I am working on a rockfall guide for QGIS and I'm currently stuck on one of the stages.
I currently at a point in the guide where I have two point layers one
"rockfall release point"-layer and
We are assuming that any rockfall will loosen from a release point, continue down the slope in the steepest direction, then begin to brake when it reaches a braking point, before stopping shortly thereafter.
I was first planning on calculating drainage area for each braking point using watersheds like in ArcGIS Pro, where you can add a
"pour point field", and then find which drainage field each release point is placed in (like in the figure above).
The only similar thing I can find in QGIS is
r.water.outlet where you have to type in one coordinate, do the calculation and start all over again - this is going to be hard considering I have 2.5m points.
A solution similar to the ArcGIS one would probably be the easiest. The other solution that I can come up with is doing a nearest neighbour analysis between the two layers, but then I also have to make sure that it only joins the point that is at the steepest slope.