[GRASS-user] Re: Hidrological network

[ALT SHN]

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 at 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<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<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<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<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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