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<div class="moz-cite-prefix">On 11/5/2020 1:08 PM, <a class="moz-txt-link-abbreviated" href="mailto:Iain@jcis.net.au">Iain@jcis.net.au</a>
wrote:<br>
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<p class="MsoNormal">I am working my way through QGIS for
Hydrological Applications Recipes for Catchment Hydrology and
Water Management.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have been shown how to create Strahler
order stream classification on Raster data. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have access to a vector dataset of
streams – is there something in QGIS that will do Strahler
orders for vector data. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Yes I have tried to search and rally only
came up with some useless Stack exchange threads plus
reference to v.stream.order which is something in Grass and I
am not sure whether it would work.</p>
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<p>AFAIK, v.stream.order requires a stream network that is:</p>
<ol>
<li> topologically correct = each segment has a node where it
intersects the next segment.</li>
<li>the line segment directions are all downstream.</li>
</ol>
<p>If those two conditions are OK, it should work</p>
<p><br>
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cite="mid:001801d6b363$fe4fdfb0$faef9f10$@jcis.net.au">
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<p class="MsoNormal"><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Any advice would be helpful – I have
assigned Strahler orders manually and it is a bit time
consuming.<o:p></o:p></p>
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<p><br>
</p>
<p>My advice: get a suitable DEM and run the GRASS modules <tt>r.watershed</tt>
and<tt> r.stream.order <br>
</tt></p>
<p>These work well, and insure a properly connected stream network
with stream order built in.</p>
<p><tt><br>
</tt></p>
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cite="mid:001801d6b363$fe4fdfb0$faef9f10$@jcis.net.au">
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Cheers<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><b><span
style="font-size:12.0pt;font-family:Papyrus;mso-fareast-language:EN-AU">Dr
Iain Stuart<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><i><span
style="font-size:12.0pt;font-family:Papyrus;mso-fareast-language:EN-AU">JCIS
Consultants <o:p></o:p></span></i></b></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-AU">P.O.
Box 2397<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-AU">Burwood
North<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-AU">NSW,
2134<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-AU"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-AU">(02)
9701 0191<br>
(0413) 380116 (m)<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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