[GRASS-user] stream network

[Janet Choate]

Stefan,
unfortunately - it's not something that is apparent by appearance.
the problem was discovered after using the raster map as an input to
another program - then it became clear that there were places where there
were no upstream or downstream neighbors to some segments.
thanks,
Janet

On Thu, Mar 3, 2016 at 1:38 AM, Stefan Lüdtke <sluedtke at gfz-potsdam.de>
wrote:

> Hi Janet,
>
> can you provide a screenshot of the river network, I think that helps to
> understand what is going on in your specific case?!
>
> Cheers,
> Stefan
>
> On 02/03/16 20:42, Janet Choate wrote:
> > Hi Will,
> > When running r.watershed on a small 35 hectare watershed, it produces a
> > fully connected stream network. However, when running r.watershed on a
> > 6400 hectare watershed, the stream network is not fully connected.
> > No preprocessing with regards to merging different raster maps, however,
> > I did try using r.fill.dir first to deal with any possible depressions
> > that might be causing non-connected stream segments.
> > thanks,
> > Janet
> >
> > On Wed, Mar 2, 2016 at 11:22 AM, Will Fields <will.openfields at gmail.com
> > <mailto:will.openfields at gmail.com>> wrote:
> >
> >     Hi Janet,
> >
> >     Can you give some more information about what you mean by larger
> >     watershed basins?  Did you do any preprocessing of the elevation
> >     raster before you tried to extract the stream networks?  Were you
> >     using an elevation raster that had been merged from different
> >     rasters?  I've ran into issues in the past where "seams" along the
> >     original edges of a raster resulted in odd stream networks.
> >
> >     Will
> >
> >     On Wed, Mar 2, 2016 at 11:40 AM, Janet Choate <jsc.eco at gmail.com
> >     <mailto:jsc.eco at gmail.com>> wrote:
> >
> >         Hi GRASS community,
> >         When creating a stream network with r.watershed, I end up with
> >         some isolated stream segments - particularly in larger watershed
> >         basins. Does anyone know how to generate a stream network that
> >         is fully connected, or how to correct this issue?
> >         thank you,
> >         Janet
> >
> >
> >
> >         _______________________________________________
> >         grass-user mailing list
> >         grass-user at lists.osgeo.org <mailto:grass-user at lists.osgeo.org>
> >         http://lists.osgeo.org/mailman/listinfo/grass-user
> >
> >
> >
> >
> >
> > --
> > Tague Team Lab Manager
> > 1005 Bren Hall
> > UCSB, Santa Barbara, CA.
> >
> >
> > _______________________________________________
> > grass-user mailing list
> > grass-user at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/grass-user
> >
>
> --
> Stefan Lüdtke
>
> Section 5.4-  Hydrology
> Tel.: +49 331 288 2821
> Fax: +49 331 288 1570
> Email: sluedtke at gfz-potsdam.de
>
> Helmholtz-Zentrum Potsdam
> Deutsches GeoForschungsZentrum GFZ
> (GFZ German Research Centre for Geoscience)
> Stiftung des öff. Rechts Land Brandenburg
> Telegrafenberg, 14473 Potsdam
> -------------------
>
> PGP Public Key: http://bit.ly/13d9Sca
>
>


-- 
Tague Team Lab Manager
1005 Bren Hall
UCSB, Santa Barbara, CA.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20160303/5a6af715/attachment.html>