1r.sim.sediment(1)           GRASS GIS User's Manual          r.sim.sediment(1)
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NAME

6       r.sim.sediment   - Sediment transport and erosion/deposition simulation
7       using path sampling method (SIMWE).
8

KEYWORDS

10       raster, hydrology, soil, sediment flow, erosion, deposition, model
11

SYNOPSIS

13       r.sim.sediment
14       r.sim.sediment --help
15       r.sim.sediment [-s]  elevation=name  water_depth=name  dx=name  dy=name
16       detachment_coeff=name       transport_coeff=name      shear_stress=name
17       [man=name]   [man_value=float]   [observation=name]   [transport_capac‐
18       ity=name]     [tlimit_erosion_deposition=name]     [sediment_concentra‐
19       tion=name]   [sediment_flux=name]    [erosion_deposition=name]    [log‐
20       file=name]     [walkers_output=name]     [nwalkers=integer]    [nitera‐
21       tions=integer]      [output_step=integer]       [diffusion_coeff=float]
22       [random_seed=integer]     [nprocs=integer]     [--overwrite]   [--help]
23       [--verbose]  [--quiet]  [--ui]
24
25   Flags:
26       -s
27           Generate random seed
28           Automatically generates random seed  for  random  number  generator
29           (use when you don’t want to provide the seed option)
30
31       --overwrite
32           Allow output files to overwrite existing files
33
34       --help
35           Print usage summary
36
37       --verbose
38           Verbose module output
39
40       --quiet
41           Quiet module output
42
43       --ui
44           Force launching GUI dialog
45
46   Parameters:
47       elevation=name [required]
48           Name of input elevation raster map
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50       water_depth=name [required]
51           Name of water depth raster map [m]
52
53       dx=name [required]
54           Name of x-derivatives raster map [m/m]
55
56       dy=name [required]
57           Name of y-derivatives raster map [m/m]
58
59       detachment_coeff=name [required]
60           Name of detachment capacity coefficient raster map [s/m]
61
62       transport_coeff=name [required]
63           Name of transport capacity coefficient raster map [s]
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65       shear_stress=name [required]
66           Name of critical shear stress raster map [Pa]
67
68       man=name
69           Name of Manning’s n raster map
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71       man_value=float
72           Manning’s n unique value
73           Default: 0.1
74
75       observation=name
76           Name of sampling locations vector points map
77           Or data source for direct OGR access
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79       transport_capacity=name
80           Name for output transport capacity raster map [kg/ms]
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82       tlimit_erosion_deposition=name
83           Name  for  output  transport  limited erosion-deposition raster map
84           [kg/m2s]
85
86       sediment_concentration=name
87           Name for output sediment concentration raster map [particle/m3]
88
89       sediment_flux=name
90           Name for output sediment flux raster map [kg/ms]
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92       erosion_deposition=name
93           Name for output erosion-deposition raster map [kg/m2s]
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95       logfile=name
96           Name for sampling points output text  file.  For  each  observation
97           vector point the time series of sediment transport is stored.
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99       walkers_output=name
100           Base name of the output walkers vector points map
101
102       nwalkers=integer
103           Number of walkers
104
105       niterations=integer
106           Time used for iterations [minutes]
107           Default: 10
108
109       output_step=integer
110           Time interval for creating output maps [minutes]
111           Default: 2
112
113       diffusion_coeff=float
114           Water diffusion constant
115           Default: 0.8
116
117       random_seed=integer
118           Seed for random number generator
119           The same seed can be used to obtain same results or random seed can
120           be generated by other means.
121
122       nprocs=integer
123           Number of threads which will be used for parallel compute
124           Default: 1
125

