[GRASS-user] Hidrological network

GRASS GRASS user
1

André wrote:

I Have a vector layer with all the rivers, and
subsidiaries up to the smallest water lines.
However I need to simplify this layer in order that
it only shows the main rivers and first, second and
third order tributary water lines.

Any hints on how to achieve this?

try the v.strahler addon module:

http://grass.osgeo.org/wiki/GRASS_AddOns#v.strahler

Hamish

2

André wrote:

I Have a vector layer with all the rivers, and
subsidiaries up to the smallest water lines.
However I need to simplify this layer in order that
it only shows the main rivers and first, second and
third order tributary water lines.

Any hints on how to achieve this?

try the v.strahler addon module:

http://grass.osgeo.org/wiki/GRASS_AddOns#v.strahler

or try the very nice r.stream.*-suite

http://grass.osgeo.org/wiki/GRASS_AddOns#r.stream.angle and following

r.stream.angle
r.stream.basins
r.stream.del
r.stream.distance
r.stream.extract
r.stream.order
r.stream.pos
r.stream.stats

https://svn.osgeo.org/grass/grass-addons/grass6/raster/r.stream.order/description.html

strahler
    Name of Strahler's stream order output map: see notes for detail.
shreve
    Name of Shreve's stream magnitude output map: see notes for detail.
horton
    Name of Horton's stream order output map (require accum file): see notes
for detail.
hack
    Name of Hack's main streams output map : see notes for detail.
top
    Name of topological dimensions streams output map: see notes for detail.

HTH
Helmut

-----
best regards
Helmut
--
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3

On 01/30/2012 04:32 PM, Helmut Kudrnovsky wrote:

André wrote:

I Have a vector layer with all the rivers, and
subsidiaries up to the smallest water lines.
However I need to simplify this layer in order that
it only shows the main rivers and first, second and
third order tributary water lines.

Any hints on how to achieve this?

try the v.strahler addon module:

http://grass.osgeo.org/wiki/GRASS_AddOns#v.strahler

or try the very nice r.stream.*-suite

http://grass.osgeo.org/wiki/GRASS_AddOns#r.stream.angle and following

r.stream.angle
r.stream.basins
r.stream.del
r.stream.distance
r.stream.extract
r.stream.order
r.stream.pos
r.stream.stats

https://svn.osgeo.org/grass/grass-addons/grass6/raster/r.stream.order/description.html

strahler
     Name of Strahler's stream order output map: see notes for detail.
shreve
     Name of Shreve's stream magnitude output map: see notes for detail.
horton
     Name of Horton's stream order output map (require accum file): see notes
for detail.
hack
     Name of Hack's main streams output map : see notes for detail.
top
     Name of topological dimensions streams output map: see notes for detail.

HTH
Helmut

-----
best regards
Helmut
--
View this message in context: http://osgeo-org.1560.n6.nabble.com/Hidrological-network-tp4351331p4351980.html
Sent from the Grass - Users mailing list archive at Nabble.com.
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I do not think that r.stream* is useful here. As I understand you have vector network and you do not need to generate it. The only question is it is topological network, if so Hamish's suggestion to use v.strahler, looks well however this tool is very unstable. If it is not topological network i have no idea how to do that.

Also check attributes of that verctor. Such databases usually comes from national hydrological surveys and have complete attributes attached to it. So maybe your problem can by solved simply by vector query?

4

Thank you for your suggestions. It seems I will be having a hard time!!

@Jarek - The vector has a good topology (I tested the topology using the layer to run a simple nearest path analysis and it worked, so I assume it’s ok) I checked the attribute table and it has hundreds of objects and only two have name and type - the main rivers).

If I manage a solution other than manually build a new layer I’ll be sure to share it here.

@ Hamish - Is it possible to test tha tool through QGIS?

Thank you all

André

2012/1/30 Jarek Jasiewicz <jarek.jasiewicz@gmail.com>

On 01/30/2012 04:32 PM, Helmut Kudrnovsky wrote:

André wrote:

I Have a vector layer with all the rivers, and
subsidiaries up to the smallest water lines.
However I need to simplify this layer in order that
it only shows the main rivers and first, second and
third order tributary water lines.

Any hints on how to achieve this?

try the v.strahler addon module:

http://grass.osgeo.org/wiki/GRASS_AddOns#v.strahler

or try the very nice r.stream.*-suite

http://grass.osgeo.org/wiki/GRASS_AddOns#r.stream.angle and following

r.stream.angle
r.stream.basins
r.stream.del
r.stream.distance
r.stream.extract
r.stream.order
r.stream.pos
r.stream.stats

https://svn.osgeo.org/grass/grass-addons/grass6/raster/r.stream.order/description.html

strahler
Name of Strahler’s stream order output map: see notes for detail.
shreve
Name of Shreve’s stream magnitude output map: see notes for detail.
horton
Name of Horton’s stream order output map (require accum file): see notes
for detail.
hack
Name of Hack’s main streams output map : see notes for detail.
top
Name of topological dimensions streams output map: see notes for detail.

HTH
Helmut

best regards
Helmut

View this message in context: http://osgeo-org.1560.n6.nabble.com/Hidrological-network-tp4351331p4351980.html
Sent from the Grass - Users mailing list archive at Nabble.com.

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I do not think that r.stream* is useful here. As I understand you have vector network and you do not need to generate it. The only question is it is topological network, if so Hamish’s suggestion to use v.strahler, looks well however this tool is very unstable. If it is not topological network i have no idea how to do that.

Also check attributes of that verctor. Such databases usually comes from national hydrological surveys and have complete attributes attached to it. So maybe your problem can by solved simply by vector query?

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grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

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