1r.sim.sediment(1) GRASS GIS User's Manual r.sim.sediment(1)
2
6 r.sim.sediment - Sediment transport and erosion/deposition simulation
7 using path sampling method (SIMWE).
8
10 raster, hydrology, soil, sediment flow, erosion, deposition, model,
11 parallel
12
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 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 --overwrite
33 Allow output files to overwrite existing files
34 --help
36 Print usage summary
37 --verbose
39 Verbose module output
40 --quiet
42 Quiet module output
43 --ui
45 Force launching GUI dialog
46 Parameters:
48 elevation=name [required]
49 Name of input elevation raster map
50 water_depth=name [required]
52 Name of water depth raster map [m]
53 dx=name [required]
55 Name of x-derivatives raster map [m/m]
56 dy=name [required]
58 Name of y-derivatives raster map [m/m]
59 detachment_coeff=name [required]
61 Name of detachment capacity coefficient raster map [s/m]
62 transport_coeff=name [required]
64 Name of transport capacity coefficient raster map [s]
65 shear_stress=name [required]
67 Name of critical shear stress raster map [Pa]
68 man=name
70 Name of Manning’s n raster map
71 man_value=float
73 Manning’s n unique value
74 Default: 0.1
75 observation=name
77 Name of sampling locations vector points map
78 Or data source for direct OGR access
79 transport_capacity=name
81 Name for output transport capacity raster map [kg/ms]
82 tlimit_erosion_deposition=name
84 Name for output transport limited erosion-deposition raster map
85 [kg/m2s]
86 sediment_concentration=name
88 Name for output sediment concentration raster map [particle/m3]
89 sediment_flux=name
91 Name for output sediment flux raster map [kg/ms]
92 erosion_deposition=name
94 Name for output erosion-deposition raster map [kg/m2s]
95 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 walkers_output=name
101 Base name of the output walkers vector points map
102 nwalkers=integer
104 Number of walkers
105 niterations=integer
107 Time used for iterations [minutes]
108 Default: 10
109 output_step=integer
111 Time interval for creating output maps [minutes]
112 Default: 2
113 diffusion_coeff=float
115 Water diffusion constant
116 Default: 0.8
117 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 nprocs=integer
124 Number of threads which will be used for parallel compute
125 Default: 1
126
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 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
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 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 Mitas, L., and Mitasova, H., 1998, Distributed soil erosion simulation
175 for effective erosion prevention. Water Resources Research, 34(3),
176 505-516.
177 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 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
188 v.surf.rst, r.slope.aspect, r.sim.water
189
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
203 Available at: r.sim.sediment source code (history)
204 Accessed: Saturday Jan 21 21:15:12 2023
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209 © 2003-2023 GRASS Development Team, GRASS GIS 8.2.1 Reference Manual
211GRASS 8.2.1 r.sim.sediment(1)