1r.sim.sediment(1) Grass User's Manual r.sim.sediment(1)
2
6 r.sim.sediment - Overland flow hydrologic model based on duality par‐
7 ticle-field concept (SIMWE)
8
10 raster
11
13 r.sim.sediment
14 r.sim.sediment help
15 r.sim.sediment [-mt] elevin=string wdepth=string dxin=string
16 dyin=string detin=string tranin=string tauin=string manin=string
17 [sites=string] [tc=string] [et=string] [conc=string]
18 [flux=string] [erdep=string] [nwalk=integer] [niter=integer]
19 [outiter=integer] [density=integer] [diffc=float] [--overwrite]
20 Flags:
22 -m Multiscale simulation
23 -t Time-series (dynamic) output
25 --overwrite
27 Parameters:
29 elevin=string
30 Name of the elevation raster file
31 wdepth=string
33 Name of the water height raster file
34 dxin=string
36 Name of the x-derivatives raster file
37 dyin=string
39 Name of the y-derivatives raster file
40 detin=string
42 Name of the detachment capacity coefficient raster file
43 tranin=string
45 Name of the transport capacity coefficient raster file
46 tauin=string
48 Name of the critical shear stress raster file
49 manin=string
51 Name of the Mannings n raster file
52 sites=string
54 Name of the site file with x,y locations
55 tc=string
57 Output transport capacity raster file
58 et=string
60 Output transp.limited erosion-deposition raster file
61 conc=string
63 Output sediment concentration raster file
64 flux=string
66 Output sediment flux raster file
67 erdep=string
69 Output erosion-deposition raster file
70 nwalk=integer
72 Number of walkers Default: 2000000
73 niter=integer
75 Number of time iterations (sec.) Default: 1200
76 outiter=integer
78 Time step for saving output maps (sec.) Default: 300
79 density=integer
81 Density of output walkers Default: 200
82 diffc=float
84 Water diffusion constant Default: 0.8
85
87 r.sim.sediment is a landscape scale, simulation model of soil erosion,
88 sediment transport and deposition caused by flowing water designed for
89 spatially variable terrain, soil, cover and rainfall excess conditions.
90 The soil erosion model is based on the theory used in the USDA WEPP
91 hillslope erosion model, but it has been generalized to 2D flow. The
92 solution is based on the concept of duality between fields and parti‐
93 cles and the underlying equations are solved by Green's function Monte
94 Carlo method, to provide robustness necessary for spatially variable
95 conditions and high resolutions (Mitas and Mitasova 1998). Key inputs
96 of the model include the following raster files: elevation ( elevin),
97 flow gradient given by the first-order partial derivatives of elevation
98 field ( dxin and dyin), overland flow water depth ( wdepth), detachment
99 capacity coefficient (detin), transport capacity coefficient (tranin),
100 critical shear stress (tauin) and surface roughness coefficient called
101 Manning's n (manin raster file). Partial derivatives can be computed
102 by v.surf.rst or r.slope.aspect module. The data are automatically con‐
103 verted data from feet to metric system using database/projection infor‐
104 mation. The water depth file can be computed using r.sim.water module.
105 Other parameters must be determined using field measurements or refer‐
106 ence literature (see suggested values in Notes and References).
107 Output includes transport capacity raster file tc in [kg/ms], trans‐
109 port capacity limited erosion/deposition raster file et [kg/m2s], sedi‐
110 ment flow rate raster file flux [kg/ms], and net erosion/deposition
111 raster file [kg/m2s]. Simulation time is controled by niter parame‐
112 ter. The default value is 1000, depending on complexity of terrain,
113 land cover and size of the area, several thousand iterations may be
114 needed to reach the steady state. Output files can be saved during sim‐
115 ulation using outiter parameter defining simulation time step for writ‐
116 ing output files. This option requires time series flag -t. Files are
117 saved with suffix containing iteration number (e.g. name.500,
118 name.1000, etc.).
119
122 v.surf.rst, r.slope.aspect, r.sim.water
123
125 Helena Mitasova, Lubos Mitas
126 North Carolina State University
127 hmitaso@unity.ncsu.edu
128 Jaroslav Hofierka
129 GeoModel, s.r.o. Bratislava, Slovakia
130 hofierka@geomodel.sk
131 Chris Thaxton
132 North Carolina State University
133 csthaxto@unity.ncsu.edu
134 csthaxto@unity.ncsu.edu
135
137 Mitasova, H., Thaxton, C., Hofierka, J., McLaughlin, R., Moore, A.,
138 Mitas L., 2004, Path sampling method for modeling overland water flow,
139 sediment transport and short term terrain evolution in Open Source GIS.
140 In: C.T. Miller, M.W. Farthing, V.G. Gray, G.F. Pinder eds., Computa‐
141 tional Methods in Water Resources, Elsevier.
142 Mitas, L., and Mitasova, H., 1998, Distributed soil erosion simulation
144 for effective erosion prevention. Water Resources Research, 34(3),
145 505-516.
146 Neteler, M. and Mitasova, H., 2004, Open Source GIS: A GRASS GIS
148 Approach, Second Edition, Kluwer International Series in Engineering
149 and Computer Science, 773, Kluwer Academic Press / Springer, Boston,
150 Dordrecht, 424 pages.
151 Last changed: $Date: 2006/11/18 09:58:59 $
153 Full index
155GRASS 6.2.2 r.sim.sediment(1)