\fBr.sim.sediment\fR\fR  \- Sediment transport and erosion/deposition simulation using path sampling method (SIMWE).
.SH KEYWORDS
raster, hydrology, soil, sediment flow, erosion, deposition, model
.SH SYNOPSIS
\fBr.sim.sediment\fR
.br
\fBr.sim.sediment \-\-help\fR
.br
\fBr.sim.sediment\fR [\-\fBs\fR] \fBelevation\fR=\fIname\fR \fBwater_depth\fR=\fIname\fR \fBdx\fR=\fIname\fR \fBdy\fR=\fIname\fR \fBdetachment_coeff\fR=\fIname\fR \fBtransport_coeff\fR=\fIname\fR \fBshear_stress\fR=\fIname\fR  [\fBman\fR=\fIname\fR]   [\fBman_value\fR=\fIfloat\fR]   [\fBobservation\fR=\fIname\fR]   [\fBtransport_capacity\fR=\fIname\fR]   [\fBtlimit_erosion_deposition\fR=\fIname\fR]   [\fBsediment_concentration\fR=\fIname\fR]   [\fBsediment_flux\fR=\fIname\fR]   [\fBerosion_deposition\fR=\fIname\fR]   [\fBlogfile\fR=\fIname\fR]   [\fBwalkers_output\fR=\fIname\fR]   [\fBnwalkers\fR=\fIinteger\fR]   [\fBniterations\fR=\fIinteger\fR]   [\fBoutput_step\fR=\fIinteger\fR]   [\fBdiffusion_coeff\fR=\fIfloat\fR]   [\fBrandom_seed\fR=\fIinteger\fR]   [\fBnprocs\fR=\fIinteger\fR]   [\-\-\fBoverwrite\fR]  [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-s\fR" 4m
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Generate random seed
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Automatically generates random seed for random number generator (use when you don\(cqt want to provide the seed option)
.IP "\fB\-\-overwrite\fR" 4m
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Allow output files to overwrite existing files
.IP "\fB\-\-help\fR" 4m
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Print usage summary
.IP "\fB\-\-verbose\fR" 4m
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Verbose module output
.IP "\fB\-\-quiet\fR" 4m
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Quiet module output
.IP "\fB\-\-ui\fR" 4m
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Force launching GUI dialog
.SS Parameters:
.IP "\fBelevation\fR=\fIname\fR \fB[required]\fR" 4m
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Name of input elevation raster map
.IP "\fBwater_depth\fR=\fIname\fR \fB[required]\fR" 4m
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Name of water depth raster map [m]
.IP "\fBdx\fR=\fIname\fR \fB[required]\fR" 4m
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Name of x\-derivatives raster map [m/m]
.IP "\fBdy\fR=\fIname\fR \fB[required]\fR" 4m
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Name of y\-derivatives raster map [m/m]
.IP "\fBdetachment_coeff\fR=\fIname\fR \fB[required]\fR" 4m
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Name of detachment capacity coefficient raster map [s/m]
.IP "\fBtransport_coeff\fR=\fIname\fR \fB[required]\fR" 4m
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Name of transport capacity coefficient raster map [s]
.IP "\fBshear_stress\fR=\fIname\fR \fB[required]\fR" 4m
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Name of critical shear stress raster map [Pa]
.IP "\fBman\fR=\fIname\fR" 4m
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Name of Manning\(cqs n raster map
.IP "\fBman_value\fR=\fIfloat\fR" 4m
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Manning\(cqs n unique value
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Default: \fI0.1\fR
.IP "\fBobservation\fR=\fIname\fR" 4m
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Name of sampling locations vector points map
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Or data source for direct OGR access
.IP "\fBtransport_capacity\fR=\fIname\fR" 4m
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Name for output transport capacity raster map [kg/ms]
.IP "\fBtlimit_erosion_deposition\fR=\fIname\fR" 4m
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Name for output transport limited erosion\-deposition raster map [kg/m2s]
.IP "\fBsediment_concentration\fR=\fIname\fR" 4m
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Name for output sediment concentration raster map [particle/m3]
.IP "\fBsediment_flux\fR=\fIname\fR" 4m
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Name for output sediment flux raster map [kg/ms]
.IP "\fBerosion_deposition\fR=\fIname\fR" 4m
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Name for output erosion\-deposition raster map [kg/m2s]
.IP "\fBlogfile\fR=\fIname\fR" 4m
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Name for sampling points output text file. For each observation vector point the time series of sediment transport is stored.
