Algorithm for catchment delineation with equal size basins

Question

I am looking to delineate catchment areas of roughly equal size at specified outlet points along a channel. I need something that adds preference to capturing the floodplain on either side of the channel in each point (ideally), rather than the current result with wbt_watershed, which has some catchment areas confined to the channel and others with much larger drainage areas (see screenshot).

In exploring existing tools, I can't find any that take in predefined outlet points and add preference in delineation to equal size catchments, so I am looking for recommendations there. I know of the whitebox tools which has the watershed function (current result), and the isobasins tool, though this one does not accept outlet points.

I also know of the plugin for polystrips that is used to define regular polygons along a line, though I am looking for something that creates polygons informed by the drainage accumulation rather than simple geometric bounds. (Generating equal sized polygons along line with PyQGIS)

wbt_watershed (as implemented in R) https://www.whiteboxgeo.com/manual/wbt_book/available_tools/hydrological_analysis.html#Watershed

Answer 1

1. A very good toolbox is the PCraster , but in order to be able to run it you need to have newer QGIS editions , check this video out https://www.youtube.com/watch?v=C3AMh3sZzJQ&t=14s. In PCraster you can compute basins for multiple points defined by their coordinates in a txt file (in this video you can see how).

2. A more simple way to compute a basin at a specific point of your interest, but cannot be "automated" for many points , is the upslope area tool from SAGA toolbox.