[GRASS-user] Strahler order starting from vector data?

[Daniel Victoria]

I ran into this software (HydroFlow [1]) from Rio de Janeiro State
University that will give you river order (srahler or Shreve) based
only on a vector river network and a basin map. I tested it on a large
basin and it did work fine but, you must have a topologically correct
vector. Hope it helps

Daniel

[1] http://www.fgel.uerj.br/labgis/hydroflow/en/index_ingles.htm

On Tue, Jan 25, 2011 at 10:03 AM, Hamish <hamish_b at yahoo.com> wrote:
> Hi,
>
> I see v.strahler and r.stream.order in addons can assign
> Strahler Order to a river network, but how to run that if you
> are starting with an existing vector river network with no
> raster DEM? could you cross with a matching coastline vector to
> extract end nodes at the river mouths? will even a rough DEM
> like SRTM data be better than nothing in that case? how good
> does it have to be? would etopo1 be ok? (1 arc-minute ~ 2 km
> cells)
>
> also, how to get around attaching lake and swamp areas which
> split the river vector line in two? convert their boundaries to
> lines and treat it as a braided river? fill them in then r.thin
> them somehow? otherwise topology would be clean.
> how about if the river goes into a cave and out somewhere else? need to trace that gap by hand? (may be too big for the sloppy=
> option)
>
>
> thanks for any tips,
> Hamish
>
>
>
>
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