[GRASS-user] Stream Ordering and Stream Extraction from a DEM

stephen sefick ssefick at gmail.com
Sat Jul 18 09:28:50 EDT 2009

I know I have been asking a lot of questions in this area, but I am
close to making progress.  How are stream network vector coverages
produced?  I imagine that they are vectorized flow accumulation
modeling from the DEM with some sort of threshold, and then converted
fro a raster to a vector.  This is the approach that I am going to
take, I think.  After extracting all of the great things from
r.watershed and r.terraflow.  I will then multiply this raster layer
by the m/day areal runoff for the HUC of the area of interest and * by
100 (1/3 arc second DEM resolution).  Then convert this measure to cfs
and use a 1cfs cutoff to delineate streams.  I would then like to
order them.  I am having a very hard time with v.strahler.  The output
is in a text file and I can not figure out how to get this "attached"
to the new vector layer produced.  It also returns many zeros, which
don't make any sense in the strahler sense.  I am working on a project
that requires these orders to decide on stratified sampling based on
the amount present over a given area.  There have been some
suggestions, but my begining knowledge is not enough to apply them.
Is there a tutorial, book, or other such thing to bring me up to
speed.  I have Markus Neteler and Helena Mitasova, 2008, Open Source
GIS: A GRASS GIS Approach waiting for me in the library when I get
back to Auburn on monday.  Thanks very much for all of your help.

Stephen Sefick
Stephen Sefick

Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods.  We are mammals, and have not exhausted the
annoying little problems of being mammals.

								-K. Mullis

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