I'm delineating some coastal subbasins using open source software. I have asked a similar question before (Delineating coastal subbasins using SAGA GIS or GRASS in QGIS?). I found that using SAGA Fill Sinks (Wang & Liu) in QGIS creates watersheds according to what I expect. the problem is I don't find any documentation about how this tool creates the watersheds.
I looked for in the tool documentation (Module Fill Sinks (Wang & Liu)), but it doesn't say how the tool works. Most of the tools used in SAGA, GRASS and other softwares create watersheds based on a previously created channel network, but here the only input is a DEM.
Does anyone know how this tool create watersheds?