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NAME
i.evapo.pt - Computes evapotranspiration calculation Priestley and Taylor formulation, 1972.
KEYWORDS
imagery,
evapotranspiration
SYNOPSIS
i.evapo.pt
i.evapo.pt --help
i.evapo.pt [-z] net_radiation=name soil_heatflux=name air_temperature=name atmospheric_pressure=name priestley_taylor_coeff=float output=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags:
- -z
- Set negative ETa to zero
- --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:
- net_radiation=name [required]
- Name of input net radiation raster map [W/m2]
- soil_heatflux=name [required]
- Name of input soil heat flux raster map [W/m2]
- air_temperature=name [required]
- Name of input air temperature raster map [K]
- atmospheric_pressure=name [required]
- Name of input atmospheric pressure raster map [millibars]
- priestley_taylor_coeff=float [required]
- Priestley-Taylor coefficient
- Default: 1.26
- output=name [required]
- Name of output evapotranspiration raster map [mm/d]
i.evapo.pt Calculates the diurnal evapotranspiration after Prestley
and Taylor (1972). The Priestley-Taylor model (Priestley and Taylor, 1972)
is a modification of Penman's more theoretical equation.
RNETD optional output from
i.evapo.potrad is giving good results as input
for net radiation in this module.
Alpha values:
- 1.32 for estimates from vegetated areas as a result of the increase in
surface roughness (Morton, 1983; Brutsaert and Stricker, 1979)
- 1.26 is applicable in humid climates (De Bruin and Keijman, 1979;
Stewart and Rouse, 1976; Shuttleworth and Calder, 1979), and temperate
hardwood swamps (Munro, 1979)
- 1.74 has been recommended for estimating potential evapotranspiration
in more arid regions (ASCE, 1990). This worked well in Greece with University
of Thessaloniki.
Alpha values extracted from:
Watflood manual.
i.evapo.mh,
i.evapo.pm,
i.evapo.time,
i.eb.netrad,
r.sun
Yann Chemin, GRASS Development Team, 2007-08
SOURCE CODE
Available at:
i.evapo.pt source code
(history)
Latest change: Monday Nov 18 20:15:32 2019 in commit: 1a1d107e4f6e1b846f9841c2c6fabf015c5f720d
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© 2003-2023
GRASS Development Team,
GRASS GIS 7.8.9dev Reference Manual