NAME

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

KEYWORDS

       raster, sediment flow, erosion, deposition

SYNOPSIS

       r.sim.sediment
       r.sim.sediment help
       r.sim.sediment  elevin=name   wdepth=name   dxin=name   dyin=name   detin=name   tranin=name   tauin=name
       [manin=name]     [maninval=float]    [tc=name]    [et=name]    [conc=name]    [flux=name]    [erdep=name]
       [nwalk=integer]    [niter=integer]    [outiter=integer]    [diffc=float]     [--overwrite]    [--verbose]
       [--quiet]

   Flags:
       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       elevin=name
           Name of the elevation raster map [m]

       wdepth=name
           Name of the water depth raster map [m]

       dxin=name
           Name of the x-derivatives raster map [m/m]

       dyin=name
           Name of the y-derivatives raster map [m/m]

       detin=name
           Name of the detachment capacity coefficient raster map [s/m]

       tranin=name
           Name of the transport capacity coefficient raster map [s]

       tauin=name
           Name of the critical shear stress raster map [Pa]

       manin=name
           Name of the Mannings n raster map

       maninval=float
           Name of the Mannings n value
           Default: 0.1

       tc=name
           Output transport capacity raster map [kg/ms]

       et=name
           Output transp.limited erosion-deposition raster map [kg/m2s]

       conc=name
           Output sediment concentration raster map [particle/m3]

       flux=name
           Output sediment flux raster map [kg/ms]

       erdep=name
           Output erosion-deposition raster map [kg/m2s]

       nwalk=integer
           Number of walkers

       niter=integer
           Time used for iterations [minutes]
           Default: 10

       outiter=integer
           Time interval for creating output maps [minutes]
           Default: 2

       diffc=float
           Water diffusion constant
           Default: 0.8

DESCRIPTION

       r.sim.sediment  is a landscape scale, simulation model of soil erosion, sediment transport and deposition
       caused by flowing water designed  for  spatially  variable  terrain,  soil,  cover  and  rainfall  excess
       conditions.  The soil erosion model is based on the theory used in the USDA WEPP hillslope erosion model,
       but it has been generalized to 2D flow. The solution is based on the concept of  duality  between  fields
       and particles and the underlying equations are solved by Green's function Monte  Carlo method, to provide
       robustness necessary for spatially variable conditions and high resolutions (Mitas  and  Mitasova  1998).
       Key  inputs of the model include the following raster maps: elevation (  elevin [m]), flow gradient given
       by the first-order partial derivatives of elevation field ( dxin and dyin), overland flow water  depth  (
       wdepth  [m]), detachment capacity coefficient (detin [s/m]), transport capacity coefficient (tranin [s]),
       critical shear stress (tauin [Pa]) and surface  roughness coefficient called Manning's  n  (manin  raster
       map).   Partial  derivatives  can  be  computed  by  v.surf.rst  or  r.slope.aspect  module. The data are
       automatically converted from  feet  to  metric  system  using  database/projection  information,  so  the
       elevation  always  should  be  in meters.  The water depth file can be computed using r.sim.water module.
       Other parameters must be determined using field  measurements  or  reference  literature  (see  suggested
       values in Notes and References).

       Output   includes   transport   capacity   raster   map   tc   in  [kg/ms],  transport  capacity  limited
       erosion/deposition raster map et [kg/m2s]i that are output almost immediately and can be viewed while the
       simulation  continues.  Sediment flow rate raster map flux [kg/ms], and net erosion/deposition raster map
       [kg/m2s] can take longer time depending on time step and simulation time.  Simulation time  is  controled
       by   niter  [minutes]  parameter.   If  the  resulting  erosion/deposition map is noisy, higher number of
       walkers, given by nwalk should be used.

NOTES

SEE ALSO

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

AUTHORS

       Helena Mitasova, Lubos Mitas
       North Carolina State University
       hmitaso@unity.ncsu.edu
       Jaroslav Hofierka
       GeoModel, s.r.o. Bratislava, Slovakia
       hofierka@geomodel.sk
       Chris Thaxton
       North Carolina State University
       csthaxto@unity.ncsu.edu
       csthaxto@unity.ncsu.edu

REFERENCES

       Mitasova, H., Thaxton, C., Hofierka, J., McLaughlin, R., Moore, A., Mitas L., 2004, Path sampling  method
       for modeling overland water flow, sediment transport and short term terrain evolution in Open Source GIS.
       In: C.T. Miller, M.W. Farthing, V.G. Gray, G.F.  Pinder  eds.,  Proceedings  of  the  XVth  International
       Conference  on Computational Methods in Water Resources (CMWR XV), June 13-17 2004, Chapel Hill, NC, USA,
       Elsevier, pp. 1479-1490.

       Mitasova H, Mitas, L., 2000, Modeling  spatial  processes  in  multiscale  framework:  exploring  duality
       between particles and fields, plenary talk at GIScience2000 conference, Savannah, GA.

       Mitas,  L., and Mitasova, H., 1998, Distributed soil erosion simulation for effective erosion prevention.
       Water Resources Research, 34(3), 505-516.

       Mitasova, H., Mitas, L., 2001, Multiscale soil erosion simulations for land use management, In: Landscape
       erosion  and  landscape evolution modeling, Harmon R. and Doe W. eds., Kluwer Academic/Plenum Publishers,
       pp. 321-347.

       Neteler, M. and Mitasova, H.,  2008,  Open  Source  GIS:  A  GRASS  GIS  Approach.  Third  Edition.   The
       International Series in Engineering and Computer Science: Volume 773. Springer New York Inc, p. 406.

       Last changed: $Date: 2008-02-22 21:58:58 -0800 (Fri, 22 Feb 2008) $

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