How can I calculate flow length in QGiS/GRASS?

Question

I have these rasters:

1. DEM
2. Flow Direction
3. Flow Accumulation

I would like to calculate the flow distance of every pixel to the outlet of a basin.

In Arc-GIS, I can use the flow length. But I don't have access to a license right now. Any other open source way to do it?

Answer 1

The GRASS addon r.streams.distance is what you need. You add it to GRASS 7 using the g.extension module to install addons.

Answer 2

Use the SAGA tool for this. Look at this: http://www.saga-gis.org/saga_module_doc/2.1.3/ta_hydrology_6.html