## NAME

r.topmodel - Simulates TOPMODEL which is a physically based hydrologic model.

## KEYWORDS

raster, hydrology, model

## SYNOPSIS

r.topmodel
r.topmodel --help
r.topmodel [-p] parameters=name topidxstats=name input=name output=name [timestep=integer] [topidxclass=integer] [topidx=name] [ntopidxclasses=integer] [outtopidxstats=name] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

### Flags:

-p
  Preprocess only and stop after generating outtopidxstats
--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:

parameters=name [required]
  Name of input TOPMODEL parameters file
topidxstats=name [required]
  Name of input topographic index statistics file
input=name [required]
  Name of input rainfall and potential evapotranspiration data file
output=name [required]
  Name for output file
timestep=integer
  Time step
  Generate output for this time step
topidxclass=integer
  Topographic index class
  Generate output for this topographic index class
topidx=name
  Name of input topographic index raster map
  Must be clipped to the catchment boundary. Used for generating outtopidxstats
ntopidxclasses=integer
  Number of topographic index classes
  Used for generating outtopidxstats
  Default: 30
outtopidxstats=name
  Name for output topographic index statistics file
  Requires topidx and ntopidxclasses

## DESCRIPTION

r.topmodel simulates TOPMODEL which is a physically based hydrologic model.

### Parameters description

parameters
  This file contains TOPMODEL parameters that describe the study area. Any lines starting with a # sign or empty lines are ignored.

      # Subcatchment name
      Subcatchment 1

      ################################################################################
      # A [m^2]: Total subcatchment area
      3.31697E+07

      ################################################################################
      # qs0 [m/h]: Initial subsurface flow per unit area
      #		"The first streamflow input is assumed to represent
      #		 only the subsurface flow contribution in the watershed."
      #								- Liaw (1988)
      0.000075

      # lnTe [ln(m^2/h)]: Areal average of the soil surface transmissivity
      4.

      # m [m]: Parameter controlling the decline rate of transmissivity
      # See Beven and Kirkby (1979)
      0.0125

      # Sr0 [m]: Initial root zone storage deficit
      0.0025

      # Srmax [m]: Maximum root zone storage deficit
      0.041

      # td [h]: Unsaturated zone time delay per unit storage deficit if greater than 0
      #  OR
      # -alpha: Effective vertical hydraulic gradient if not greater than 0.
      #
      # For example, -10 means alpha=10.
      60.

      # vch [m/h]: Main channel routing velocity
      20000.

      # vr [m/h]: Internal subcatchment routing velocity
      10000.

      ################################################################################
      # infex: Calculate infiltration excess if not zero (integer)
      0

      # K0 [m/h]: Surface hydraulic conductivity
      2.

      # psi [m]: Wetting front suction
      0.1

      # dtheta: Water content change across the wetting front
      0.1

      ################################################################################
      # d [m]: Distance from the catchment outlet
      #		The first value should be the mainstream distance from
      #		the subcatchment outlet to the catchment outlet.
      # Ad_r:  Cumulative area ratio of subcatchment (0.0 to 1.0)
      #		The first and last values should be 0 and 1, respectively.

      #   d  Ad_r
          0   0.0
       1000   0.2
       2000   0.4
       3000   0.6
       4000   0.8
       5000   1.0

input
  This file contains observed weather data.

      # dt [h]: Time step
      24

      ################################################################################
      # R [m/dt]:  Rainfall
      # Ep [m/dt]: Potential evapotranspiration

      # R             Ep
      0.000033        0.000000
      0.000053        0.011938
      0.004821        0.000000
      .
      .
      .

timestep
  If a time step is specified, output will be generated for the specific time step in addition to the summary and total flows at the outlet. This parameter can be combined with topidxclass to specify a time step and topographic index class at the same time. If no topidxclass is given, output will be generated for all the topographic index classes.
toptopidxclass
  If a topographic index class is specified, output will be generated for the given topographic index class. This parameter can be combined with timestep. If no timestep is given, output will be generated for all the time steps.
topidx, ntoptopidxclasses, outtoptopidxstats
  The topidx map can optionally be used for creating a new topographic index statistics file. This map has to be already clipped to the catchment boundary. The entire range of topographic index values will be divided into ntoptopidxclasses and the area ratio of each class will be reported in the outtoptopidxstats file. These three parameters can be omitted unless a new topidxstats file needs to be created.

## REFERENCES

- Beven, K. J., 1984. Infiltration into a class of vertically non-uniform soils. Hydrological Sciences Journal 29 (4), 425-434.
- Beven, K. J., Kirkby, M. J., 1979. A physically based, variable contributing area model of basin hydrology. Hydrological Sciences Bulletin 24 (1), 43-69.
- Beven K. J., R. Lamb, P. Quinn, R. Romanowicz, and J. Freer, 1995. TOPMODEL, in V.P. Singh (Ed.). Computer Models of Watershed Hydrology. Water Resources Publications.
- Cho, H., 2000. GIS Hydrological Modeling System by Using Programming Interface of GRASS. Master's Thesis, Department of Civil Engineering, Kyungpook National University, Korea.
- Liaw, S. C., 1988. Streamflow Simulation Using a Physically Based Hydrologic Model in Humid Forested Watersheds. Dissertation, Colorado State University, CO. p163.
- Morel-Seytoux, H. J., Khanji, J., 1974. Derivation of an equation of infiltration. Water Resources Research 10 (4), 795-800.

## SEE ALSO

r.fill.dir, r.mapcalc, r.topidx
How to run r.topmodel

## AUTHORS

Huidae Cho, Hydro Laboratory, Kyungpook National University, South Korea

Based on TMOD9502.FOR by Keith Beven.

## SOURCE CODE

Available at: r.topmodel source code (history)

Accessed: Tuesday Jun 16 04:04:58 2026

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