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
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@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@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
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@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@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@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
Tague Team Lab Manager
1005 Bren Hall
UCSB, Santa Barbara, CA.
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,
JanetOn Wed, Mar 2, 2016 at 11:22 AM, Will Fields <will.openfields@gmail.com
<mailto:will.openfields@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@gmail.com
<mailto:jsc.eco@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@lists.osgeo.org <mailto:grass-user@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@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@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
HI Janet,
can you specify what you mean by ‘fully connected stream network’? ‘connected’ doesnt mean much on a raster map or did you convert it a vector?
I would try to build your stream network from the accumulation raster map by thresholding it with a certain catchment size (in cells). Eg.
r.mapcalc exp=‘streams=if(accumulation>1000, 1, null())’
That way you see what is happening in the accumulation map as a result of the DEM.
Best,
Michel
···
On 03/02/2016 08:42 PM, 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,
JanetOn Wed, Mar 2, 2016 at 11:22 AM, Will Fields <will.openfields@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@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@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@lists.osgeo.org](mailto:grass-user@lists.osgeo.org) [http://lists.osgeo.org/mailman/listinfo/grass-user](http://lists.osgeo.org/mailman/listinfo/grass-user)
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@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,
StefanOn 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,
JanetOn Wed, Mar 2, 2016 at 11:22 AM, Will Fields <will.openfields@gmail.com
mailto:[will.openfields@gmail.com](mailto:will.openfields@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@gmail.com
mailto:[jsc.eco@gmail.com](mailto:jsc.eco@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@lists.osgeo.org mailto:[grass-user@lists.osgeo.org](mailto:grass-user@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@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user–
Stefan LüdtkeSection 5.4- Hydrology
Tel.: +49 331 288 2821
Fax: +49 331 288 1570
Email: sluedtke@gfz-potsdam.deHelmholtz-Zentrum Potsdam
Deutsches GeoForschungsZentrum GFZ
(GFZ German Research Centre for Geoscience)
Stiftung des öff. Rechts Land Brandenburg
Telegrafenberg, 14473 PotsdamPGP Public Key: http://bit.ly/13d9Sca
–
Tague Team Lab Manager
1005 Bren Hall
UCSB, Santa Barbara, CA.
Michel,
thank you - i’ll try your r.mapcalc and vector suggestions.
Janet
···
On Thu, Mar 3, 2016 at 8:22 AM, Michel Wortmann <wortmann@pik-potsdam.de> wrote:
HI Janet,
can you specify what you mean by ‘fully connected stream network’? ‘connected’ doesnt mean much on a raster map or did you convert it a vector?
I would try to build your stream network from the accumulation raster map by thresholding it with a certain catchment size (in cells). Eg.
r.mapcalc exp=‘streams=if(accumulation>1000, 1, null())’
That way you see what is happening in the accumulation map as a result of the DEM.
Best,
MichelOn 03/02/2016 08:42 PM, 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_______________________________________________ grass-user mailing list [grass-user@lists.osgeo.org](mailto:grass-user@lists.osgeo.org) [http://lists.osgeo.org/mailman/listinfo/grass-user](http://lists.osgeo.org/mailman/listinfo/grass-user)
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
–
On Wed, Mar 2, 2016 at 11:22 AM, Will Fields <will.openfields@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
–
Tague Team Lab Manager
1005 Bren Hall
UCSB, Santa Barbara, CA.
On Wed, Mar 2, 2016 at 11:40 AM, Janet Choate <jsc.eco@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@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
Tague Team Lab Manager
1005 Bren Hall
UCSB, Santa Barbara, CA.
On Wed, Mar 2, 2016 at 8:42 PM, Janet Choate <jsc.eco@gmail.com> 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.
Please note that r.watershed does not require filled depressions. If
you want a properly connected stream network in vector format, use
r.stream.extract.
thanks,
JanetOn Wed, Mar 2, 2016 at 11:22 AM, Will Fields <will.openfields@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@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@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@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user