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NAME

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

KEYWORDS

       raster, hydrology, soil, sediment flow, erosion, deposition, model

SYNOPSIS

       r.sim.sediment
       r.sim.sediment --help
       r.sim.sediment   [-s]   elevation=name    water_depth=name    dx=name    dy=name    detachment_coeff=name
       transport_coeff=name     shear_stress=name      [man=name]      [man_value=float]      [observation=name]
       [transport_capacity=name]         [tlimit_erosion_deposition=name]          [sediment_concentration=name]
       [sediment_flux=name]         [erosion_deposition=name]        [logfile=name]        [walkers_output=name]
       [nwalkers=integer]       [niterations=integer]       [output_step=integer]        [diffusion_coeff=float]
       [random_seed=integer]   [nprocs=integer]   [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       -s
           Generate random seed
           Automatically  generates  random seed for random number generator (use when you don’t want to provide
           the seed option)

       --overwrite
           Allow output files to overwrite existing files

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:
       elevation=name [required]
           Name of input elevation raster map

       water_depth=name [required]
           Name of water depth raster map [m]

       dx=name [required]
           Name of x-derivatives raster map [m/m]

       dy=name [required]
           Name of y-derivatives raster map [m/m]

       detachment_coeff=name [required]
           Name of detachment capacity coefficient raster map [s/m]

       transport_coeff=name [required]
           Name of transport capacity coefficient raster map [s]

       shear_stress=name [required]
           Name of critical shear stress raster map [Pa]

       man=name
           Name of Manning’s n raster map

       man_value=float
           Manning’s n unique value
           Default: 0.1

       observation=name
           Name of sampling locations vector points map
           Or data source for direct OGR access

       transport_capacity=name
           Name for output transport capacity raster map [kg/ms]

       tlimit_erosion_deposition=name
           Name for output transport limited erosion-deposition raster map [kg/m2s]

       sediment_concentration=name
           Name for output sediment concentration raster map [particle/m3]

       sediment_flux=name
           Name for output sediment flux raster map [kg/ms]

       erosion_deposition=name
           Name for output erosion-deposition raster map [kg/m2s]

       logfile=name
           Name for sampling points output text file. For each observation  vector  point  the  time  series  of
           sediment transport is stored.

       walkers_output=name
           Base name of the output walkers vector points map

       nwalkers=integer
           Number of walkers

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

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

       diffusion_coeff=float
           Water diffusion constant
           Default: 0.8

       random_seed=integer
           Seed for random number generator
           The same seed can be used to obtain same results or random seed can be generated by other means.

       nprocs=integer
           Number of threads which will be used for parallel compute
           Default: 1

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 (elevation [m]), flow gradient given
       by the first-order partial derivatives of elevation field  (  dx  and  dy),  overland  flow  water  depth
       (water_depth   [m]),   detachment  capacity  coefficient  (detachment_coeff  [s/m]),  transport  capacity
       coefficient (transport_coeff [s]), critical shear  stress  (shear_stress  [Pa])  and  surface   roughness
       coefficient  called  Manning’s  n (man 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 transport_capacity  in [kg/ms], transport capacity limited
       erosion/deposition raster map tlimit_erosion_deposition [kg/m2s]i that are output almost immediately  and
       can  be  viewed  while the simulation continues. Sediment flow rate raster map sediment_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   controlled  by  niterations  [minutes]  parameter.   If  the  resulting
       erosion/deposition map is noisy, higher number of walkers, given by nwalkers should be used.

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.

SOURCE CODE

       Available at: r.sim.sediment source code (history)

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       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual