1r.sim.sediment(1)           GRASS GIS User's Manual          r.sim.sediment(1)
2
3
4

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       parallel
12

SYNOPSIS

14       r.sim.sediment
15       r.sim.sediment --help
16       r.sim.sediment [-s] elevation=name water_depth=name dx=name dy=name de‐
17       tachment_coeff=name transport_coeff=name shear_stress=name   [man=name]
18       [man_value=float]      [observation=name]     [transport_capacity=name]
19       [tlimit_erosion_deposition=name]          [sediment_concentration=name]
20       [sediment_flux=name]      [erosion_deposition=name]      [logfile=name]
21       [walkers_output=name]     [nwalkers=integer]      [niterations=integer]
22       [output_step=integer]   [diffusion_coeff=float]   [random_seed=integer]
23       [nprocs=integer]    [--overwrite]   [--help]   [--verbose]    [--quiet]
24       [--ui]
25
26   Flags:
27       -s
28           Generate random seed
29           Automatically  generates  random  seed  for random number generator
30           (use when you don’t want to provide the seed option)
31
32       --overwrite
33           Allow output files to overwrite existing files
34
35       --help
36           Print usage summary
37
38       --verbose
39           Verbose module output
40
41       --quiet
42           Quiet module output
43
44       --ui
45           Force launching GUI dialog
46
47   Parameters:
48       elevation=name [required]
49           Name of input elevation raster map
50
51       water_depth=name [required]
52           Name of water depth raster map [m]
53
54       dx=name [required]
55           Name of x-derivatives raster map [m/m]
56
57       dy=name [required]
58           Name of y-derivatives raster map [m/m]
59
60       detachment_coeff=name [required]
61           Name of detachment capacity coefficient raster map [s/m]
62
63       transport_coeff=name [required]
64           Name of transport capacity coefficient raster map [s]
65
66       shear_stress=name [required]
67           Name of critical shear stress raster map [Pa]
68
69       man=name
70           Name of Manning’s n raster map
71
72       man_value=float
73           Manning’s n unique value
74           Default: 0.1
75
76       observation=name
77           Name of sampling locations vector points map
78           Or data source for direct OGR access
79
80       transport_capacity=name
81           Name for output transport capacity raster map [kg/ms]
82
83       tlimit_erosion_deposition=name
84           Name for output transport  limited  erosion-deposition  raster  map
85           [kg/m2s]
86
87       sediment_concentration=name
88           Name for output sediment concentration raster map [particle/m3]
89
90       sediment_flux=name
91           Name for output sediment flux raster map [kg/ms]
92
93       erosion_deposition=name
94           Name for output erosion-deposition raster map [kg/m2s]
95
96       logfile=name
97           Name  for  sampling  points  output text file. For each observation
98           vector point the time series of sediment transport is stored.
99
100       walkers_output=name
101           Base name of the output walkers vector points map
102
103       nwalkers=integer
104           Number of walkers
105
106       niterations=integer
107           Time used for iterations [minutes]
108           Default: 10
109
110       output_step=integer
111           Time interval for creating output maps [minutes]
112           Default: 2
113
114       diffusion_coeff=float
115           Water diffusion constant
116           Default: 0.8
117
118       random_seed=integer
119           Seed for random number generator
120           The same seed can be used to obtain same results or random seed can
121           be generated by other means.
122
123       nprocs=integer
124           Number of threads which will be used for parallel compute
125           Default: 1
126

