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


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


       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]

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

           Allow output files to overwrite existing files

           Print usage summary

           Verbose module output

           Quiet module output

           Force launching GUI dialog

       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]

           Name of Manning’s n raster map

           Manning’s n unique value
           Default: 0.1

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

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

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

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

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

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

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

           Base name of the output walkers vector points map

           Number of walkers

           Time used for iterations [minutes]
           Default: 10

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

           Water diffusion constant
           Default: 0.8

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

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


       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 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, r.slope.aspect, r.sim.water


       Helena Mitasova, Lubos Mitas
       North Carolina State University
       Jaroslav Hofierka
       GeoModel, s.r.o. Bratislava, Slovakia
       Chris Thaxton
       North Carolina State University


       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,

       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.


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

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