1r.sim.sediment(1) Grass 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, sediment flow, erosion, deposition
11
13 r.sim.sediment
14 r.sim.sediment help
15 r.sim.sediment elevin=name wdepth=name dxin=name dyin=name detin=name
16 tranin=name tauin=name [manin=name] [maninval=float] [vector=name]
17 [tc=name] [et=name] [conc=name] [flux=name] [erdep=name]
18 [nwalk=integer] [niter=integer] [outiter=integer] [density=inte‐
19 ger] [diffc=float] [--overwrite] [--verbose] [--quiet]
20 Flags:
22 --overwrite
23 Allow output files to overwrite existing files
24 --verbose
26 Verbose module output
27 --quiet
29 Quiet module output
30 Parameters:
32 elevin=name
33 Name of the elevation raster map [m]
34 wdepth=name
36 Name of the water depth raster map [m]
37 dxin=name
39 Name of the x-derivatives raster map [m/m]
40 dyin=name
42 Name of the y-derivatives raster map [m/m]
43 detin=name
45 Name of the detachment capacity coefficient raster map [s/m]
46 tranin=name
48 Name of the transport capacity coefficient raster map [s]
49 tauin=name
51 Name of the critical shear stress raster map [Pa]
52 manin=name
54 Name of the Mannings n raster map
55 maninval=float
57 Name of the Mannings n value
58 Default: 0.1
59 vector=name
61 Name of the sampling locations vector points map
62 tc=name
64 Output transport capacity raster map [kg/ms]
65 et=name
67 Output transp.limited erosion-deposition raster map [kg/m2s]
68 conc=name
70 Output sediment concentration raster map [particle/m3]
71 flux=name
73 Output sediment flux raster map [kg/ms]
74 erdep=name
76 Output erosion-deposition raster map [kg/m2s]
77 nwalk=integer
79 Number of walkers
80 niter=integer
82 Time used for iterations [minutes]
83 Default: 10
84 outiter=integer
86 Time interval for creating output maps [minutes]
87 Default: 2
88 density=integer
90 Density of output walkers
91 Default: 200
92 diffc=float
94 Water diffusion constant
95 Default: 0.8
96
98 r.sim.sediment is a landscape scale, simulation model of soil erosion,
99 sediment transport and deposition caused by flowing water designed for
100 spatially variable terrain, soil, cover and rainfall excess conditions.
101 The soil erosion model is based on the theory used in the USDA WEPP
102 hillslope erosion model, but it has been generalized to 2D flow. The
103 solution is based on the concept of duality between fields and parti‐
104 cles and the underlying equations are solved by Green's function Monte
105 Carlo method, to provide robustness necessary for spatially variable
106 conditions and high resolutions (Mitas and Mitasova 1998). Key inputs
107 of the model include the following raster maps: elevation ( elevin
108 [m]), flow gradient given by the first-order partial derivatives of
109 elevation field ( dxin and dyin), overland flow water depth ( wdepth
110 [m]), detachment capacity coefficient (detin [s/m]), transport capacity
111 coefficient (tranin [s]), critical shear stress (tauin [Pa]) and sur‐
112 face roughness coefficient called Manning's n (manin raster map).
113 Partial derivatives can be computed by v.surf.rst or r.slope.aspect
114 module. The data are automatically converted from feet to metric system
115 using database/projection information, so the elevation always should
116 be in meters. The water depth file can be computed using r.sim.water
117 module. Other parameters must be determined using field measurements or
118 reference literature (see suggested values in Notes and References).
119 Output includes transport capacity raster map tc in [kg/ms], transport
121 capacity limited erosion/deposition raster map et [kg/m2s]i that are
122 output almost immediately and can be viewed while the simulation con‐
123 tinues. Sediment flow rate raster map flux [kg/ms], and net ero‐
124 sion/deposition raster map [kg/m2s] can take longer time depending on
125 time step and simulation time. Simulation time is controled by niter
126 [minutes] parameter. If the resulting erosion/deposition map is noisy,
127 higher number of walkers, given by nwalk should be used.
128
131 v.surf.rst, r.slope.aspect, r.sim.water
132
134 Helena Mitasova, Lubos Mitas
135 North Carolina State University
136 hmitaso@unity.ncsu.edu
137 Jaroslav Hofierka
138 GeoModel, s.r.o. Bratislava, Slovakia
139 hofierka@geomodel.sk
140 Chris Thaxton
141 North Carolina State University
142 csthaxto@unity.ncsu.edu
143 csthaxto@unity.ncsu.edu
144
146 Mitasova, H., Thaxton, C., Hofierka, J., McLaughlin, R., Moore, A.,
147 Mitas L., 2004, Path sampling method for modeling overland water flow,
148 sediment transport and short term terrain evolution in Open Source GIS.
149 In: C.T. Miller, M.W. Farthing, V.G. Gray, G.F. Pinder eds., Proceed‐
150 ings of the XVth International Conference on Computational Methods in
151 Water Resources (CMWR XV), June 13-17 2004, Chapel Hill, NC, USA, Else‐
152 vier, pp. 1479-1490.
153 Mitasova H, Mitas, L., 2000, Modeling spatial processes in multiscale
155 framework: exploring duality between particles and fields, plenary talk
156 at GIScience2000 conference, Savannah, GA.
157 Mitas, L., and Mitasova, H., 1998, Distributed soil erosion simulation
159 for effective erosion prevention. Water Resources Research, 34(3),
160 505-516.
161 Mitasova, H., Mitas, L., 2001, Multiscale soil erosion simulations for
163 land use management, In: Landscape erosion and landscape evolution mod‐
164 eling, Harmon R. and Doe W. eds., Kluwer Academic/Plenum Publishers,
165 pp. 321-347.
166 Neteler, M. and Mitasova, H., 2008, Open Source GIS: A GRASS GIS
168 Approach. Third Edition. The International Series in Engineering and
169 Computer Science: Volume 773. Springer New York Inc, p. 406.
170 Last changed: $Date: 2008-02-28 13:35:40 +0100 (Thu, 28 Feb 2008) $
172 Full index
174 © 2003-2008 GRASS Development Team
176GRASS 6.3.0 r.sim.sediment(1)