I am fiddling with the GRASS plugin in QGIS to produce watersheds and drainage basins as well as being able to identify all the basins and watersheds leading to one point (depending where i chose to question the information).
Through researches, I found someone who created something similar to what he would get in arcHYDRO with QGIS and following his steps, I'm brought to use the GRASS function r.stream.extract, but the resulting layers are definitely way too dense for my purpose. Since this process took quite a long time, in order to avoid re-doing it I am looking for clarifications regarding the algorithm's settings and which to raise to make the result a bit less dense.
I have left all the settings by default in my first attempt. I will of course continue my researches to try and clarify this.
My suspicions are the "Minimum flow accumulation for streams" and "Delete stream segments shorter than cells" parts that could be played with, but i don't know the scale of impact which numbers would have.
P.S. Cell size is 10m/pixel