<div class="gmail_extra">Hi Rich,<br><br><div class="gmail_quote">On Thu, Apr 26, 2012 at 5:40 PM, Rich Shepard <span dir="ltr"><<a href="mailto:rshepard@appl-ecosys.com" target="_blank">rshepard@appl-ecosys.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> The r.basin command line needs the geographic coordinates of the basin<br>
outlet, and these should be derived from r.stream.extract. When I look at<br>
the stream output from r.stream.extract (both vector and raster) with the<br>
HUC-12 vector boundary I see what appear to be four different outlets of the<br>
basin (see attached chicken_creek.pdf). I refer to them as north, west,<br>
south, and southeast.</blockquote><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Do I take this to mean that there are four basins identified by<br>
r.stream.extract to be described by r.basin? For my current projects, the<br>
HUC-12 subbasins are the appropriate analytical units; finer resolution will<br>
add confusion rather than clarity because this is all in a regulatory<br>
context. My last question, then, is how do I pick an outlet point so r.basin<br>
describes the area within the vector boundary in the attached figure as a<br>
single basin?<br>
<br>
The streams seem to cross the HUC-12 basin boundary at each of these<br>
potential basin outlet points. How should I interpret these results?<br>
<br>
On one project I have 12 subbasins like this one; the other project has 4<br>
subbasins.</blockquote><div><br></div><div>What you get by r.basin is the basin defined by the entire upslope area drained by the river system into the closing section (outlet) that you indicate by the coordinates in input. The vector layer that I can see in your attached file doesn't look like a basin but a portion of a sub-basin which doesn't include the sources (the points where actually the river begins). If you are trying to reproduce that, r.basin is not the appropriate tool. Technically, I think the correct term of what you are trying to delineate is inter-basin (but english native speakers can give me an insight), while r.basin only can delineate basins and sub-basins.</div>
<div><br></div><div>HTH,</div><div>madi</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="HOEnZb"><font color="#888888"><br>
<br>
Rich</font></span><br>_______________________________________________<br>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br>Ing. Margherita Di Leo, Ph.D.<br>
</div>