I am using the GrassGIS r.stream.extract extension to delineate a stream network with the options 'mexp' (Montgomery exponent) and 'd8cut' (Use SFD above this threshold). It works perfect so far and is a great improvement over r.watershed. My problem is that if I use r.stream.basins afterwards I cannot extract half basins (left and right site of a river) as it was possible in r.watershed. I wonder if there is a tool with whom I can do that? r.stream.extract delivers a flow direction map and the stream network.