r.basins.fill(1)

💧 r.basins.fill — the GRASS GIS manual, but make it cute ✨

okay bestie, welcome to the GRASS GIS User's Manual page for r.basins.fill(1) 🫶 this one's all about carving out watershed subbasins and honestly? it's giving hydrology main character energy 🌊

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🌸 NAME 🌸

r.basins.fill — generates watershed subbasins raster map. that's it, that's the whole job 💅

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🏷️ KEYWORDS 🏷️

raster, hydrology, watershed 🌈

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✨ SYNOPSIS ✨

okay so here's how you actually call it:

r.basins.fill
r.basins.fill --help
r.basins.fill cnetwork=name tnetwork=name output=name number=integer
[--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]

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🎀 Flags 🎀

little toggle besties, no values needed:

• --overwrite — let your output files just bulldoze whatever's already sitting there. yes, fr fr, it overwrites existing files 💀
• --help — prints the usage summary. your lil "what does this do again" button 🙈
• --verbose — verbose module output. she's chatty, she tells you everything 👑
• --quiet — quiet module output. shhh, minimal talking only 🤫
• --ui — force launching GUI dialog. for when you want the pretty windows instead 🪟✨

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🧚 Parameters 🧚

these ones are the actual ingredients, and every single one is [required] — no skips, no substitutions:

• cnetwork=name [required] — name of input coded stream network raster map. this is the one where every channel segment got "coded" with its own unique category value 🏷️
• tnetwork=name [required] — name of input thinned ridge network raster map. the ridges, bestie, we need the ridges ⛰️
• output=name [required] — name for output raster map. name your baby 💖
• number=integer [required] — number of passes through the dataset. how many laps are we doing 🔁

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💖 DESCRIPTION 💖

okay so r.basins.fill generates a raster map layer depicting subbasins, and it does this based on input raster map layers for:

1. the coded stream network (where each channel segment has been "coded" with a unique category value), and
2. the ridges within a given watershed 🏔️

the raster map layer depicting ridges should include the ridge which defines the perimeter of the watershed. don't forget the perimeter ridge, she matters 🫶

the coded stream network can be generated as part of the r.watershed program — slay, automated ✨ but the map layer of ridges will need to be created by hand (for example, through digitizing done in wxGUI vector digitizer). yes bestie, by hand. manual labour. we love a craft project 🎨

the resulting output raster map layer will code the subbasins with category values matching those of the channel segments passing through them 👑 matchy matchy, iconic.

a user-supplied number of passes through the data is made in an attempt to fill in these subbasins. and here's the tea: if the resulting map layer from this program appears to have holes within a subbasin, the program should be rerun with a higher number of passes 🔁🔁🔁 more laps, fewer holes, periodt.

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📝 NOTES 📝

⚠️ the current geographic region setting is ignored. instead, the geographic region for the entire input stream's map layer is used. so don't come crying to her about your region settings, she's not looking at them 🙈

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👀 SEE ALSO 👀

• See Appendix A of the GRASS Tutorial: r.watershed for further details on the combined use of r.basins.fill and r.watershed 📚
• r.water.outlet
• r.watershed
• wxGUI vector digitizer

iykyk, the whole watershed squad 🫶

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💅 AUTHORS 💅

• Dale White, Dept. of Geography, Pennsylvania State University
• Larry Band, Dept. of Geography, University of Toronto, Canada

legends, honestly. ate and left no crumbs 🎀

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🔥 SOURCE CODE 🔥

Available at: r.basins.fill source code (history)

Accessed: Saturday Jan 17 05:40:43 2026

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© 2003-2025 GRASS Development Team, GRASS GIS 8.4.2 Reference Manual

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and that's the whole page bestie!! 🌈 this was GRASS 8.4.2, page r.basins.fill(1), and you absolutely slayed reading it 💖✨ go fill some subbasins, no cap 🦋