[Qgis-user] Correcting river flow

[Nicolas Cadieux]

Hi,

I have a difficult problem.  I have a very large river network file made 
with a 2D shapefile.  (I have the SRTMs for the same region).  I would 
like to model a river network but I need to keep in mind the river flow 
direction.  Unfortunately, I think this file was manually digitized and 
therefore, line directions have no relationship with river flow direction.

Can anyone suggest a way to use my SRTMs to change the line directions 
or to add a flow direction variable without resorting to manually 
editing the layer?

Thanks,

Nicolas