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NAME - Computes evapotranspiration calculation modified or original Hargreaves formulation, 2001.


imagery, evapotranspiration

SYNOPSIS --help [-zhs] netradiation_diurnal=name average_temperature=name minimum_temperature=name maximum_temperature=name [precipitation=name] output=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]


Set negative ETa to zero

Use original Hargreaves (1985)

Use Hargreaves-Samani (1985)

Allow output files to overwrite existing files

Print usage summary

Verbose module output

Quiet module output

Force launching GUI dialog


Name of input diurnal net radiation raster map [W/m2/d]

Name of input average air temperature raster map [C]

Name of input minimum air temperature raster map [C]

Name of input maximum air temperature raster map [C]

Name of precipitation raster map [mm/month]
Disabled for original Hargreaves (1985)

Name for output raster map [mm/d]

DESCRIPTION calculates the reference evapotranspiration (ET) after Hargreaves et al. (1985), Hargreaves and Samani (1985) and the Modified Hargreaves version found in Droogers and Allen (2002).

SEE ALSO,, i.evapo.time, r.sun


  • Hargreaves GL, Hargreaves GH, Riley JP, 1985. Agricultural benefits for Senegal River Basin. Journal of Irrigation and Drainange Engineering, ASCE, 111(2):113-124.
  • Droogers P, Allen RG, 2002. Towards a simplified global reference evapotranspiration equation. Irrigation Science.
  • Droogers, P., Allen RG. 2002. Estimating reference evapotranspiration under inaccurate data conditions. Irrigation and Drainage Systems 16: 33-45.
  • Hargreaves GH, Samani ZA, 1985. Reference crop evapotranspiration from ambient air temperature. American Society of Agricultural Engineers (Microfiche collection)(USA). no. fiche no. 85-2517.


Yann Chemin, GRASS Development team, 2007-2016


Available at: source code (history)

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GRASS 7.8.5