[GRASS-user] Re: Hidrological network

[Jarek Jasiewicz]

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
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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?