DESCRIPTION

128       r.sim.sediment  is a landscape scale, simulation model of soil erosion,
129       sediment transport and deposition caused by flowing water designed  for
130       spatially variable terrain, soil, cover and rainfall excess conditions.
131       The soil erosion model is based on the theory used  in  the  USDA  WEPP
132       hillslope  erosion  model,  but it has been generalized to 2D flow. The
133       solution is based on the concept of duality between fields  and  parti‐
134       cles  and the underlying equations are solved by Green’s function Monte
135       Carlo method, to provide robustness necessary  for  spatially  variable
136       conditions  and high resolutions (Mitas and Mitasova 1998).  Key inputs
137       of the model include the following raster  maps:  elevation  (elevation
138       [m]), flow gradient given by the first-order partial derivatives of el‐
139       evation field ( dx and dy),  overland  flow  water  depth  (water_depth
140       [m]),  detachment capacity coefficient (detachment_coeff [s/m]), trans‐
141       port capacity coefficient (transport_coeff [s]), critical shear  stress
142       (shear_stress [Pa]) and surface  roughness coefficient called Manning’s
143       n (man raster map).  Partial derivatives can be computed by  v.surf.rst
144       or  r.slope.aspect  module.  The  data are automatically converted from
145       feet to metric system using database/projection information, so the el‐
146       evation  always  should be in meters.  The water depth file can be com‐
147       puted using r.sim.water module. Other parameters must be determined us‐
148       ing field measurements or reference literature (see suggested values in
149       Notes and References).
150
151       Output includes transport capacity raster  map  transport_capacity   in
152       [kg/ms],  transport  capacity  limited  erosion/deposition  raster  map
153       tlimit_erosion_deposition [kg/m2s]i that are output almost  immediately
154       and  can  be  viewed while the simulation continues. Sediment flow rate
155       raster map sediment_flux [kg/ms], and net erosion/deposition raster map
156       [kg/m2s]  can  take  longer  time depending on time step and simulation
157       time.  Simulation time is controlled by niterations  [minutes]  parame‐
158       ter.   If  the resulting erosion/deposition map is noisy, higher number
159       of walkers, given by nwalkers should be used.
160

REFERENCES

162       Mitasova, H., Thaxton, C., Hofierka, J., McLaughlin, R., Moore, A., Mi‐
163       tas  L.,  2004,  Path sampling method for modeling overland water flow,
164       sediment transport and short term terrain evolution in Open Source GIS.
165       In:  C.T.  Miller, M.W. Farthing, V.G. Gray, G.F. Pinder eds., Proceed‐
166       ings of the XVth International Conference on Computational  Methods  in
167       Water Resources (CMWR XV), June 13-17 2004, Chapel Hill, NC, USA, Else‐
168       vier, pp. 1479-1490.
169
170       Mitasova H, Mitas, L., 2000, Modeling spatial processes  in  multiscale
171       framework: exploring duality between particles and fields, plenary talk
172       at GIScience2000 conference, Savannah, GA.
173
174       Mitas, L., and Mitasova, H., 1998, Distributed soil erosion  simulation
175       for  effective  erosion  prevention.  Water  Resources Research, 34(3),
176       505-516.
177
178       Mitasova, H., Mitas, L., 2001, Multiscale soil erosion simulations  for
179       land use management, In: Landscape erosion and landscape evolution mod‐
180       eling, Harmon R. and Doe W. eds.,  Kluwer  Academic/Plenum  Publishers,
181       pp. 321-347.
182
183       Neteler,  M.  and  Mitasova, H., 2008, Open Source GIS: A GRASS GIS Ap‐
184       proach. Third Edition.  The International  Series  in  Engineering  and
185       Computer Science: Volume 773. Springer New York Inc, p. 406.
186

SEE ALSO

188       v.surf.rst, r.slope.aspect, r.sim.water
189

AUTHORS

191       Helena Mitasova, Lubos Mitas
192       North Carolina State University
193       hmitaso@unity.ncsu.edu
194       Jaroslav Hofierka
195       GeoModel, s.r.o. Bratislava, Slovakia
196       hofierka@geomodel.sk
197       Chris Thaxton
198       North Carolina State University
199       csthaxto@unity.ncsu.edu
200       csthaxto@unity.ncsu.edu
201

SOURCE CODE

203       Available at: r.sim.sediment source code (history)
204
205       Accessed: Saturday Jan 21 20:39:03 2023
206
207       Main  index  | Raster index | Topics index | Keywords index | Graphical
208       index | Full index
209
210       © 2003-2023 GRASS Development Team, GRASS GIS 8.2.1 Reference Manual
211
212
213
214GRASS 8.2.1                                                  r.sim.sediment(1)
Impressum