The r.basin command line needs the geographic coordinates of the basin outlet, and these should be derived from r.stream.extract. When I look at the stream output from r.stream.extract (both vector and raster) with the HUC-12 vector boundary I see what appear to be four different outlets of the basin (see attached chicken_creek.pdf). I refer to them as north, west, south, and southeast.
Do I take this to mean that there are four basins identified by r.stream.extract to be described by r.basin? For my current projects, the HUC-12 subbasins are the appropriate analytical units; finer resolution will add confusion rather than clarity because this is all in a regulatory context. My last question, then, is how do I pick an outlet point so r.basin describes the area within the vector boundary in the attached figure as a single basin? The streams seem to cross the HUC-12 basin boundary at each of these potential basin outlet points. How should I interpret these results? On one project I have 12 subbasins like this one; the other project has 4 subbasins. Rich
chicken_creek.pdf
Description: Adobe PDF document
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