DESCRIPTION

127       r.sim.sediment is a landscape scale, simulation model of soil  erosion,
128       sediment  transport and deposition caused by flowing water designed for
129       spatially variable terrain, soil, cover and rainfall excess conditions.
130       The  soil  erosion  model  is based on the theory used in the USDA WEPP
131       hillslope erosion model, but it has been generalized to  2D  flow.  The
132       solution  is  based on the concept of duality between fields and parti‐
133       cles and the underlying equations are solved by Green’s function  Monte
134       Carlo  method,  to  provide robustness necessary for spatially variable
135       conditions and high resolutions (Mitas and Mitasova 1998).  Key  inputs
136       of  the  model  include the following raster maps: elevation (elevation
137       [m]), flow gradient given by the  first-order  partial  derivatives  of
138       elevation  field  (  dx and dy), overland flow water depth (water_depth
139       [m]), detachment capacity coefficient (detachment_coeff [s/m]),  trans‐
140       port  capacity coefficient (transport_coeff [s]), critical shear stress
141       (shear_stress [Pa]) and surface  roughness coefficient called Manning’s
142       n  (man raster map).  Partial derivatives can be computed by v.surf.rst
143       or r.slope.aspect module. The data  are  automatically  converted  from
144       feet  to  metric  system  using database/projection information, so the
145       elevation always should be in meters.  The water depth file can be com‐
146       puted  using  r.sim.water  module.  Other parameters must be determined
147       using field measurements or reference literature (see suggested  values
148       in Notes and References).
149
150       Output  includes  transport  capacity raster map transport_capacity  in
151       [kg/ms],  transport  capacity  limited  erosion/deposition  raster  map
152       tlimit_erosion_deposition  [kg/m2s]i that are output almost immediately
153       and can be viewed while the simulation continues.  Sediment  flow  rate
154       raster map sediment_flux [kg/ms], and net erosion/deposition raster map
155       [kg/m2s] can take longer time depending on  time  step  and  simulation
156       time.   Simulation  time is controlled by niterations [minutes] parame‐
157       ter.  If the resulting erosion/deposition map is noisy,  higher  number
158       of walkers, given by nwalkers should be used.
159

SEE ALSO

161       v.surf.rst, r.slope.aspect, r.sim.water
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AUTHORS

164       Helena Mitasova, Lubos Mitas
165       North Carolina State University
166       hmitaso@unity.ncsu.edu
167       Jaroslav Hofierka
168       GeoModel, s.r.o. Bratislava, Slovakia
169       hofierka@geomodel.sk
170       Chris Thaxton
171       North Carolina State University
172       csthaxto@unity.ncsu.edu
173       csthaxto@unity.ncsu.edu
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REFERENCES

176       Mitasova,  H.,  Thaxton,  C.,  Hofierka, J., McLaughlin, R., Moore, A.,
177       Mitas L., 2004, Path sampling method for modeling overland water  flow,
178       sediment transport and short term terrain evolution in Open Source GIS.
179       In: C.T. Miller, M.W. Farthing, V.G. Gray, G.F. Pinder  eds.,  Proceed‐
180       ings  of  the XVth International Conference on Computational Methods in
181       Water Resources (CMWR XV), June 13-17 2004, Chapel Hill, NC, USA, Else‐
182       vier, pp. 1479-1490.
183
184       Mitasova  H,  Mitas, L., 2000, Modeling spatial processes in multiscale
185       framework: exploring duality between particles and fields, plenary talk
186       at GIScience2000 conference, Savannah, GA.
187
188       Mitas,  L., and Mitasova, H., 1998, Distributed soil erosion simulation
189       for effective erosion  prevention.  Water  Resources  Research,  34(3),
190       505-516.
191
192       Mitasova,  H., Mitas, L., 2001, Multiscale soil erosion simulations for
193       land use management, In: Landscape erosion and landscape evolution mod‐
194       eling,  Harmon  R.  and Doe W. eds., Kluwer Academic/Plenum Publishers,
195       pp. 321-347.
196
197       Neteler, M. and Mitasova, H.,  2008,  Open  Source  GIS:  A  GRASS  GIS
198       Approach.  Third  Edition.  The International Series in Engineering and
199       Computer Science: Volume 773. Springer New York Inc, p. 406.
200

SOURCE CODE

202       Available at: r.sim.sediment source code (history)
203
204       Main index | Raster index | Topics index | Keywords index  |  Graphical
205       index | Full index
206
207       © 2003-2020 GRASS Development Team, GRASS GIS 7.8.5 Reference Manual
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211GRASS 7.8.5                                                  r.sim.sediment(1)
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