This is a simplified set of tools for deriving a river network from digital elevation data.
The package relies on GRASS GIS (v7.8, 7.6, or 7.4) to do the heavy lifting, thus an installation of GRASS GIS and the rgrass7 package is required for watershed to function.
Note that this is meant to be a simplified workflow for watershed delineation using only R code; for more options users can use rgrass7 to access GRASS GIS functions directly.
Before installing this package, you should install GRASS GIS. The latest tested version is 7.8; versions 7.6 and 7.4 also work, earlier or later versions are unknown (but please send us feedback if you try this!).
Windows: The preferred distribution is the OSGeo4W distribution; watershed should be able to auto-detect your grass installation if you install this version.
Mac: watershed can auto-detect grass binary installations (which are usually installed in /Applications/). Command-line installations may also work; try following the linux instructions.
Linux/Unix: Install grass however you like. For auto-detection to work, make sure the grass binary (grass74, grass76, grass78) is in your $PATH and visible from within R; try, e.g., system2('grass76', args = c("--config", "path")) to see if this is working, it should output the location of your grass installation. If you want a different version of grass, you can alias grass78 to whatever binary you like, or see *Changing the default grass below.
The watershed package can be easily installed using the remotes package within R as follows:
remotes::install_github("flee-group/watershed", dependencies = TRUE)
If auto-detection fails, or if you want to use a grass version other than the default, you can do so easily:
options(gisBase = "/path/to/grass_directory")
For example, if the grass executable is located at /usr/local/bin/grass/grass79/grass79, then you would use /usr/local/bin/grass/grass79 as the gisBase.
We recommend following the first two steps in the vignette to see if the package is working.
Please contact us, or raise an issue on github if you encounter any problems!