i.evapo.mh(1grass)

💧 i.evapo.mh — the evapotranspiration girlies' manual page (that's i.evapo.mh(1grass) bestie, straight out of the GRASS User's Manual)

okay so. hi. welcome to the manual page for i.evapo.mh and let me tell you, she is serving hydrology. this is the one that does the evapotranspiration math, and she does it in three whole flavors, which is honestly iconic of her. grab a strawberry 🍓 and let's get into it.

---

✨ NAME ✨

i.evapo.mh — computes evapotranspiration calculation modified or original Hargreaves formulation, 2001.

like. she evaporates. she transpires. she computes. main character energy fr fr 💅

---

🌸 KEYWORDS 🌸

imagery, evapotranspiration

---

🦋 SYNOPSIS 🦋

i.evapo.mh
i.evapo.mh --help
i.evapo.mh [-zhs] netradiation_diurnal=name average_temperature=name
minimum_temperature=name maximum_temperature=name  [precipitation=name]
output=name  [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]

🎀 Flags 🎀

• -z — sets negative ETa to zero. no negativity allowed in this household 🙅‍♀️
• -h — use the original Hargreaves (1985). the vintage one. the classic.
• -s — use Hargreaves-Samani (1985). the collab era.
• --overwrite — lets output files overwrite files that already exist. yes, she will bulldoze. use with intention boo.
• --help — prints the usage summary. your girl when you're lost.
• --verbose — verbose module output. she will TELL you things.
• --quiet — quiet module output. she will not. 🤫
• --ui — forces the GUI dialog to launch. point and click era.

🍓 Parameters 🍓

• netradiation_diurnal=name — [required] name of input diurnal net radiation raster map [W/m2/d]. cannot skip her, she's mandatory.
• average_temperature=name — [required] name of input average air temperature raster map [C].
• minimum_temperature=name — [required] name of input minimum air temperature raster map [C].
• maximum_temperature=name — [required] name of input maximum air temperature raster map [C].
• precipitation=name — name of precipitation raster map [mm/month]. disabled for original Hargreaves (1985) — so if you're in original 1985 mode, she simply does not want it, don't bring it up.
• output=name — [required] name for output raster map [mm/d]. the whole point. the reveal. ✨

---

💖 DESCRIPTION 💖

i.evapo.mh 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).

three recipes, one module. she ate, genuinely. 🔥

---

📚 REFERENCES 📚

• 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.

the receipts. she cited her sources, unlike some people. 🫶

---

👀 SEE ALSO 👀

i.evapo.pt, i.evapo.pm, i.evapo.time, r.sun

the whole evapo squad + r.sun. they run together, iykyk. 💜

---

👑 AUTHOR 👑

Yann Chemin, GRASS Development team, 2007-2016

---

🧚 SOURCE CODE 🧚

Available at: i.evapo.mh source code (history)

Latest change: Friday Apr 17 01:04:26 2026 in commit: 32a143358df26b2e518b03c7e0d79541e8d1e5b1

Main index | Imagery index | Topics index | Keywords index | Graphical index | Full index

---

lowkey obsessed with the fact that this page lives in the GRASS 8.5.0 Reference Manual under copyright © 2003-2026 GRASS Development Team — yeah she's been on the scene since 2003 and she's still glowing 💖

and that's the whole page bestie. go water your crops, compute your ET, and remember: -z for no negativity, always. periodt. 💅✨🌈