.IP "\fBwalkers_output\fR=\fIname\fR" 4m
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Base name of the output walkers vector points map
.IP "\fBnwalkers\fR=\fIinteger\fR" 4m
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Number of walkers
.IP "\fBniterations\fR=\fIinteger\fR" 4m
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Time used for iterations [minutes]
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Default: \fI10\fR
.IP "\fBoutput_step\fR=\fIinteger\fR" 4m
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Time interval for creating output maps [minutes]
.br
Default: \fI2\fR
.IP "\fBdiffusion_coeff\fR=\fIfloat\fR" 4m
.br
Water diffusion constant
.br
Default: \fI0.8\fR
.IP "\fBrandom_seed\fR=\fIinteger\fR" 4m
.br
Seed for random number generator
.br
The same seed can be used to obtain same results or random seed can be generated by other means.
.IP "\fBnprocs\fR=\fIinteger\fR" 4m
.br
Number of threads which will be used for parallel compute
.br
Default: \fI1\fR
.SH DESCRIPTION
\fIr.sim.sediment\fR 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\(cqs
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 (\fIelevation\fR [m]), flow gradient given by the first\-order partial
derivatives of elevation field (\fI dx\fR and \fIdy\fR),
overland flow water depth (\fIwater_depth\fR [m]), detachment capacity coefficient
(\fIdetachment_coeff\fR [s/m]), transport capacity coefficient (\fItransport_coeff\fR [s]),
critical shear stress (\fIshear_stress\fR [Pa])
and surface  roughness coefficient called Manning\(cqs n (\fIman\fR 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).
.br
.PP
Output includes transport capacity raster map \fItransport_capacity\fR  in [kg/ms],
transport capacity limited erosion/deposition raster map
\fItlimit_erosion_deposition\fR [kg/m\u2\ds]i that are output almost immediately and
can be viewed while the simulation continues. Sediment flow rate raster map
\fIsediment_flux\fR [kg/ms], and net erosion/deposition raster map [kg/m\u2\ds]
can take longer time depending on time step and simulation time.
Simulation time is controlled by \fIniterations\fR [minutes] parameter.
If the resulting erosion/deposition map is noisy, higher number of walkers,
given by \fInwalkers\fR should be used.
.br
.SH SEE ALSO
v.surf.rst,
r.slope.aspect,
r.sim.water
.SH AUTHORS
Helena Mitasova, Lubos Mitas
.br
North Carolina State University
.br
hmitaso@unity.ncsu.edu
.br
.br
Jaroslav Hofierka
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GeoModel, s.r.o. Bratislava, Slovakia
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hofierka@geomodel.sk
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Chris Thaxton
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North Carolina State University
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csthaxto@unity.ncsu.edu
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csthaxto@unity.ncsu.edu
.SH REFERENCES
.PP
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.
.PP
Mitasova H, Mitas, L., 2000, Modeling spatial processes in multiscale framework:
exploring duality between particles and fields,
plenary talk at GIScience2000 conference, Savannah, GA.
.PP
Mitas, L., and Mitasova, H., 1998, Distributed soil erosion simulation
for effective erosion prevention. Water Resources Research, 34(3), 505\-516.
.PP
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.
.PP
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.
.PP
.SH SOURCE CODE
.PP
Available at: r.sim.sediment source code (history)
.PP
Main index |
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Topics index |
Keywords index |
Graphical index |
Full index
.PP
© 2003\-2020
GRASS Development Team,
GRASS GIS 7.8.5 Reference Manual