Get upstream sections of a network

Question

Is there any extension to get all upstream sections of a polyline shapefile which represent an hydrographic network in QGIS?

It could work like this:

• you choose a specific branch and a direction
• then the algorithm will select all the sections recursively until you have all the branches.

Answer 1

You can use "Flow trace" plugin in QGIS. Take any river network, select a segment of river and press flow trace icon to get all upstream rivers selected.

Answer 2

I did this in QGiS using the GRASS tools.

1. It is merely convert line to point > upstream area (r.water.outlet) - > Convert to Polygon > Selection.
2. Use the netowrk vector tools to get upstream lines. The Grass implementation is (https://grasswiki.osgeo.org/wiki/Vector_extract_upstream_network)
3. USe the Stream Reach tool in QGIS.